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The response of terrestrial salamanders to forest harvesting in southwestern British Columbia Maxcy, Katherine Alexandra 2000

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THE RESPONSE OF TERRESTRIAL SALAMANDERS TO FOREST HARVESTING IN SOUTHWESTERN BRITISH COLUMBIA by KATHERINE ALEXANDRA MAXCY B.Sc, University of British Columbia, 1996  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  In THE FACULTY OF GRADUATE STUDIES Department of Forest Sciences Faculty of Forestry We accept this thesis as conforming To the required standard  THE UNIVERSITY OF BRITISH COLUMBIA November 2000 © Katherine Alexandra Maxcy 2000  In presenting  this thesis in partial fulfilment of the requirements for an advanced  degree at the University of British Columbia, I agree that the Library shall make it freely available for reference  and study. I further agree that permission for extensive  copying of this thesis for scholarly purposes may be granted by the head of my department  or by his or her representatives.  It is understood  that  copying or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department of ^ ^ g j -  0<Ai<f)(RjQ  The University of British Columbia Vancouver, Canada  DE-6  (2/88)  ABSTRACT  Forest harvesting reduces the abundance of terrestrial salamanders although the mechanism of the response is unknown. Maintaining riparian buffers around headwater streams has been suggested as one strategy to protect amphibians from the effects of forest harvesting. To understand better the proximate response of terrestrial salamanders to forest harvesting and to determine the efficacy of 30 m riparian buffers in mitigating these effects, I sampled amphibians with increasing distance from streams before and after harvesting. The three treatments were each replicated twice: control, 30 m buffer and clearcut. The relative abundance of aquatic-breeding salamanders (Ambystoma gracile and Taricha granulosa) changed little one year post-harvest in the buffer and clearcut treatments indicating harvesting did not immediately impact their numbers. The response of the terrestrial salamanders to forest harvesting was more variable. The relative abundance of Ensatina eschscholtzii decreased on the buffer and clearcut sites while the relative abundance of Plethodon vehiculum increased after harvesting. I suggest the changes in relative abundance by the terrestrial-breeding salamanders are due to changes in movement patterns which alter their capture rates rather than an actual increase or decrease in relative abundance for either salamander. Movement patterns provided ambiguous results for all four salamanders as to whether they were showing compensatory behaviour in response to harvesting. The movement distances and rates of the four species did not appear to be related to habitat type. The growth rates of Ambystoma gracile, Ensatina eschscholtzii, and Plethodon vehiculum recaptured in clearcuts were lower than those individuals recaptured in forested habitat, indicating there was some cost associated with being in clearcut habitat. Thirty-meter riparian buffers appear to be effective in mitigating the effects of forest harvesting for three of the four salamanders captured. The proportion of captures within 30 m increased in the buffer after harvesting for Ambystoma gracile, Taricha granulosa, and Plethodon vehiculum. Buffer strips may be even more critical to juvenile survival since over 80% of juvenile Ambystoma gracile were captured within 30 m of the stream in the buffer treatment and only 40% in the control and clearcut treatments respectively. Additionally, the proportion of aquatic-breeding salamanders moving parallel to the stream increased postharvest in the buffer treatments indicating the riparian buffer may be used as a corridor for movement during their breeding migrations. Overall, all species were present on treated sites after harvesting indicating direct mortality from the physical process of logging itself was limited. Shifts in distribution and increased parallel movement for the aquatic-breeding salamanders in the buffer treatments indicate these buffers are acting as corridors for movement.  ii  T A B L E OF  CONTENTS  ABSTRACT  II  LIST OF T A B L E S  IV  LIST OF FIGURES  V  A C K N O W L E D G E M E N T S  VII  INTRODUCTION  1  METHODS  5  S T U D Y SITE  5  TRAPPING METHODS  6  TRAPPING SCHEDULE  7  M A R K I N G TECHNIQUES  8  DATA ANALYSES  8  RESULTS  15  SPECIES COMPOSITION A N D R E L A T I V E A B U N D A N C E  15  EFFECTS OF RIPARIAN HARVESTING O N TERRESTRIAL S A L A M A N D E R S  16  E F F I C A C Y O F R I P A R I A N B U F F E R STRIPS  20  DISCUSSION  23  EFFECTS OF RIPARIAN HARVESTING O N TERRESTRIAL S A L A M A N D E R S  24  E F F I C A C Y O F R I P A R I A N B U F F E R STRIPS  34  M A N A G E M E N T IMPLICATIONS  39  LITERATURE CITED A P P E N D I X 1.  M E A N P E R C E N T G R O U N D C O V E R (± S E ) O F U N D E R S T O R Y  67 VEGETATION BY  SITE B E F O R E H A R V E S T I N G A P P E N D I X 2.  H A R V E S T I N G S C H E D U L E F O R E A C H S T U D Y SITE. N O T E C O N T R O L  75 SITES  HAVE NO HARVESTING  76  A P P E N D I X 3. T O T A L A N D R E L A T I V E N U M B E R O F E A C H S P E C I E S C A P T U R E D I N A . P I T F A L L T R A P A R R A Y S A N D B. C O V E R B O A R D S B E F O R E A N D A F T E R H A R V E S T I N G A T E A C H SITE (INCLUDES  RECAPTURES)  A P P E N D I X 4.  S U M M A R Y OF TAILED-FROG RESULTS  77 81  iii  LIST OF TABLES Table 1. General description of site characteristics before harvesting  42  Table 2. Trapping schedule including total number of nights the traps were open for each session  43  Table 3. Percentage of days that temperature was recorded above 20°C and 35°C before and after harvesting during July and August of 1998 (before harvesting) and 1999 (after harvesting) 44 Table 4. The number of soil samples collected before and after harvesting at each site. 45 Table 5. The total number of amphibians captured at all sites combined by species and the number of sites where each species was present (includes recaptures) 46 Table 6. Repeated measures analysis of variance on numbers captured/100TN showing the between-subject effects of treatment and within-subjects effects of time and time*treatment on each species by different trap type 47 Table 7. Repeated measures analysis of variance on numbers captured per 100TN within 30 m of the stream showing the between-subject effects of treatment and withinsubjects effects of time and time*treatment on each species 48 Table 8. Repeated measures analysis of variance on the proportion of captures moving parallel to the stream showing the between-subject effects of treatment and withinsubjects effects of time and time*treatment on each species 49 Table 9. Summary of results for each species demonstrating consistent trends in response to forest harvesting  50  iv  LIST OF FIGURES Figure 1. Map of relative site locations  51  Figure 2. Arrangement of trapping grids designed to determine terrestrial amphibian abundance, patterns of movement and spatial distribution relative to the stream 52 Figure 3. Arrangement at S C K (30 m buffer site) trapping grid after harvesting including additional traps added  53  Figure 4. Arrangement of site B (clearcut) trapping grid after harvesting including additional traps added  54  Figure 5. Mean number of salamanders captured per 100 trap nights (± SE) before and after harvesting in control, 30 m buffer and clearcut sites (N=2) 55 Figure 6. A. Mean movement distance (m ± SE) and B. rate (m/day ± SE) of four species of salamanders captured and recaptured in forested habitat or clearcut habitat :  56  Figure 7. Frequency distribution of minimum distance (m) moved  57  Figure 8. Mean growth rate (g/g/month) of adult salamanders recaptured in forested or clearcut habitat 58 Figure 9. Comparison of initial mean weight and final mean weight (g) of salamanders recaptured in forest habitat and clearcut habitat 59 Figure 10. Size-class distributions of A. Ensatina and B. Western redback salamander in forested and clearcut habitat 60 Figure 11. The percentage of captures within 30 m from the stream vs. upslope before harvesting (N=6) 61 Figure 12. The mean percent of captures (± SE) within 30 m from the stream after harvesting (bars) and the mean change in the percent of captures (± SE) within 30 m of the stream from before to after harvesting (lines) 62 Figure 13. Mean percent of captures (±SE) of juvenile northwestern salamanders within 30 m vs. greater than 30 m of the stream after harvesting in control (N=2), buffer (N=2), and clearcut (N=l) sites 63 Figure 14. The mean percentage (± SE) of salamanders moving parallel to the stream vs. perpendicular before harvesting (N=6) 64  v  Figure 15. The mean percent of captures (± SE) moving parallel to the stream after harvesting (bars) and the mean change in the percent of captures (± SE) in parallel movement from before to after harvesting (lines) 65 Figure 16. The mean water content (± SE) of the soil as a percent of soil dry weight... 66  vi  ACKNOWLEDGEMENTS I would like to express thanks to John Richardson, my advisor, for his support and guidance throughout my studies; I sincerely appreciate the opportunity to conduct this research. My research committee, Scott Hinch and Charley Krebs, for thoughtful comments and constructive criticism on my thesis as well as knowing limits for my research when I didn't. I also received helpful input from some amazing people along the way, including: Shelly Boss, Jim Herbers, Dave Huggard, Peter Kiffney, Karl Mallory, Brett Sandercock, and Kyle Young. Thanks to the many people that provided field assistance including: Kendra Claire, Robyn Scott, Dan O'Donoghue, Amy Blaylock, Jeff Shatford, Melanie Grant, Jen Wild, and Tatiana Lee. Additional thanks to all the people who volunteered their time (and saved the day on occasion) including: Shelly Boss, Suzie Lavallee, Jim Herbers, Susannah Maxcy, Jon Zuccolo, Stephanie Maxcy, Miriam Maxcy, Paul Pittmann, Christine Muchow, Mike McArther, and Kyle Young. Forest Renewal B.C. and the Habitat Conservation Trust Fund provided funding for this project. Special thanks to the staff at the Malcolm Knapp Research for logistical support. On a personal note, I would like to thank my friends and family for their love and support. In particular, Kerri Bates, Shelly Boss, Allison Glanfield, Kirsten Hannam, Suzie Lavallee, Paul Pittman, Cherie Skripnik, and Leanne Walsh who all helped me keep perspective and balance in my life. All my lovely sisters: Sarah, Rachael, Miriam, Little Sue, and Stephanie as well as my "big brother" Adam for the laughter. My dad who has supported me even though he had no idea what I was doing. M y thanks and love to Jim Herbers who has made this one of the best times of my life. And lastly, I cannot forget the little creatures without which this thesis would not exist, the sallys. I can only hope their "alien abduction" to my refrigerator was not too traumatic.  vii  INTRODUCTION Forest fragmentation and habitat loss are the principal threats to species in the temperate zone (Soule 1991; Harris and Silva-Lopez 1992; Meffe and Carroll 1997). Amphibians are particularly susceptible to forest canopy removal because of their physiological requirements for cool, moist conditions. Indeed, numerous correlative studies have shown that the abundance of many amphibian species is lower in harvested habitat compared to mature forest in both western (Bury 1983; Bury and Corn 1988; Dupuis et al. 1995; Dupuis and Bunnell 1999; Grialou et al. 2000; but see Corn and Bury 1991) and eastern (Pough et al. 1987; Ash 1988, 1997; Petranka et al. 1994a, 1994b; Waldick 1997) North American forests. Salamanders in particular appear to be reduced as they are, on average, 3.5 times more abundant in forested sites compared to clearcut sites (deMaynadier and Hunter 1995). So while there is little doubt forest harvesting negatively impacts terrestrial amphibians, the mechanism(s) responsible for the observed pattern of lower amphibian abundance in clearcuts is still unknown. There has been some debate as to the fate of amphibians following forest harvesting (Ash and Bruce 1994; Petranka 1994; deMaynadier and Hunter 1995). First, it is unknown what proportion of the amphibian population is killed by the actual physical process of the logging (deMaynadier and Hunter 1995; Chazal and Niewiarowski 1998). Second, if the amphibians are capable of surviving this initial disturbance, it is unclear whether the salamanders migrate vertically into the substrate, eventually dying due to the altered environmental conditions (vertical migration hypothesis) or whether they emigrate from the clearcut into the surrounding forest habitat (emigration hypothesis). There is indirect evidence supporting both hypotheses. For example, individual Pacific  1  giant salamanders (Dicamptodon tenebrosus) located in clearcut habitats remained in refugia for longer periods of time, moving shorter distances than did salamanders in forested habitats (Johnston 1998), results more consistent with the vertical migration hypothesis. In contrast, the movement rate of ensatinas (Ensatina eschscholtzii) were higher in bare corridors where they experienced greater dehydration rates compared to vegetated corridors (Rosenberg et al. 1998), results more consistent with the emigration hypothesis. So while both hypotheses explain the pattern of lower abundance in clearcut habitat, documenting changes in amphibian behaviour including movement frequency, distance and rate are key to differentiating between these two alternatives. Survival of amphibians may be reduced in clearcuts due to lower body condition (Kramer et al. 1993; Petranka 1994a). Growth rate is not independent of environmental conditions (Hota 1994); foraging opportunities are generally reduced in hot, dry conditions (Fraser 1976; Mairorana 1976; Jaeger 1980a). Therefore, it is expected that the microclimatic changes associated with forest harvesting including decreased humidity, increased temperatures, and decreased soil moisture (Chen and Franklin 1990; Chen et al. 1993; Brosofske et al. 1997), will reduce foraging opportunities for amphibians, and thus growth rates. If growth rates are reduced in harvested areas, there are potential repercussions for overall lifetime fitness and survival of individuals found in this habitat. Limited evidence provides support for reduced body condition and fitness of individuals in clearcuts. Chazal and Niewiarowski (1998) found trends (not significant) of greater mass loss, lower egg production and mean egg lipid content for individual mole salamanders (Ambystoma talpoideum) in clearcuts relative to forested control plots. Grialou et al. (2000) reported western redback salamander (Plethodon vehiculum) snout-  2  vent lengths were skewed toward smaller size classes in clearcuts compared to forested habitats in one year of study but not the other. In contrast, Dupuis and Bunnell (1999) found no relationship between snout-vent length size classes and stand age for the western redback salamander. Thus, the effect of harvesting practices on salamander body condition is still unclear. Maintaining riparian buffers is one method suggested to maintain amphibian species on harvested landscapes (Bury 1988; Walls et al. 1992; Petranka et al. 1994a; Dupuis etal. 1995; Dupuis 1997; deMaynadier and Hunter 1995; Waldick 1997; Bunnell et al. 1999; Davis 1999). The riparian zone defined as the interface between terrestrial and aquatic ecosystems (Gregory et al. 1991) has a unique set of environmental conditions, unlike those conditions found in upslope areas, that may favour amphibian species (Brosofske et al. 1997). A few studies have observed higher capture rates of amphibians in riparian areas compared to upslope habitats (e.g. McComb et al. 1993; Gomez and Anthony 1996). However, it is unknown whether this is a broad pattern across regions and seasons, or restricted to specific sites, sizes of streams, or environmental conditions. Further, the width of buffer necessary to maintain viable populations of amphibians is unknown. Within British Columbia, streamside protection depends on the size of the stream, community watershed value and the presence or absence of fish (BC Ministry of Forests 1995). Headwater streams require no reserve zones around them despite the fact both stream and terrestrial amphibians tend to benefit from buffers (e.g. Vesely 1996; Cole et al. 1997; Johnston 1998). The relationship between buffer width and how it would function (i.e. corridor for movement or habitat)  3  still needs to be quantified to determine whether this is an effective strategy to maintain amphibians in a harvested landscape. As part of a larger riparian management experiment, I designed a study to investigate the proximate response of terrestrial amphibians to forest harvesting. The vertical migration hypothesis and the emigration hypothesis were tested for four species of salamanders, two aquatic-breeding salamanders: the northwestern salamander {Ambystoma gracile Baird 1957) and rough-skinned newt (Taricha granulosa Skilton 1849), and two terrestrial-breeding salamanders: the ensatina (Ensatina eschscholtzii Gray 1850) and western redback salamander (Plethodon vehiculum Cooper 1860). Along with comparisons of salamander relative abundance before and after harvesting, specific behavioural patterns that would support one of the two alternative hypotheses were predicted. Reduction in the movement frequency, distance or rate of movement were expected if salamanders responded to clearcut conditions by migrating vertically into the substrate. In contrast, these movement parameters were expected to increase if the salamanders emigrate offsite. I also predicted that salamanders in clearcut habitat would have reduced body condition compared to salamanders in forested habitat. Finally, 30 m riparian buffer strips were examined for their effectiveness in maintaining terrestrial salamander populations. For buffers to be beneficial to amphibian populations, I predicted the relative abundance would stay the same or increase within 30 m of the stream in the buffer treatment postharvest. Further, parallel movement is expected to increase if the buffers are acting as corridors for movement.  4  METHODS Study site This study was conducted in the Malcolm Knapp Research Forest (122° 34' W, 49° 16' N) located approximately 60 km east of Vancouver, British Columbia. The study area is within the Coastal Western Hemlock biogeoclimatic zone, characterised by rainy, cool winters and dry summers. Six sites were selected in naturally regenerated 70-yearold second-growth forests, all of which were logged in the early part of the century and then burned in a stand replacing fire in 1931. The area surrounding the sites consists mostly of continuous forest of uniform age and disturbance history with small logging operations interspersed. For the ten streams included in the riparian management study, a total of 41.6 ha were harvested (including cutblock area and new roads). See Figure 1 for spatial configuration of the study area. Although all the sites have a similar disturbance history, the sites could generally be divided into two groups based on the degree of canopy closure (Table 1). Three sites, Spring, H , and B all had fairly open canopies with a high percent cover of moss and understory vegetation. Sites SCK and I had closed canopies and virtually no undergrowth. One control, Mike Creek was intermediate between these two groups of sites. All sites contained a similar composition of overstory trees. Western hemlock (Tsuga heterophylla) was the predominant tree species, however Western red cedar {Thuja plicata) and Douglas-fir (Pseudotsuga menziesii) were also present, and vine maple (Acer circinatum) was common in sites with open canopies. A list of species present at each site along with their percent ground cover is provided in Appendix 1. General characteristics of each site are described in Table 1. Each site received one of  5  three treatments: control, 30 m buffer and clearcut. Details of the harvesting schedule are provided in Appendix 2. Trapping Methods Pitfall trap arrays, single pitfall traps and cover boards were set up in a 50 m by 50 m grid at each site (Figure 2). Trapping grids consisted of three parallel lines of three pitfall trap arrays at 5, 30, and 55 m distances from the stream. Within each array, four pitfall traps were buried flush with the ground and installed such that one trap each was oriented both downslope (trap 1) and upslope (trap 3) of the stream, as well as in the downstream (trap 2) and upstream (trap 4) direction (Figure 2). This pitfall trap arrangement was designed to determine the direction of movement of the amphibians captured relative to the stream. Sixteen cover boards and 6 single pitfall traps were installed at regular intervals in the spaces between the arrays to increase amphibian capture probabilities. The pitfall traps were made from 6" diameter PVC piping cut into 15" tubes. The bottoms of the traps were 6" diameter plastic margarine containers punched with holes to allow for water drainage. Margarine containers with the bottom cut out were also used as collars placed at the top of the pitfall traps acting as funnels so animals that fell into the trap would not be able to escape. Knotted twine with a stick tied to both ends was anchored at the top of each trap, while the other end dangled approximately two cm from the bottom. The ladders appeared to be effective for escape of all small mammals except shrew moles. The drift fences used in the pitfall arrays were cut from rolls of transparent, medium weight polyfilm cut into 5.3 m by 60 cm lengths. The sections were folded over wooden stakes driven into the ground to which the plastic was stapled. The finished  fences were 5 m long with 25 cm above the surface of the ground and 5 cm buried below. The cover boards (1 m x 30 cm) were cut from five ply (5/8"), untreated plywood. Additional traps were added at two of the six sites (sites SCK and B) in 1999 because the applications of the harvesting plans were not located where expected (Figure 3 and 4). Amphibians captured in these traps were excluded from any calculation of relative abundance, spatial distribution relative to the stream and direction of movement because no pretreatment data were available. Also, traps that did not receive the expected treatment were excluded from further analyses that included relative abundance for both pretreatment and posttreatment data collection. Figure 3 and Figure 4 highlight the traps included in analyses for these two sites. Trapping schedule The trapping effort was similar among sites but varied from season to season (Table 2). Two exceptions occurred at sites SCK and B due to changes in the harvesting schedule. Harvesting did not occur as planned in the summer of 1998 at these two sites, delaying the re-establishment of the trapping grids until February of 1999. Site SCK was inaccessible during the fall of 1998 because the trees had been felled but not removed from the site. At site B, harvesting did not begin until November so an extra month of pretreatment data was gathered. During trapping sessions, traps were open continuously and were checked every two to three days. Some individual traps were excluded from analysis because of flooding or bear damage resulting in an uneven number of trap nights per site.  7  Marking techniques Two marking techniques were used depending on the species and size of the individual captured. Juvenile aquatic-breeding salamanders and all terrestrial-breeding salamanders were marked in the field using a unique combination of elastomer dyes (Northwest Marine Technology, Inc) and toe clips. One of four colours (red, orange, yellow, and green) was injected into one of five positions on the salamanders including the tail, and the inside of all four legs of the salamanders. PIT tags (passive integrated transponders, BioMark) were used to individually mark adult northwestern salamanders and rough-skinned newts. Animals to be PIT-tagged were taken to the lab, and anaesthetised using MS-222 (tricaine methanosulfonate). A small incision (~ 2 mm) was then made in their lower abdomen, a PIT tag inserted, and the incision sealed using a small amount of Vetbond (a surgical glue that sloughs off after a few days). Animals were kept overnight in a refrigerator to monitor their recovery and then returned to their point of capture the following day. The following data were recorded for each amphibian captured: species, date, location of capture, snout-vent length, total length, mass, sex (if possible), age (juvenile or adult), individual mark, and capture history (new or recapture). If an animal was captured in a pitfall trap array, it was released on the opposite side from where it was initially captured on the assumption that was the direction the animal was moving. Amphibians captured under cover boards were returned to the cover board and those captured in single pitfall traps were released under the nearest cover object (e.g. log). Data Analyses  Data included in analyses  8  Relative abundance indices were calculated using data from the spring (March 21June 21) and fall (September - November) for all years of sampling to keep timing consistent between years. All parameters were tested for normality. Nonparametric tests were used for those parameters that were not normally distributed even after appropriate transformation. An alpha level of p = 0.05 was used as the critical limit for all statistical analyses.  Relative Abundance Although data was collected using mark-recapture techniques that should have allowed for estimates of absolute abundance, recapture rates were too low for any species to provide reliable density estimates. Therefore, I calculated relative abundance standardised to number captured per 100 trap nights (TN) for each site. I used two trapping methods to estimate relative abundance of the salamanders: pitfall trap arrays for all four species and cover boards for the terrestrial-breeding salamanders. Single pitfall traps were excluded in these calculations because they accounted for less than 5% of the total captures for any species. Calculation of relative abundance from cover boards was limited to terrestrial-breeding salamanders because boards were ineffective in sampling the aquatic-breeding salamanders. Recaptures were excluded from all relative abundance estimates. Each trapping grid was an experimental unit. A repeated-measures A N O V A was used to test for the effects of treatment, time and, time*treatment interactions on the relative abundance of the amphibians.  Movement distances and rates The movement parameters used in this study include minimum average distance moved (m) and movement rate (m/day). Distances moved were defined as the minimum  9  average distance because grids were a fixed size of 50 x 50 m, only distances moved within this area could be detected, and longer movements were missed. Estimates for both distance and rate for all four species were calculated based on recapture data in forest and clearcut habitats. Forest movements include capture-recapture data collected before harvesting at all sites and data collected in unharvested areas posttreatment. Clearcut movements were estimated using capture-recapture data collected from clearcut habitat only. Individuals that were initially captured before harvesting and then recaptured after harvesting at any site were not included in either estimate of movement because time of movement could not be determined (i.e., before, during, or after harvesting). Movements that occurred during this preharvest to postharvest time interval in control sites were also excluded to minimize temporal variation in these parameters. Movements that occurred between forest and clearcut habitats were also excluded. Salamanders that were recaptured in the same array but opposite trap from where it was originally caught were left out as well. For the northwestern salamander and rough-skinned newt, movement distances and rates were calculated for individuals that were recaptured within 35 days of previous capture. Within this time frame, it could generally be determined that the salamanders were in the process of completing one portion of their breeding migration, either immigration or emigration from the breeding pond. To ensure independence of observations, recaptures of the ensatina and western redback salamander that occurred within 14 days of each other under the same cover board were considered one observation. Both species have small home ranges and  10  repeated captures under the same cover board or trap is not uncommon (Bonin and Bachand 1997; Davis 1997). All juveniles (<1.0 g) were excluded from the movement analysis to minimize variation in movement parameters due to age. The Mann-Whitney U test was used to test for differences between pretreatment and posttreatment movement distances and rates in forested habitat for all species. No significant difference was found for any species (Mann-Whitney test: P>0.05); therefore, all movements in forested areas were combined and were compared with clearcut habitat movements again using a Mann-Whitney U test.  Growth Rates The growth rates for adult northwestern salamanders, ensatinas and western redback salamanders were calculated in g/g/month to approximately correct for differences in initial size; too few rough-skinned newts were recaptured to estimate growth rate. Northwestern salamanders were defined as adults if they were over 12 g at the time of first capture. Ensatina and western redback salamander were considered adults if they were greater than 4.2 cm S V L (Peacock and Nussbaum 1973; Ovaska and Gregory 1988; Rosenberg 1995). Although salamanders have indeterminate growth, their rate of growth is very slow once they have reached adult size (Hota 1994). Therefore, I assumed animals greater than the minimum size selected to calculate growth rate for each species had flat weight-specific growth rates. Juveniles and subadults were excluded from this analysis because growth rates vary with age (Stebbins 1954; Peacock and Nussbaum 1973; Ovaska and Gregory 1988; Staub et al. 1995). To be included in growth rate calculations, time between successive recaptures was a minimum of 25 days. Captures of gravid females that were recaptured after they had laid their eggs were  11  excluded from analysis. Ensatinas that were first captured with tails and subsequently without were also excluded. The absolute difference between weight at first and last capture was used to calculate growth rate when animals were recaptured more than once. Calculating growth rate for the northwestern salamander was problematic because of its reproductive period; salamanders can potentially lose weight from laying eggs or courting (Eagleson 1976). Therefore, I decided to calculate growth rates for those salamanders that were captured at the end of their reproductive cycle in the spring and that were subsequently recaptured the next fall or at the beginning of the subsequent breeding season. I assumed the growth rates for the adult northwestern salamanders from the spring to fall, or from the spring to the beginning of the next breeding season would be indicative of conditions of their habitat. Thus, only the growth rates for those animals captured and recaptured in this specific time period were included in the analysis for this species. Small numbers of recaptures were obtained for all three species; therefore analysis of growth rates was done to contrast forest and clearcut habitats. Animals that were captured on the forest edge were included in the forest growth rate estimates. A Mann-Whitney U test was used to test differences between growth rates in the two habitats. To determine whether differences in growth rate at the individual level could be seen at the population level, the size class distribution was compared between pretreatment and posttreatment to look for any shifts in size class distribution between forest and clearcut habitat. Although not a direct measure of growth rate, a shift in the size class distribution toward smaller size classes in clearcut habitat may indicate growth  12  rate is reduced, survival to adulthood is reduced, or that recruitment is increased. Therefore, individuals of ensatinas and western redback salamanders were divided into four size classes based on weights. These classes were determined by examining the frequency distribution of weights for both species in forested habitat to find the natural grouping of sizes by weights. For the ensatina, the four classes include <0.60 g, 0.60 1.8 g, 1.81 - 3.0 g, >3.0 g. The size classes for the western redback salamander include <0.80 g, 0.80 - 1.40 g, 1.41 - 2.0 g, and> 2.0 g. The weight size classes for ensatinas and western redback salamanders were compared between individuals captured in forested habitat compared to clearcut habitat using a contingency table. The size class distribution was not compared between habitats for the northwestern salamander because shifts in the size class distribution due to reproduction would likely mask any shifts due to treatment.  Efficacy of riparian buffer strips Calculation of distribution within 30m of the stream To determine the effectiveness of riparian buffer strips in maintaining terrestrial salamander populations, I calculated the number captured per 100 T N within 30 m from the stream compared to the 55 m line (i.e. outside the buffer). The relative abundance estimates of salamanders captured within 30 m from the stream are based on captures from six pitfall trap arrays compared to three upslope. Using these relative abundance estimates, the proportions of captures in the buffer and upslope habitat were calculated. The proportions were arcsine transformed (Zar 1984) and a repeated-measures A N O V A was used to test for the effects of treatment, time and the interaction of time*treatment on the spatial distribution of the salamanders relative to the stream.  13  For the aquatic-breeding salamanders, fewer than five individuals were captured in one clearcut site (B) postharvest. Therefore, to examine the shifts in their spatial distribution, only the control and buffer sites were compared; the second clearcut site (I) is included in graphs for comparative purposes. All treatments were analyzed for the terrestrial-breeding salamanders. Juvenile and adult northwestern salamanders were analyzed separately; small sample sizes of juveniles for the three other species precluded a similar analysis by age. Movement direction I calculated the direction of movement relative to the stream (parallel or perpendicular) for each species of salamander before and after harvesting. Movement was considered parallel to the stream if animals were captured in traps 2 and 4 of the pitfall trap arrays, whereas, animals captured in Traps 1 and 3 were considered moving perpendicular (Figure 2). The total number of animals captured moving parallel and perpendicular were summed and then standardised per 100 T N to take into account differences in trapping effort. The proportion of salamanders moving parallel to the stream was calculated for each treatment. The proportions were arcsine transformed (Zar 1984) and a repeated-measures A N O V A to test for the effects of treatment, time, and treatment*time. Again, due to the limited captures at clearcut site B postharvest for the aquatic-breeding salamanders, the movement direction was compared between the control and buffer sites only; the second clearcut site (I) is included in graphs for comparative purposes.  Environmental variables Temperature  14  Temperature was recorded at each site using temperature loggers (HOBO temp loggers). Before harvesting, there were not enough loggers to place at each site so three were located at one buffer (SCK) and one clearcut (B) site at 5, 30 and 55 m from the stream. After harvesting, all sites had loggers at these three distances. Temperature was recorded every two hours in July and August in 1998 (before harvesting) and 1999 (after harvesting). As terrestrial salamanders are rarely found under cover objects above 20°C, and their lethal limit is above 30°C (Stebbins 1954; Dumas 1956), the percentage of days the loggers recorded temperatures above these thresholds were recorded (Table 3). Soil Moisture Soil samples were collected from approximately 5 cm below the surface at 5, 30, and 55 m from the stream before and after harvesting. The number of soil samples collected before and after harvesting varied between sites due to differences in timing of harvesting (Table 4). Samples of soil (27 cm ) were placed in tin sample boxes. The 3  samples were taken back to the lab, weighed immediately, oven dried at 70°C for 24 hours, and then reweighed. The mass of water lost was expressed as a percentage of mass of the dried soil. Results Species composition and relative abundance A total of 3,967 amphibians were captured including 5 salamander and 4 anuran species in 83,332 trap nights (Table 5). All species were detected at all six sites with the exception of the Pacific treefrog (Hyla regilla) which was captured at one site only. The most abundant species was the northwestern salamander which accounted for 43% of the  15  total captures, followed by the western redback salamander with 19%, ensatina at 14%, and the rough-skinned newt making up 12% of the captures. The remaining species totalled 12% of all captures combined. The western toad (Bufo boreas) was the most abundant anuran with 205 captures. However, of these, over 96% were juveniles captured in the first two seasons of trapping. The high capture rate of juveniles likely indicates 1997 was a successful breeding season whereas the remaining years of the study were not. For the tailed-frog {Ascaphus truei), although it was detected at all sites, it was abundant at only two: one control site (Spring) and one 30 m buffer site (H) (see Appendix 4). There were 47 red-legged frogs (Rana aurora) captured over the five seasons of trapping. Most of these captures occurred in the spring of 1998. Finally two tree frogs (Hyla regilla) were captured; trapping methods are generally ineffective at capturing tree frogs. Due to the low capture rates and unreliability of the trapping methods used to sample anurans in this study, they were not considered in the rest of the analysis. See Appendix 3 for a summary of the total number of species caught at each site and their relative abundance estimates by season. Effects of riparian harvesting on terrestrial salamanders  Relative abundance There was no consistent pattern of response to forest harvesting by the four species of salamanders examined in this study. The relative abundance of northwestern salamanders increased at all sites after harvesting (Figure 5a). There was a three-fold increase in relative abundance in the control sites whereas only slight increases occurred in the buffer and clearcut treatments after harvesting, however, there was no significant effect of time or time*treatment (Table 6). The rough-skinned newt relative abundance  16  exhibited no consistent pattern of change from preharvest to postharvest with abundance increasing on the control and buffer sites, and decreasing slightly in the clearcuts (Table 6, Figure 5b). The mean relative abundance of ensatinas estimated using pitfall trap arrays declined after harvesting; the largest decline occurred in the buffer treatment, followed by the clearcut and control sites (Figure 5c). In spite of this pattern of decline on harvested sites, no significant effect of time or the interaction of time and treatment was detected (Table 6). A similar pattern of decline was observed for the relative abundance of the ensatina using the cover boards, as captures decreased in all treatments following harvesting (Table 6, Figure 5d). There was only a slight decline in abundance observed in the control treatment, however, the capture rate declined by 60% in the buffer treatment and by 90% in the clearcut treatment. In contrast to the ensatina, the capture rate of western redback salamander in the pitfall arrays increased after harvesting at all sites (Table 6, Figure 5e); there was a 42% increase in the control treatment, 32% increase in the buffer treatment, and an increase of 113% in the clearcut treatment. The opposite pattern was observed for western redback salamanders captured under cover boards (Figure 5f). The mean relative abundance showed virtually no change from pretreatment to posttreatment in the control sites, however declines of 67% and 92% occurred in the buffer and clearcut sites respectively.  Distance of Movement The distance moved by recaptured northwestern salamanders and ensatinas was approximately 5 m more in clearcut habitat as compared to individuals recaptured in forest habitat, however, this difference was not significant for either species (Mann-  17  Whitney U test, northwestern salamander: Un.o5(2), 89,24 = 811.5, p = 0.072; Ensatina: Uo.o5(2), 22,4 = 28, p = 0.224)(Figure 6a). In contrast, the mean distance moved by the rough-skinned newt was 5 m less in clearcuts compared to forested habitat but again this difference was not significant (Mann-Whitney U test, rough-skinned newt: Un.o5(2), 8,9 = 41.5, p = 0.60). The distance moved by western redback salamanders in clearcuts was apparently greater than individuals in unharvested areas but this pattern is the result of one animal moving 32 m in the clearcut habitat; there was no significant difference in distance moved between the two habitats (Mann-Whitney U test, western redback salamander: Un.o5(2), 24,2 = 22, p = 0.831).  Rate of movement Recaptured individuals of northwestern salamanders and ensatinas in clearcut habitat moved approximately 2 m more per day than individuals recaptured in forested habitat, however, these differences were not significant for either species (Mann-Whitney U test, northwestern salamander: Un.o5(2), 89,24 = 811.5, P=0.555; ensatina: Un.o5(2), 22,4 = 28.0, P=0.224)(Figure 6b). The rough-skinned newt and western redback salamander showed the opposite pattern as the movement rate of rough-skinned newts declined by 6 m/day and western redback salamanders by 0.4 m/day in clearcut habitat but again these results were not significant (Mann-Whitney U test, rough-skinned newt: Un.o5(2), 8,9 = 48.5, P=0.229; western redback salamander: U .o5(2), 24,2 = 22.0, P=0.831). 0  Mode of movement distances The mode of the movement distances for both northwestern salamanders and rough-skinned newts was greater than 30 m (Figure 7a and 7b). A single northwestern salamander moved over 1.25 km between sites over one and a half years of this study.  18  For the ensatina and western redback salamander, the mode of the movement distances was 0 m, however movement distances of greater than 60 m were documented for both species (Figure 7c and 7d).  Growth rate There was no significant difference between pretreatment and posttreatment growth rates in forested habitat for any species, therefore these rates were combined to compare with clearcut growth rates. Adult northwestern salamanders, ensatinas and western redback salamanders all had higher growth rates in the forest compared to clearcut habitat (Figure 8). Northwestern salamander growth rate in forested habitat was 1.5 times greater than clearcut, with salamanders in the forest gaining approximately 1.25 g more weight overall, in forests than those northwestern salamanders in clearcuts (Mann-Whitney test, U .o5(2),7,5 = 29, P = 0.062, Figure 8 and 9a). The mean growth rate 0  of ensatinas in forested habitat was six times the growth rate in clearcut habitat but this difference was not significant (Mann-Whitney test, Un.o5(2),  12,5  = 44.5, P = 0.246, Figure  8). The initial mean weight of ensatinas in the forest was about 0.3 g lighter than the mean weight of ensatinas in clearcut habitat, however, final weights had almost converged in these two habitats (Figure 9b). The western redback salamander growth rate in forested habitat was approximately five times greater than the growth rate of individuals in clearcut habitat and this difference was significant (Mann-Whitney test, Uo.o5(2), 1 3 , 4 =  41, P < 0.05, Figure 8). The initial and final weight of western redback  salamander in clearcut habitat was virtually unchanged while western redback salamander in forested sites added 0.2 g (Figure 9c). At the population level, there was no significant difference in size-classes between forested and clearcut habitat for both the  19  ensatina (Contingency table, % o.o5, = 2.12, P > 0.50) and western redback salamander 2  3  (Contingency table, % .o5,3 = 2.98, P > 0.25) (Figure 10a and 10b). 2  0  Efficacy of riparian buffer strips Spatial Distribution  Relative to the Stream  Prior to harvesting, the distribution of the northwestern salamander, roughskinned newt, and western redback salamander did not appear to be influenced by the stream location (Figure 11). The percentage of captures within 30 m of the stream compared to upslope ranged from 45% to 55% for these three species. For the ensatina, in contrast, there were 20% more captures upslope. When examining the effects of harvesting on the spatial distribution of the four salamanders, adult northwestern salamanders, rough-skinned newts, and western redback salamanders had similar distribution shifts in the buffer and clearcut treatment from preto posttreatment. The proportion of captures within 30 m of the stream increased by 15%, 12%, and 14% for each salamander respectively in the buffer treatment (Figure 12a, 12b, and 12d). The opposite pattern was observed in the clearcut as the proportion of captures increased upslope by 2% for the adult northwestern salamander, 22% for the rough-skinned newt, and 20% for the western redback salamander. Although these species had similar patterns, the shift in spatial distribution approached significance for the western redback salamander only (Table 7). However, almost 60% of adult northwestern salamander captures and 77% of rough-skinned newt captures occurred within the riparian zone on the buffer treatment with only 40% and 55% captured in the riparian zone in the controls for each species respectively. For the juvenile northwestern  20  salamanders, the proportion of captures within the riparian zone was over 80% in the buffer treatment and only 40% in the control and clearcut sites (Figure 13). In contrast to the other species, the proportion of ensatina captures upslope increased in each treatment after harvesting by approximately 20% in the controls, and 5% in both the buffer and clearcut treatments (Table 7, Figure 12c).  Direction of movement Before harvesting occurred, all species had a tendency to move parallel to the stream as opposed to perpendicular (Figure 14). The northwestern salamander had the greatest percentage of individuals moving parallel to the stream (61%), followed by the western redback salamander (58.5%), ensatina (55%) and rough-skinned newt (51%). The proportion of northwestern salamanders moving parallel to the stream increased on all treatments after harvesting (Table 8, Figure 15a). A 9% increase occurred in the control followed by a 6% and 4% increase in the buffer and clearcut treatments respectively. There was a 40% increase in the proportion of rough-skinned newts moving parallel to the stream after harvesting in the buffer treatment with virtually no change in direction in either the control or clearcut (Table 8, Figure 15b). The directional movement of the ensatina showed no clear pattern by treatment or over time as the proportion moving parallel to the stream increased after harvesting in both the control and buffer treatments, but decreased in the clearcut sites (Table 8, Figure 15c). There were also no clear changes to the movement pattern of the western redback salamander (Figure 15d). No change in direction was seen in the control and buffer treatments, and the proportion moving parallel to the stream declined by approximately 15% in the clearcut treatment (Table 8).  21  Although many of the results were non-significant, a number of the observed trends were in the predicted direction for more than one species including a reduction in growth rate, increased capture rate within the 30 m buffer and increased parallel movement in buffer treatment (Table 9). For relative abundance there were no consistent patterns of change after harvesting for any species. However, the northwestern salamander, ensatina, and western redback salamander, had lower growth rates in clearcuts compared to forested habitat. The proportion of captures within 30 m of the stream increased after harvesting in the buffer treatment for the northwestern salamander, rough-skinned newt and western redback salamander. In addition, the proportion of both aquatic-breeding salamanders moving parallel to the stream increased after harvesting in the buffer treatment.  Microclimate change Temperature In the sites where data loggers were present before harvesting, the percentage of days temperatures reached 20°C ranged from 6% to 30%, however, the salamanders' lethal limit of 35°C was never reached (Table 3). After harvesting, control sites recorded temperatures above 20°C on 2% of the days. In the 30 m buffer treatment, extreme temperature fluctuations near the stream were minimized; although 20°C temperatures were recorded, the lethal limit of 35°C was never reached. In contrast, the lines 30 m and 55 m from reached the 35°C mark numerous times. Similarly, in the clearcut treatments, those lines that received no shading recorded temperatures above 20°C and 35°C on most days. Soil Moisture  22  In the control treatment, the pattern of moisture content in the soil was similar before and after harvesting: percent moisture was highest 5 m from the stream, declined to a low 30 m from the stream, and then increased again 55 m from the stream (Figure 16a). The highest soil moisture content in the buffer treatment occurred at 5 and 30 m from the stream and was minimal 55 m from the stream before harvesting (Figure 16b). After harvesting, however, there appeared to be a transriparian gradient present with soil moisture highest nearest the stream and declining with increasing distance away from the stream. In the clearcut treatment, moisture content was highest near the stream and declined with increasing distance from the stream before harvesting (Figure 16c). After harvesting, this gradient disappeared as soil moisture was approximately equal regardless of distance from the stream. DISCUSSION  The results of my study show the relative abundance of three of the four salamander species did not decline immediately following harvesting. Therefore, most of the salamanders were able to survive the physical disturbance of the logging activity itself. Although, salamander abundance was not immediately reduced after harvesting, detrimental effects of logging were manifested in the form of lower growth rates for the northwestern salamander, ensatina, and western redback salamander in clearcut habitat compared to forested habitat. The maintenance of a riparian buffer did appear to be an effective strategy mitigating the effects of forest harvesting. Both the proportions of captures within 30 m of the stream and parallel movement increased in the buffer treatment after harvesting for the aquatic-breeding salamanders indicating selection for the buffer may have occurred. This pattern was particularly strong for juvenile  23  northwestern salamanders as over 80% of the captures occurred in the riparian area of the buffer treatment. Overall, in this study, many of the results were in the predicted direction, however few significant results were obtained due to low statistical power. Conclusions are made stronger in many cases because the observed trends were in the predicted direction for more than one species.  Effects of riparian harvesting on terrestrial salamanders Relative abundance - Aquatic-breeding salamanders I found the abundance of northwestern salamanders and rough-skinned newts changed little after harvesting in both buffer and clearcut treatments indicating their populations were not immediately reduced after harvesting. This lack of response for both salamanders supports neither the vertical migration hypothesis nor the emigration hypothesis. For the rough-skinned newt, these results are similar to Cole et al. (1997) who also found no significant response in relative abundance one and two years postharvest. Cole et al. (1997) did not capture northwestern salamanders in sufficiently high numbers to detect any treatment effects. The lack of response in relative abundance by the northwestern salamander and rough-skinned newt shown in this study might be expected for a number of reasons. The first explanation for the aquatic-breeding salamanders' lack of response is their dependency on aquatic habitat for breeding. Several comparative studies of aquatic-breeding salamanders in the Pacific Northwest have documented inconsistent responses in abundance relative to stand-age (Aubry and Hall 1991; Bury et al. 1991; Corn and Bury 1991; Gilbert and All wine 1991). It has been suggested the spatial distribution of aquatic-breeding salamanders may be related more to the proximity of suitable breeding habitat than to forest harvesting practices (Welsh and  24  Lind 1988; Bury et al. 1991; Corn and Bury 1991). Indeed, in this study, both the northwestern salamander and rough-skinned newt were 1.5 to 12 times more abundant at sites that were located within 500 m of large breeding ponds (including one clearcut site) compared to sites further away. Therefore, as long as suitable breeding sites are close by, forested terrestrial habitat may not be necessary to maintain their populations and no response to forest harvesting may be expected. This seems unlikely however given that both salamanders have evolved under the cool, moist conditions provided by the forest canopy. In addition, salamanders as a group are a median of 3.5 times more abundant in forested compared to clearcut habitat (deMaynadier and Hunter 1995); there are other more parsimonious explanations. The second possible reason for the lack of response by the aquatic-breeding salamanders is the small size of the clearcuts. There is limited information on the distance northwestern salamanders and rough-skinned newts can move. However, related species in the genera Ambystoma and Taricha move an average distance of over 100 m with maximum distance moved greater than half a kilometre from breeding ponds (Pimental 1960; Twitty 1966; Blaustein etal. 1995; Semlitsch 1998). In this study, I documented the movement of one northwestern salamander from one site to another, a distance of over one kilometre. The largest clearcut in this study was 2.2 hectares. The salamanders were never more than 100 m from forested habitat and therefore within a distance the salamanders are capable of moving. Thus, salamanders would have only limited exposure to altered environmental conditions in clearcuts if, for example, they were moving through during their breeding migrations.  25  The third explanation for the lack of response by aquatic-breeding salamanders is timing of their movements, which may further buffer the impacts of forest harvesting. Mass movements of both species are correlated with cool, moist conditions in the spring and fall (Snyder 1956; Pimental 1960; Oliver and McCurdy 1974). Although limited sampling was conducted in the summer, fewer than 10% of the total captures occurred during this time. This adaptive behaviour which restricts the salamanders' activity to the optimal environmental conditions also limits their exposure to the summer's high temperatures and dry conditions which are intensified by the removal of the forest canopy (Chen and Franklin 1990; Chen et al. 1993; Brosofske et al. 1997). As a result of this specific seasonal activity by northwestern salamanders and rough-skinned newts, their risk of mortality due to the altered environmental conditions may be lower. Finally, it is possible that the northwestern salamander and rough-skinned newt did respond to forest harvesting but no effect was detected due to large variation in abundance spatially and temporally for both species. The preharvest spatial variation in abundance among the six sites for both salamanders was very high with coefficients of variation in capture rates of over 100% (Maxcy and Richardson 2000). Long-term censuses of amphibian populations are limited but there is evidence that the abundance of aquatic-breeding amphibians can vary by orders of magnitude annually (Pechmann et al. 1991; Semlistch et al. 1996). Indeed, an ongoing debate about the apparent global decline of amphibians is how to distinguish population declines from natural fluctuations in population abundance (Pechmann et al. 1991; Pechmann and Wilbur 1994; Blaustein 1994; McCoy 1994; Alford and Richards 1999). This is also a problem for studies investigating the effects of forest harvesting on amphibians. For example, Cole et al.  26  (1997) suggest the apparent lack of response by rough-skinned newts to forest harvesting was due to high site to site variability in capture rates and thus low power of statistical tests. In my study, the northwestern salamander had the largest increase in abundance on the control sites from preharvest to postharvest. It is unclear whether a similar increase in abundance should have been expected in the harvested treatments but did not occur because there was an effect of harvesting or whether temporal variation in abundance differs from site to site. Longer time series of population estimates are required to differentiate declines versus natural fluctuation in abundance.  Relative abundance - Terrestrial-breeding salamanders Pitfall trap arrays The relative abundance of ensatinas declined immediately after harvesting while western redback salamanders increased; Cole et al. (1997) also observed these trends. The opposite trends in relative abundance shown by the terrestrial-breeding salamanders provide support for the two competing hypotheses regarding their fate after harvesting; the reduced abundance of the ensatina supports the vertical migration hypothesis while the increase in relative abundance by the western redback salamander in the clearcut treatments supports the emigration hypothesis. One of the main assumptions when using passive sampling techniques such as pitfall trapping to estimate relative abundance is that the movement patterns of the animals do not change between the habitats being compared (Remsen and Good 1996). However, this assumption is certainly violated when comparing the relative abundance of the terrestrial-breeding salamanders immediately after harvesting to preharvest abundance estimates or controls. The apparent changes in relative abundance from  27  pretreatment to posttreatment may reflect trends in salamander abundance, but also can be explained by alterations in their movement patterns in response to the modified environmental conditions (e.g. temperature, moisture, humidity) after harvesting (Winker et al. 1995; Remsen and Good 1996). If ensatinas migrated vertically into the substrate immediately after harvesting, there would be a consequent decrease in one or a combination of the frequency, timing, or distance moved. Reduction of these movement parameters would lower the capture probability of ensatinas, as the animals would not encounter the drift fences as often. Thus, the reduced relative abundance of ensatinas in buffer and clearcut treatments could be explained by changes to any of these movement parameters. This result is generally expected for plethodontids due to their low vagility and high site fidelity (Kramer et al. 1993; Petranka et al. 1994a, 1994b). In contrast, an increase in any of these movement parameters by individuals would result in higher encounter rates with the pitfall arrays and thus capture rates as seen by the western redback salamander in my study. For the western redback salamander, there is limited evidence supporting increased movements after, clearcutting. Cole et al. (1997) also recorded increased capture rates of western redback salamanders one year after harvesting and suggested this increase was due to the salamanders' attraction for the microclimatic conditions provided by the pitfall traps. This explanation is also consistent, and not mutually exclusive with, an increase in salamander movements. Waldick et al. (1999) reported that 95% of their total captures of the redback salamander (Plethodon cinereus) occurred in pitfall traps that were located adjacent to a recently clearcut area; P. cinereus was captured only three times at five other sites used in the study. They suggest the huge influx of salamanders was due to  28  mass emigration from this newly clearcut habitat. Combined, these results generally suggest western redback salamanders have changed their movement patterns after harvesting. Unfortunately, due to low recapture rates of the terrestrial-breeding salamanders, I could not detect changes in movement patterns that would corroborate either the vertical migration or the emigration hypothesis. There are alternative explanations for the observed patterns of abundance for the terrestrial-breeding salamanders. The apparent decline of ensatinas could also be a result of increased mortality in the buffer and clearcut treatments as a result of the physical process of logging. Ensatinas and western redback salamanders should have comparable survivorship in the clearcuts because of their similar habitat requirements (Aubry et al. 1988), but the increase in capture rates of western redback salamanders after harvesting suggests high mortality did not occur. It is also possible ensatinas emigrated offsite but were not detected due to timing of sampling, spacing of the arrays, or both. For the western redback salamander, immigration from the surrounding areas into the clearcut habitat may have also resulted in a higher population size. A shift towards a smaller size class distribution is expected under this hypothesis because presumably the clearcut habitat is of lower quality than the forested habitat and would thus act as a population sink. Larger individuals in the genus Plethodon  tend to dominate over small individuals  (Ovaska 1987; Mathis 1990; Gabor 1995; Marvin 1998) so it would be expected the smaller salamanders would immigrate into the clearcut habitat. However, I did not observe a shift toward smaller size classes. Alternatively, the increase in relative abundance after harvesting could reflect an actual increase in abundance due to higher reproduction, but again a shift towards smaller size classes is expected under this  29  hypothesis and none was observed. Further work needs to be done on the individual movements of terrestrial-breeding salamanders in clearcut and forested habitat to distinguish between the alternative hypotheses. Cover boards The cover board estimates of the relative abundance of terrestrial-breeding salamanders showed the expected treatment response after harvesting. Intermediate declines occurred in the buffer treatment and almost no salamanders were located under cover boards in the clearcut treatment postharvest. I suggest these apparent declines in relative abundance reflect a change in the habitat after harvesting that makes the cover boards unsuitable for use, rather than a change in local abundance. The ability of natural cover objects to protect salamanders from heat and desiccation changes with environmental conditions (Dumas 1956; Heatwole and Lim 1961; Heatwole 1962; Jaeger 1971, 1980b; Keen 1985; Mathis 1990; DeGraaf and Yamasaki 1992; Marvin 1998). For example, Mathis (1990) observed more redback salamanders (Plethodon cinereus) under large cover objects that had cooler air and soil surface temperatures beneath them as compared to small cover objects. The thermal maxima for the ensatina and western redback salamander is above 30°C; neither species were ever located under cover objects in the natural environment that had temperatures above 20°C (Stebbins 1954; Dumas 1956). In this study, the temperatures on the harvested sites were above the lethal limit for both the ensatina and western redback salamander more often in clearcut habitat compared to interior forest habitat. In fact, the soil surface temperature in the forest habitat rarely reached 20°C and never was over the salamanders' critical thermal limit of 30°C. When the canopy was removed, the substrate beneath the cover boards dried very  30  quickly. The terrestrial-breeding salamanders would likely have to use large pieces of well-decayed coarse woody debris to maintain suitable microclimatic conditions, or migrate into the substrate. Therefore, the size and thickness of the cover boards used in this study became ineffective as habitat after harvesting had occurred.  Movement distance and rates The distance and rate of movement in forested and clearcut habitat were uninformative in determining whether the salamanders showed compensatory movement in response to forest harvesting. For the aquatic-breeding salamanders, the size of the trapping grid was inappropriate to examine whether movement distance changed between the two habitat types. Both northwestern salamanders and rough-skinned newts are capable of moving several hundred meters during their breeding migrations (Blaustein et al. 1995) and therefore can easily move across the 50 x 50 m trapping grid used in this study. Thus, mean minimum distances moved reflect distances between traps rather than how far the salamanders can travel during their terrestrial movements. For the terrestrialbreeding salamanders, the movement distance should provide insight as to whether the animals showed compensatory behaviour and thus support the vertical migration hypothesis or the emigration hypothesis. However, recapture rates of the terrestrialbreeders were too low in clearcut habitat to provide further support for either hypothesis. Similar problems were encountered when analyzing movement rates of the salamanders in forest and clearcut habitat. No information is available on movement rates for any of these species in either forested or clearcut habitat making it difficult to speculate whether changes in movement rates after harvesting were, in fact, real behavioural changes or just due to an artifact of sampling and low samples size.  31  Growth rate As predicted, the growth rates of northwestern salamanders, ensatinas and western redback salamanders were lower in clearcut habitat compared to forested habitat. Although there has been some speculation that alteration to amphibian microhabitat by forest harvesting may affect the foraging opportunities and thus body condition of terrestrial salamanders (Petranka et al. 1994a; Harpole and Haas 1999), this is the first study that has documented a reduction in body condition in response to harvesting for aquatic and terrestrial-breeding salamanders. Other researchers have examined both directly and indirectly the effects of forest harvesting on amphibian growth rates but with mixed results. Chazal and Niewiarowski (1998) used an enclosure experiment to examine harvesting effects on various individual traits, including growth rate of juvenile mole salamanders {Ambystoma talpoideum). While no significant differences were observed, individuals in clearcut enclosures lost slightly more weight than juveniles in forested enclosures. As well, females in clearcuts had smaller clutch sizes with lower egg lipid content compared to females in forests. Populations of western redback salamanders in clearcuts had snout-vent lengths skewed toward smaller size classes when compared with to mature forest in one year of study but not the other (Grialou et al. 2000); no such skewness was observed in snout-vent length size classes for ensatinas in this study. Similar to my study, Dupuis and Bunnell (1999) found no relationship between size classes and forest age for western redback salamanders. In my study, growth rates were measured by changes in body mass and not snoutvent length. Thus the differences in growth rate between the two habitats can be  32  attributed to growth via the addition of new tissue, differences in hydration levels by individuals in the two habitats, or both. Water makes up 70 to 80% of amphibian body mass (Duellman and Trueb 1986) and salamanders can lose over 40% of their weight via dehydration before they die (Stebbins 1954; Ray 1958; Rosenberg et al. 1998). The mass lost via dehydration can be quite significant in a very short period of time depending on the size of the animal (e.g. Feder 1983), relative humidity (e.g. Dumas 1956; Spotila 1972), temperature (e.g. Dumas 1956; Spotila 1972), and wind speed (Stebbins and Cohen 1995). For example, ensatinas lost 8% of its mass per day in a bare microlandscape compared to only 2% in a vegetated corridor (Rosenberg et al. 1998). The removal of the forest canopy affects the microclimate by decreasing relative humidity, increasing temperature extremes (both hot and cold), and increasing wind. Thus, except under optimal environmental conditions, an active salamander in a clearcut it is likely to lose more mass via dehydration than an individual in the forest; this would explain differences in growth rate between the two habitats. If foraging opportunities are reduced on clearcuts due to increased dehydration rates, the long-term consequence is an actual reduction in growth rate (i.e. new tissue produced). The lower body condition observed for the northwestern salamander, ensatina and western redback salamander from the clearcuts in this study might reduce overall fitness of individuals. In amphibians, including neotenous northwestern salamanders (Eagleson 1976), ensatinas (Stebbins 1954), and western redback salamanders (Peacock and Nussbaum 1973; Ovaska and Gregory 1989), the number and size of eggs are positively related to body size. Therefore, any changes to the habitat that slow the growth rate of the salamanders potentially has a number of fitness consequences including increased  33  time to maturation, lower egg production, and increased time between successive clutches. Changes to any or all of these factors influence the number of new recruits into the population and the time to recovery after harvesting.  Efficacy of riparian buffer strips Due to the physiological requirements of amphibian species, it has been suggested that riparian areas provide optimal habitat for amphibians (Bury 1988; deMaynadier and Hunter 1995; Dupuis etal. 1995; Waldick 1997; Bunnell et al. 1999; Davis 1999). Humidity and temperature are two important factors determining the distribution of many amphibian species (Spotila 1972); higher humidity and lower temperatures are often associated with streams (Brosofske et al. 1997). In this study, stream proximity did not appear to affect the spatial distribution for any of the salamanders before harvesting aside from the ensatina, which was captured proportionally more often beyond 30 m from the stream. However, as predicted, the proportion of captures within 30 m of the stream increased in the buffer treatments for the northwestern salamander, rough-skinned newt and western redback salamander after harvesting. Thus, riparian buffers appear to be beneficial in maintaining the amphibian component of terrestrial vertebrate biodiversity. Similar to this study, a number of studies have captured ensatinas more often in upslope habitat (M Comb et al. 1993; Gomez and Anthony 1996; Vesely 1996; Cole et c  al. 1997). At the stand level, ensatina abundance is also correlated with dry forests in Washington and Oregon (Bury and Corn 1988; Corn and Bury 1991; Gilbert and Allwine 1991); the line furthest from the stream in my study also tended to have the lowest amount of soil moisture. These results suggest one of two things: ensatinas are adapted to drier forest conditions compared to the other forest-dwelling salamanders, or are  34  competitively excluded from the more optimal riparian habitat by other amphibian species present in this zone. This greater relative abundance upslope may, in fact, make it more susceptible to harvesting practices because proportionally more of its population would be impacted outside the buffer. However, Vesely (1996) recorded higher densities of ensatinas on sites with increasing buffer width size from narrow (<20 m) to wide (>40 m), compared to harvested sites which indicates maintaining wide buffers around streams may still be an effective strategy in mitigating the effects of harvesting on ensatina. As for the remaining species, other researchers have reported inconsistent results when examining salamander spatial distribution with respect to stream proximity in forested stands. No information is currently available on the spatial distribution of the northwestern salamander in headwater riparian areas with which to make comparisons; in this study it did not appear to have any preference for the riparian zone. For the roughskinned newt and western redback salamander, both species have shown inconsistent distributional patterns associated with streams with some researchers recording higher abundances along streams (e.g. Dupuis and Bunnell 1995; Gomez and Anthony 1996; Vesely 1996), and others no change from the stream to various distances upslope (e.g. McComb et al. 1993; Dupuis et al. 1995; Vesely 1996; Cole et al. 1997). This discrepancy in results may reflect a difference in the scales, the sizes of the streams, or environmental conditions in the various studies. Although the northwestern salamander, rough-skinned newt, and western redback salamander may use riparian habitat, the conditions found in the riparian zone are not critical for the salamanders to meet their life history requirements in intact forest.  35  Few studies in the Pacific Northwest have examined the effectiveness of riparian buffers in maintaining terrestrial amphibian populations. Vesely (1996) observed that populations of rough-skinned newts and western redback salamanders persisted at least five years postharvest in riparian reserve zones, with wide buffers (> 40 m) containing approximately two times the density of salamanders as narrow buffers (< 20 m). However, he did not collect pretreatment data to determine how the spatial distribution may have changed from pretreatment to posttreatment, nor did he explicitly compare capture rates of salamanders within three buffer classes to upslope clearcut habitat to allow for any spatial comparisons. Cole et al. (1997) used a before-after-control-impact (BACI) design similar to my study. Results from Cole et al.'s study are equivocal, however, due to the large amount of variation in the data set, so no strong inferences about potential shifts in distribution or behaviour could be made for any species captured. In my study, selection for forested habitat is one explanation for the apparent shift in spatial distribution from pretreatment to posttreatment in the buffer and clearcut treatments. There is evidence to suggest that some aquatic-breeding amphibians are capable of selecting their movement pathways. Semlitsch (1981) found the mole salamander (Ambystoma talpoideum) preferred to move through corridors of hardwood vegetation rather than open, grassy areas when migrating from their breeding sites. In another study of the mole salamander, there was a net displacement of migrating salamanders away from the clearcut side of the pond toward the forested side of the pond (Raymond and Hardy 1991). In addition, wood frog (Rana sylvatica) metamorphs selected forest rather than cleared habitat upon commencement of emigration from their artificial breeding ponds (deMaynadier and Hunter 1999). Finally, when Pacific giant  36  salamanders (Dicamptodon tenebrosus) were placed on the forest-clearcut interface, six of seven salamanders moved into the forest (Johnston 1998). Others have observed no selection of vegetated or forested habitat for movement, although the surrounding habitat was unaltered in these studies (e.g. Douglas 1981; Dodd and Cade 1998). The shift in the distribution of the two aquatic-breeding salamanders in this study may reflect selection for the forested habitat over the clearcut habitat during their breeding migrations irrespective of stream presence. The abrupt edge of the forest-clearcut interface may act as a reflective barrier, increasing directional movement through the riparian buffer (Rosenberg et al. 1997). This increased directional component to their movement may be important to increasing survival of individuals within the buffer (Rosenberg et al. 1997). Studies that track individual movement patterns during the salamanders' breeding migrations are required to determine if selection for the buffer is occurring. The buffer strips may be of even greater importance to juveniles of the aquaticbreeding salamanders. Over 80% of the juvenile northwestern salamanders were captured in the riparian zone of the buffer treatment, compared to only 40% in the controls and clearcut respectively. deMaynadier and Hunter (1999) also observed greater selection for forested habitat by juvenile wood frogs and mole salamanders during emigration over clearcut habitat compared to adults. This selectivity may be due to the greater risk of desiccation faced by the juveniles. Juvenile amphibians are considered the dispersing portion of the population (Duellman and Trueb 1986). However, upon initial metamorphosis, movements from the natal pond tend to be restricted due to physiological constraints (Semlitsch 1981), i.e., juveniles have larger surface area to volume ratios relative to adults. Moreover, the timing of the juvenile movements often coincide with  37  the hottest, driest times of the year which makes them particularly vulnerable to desiccation (Watney 1941; Snyder 1956; Eagleson 1976; Semlitsch 1981, 1998; Duellman and Trueb 1986; Stebbins and Cohen 1995; deMaynadier and Hunter 1999). For these reasons, juvenile salamanders emigrating from the pond after metamorphosis may be more discriminating in their movement pathways to minimize their risk of mortality due to desiccation. The habitat contrasts between forested and clearcut habitat may be greatest in the summer months as the salamanders metamorphose. Ground temperatures never reached lethal limits under the forest canopy in the summer but did so numerous times in the clearcut habitat creating a strong microclimatic gradient across the forest-clearcut edge. In contrast, the greatest activity of adults occurs in the mild conditions of spring and fall, when the microclimatic gradient is weaker so adults may not have to be as selective in their path of movement. It is possible the greater proportion of captures occurred in the buffer because juveniles located in the clearcut habitat died; this possibility cannot be ruled out with the available data. Due to the small home ranges and high site fidelity of plethodontids, it is likely the buffer would not act as a corridor for movement but would rather function as an area of population refuge until the adjacent clearcut has recovered to provide better habitat. Currently, there is only limited evidence to suggest that plethodontids are capable of moving between habitats after harvesting. As mentioned previously, Waldick et al. (1999) reported a great influx of redback salamanders (Plethodon cinereus) in pitfall traps located adjacent to a recent clearcut and suggested this was due to mass emigration of these salamanders from the disturbed area. Although the movements of the redback salamander were not being investigated specifically, this observation provides indirect  38  evidence that plethodontids may show some behavioural plasticity in response to the disturbance. The increased capture rates in or near the forested habitat in the buffer and clearcut treatments in this study also suggest individuals of western redback salamanders are emigrating from the clearcut into the surrounding forested habitat. However, this apparent shift in spatial distribution toward forested habitat may be due to differences in the activity pattern of western redback salamander and cannot be distinguished from mass movement.  Management implications Although the responses of the four species to forest harvesting are inconsistent, one important fact remains; they are all still present on the sites one year after harvesting. This study along with other studies (e.g. Ash 1988; Cole et al. 1997; Harpole and Haas 1999; Grialou et al. 2000) indicates actual mortality from the physical process of logging may be limited. In previous studies, the lower abundance of these salamanders in clearcuts likely occurred in the years after harvesting, although the mechanism of the response is still unclear. The reduced growth rate observed for three of my four species indicate dehydration rates and/or foraging opportunities are lower for individuals in clearcuts. The presence of 30 m wide buffer strips around headwater streams appears to be an effective strategy in mitigating the effects of forest harvesting on terrestrial salamanders. Three of the four species of salamanders in this study increased in relative abundance in the buffer zone after harvesting in the riparian treatment. Thus, while these salamanders are all capable of recovering with the return of canopy cover as indicated by their abundance in second-growth forests from pretreatment data in this study and others (e.g. Dupuis et al. 1995; Ash 1997), managing for habitat elements such as downed  39  wood, understory and overstory cover, and riparian areas may quicken terrestrial salamander recovery on harvested sites. This may be particularly important as managed forests within British Columbia begin to enter their second rotation. A typical 60-80 year rotation is not long enough to develop the same structural characteristics of older forests (snags, large old pieces of downed wood, multi layers of canopy). Coarse woody debris (CWD) is an important structural attribute to amphibians but the biological "legacies" that still remain from previous old-growth are being broken down and are not being replaced (Maser et al. 1988; Hunter 1990). It is unknown what factors may limit salamander populations but the lack of large, old pieces of C W D may serve to limit the density of salamanders in second-growth forests. Recent research suggests less intensive harvesting methods, such as thinning, may minimize changes to their habitat and microclimate that may enable the salamanders to persist after the disturbance (Messere and Ducey 1998; Brooks 1999; Grialou et al. 2000; but see Harpole and Haas 1999), as well as provide sources for new input of CWD. Future research should consider the mechanisms and scales of impacts on terrestrial salamanders from logging. The mechanisms underlying population-level responses to logging require tracking individual salamanders to provide information on behavioural changes to differentiate between the vertical migration hypothesis and the emigration hypothesis. Also, sampling methods and scale of future studies should take into account differences in life history characteristics; for example, the same scale likely can not be used for aquatic- and terrestrial-breeding salamanders. In addition, past research investigating the effects of forest harvesting has ignored the of role aquatic breeding-habitat in affecting amphibian abundance. To determine forestry effects on  40  aquatic-breeding salamanders, changes in abundance due to aquatic-breeding habitat must be distinguished from changes in abundance due to terrestrial habitat alterations. Experimental designs should focus on the breeding site in conjunction with the surrounding upland habitat as experimental units.  41  Table 1. General description of site characteristics before harvesting.  Control Mike Area of watershed (ha) Area of watershed harvested (ha) 0 Elevation (m) 300 10.67 Mean PAR (u.E/m /sec)' Understory vegetation (mean % cover) 20.78 Moss (mean % cover) 38.11 Litter (mean % cover) 59.72 Volume of C W D (m /grid) 121.33 Distance to nearest large pond (m) <500 PAR = photosynthetically active radiation 2  3  30 m Buffer  Spring  0 350 28.67 14.94 50.83 46.39 146.3 >500  H 28.2 1.6 230 38.33 29.61 55.00 36.00 138.7 >500  SCK 18.6 1.9 250 4.18 5.24 11.88 89.12 74.12 >500  Clearcut B 13.5 1.9 120 20.33 14.17 56.11 37.78 43.16 >500  I 12.6 2.2 260 9.33 7.33 16.22 82.50 95.94 <500  1  42  Table 2. Trapping schedule including total number of nights the traps were open for each session.  Pretreatment  Posttreatment  Trapping Sept-Nov 1997 Feb-July 1998 Oct-1998 Oct-Nov 1998 Mar-June 1999 Oct-Nov 1999  Control Mike Spring 12 12 88 88 56 95 39  56 95 40  30 m buffer H SCK 12 13 88 89 56 95 41  0 95 38  Clearcut B I 13 13 89 92 26 0 56 95 95 39 41  43  Table 3. Percentage of days that temperature was recorded above 20 C and 35 C before and after harvesting during July and August of 1998 (before harvesting) and 1999 (after harvesting). Temperature loggers were not available for all sites in 1998 so only those sites with loggers are recorded.  Site Control  Mike Spring  Buffer  H  SCK  Clearcut  B  I  Distance from stream (m)  Pre Days (% ) Days (%) >20 °C >35 °C  Days (%) >20 °C 2 2  Post Days (%) >35 °C 0 0  5 30 55 5 30 55  19 N/A N/A 24 30 30  0 N/A N/A 0 0 0  24 82 76 43 N/A 56  0 65 31 0 N/A 0  5 30 55  8 6 6 N/A  0 0 0 N/A  21 84 35 87  0 68 0 76  44  Table 4. The number of soil samples collected before and after harvesting at each site.  Pretreatment Posttreatment  Control Mike Spring 3 3 8 8  Buffer H SCK 3 3 8 4  Clearcut B I 6 3 4 8  45  Table 5. The total number of amphibians captured at all sites combined by species and the number of sites where each species was present (includes recaptures). Species Salamanders Ambystoma graciles Ambystoma macrodactylum Ensatina eschscholtzii Plethodon vehiculum Taricha granulosa Anurans Ascaphus truei Bufo boreas Hyla regilla Rana aurora  Common name  Northwestern salamander Long-toed salamander Ensatina Western redback salamander Rough-skinned newt Tailed frog Western toad Tree frog Red-legged frog  Total 3548 1690 59 571 734 494 419 165 205 2 47 3967  Number of sites where captured 6 6 6 6 6 6 6 1 6  46  Table 6. Repeated measures analysis of variance on numbers captured/100TN showing the between-subject effects of treatment and within-subjects effects of time and time*treatment on each species by different trap type. A M G R - Northwestern salamander; T A G R - Rough-skinned newt; E N E S - Ensatina; P L V E - Western redback salamander. B e t w e e n subjects effects Species Trap type AMGR Array TAGR Array ENES Array ENES Cover board PLVE Array PLVE Cover board Within subjects effects Species Trap type AMGR Array TAGR  Array  ENES  Array  ENES  Cover board  PLVE  Array  PLVE  Cover board  Independent variable Trmt Trmt Trmt Trmt Trmt Trmt  DF 2 2 2 2 2 2  F 0.67 0.66 0.99 1.43 0.67 3.12  P 0.576 0.581 0.468 0.367 0.574 0.185  Independent variable Time Time*Trmt Time Time*Trmt Time Time*Trmt Time Time*Trmt Time Time*Trmt Time Time*Trmt  DF 1 2 1 2 1 2 1 2 1 2 1 2  F 1.86 1.17 1.80 1.23 2.55 0.65 22.43 6.90 17.70 3.52 6.84 1.76  P 0.266 0.422 0.273 0.406 0.209 0.583 <0.05 0.075 <0.05 0.163 0.079 0.312  47  Table 7. Repeated measures analysis of variance on numbers captured per 100TN within 30 m of the stream showing the between-subject effects of treatment and within-subjects effects of time and time*treatment on each species. A M G R - Northwestern salamander; T A G R - Rough-skinned newt; ENES - Ensatina; P L V E - Western redback salamander. Between subjects effects Species AMGR TAGR ENES PLVE  Independent variable Trmt Trmt Trmt Trmt  Num D F 1 1 2 2  Den D F 2 2 3 3  F 0.48 1.90 0.04 0.74  P 0.56 0.30 0.96 0.55  Num D F  Den D F 2 2 2 2 3 3 3 3  F 1.08 0.10 1.68 0.00 7.97 1.66 1.76 6.65  P 0.41 0.78 0.32 0.96 0.07 0.32 0.28 0.08  Within subjects effects Species AMGR TAGR ENES PLVE  Independent variable Time Time*Trmt Time Time*Trmt Time Time*Trmt Time Time*Trmt  1 1  1 1 1 2 1 2  48  Table 8. Repeated measures analysis of variance on the proportion of captures moving parallel to the stream showing the between-subject effects of treatment and withinsubjects effects of time and time*treatment on each species. A M G R - Northwestern salamander; T A G R - Rough-skinned newt; ENES - Ensatina; P L V E - Western redback salamander.  Between subjects effects Species Independent variable AMGR Trmt TAGR Trmt ENES Trmt PLVE Trmt Within subjects effects Species Independent variable AMGR Time Time*Trmt TAGR Time Time*Trmt ENES Time Time*Trmt PLVE Time Time*Trmt  Num DF 1 1 2 2  Den DF 2 2 3 3  F 6.83 0.13 0.97 0.01  P 0.12 0.75 0.47 0.99  Num DF 1 1 1 1 1 2 1 2  Den DF 2 2 2 2 3 3 3 3  F 126.07 4.34 27.27 23.36 3.27 3.98 1.23 2.13  P <0.05 0.17 <0.05 <0.05 0.17 0.14 0.35 0.27  49  o in  S rt CU N O C  03  .CJ  S3  c  4 -—1  -a  3  es  1 ^ .s >  Q « bo  .5 -5 to >  cu ^  a  CO S-  "a  <  > <—  o  CO  6X  C ITS  cu cu o 03 CO CU  CJ •St  ? —> -> C3  -G O  03  H  S  -t—»  *- £ ii co O S ii c Zi o & "3 c  °5 5 CU O co  •£  c  <o  c<j  CO  § in is x>  £ . 3 13  "3  OX) fi  03  c  CU 03 o  Td  o <u o3 rt l-H CO H-J -HH  ITS CU cu |J5  O •H-i  a c  .CJ  cj  2  CS  cr  \< §  ^  6 £ cu  co C CD \ 3 OH  C  OO c3  4-H  xCU : xs £ o  X)  i2  CU OH  CU  3  CU O  ^  a rt  g  £  T3 C X> -O  ^ .2  rt "C C rt  P C  00  >  CO <+-H  rt  es XO!  rt rt3_ > cu > CU  o  CU  ?  > o  I Ii E  O UOH t3 i= OH 2 o3 cu rt  Riparian Management Research Trial U B C Malcolm Knapp Research Forest  Watershed I Watershed H  Watershed G Watershed D  Watershed Sck Watershed E Watershed F  Watershed C Watershed B " Watershed A  Figure 1. Map of harvested sites included in the riparian management project. The sites used in this study include: 30 m buffer sites: H, SCK; Clearcut sites: B, I.  51  5m Legend  30m O  55m  Single pitfall Cover board  ^X^ Pitfall array  Figure 2. Arrangement of trapping grids designed to determine terrestrial amphibian abundance, patterns of movement and spatial distribution relative to the stream. Enlargement at right illustrates design of a single pitfall trap array and arrangement of pitfall traps.  52  Stream  D  O  O  D  o  m  A o  ni  Q CD  D  o  CD  D  O  Q CD  LCD 5m  Legend  D  o  CD 30m  O I I  Single pitfall trap Cover board  ^X^  Pitfall array  55m  Forest edge LZD  Forest interior  • Traps included in analysis r—• ! Traps added after harvesting  Figure 3. Arrangement at SCK (30 m buffer site) trapping grid after harvesting including additional traps added. Traps that received the expected treatment and therefore included in the analyses are enclosed in bold lines.  Legend  Stream  O  Single pitfall trap  1-^ Cover board  25ln  D  X  j  o  Pitfall array  j Traps included in analysis  __ i  ; Traps added after harvesting Forest edge Forest interior  D  o  •  o  CD  5m  30m  55m  Figure 4 . Arrangement of site B (clearcut) trapping grid after harvesting including additional traps added. Traps that received the expected treatment and were therefore included in the analyses are enclosed in bold lines.  54  14  A. Northwestern - Pitfall Arrays  2  Q  B. Rough-skinned newt - Pitfall Arrays  => Pretreatment  12  Posttreatment  10 8 6 4 2 0  O)  C. Ensatina - Pitfall Arrays  4  H  3  t3  2  4  D. Ensatina - Cover Boards  E. Western redback - Pitfall Arrays  Control  Buffer  Clearcut  F. Western redback - Cover Boards  Control  Buffer  Clearcut  Figure 5.  Mean number of salamanders captured per 100 trap nights (± SE) before and after harvesting in control, 30 m buffer and clearcut sites (N=2). Recaptures are excluded from all relative abundance estimates.  55  50  ^  45  TJ  9>  35  £  30  O  A.  24 89  ±  <D  0  1 S  25  22  20  .24.1  10  AMGR  TAGR  ENES  PLVE  AMGR  TAGR  ENES  PLVE  Species Figure 6. A. Mean movement distance (m ± SE) and B. rate (m/day ± SE) of four species of salamanders captured and recaptured in forested habitat or clearcut habitat. Sample size is given above each bar. The species include: A M G R - Northwestern salamander, T A G R - Rough-skinned newt, ENES - Ensatina, P L V E - Western redback salamander  56  45  A. Northwestern salamander  y.  10  B. Rough-skinned newt  40  8  35 30  6  25 20  4  15 10  o  5  CD  0  CX CD  2  0 25  10 20 30 40 50 60 70  1250  C. Ensatina  0 45  10 20 30 40 50 60 70 80 90  D. Western redback salamander  40 20  35 30  15  25 20  10  15 10  5  5  :  0  0  0  10 20 30 40 50 60 70 80 90  0  10 20 30 40 50 60 70 80 90  Distance moved (m) Figure 7. Frequency distribution of minimum distance (m) moved.  57  0.06 0.05  1 Forest 3 Clearcut  -\  0.04 c o  E  DC  i  0.03 0.02  CD CC  7 12  13  -|  0.01 0.00  o -0.01 -0.02 -0.03  AMGR  ENES  PLVE  Figure 8. Mean growth rate (g/g/month) of adult salamanders recaptured in forested clearcut habitat. Sample size is given above each bar. A M G R - Northwestern salamander, ENES -Ensatina, P L V E -Western redback salamander.  22  A. Northwestern salamander  20  18  16 14  12 3.4  B. Ensatina  3.2  3.0  2.8 2.6 2.4  2.2 i C . W e s t e r n redback salamander 2.0  1.8  1.6  1.4  1.2  Initial  Final  Figure 9 . Comparison of initial mean weight and final mean weight (g) of salamanders recaptured in forest habitat and clearcut habitat. Error bars are ± SE. A. Northwestern salamander (Forested N=7, Clearcut N=6), B. Ensatina (Forested N=12, Clearcut N=5), C. Western redback salamander (Forested N=13, Clearcut N=4).  59  A.  0.4  -I  0.3  H  Ensatina  0.2 H  |1  0.1 o o.o g  <0.60 0.60- 1.80 1.80-3.0  > 3.0  ] Forest ] Clearcut  O  B. W e s t e r n redback s a l a m a n d e r  PT  o.4 -i 0.3 ^  0.2  1  0.0 <0.80  0.80- 1.4 1.4-2.0  > 2.0  Size classes (g) Figure 10. Size-class distributions of A. Ensatina and B. Western redback salamander in forested and clearcut habitat.  60  : <30 3 >30  20 10 H-  AMGR  TAGR  ENES  PLVE  Species  Figure 11. The percentage of captures within 30 m from the stream vs. upslope before harvesting (N=6). A M G R = Northwestern salamander, T A G R = Rough-skinned newt, ENES = Ensatina, P L V E = Western redback salamander.  61  A  Northwestern salamander - adults  C . Ensatina  B , Rough-skinned newt  D . Western redback salamander  11  T _JC_  Control  Buffer  Clearcut  Control  Buffer  Clearcut  Figure 12. The mean percent of captures (± SE) within 30 m from the stream after harvesting (bars) and the mean change in the percent of captures (± SE) within 30 m of the stream from before to after harvesting (lines). For the aquatic-breeding salamanders, means are calculated for control (N=2), buffer (N=2), and clearcut (N=l) treatments. For the terrestrial-breeding salamanders, means are calculated for control, 30 m buffer, and clearcut sites (N=2). Positive values indicate the proportion of animals captured within 30 m from the stream increased after harvesting and negative values indicate that the percentage decreased after harvesting.  62  100  A M G R - juveniles J < 30 m i > 30 m  80  60  40  20  0 Control  Buffer  Clearcut  Figure 13. Mean percent of captures (±SE) of juvenile northwestern salamanders within 30 m vs. greater than 30 m of the stream after harvesting in control (N=2), buffer (N=2), and clearcut (N=l) sites.  63  70 60  _L  i  i  Parallel  I  i  Perpendicular  _I_  50  03 O  I  40 30 20 10 4 0 -|  •  |  A M G R  I  I  [il I  T A G R  I  |  E N E S  I  I  | - I  |  P L V E  S p e c i e s  Figure 14. The mean percentage (± SE) of salamanders moving parallel to the stream perpendicular before harvesting (N=6). A M G R = Northwestern salamander, T A G R = Rough-skinned newt, ENES = Ensatina, P L V E = Western redback salamander.  CO  XCU  00  cU <U s p  5 6 rt* ^  co CU  c zs rt rt  co 00  o o  rt Tcu 3 c 3 rt rt rt CO 00  IU31U3AOUI |a||Bjed u; aBueuo a6eiuaojad o oo  o co  o  o  o oo  o  CD  o  o  C\i  C  o  CM  s  H  CO  T3  rt  r-  -9  3  CU co CU  rt CU o o rt rt 3  3  3  rt co  £ C rt X) O X X > g < ^-^ rt 00 cu 2 o c U C XI is rt t-c co O . CU O CU CU c3 u CU X < S i X! o c u X! co rt T3 CU 3 a C cu rt bJ3 _ 00 rt co fi E s 3 <P ^ 0O  «  „s  00  w  3 rt \n CU co "rt 2t* H CU oo > 2 «u ja •sC_U rt S-H O cU 'co 3  O XJ  Oh OH Q  3  'I cE -?3  E  ffl  +1  a>  *^  +-»  CU /~\ rt CN O II '-3 Z fi  •ti J2 'oo 13 3  >  UH  >  O " CN 3 -xi IIrt rt t> rt  cS^  cu  UH  3  3 ,  ,  .4-" rt T3 .  „  3  rt rt o BI-, bo o rt ^  OH CN  X to  c •S z 3 CU CJ  E j>  O  rt  c3u +ffl'75 m x rt 1 3 ra  cu Xcu 6uj)saAjei| jaye uieajis am oj |a||B4ed 6ujAoui sajnjdeo jo juaojad  IT) rH  CU 11  w  O  co o O 2 >- is fa OU T3 CO 3 ,° O C UH  rt  Q  3  CJ  OXi3  rt  u <2 c u. o CU _ e  -  6  s CU ^ _CJrt is(U •-• CU cj CO DH rt UH  80 i A. Control 70 60 50  i  40 30 20 80  B. Buffer  70 60 50 -I  Pretreatment Posttreatment  40 30 20 80  C. Clearcut  70 60 -I 50 40 -I 30 5 m  30 m  55 m  Distance from stream (m) Figure 16. The mean water content (± SE) of the soil as a percent of soil dry weight.  66  LITERATURE CITED Alford, R.A. and S.J. 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Prentice-Hall, Englewood, N.J.  74  in ,—  C N ON o—^ CN CN CN  3  a  VO oo m o o— ' d o ^—• ,—> VO y— m d d 1  00  PQ  >  CO CN ON co oq co UO CN o w o  VO o d VO o  ON  3 vo oo VO CN d d rt OO CT\ CN d d  Hi  C O  16  co* 0)  rt  1  o o  oo +1, D > O  c  0 CN d _ O, is- 0 O N VO 0 CN d d  o  ON  d d ON  oo  d d  vq in rvo vd  o  o o o o  w  CO  CN oo  O  ON  rt  00 ON  00  CN  1  CO  ro rt  ^>  O* VO* 0 0 * VO rt O N * C ON O CN in 0 d d •ri d Cd ON 0 vo vo O N 0 O ro m 0 O CN d rt d CN CN d  ON  ON*  p vd co O O O oo d in  rt oo rt O N ~ p oo 00 CO t~ vd CN d d zi, o o d o CN rt O O O O w CN vo CN vo f-; rt in vq m ON 00 ^t d d d >n ro 00  u PH  ON  v  o CO  cn  . \  rt  VO  <ZZs w  VD VD O O O O  o* f^* CO rt*~ G* >/-) o vo 0 0 as i—i o d „ d „ rt'*—' rt'— ' o —' o O O O w o w O —i CO o o C O vO oo ,*— 1 CN CO o o oo O CN iri mi d CN d rt CO w  vo vo ^ o o c 0 0 i>  PH  d  00  CO  VO* o d o VO o d  rt ro d rt VO rt  vo o d vo O d  o CN CN d d ro O N ro —> d d 00  G* 0  vo* O S 0 d VO vo 0 0 d d VO O N 0 0 O O CO o d d vo r~ r~ O rt VD o d d  .to  s  T3 C 3 O •_  -  «  a  c  c co 00  c c  o  E  B o  o  •2  I-  00  S3  O  to  S5  <3  05  s |  S c  •3  s s •Si c «3  § s S .2 VJ  5  to  c o  a  2 S •£*  to  <3  s  a  S .VJ & s to >>- a 3 55 vi % v5  £ M cd cd CO rt cn rt A c d r> -a "2 6^ c C CO CW - CO cd " CO 3 rt Id u p a, B 0 0 cd o c % c CO CD O feb I H rt bj) — C O 3 co "3 O 3 td .« PP PP PP Q o u , cd i i ffi ffi 1—1 J  to  a  s  to  C  W) -*—»  c §  .s So s  •S -2 a c v>  u  Da  o  IT)  c. d d  w  c  vo  vo oo in CN CN d  >  Cm  ON  r-~ c~~ CN rt  ci d  oo o c d CO CO  oo CN| iri d  rt  CO  ro  co W) CO  >-l OJ  rt rt  CM  rt h rt rt rt  O  ON  00  oo  Prese  co  <D o  IO  00 VO O o o O ^ O O O VD VO O m d CN  iri  oo CN d oo CN d  C 00 C Ow "3 D •St-  vd rt r-  IPP  co T3 c 3  rt  r~ vo CO  c  CN  VO rt 00 C N vo r~ o oo  vo V O CN IT) in c O VO O, rt CO d o o VO OO CO vo o o in CN d CN Cm d  vo O d u CO O O O O vo 00 0 0 o CN  c c co d CO O cn w o C CO uO . CN P H OH CN d  d vo O0  cd co  10  rt OV O ON ^ CN co C N o o o  CN c CN co PH vo CN  s  co 00 >• cd CO cd c o o rt s c  5  .to  s ^ •a ^  a o .2 §a, t-H  s °  1 5 -« s s 3 3  OS  CO *td CO CO  £ s  S s a  fc  E tS •a o o  to  « .2 to 3  t5 Ei; o o  CO CO  rt  rt  E  CO c CO rt t/3 cd  cn  Appendix 2 . Harvesting schedule for each study site. Note control sites have no harvesting. Treatment  Site  Control  Mike Spring H SCK B I  30 m Buffer Clearcut  Cutblock area (ha) N/A N/A 1.6 1.9 1.9 2.2  Harvesting system  Start date  End Date  N/A N/A Ground Skyline Skyline Ground  N/A N/A Aug 10/98 Oct 19/98 Nov 2/98 Aug 10/98  N/A N/A Sept 4/98 Jan 14/99 Feb 5/99 Sept 11/98  76  ON ON  I  rt PU  b4g^  CU  UH  u  CM oo  ON  CU  C4Xt  HO  co  cU  O  -a  UH  CU  -D  UH  03 O  CM  s 00 3  X> UH  cu > o u  PQ  rt  xt c  Ph  CO  ON ON  <4-H  rt  rt  >^ rt  Ph ON ON  UH  UH 'SH  rt  -a  CU  T3 CU  UH  co CU  CU  VO  r- VO •<cr o o ON q o vd o d  m VO m o CN o o o d d d d d d  VO m o o oo m O CN d d d d d  00 CN  •sr r-- co rt CN 00 co co CN in in CN 3 CN  in m o o CN d d d  rt m o CN o 3 d d  in VO ON rt VO o m VO CN VO d d d 3 d  in o q CO vq d  ON CO vo CN IT; CN CN o d d CN ^  CN VO OO O o o o o o o d d d d d d  vo ON m O oo in m CN CN d d d d d  m in rCN CO d d d  CN On CO CN o VO ON ON o vq O d d  o CO o o o o o CN o o o o d d d d d d  On ON OO ON CO rVO CO c-- m 00 q  00 CO CN  CN vo  o CN vq CN d  CN ^H ^H CN CN CN  CN ON oo vo  00 CO ON CN  CN CO cn ON CN CN  r--  o vo 00 CO ^ oo CN CN CN  00  CN ^  c-- co >-h  VD vo  CO  1 1  d  1 1  CN oo  d d d  d  r-  CN  co VD CO  C CN N^ ^  >o ^  CN vo CO  CN vo r-  ^ VD ON  CN  2 ^2  in CN  CO  B  3 3  PH  O  o rt cu CU  E  -4—» DH  cU  CU oo  O O H rt ^ cu  CM  X bO  3 .S § 1  a > «< rt  <, -3  —'  vo  CN  CO  ON  2  CN  (N ^ O CO VO — CN - H  co ^ t  rt  OX) CU CU  >5  •4—1  OO  on —  ^  3  °  H  CU . _ .  O _  00 hh 00 Oh  2  bO  3  bO  3 £ "£ CU  00 ffi OO Oh  CU  2 oo Pu oo pq  3  00 ffi  co rt UH  3  UH  O £ U cu  _• H—»  rt  -H  Ph  3 rt C o > 43 •n ^u rt 3 UH 3 3 c u rt * J "3  o  ON  UH  3  CO co oo m 00  CO  CU  CO  ON ON On CN CN  co o c-•<cr vo  UH  'o cu  HO  CM  § o  UH  vo in vo d d d d d d CO VO  3 00  O  O  ON CN CO o o d d d d d d  o 00 o  CU  CUH  r- o vo m o 00 in 00 o ON VO d d d CO  DH  rt CUH  3 .23 rt {V '3 i * <->, CO  "rt oCoM00  ^ <  .CU  O UH  pq  3  3  urt  3  O c o U  <  UH  3 PQ  rt CU  U  3  O U  CUH  3  pq  O UH rt cu U  o UH  H—»  3  o u  00  pq  pq  - H  PJ  > Ph  3  pq  o in CN co  >n o  in  VO >n vo CN CN m ON CN CO d d CN d  ON  vo d  ON m VO CO oo CN co oo rt oo d d d d d CN  ^1- rt o o •<* o o o d d d d d d  o vo o o o o rt o d d d d d d  o o o o vo o o o o •— d d d d d  m m o CN o d d d d d d  VO o oo o m o o o rt d d d d d d  o o o o o o o o o o d d d d d  o m >n O O rt o d d  O O O O O O o d d  CO  rt co  o o >n cd o  1  o m O rt d d  VO ON CN CN  ON m o ON -5 CN o in q d d c  m o  VO CN m CN rt d d d  o >n o vo ON m CN CN CN CN O O d d d d d CN  vo o ON o o vo p o O o d d rt d d d  00 CN VO CN vd d  CN vo CO CN VO r- co m d d rt  VO CO vo o o o ON 00 ON O 00 rt cN rt O O O czi <z5 ^ ci ci czi vo r- vo - H rt vo d CN d d d  VO O CN rt CN CN  vo oo rt CN  CN CN VO  CN rt oo rt cN rt  CO CN r -  ON  wo  VO  rt rt  VO CN  rt CO Tj"  ON  ^ CO  M o „ oo CQ  CO  u  CN 00  VO  CN  CN CN  m vo m in rt  r~- m ^ ^t-  CN  rt  CM  u  Pi  O <  d  CO  C d  rt  ON ^  ^  d  rt  <->  !rt  3 CQ  3 U s-.  cd CO  U  VO m m in m ro CO ^t C O d rt rt O rt d  rt ^  ^  in vo ro  rt  CN  CN  co £J co  S  CO  00 ffi  u rt C  o U  rt 3 CQ  CO CU  u  £ ^  2  oo  -xt-  rt  rt  rt co  60  'S  CM ,_I  CO  00 ffi 00  .  PQ  '"S  CM  rt, O  c o U  CQ CQ  i-  H-  1  rt 3 CQ  cd co U  „  2 oo ffi oo CQ  3 O  O Pi  O O O O O O O O O O O O O O O  00 3  3  o  I  o oo CQ  O o o o o o o o o o d d d d d  ro  rt oo co ^ > rt CO CO  m  o o d  rt  rt rt cN ^O  co a  2 oo ffi oo CQ  c o  d  bJO  co 1=  3 O  cd  CN  CN CO  3 o u  rt 3 CQ  3 o  1-, cd CO  u  oo r--  o o d o o  ON ON  o r- o o -sr o o o o o vo o d d d d d d  rt Xi 00  r-- o o o o o o o o o o o d d d d d d  m o o o o o o o o o o d d d d d d  o o o o o o o o o o d d d d d d  o o o o o o o o o o o o d d d d d d  ON ON  -H  CN  c^  UH H—* 0 0  T~<  00  UH  ON  o o o o o o T3 ~3 o d d CD LL  mom o m o o o c<3o o o d d d d  m o O d d  PH  •-H  o o o o d  O O O O O oo O O O O O d d d d d d ON  CU i OH  O O O O O O  CO — CN d d  VO  O O O JH o o o o o -5 o o o d d d d  o  o o co co o o o o o o  00 o o o o  o CO o o o o o d d d d d d  CO CN CO  o o o o o o o o o o o o d d d d d d  o o o o o o o o o o o o d d d d d d  Tfr- OO ^ H VO ~ m  „  c  o CN —'•  VO  3  o o  CJ  o o o m r- o (N CN O O CN + d d d d d d  C3N  UH <D  T  1  UH I O-J  X)  E&  ON  ON  ON  3  o o  < o CO O O O — o CN O O O CN d d d d d d  ON  rt PH ON ON  rt  CN  PH  ON ON  CN  A  T3  S  OJ O0  3  tT O  00  ON  2 ^  m m  CN  CM  vo r-  00  r-  ON  m  rt  PH  oo cu s £ 'E <* 2 oo ffi oo pq  CJ  00 3  <D  CU  H—» 00  § oo ffi oo pq  o UH  o o U  < CH  UH <H-H  pq  3 O UH  rt CO  U  CU  £ '5 HH  *S 2  •4—»  oo  00 3  OH . _ .  oo  PH  3  is  -d  fe o  pq  <*H 3  X> UH CU co > .Sh O 'o CO U  ,«-*  OH 00  pq  u  oo pq  a  3  cj  B rt OJ  CJ  UH 3  pq  rt CU  U  3 O  U 00  W  3  OH  oo  ON  o CO m O o o o oo o o o d d d d d d  o o in o o o o o o o o d d d d d d  o CN o o o On o o o o rd d d d d d  oo o m r- CO CO d d CN  VD o o o rvq CN ' — m o o —« — CN d d d  o o o o o o CN o o o o d d d d d d  o o o o o o o o o o co d d d d d —<  O .03 o o o d 3 d  VD m o cc CN VD O O  VO o o CN  o o o o d d  o VD o rt O ro CN o O d d d 3 d V dO  oo o VO o o o  ON ON o o o r>—*  CN  ^in  r- vo  o o  CN CN  m  «  r - co  2 2  ^  H  1  d  d  CN  ON o o r- p o in d  "—I  —<  O ON o o d ON  3  CN CN  CO  CO  o  CN  in 00 o •<cr' —< vo d  VD  1  d  in o in o  d  <N  oo vo  ON  ^o £  m £  pq  rt CO  U  H  o o o o o o o o o o d d d d d  3 O  U  <H-H  3  pq  O  fe CO  U  ^  Oh  00 CO 3 ^  O  .  ^  2 oo ffi oo pq o 3  UH H—»  O  u  O OH  CO  CN  S oo E oo pq  3  CN  00 CO 3  3 UH  "Cf o o o o o o o o o o d d d d d  ^  2  00  (fl  O  o o o d d d d d  CN  00 CO 3  4-i  o m o o o d d d d d d CO  CN  vO  ffi oo pq  o o d d d  n/a  00 o m 00 VO o vo CO CN d d CN  UH  , 4—I U  3  pq  Oh  ,_,  3  .  3  a  3  rt co  u  O  2 oo ffi oo pq  O  U  co 3  S P* oo  4-H  3  pq  U  rt CO UH  u  O  00  Appendix 4. Summary of tailed-frog results. Results  Total number captured and relative abundance A total 165 tailed frogs were captured in 83,332 trap nights (Table A4-1); they were detected at all six sites. Tailed frogs had very high site to site variation in abundance both before and after forest harvesting with the coefficients of variation in capture rates calculated at 107% and 120% respectively. Sufficient captures for analysis occurred at two sites only: one control site (Spring) and one 30 m buffer site (H). Therefore, these two sites were the only ones considered for comparisons. The relative abundance of tailed frogs before harvesting ranged from 0 to 1.08 captured/ 100TN (Table A4-1); tailed-frogs were not detected at two sites. After harvesting, the relative abundance of tailed-frogs ranged from 0.03 to 0.78 captured/100TN and were present at all sites. At the two sites where tailed frogs were most abundant, sites Spring and H, relative abundance declined by 50% and 38% respectively from pretreatment to posttreatment.  Movement distance and rate In the control site, tailed frogs moved an average (±SE) of 42.86 ± 6.96 m before harvesting (Figure A4-la). Only one animal was captured postharvest; it moved 24.6 m. Tailed frogs moved an average of 23.17 ± 7.10 m in the buffer site pretreatment. Average distance moved increased to 38.17 ± 7.87 m postharvest. The average movement rate (±SE) of tailed-frogs in forested habitat of 12.27 ± 3.48 m was greater than the movement rate of tailed-frogs in the buffer habitat (8.53 ± 5.01) (Figure A4-lb).  Efficacy of riparian buffer strips Spatial distribution relative to the stream Before harvesting, almost 60% of tailed frogs captures occurred within 30 m of the stream in the control site compared to only 40% in the buffer site (Figure A4-2). After harvesting, tailed frog distribution was reversed for the two sites. Only 37% of tailed frogs captures occurred within 30 m from the stream in the control site whereas over 80% of captures occurred within 30 m of the stream in the buffer treatment.  Direction of movement Tailed-frog directional movement patterns were similar in both sites before and after harvesting. Before harvesting, 60% to 70% of the frogs were moving perpendicular to the stream (Figure A4-3). In contrast, after harvesting the percentage of frogs moving  81  parallel to the stream increased by approximately 25% in the control site and by almost 20% in the buffer site.  82  Table A4 - 1. Summary of total number captured and relative abundance (number captured/100TN) of tailed-frogs at all sites before and after harvesting. Pre Treatment Site # captured #/100TN Control Mike 3 0.10 Spring 16 0.56 Buffer H 1.08 31 SCK 0.00 Clearcut B 1 0.06 I 0.00  # captured 10 17 48 1 3 5  Post #/100TN 0.17 0.28 0.78 0.03 0.16 0.08  60  A. i i Pretreatment i — » i Posttreatment I  50 •a  > o £  40 30  CO o  5 10  18  Control  Buffer  Forest  Buffer  B.  16 co  TJ  14 12 -I-  CD  10 as }— *— •< 8 c 0)  E 0)  > o  6 4 2 0  Figure A4 - 1 A. The mean distance moved (±SE) by tailed frogs in a control and buffer site before and after harvesting. A4 - IB. The mean rate of movement (±SE) by tailed frogs in forested and buffer treatments after harvesting.  84  100 o CO  TJ  Q. (0  n Pretreatment ^ Posttreatment  80 60 40  U  c  <D U mm  20 -  0) Cu  0 Control  Buffer  Figure A4 - 2. Proportion of tailed frog captures within 30 m of the stream before and after harvesting in control (N=l) and buffer (N=l) sites.  85  a>  60  (0 mm (0 Q.  50  I  40  I  30  Q.  g  • Pretreatment n---- •'"I Posttreatment  20  c 10 o o o  CL  0 Control  Buffer  Figure A4 - 3. Percent of tailed frogs moving parallel to the stream before and after harvesting in control (N=l) and clearcut (N=l) sites.  86  

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