Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Influence of alternative vegetation management treatments on plant community attributes : abundance,… Lindgren, Pontus Mauritz Fredrik 2000

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-ubc_2000-0104.pdf [ 3.15MB ]
Metadata
JSON: 831-1.0075409.json
JSON-LD: 831-1.0075409-ld.json
RDF/XML (Pretty): 831-1.0075409-rdf.xml
RDF/JSON: 831-1.0075409-rdf.json
Turtle: 831-1.0075409-turtle.txt
N-Triples: 831-1.0075409-rdf-ntriples.txt
Original Record: 831-1.0075409-source.json
Full Text
831-1.0075409-fulltext.txt
Citation
831-1.0075409.ris

Full Text

INFLUENCE OF ALTERNATIVE VEGETATION MANAGEMENT TREATMENTS ON PLANT COMMUNITY ATTRIBUTES: ABUNDANCE, SPECIES DIVERSITY, AND STRUCTURAL DIVERSITY. by Pontus Mauritz Fredrik Lindgren B.Sc. (Forestry), The University of British Columbia, 1995 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 December 1999 © Pontus Mauritz Fredrik Lindgren, 1999  In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the head of my department or by h i s or her r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n .  Department of The U n i v e r s i t y of B r i t i s h Columbia Vancouver, Canada  Abstract  This study was designed to test the hypothesis that alternative vegetation management treatments (manual cutting and cut-stump applications of glyphosate herbicide), applied to young plantations, would decrease plant community abundance (crown volume index), species diversity, and structural diversity. The experimental design consisted of nine operational-sized plantations stratified on the basis of location and elevation into 3 blocks (i.e., 1 control, 1 manual, and 1 cut-stump plantation per block), and with 5 permanent strip-transects to sample vegetation within each plantation. Vegetation management treatments did not significantly (P > 0.10) affect the crown volume index of the herb, shrub, or coniferous tree layers. However, both manual and cut-stump treatments significantly reduced the crown volume index of deciduous trees in the first posttreatment year (P = 0.05 and P < 0.01, respectively). Due to prolific growth of stump sprouts, the manual treatment effect did not extend past the first post-treatment year. In contrast, the cut-stump treatment impeded sprouting and, relative to control and manual treatments, significantly suppressed deciduous growth for at least four years (P < 0.05). Species richness, diversity, and turnover of the herb, shrub, and tree layers were not significantly (P > 0.10) different between treatments and control. Similarly, the structural diversity of herb, shrub, and tree layers were also not significantly (P > 0.10) different between treatments and control. By opening the canopy and decreasing the dominance of the deciduous tree layer, both manual and cut-stump treatments showed greater total structural diversity (herb, shrub, and tree layers combined) relative to the control. However, differences in total structural diversity between treatments and control were,  for the most part, not significant (P > 0.10). Therefore, the vegetation management treatments used in this study decreased only the volume of the targeted deciduous tree layer and did not adversely affect the species richness, diversity, turnover, or structural diversity of the plant community.  Table of Contents  Abstract  ii  List of Tables  vi  List of Figures  vii  Acknowledgements Introduction  viii 1  Study Areas  6  Materials and Methods  7  Experimental Design  7  Vegetation Sampling Crown Volume Index Species Richness Species Turnover Species Diversity Structural Diversity  9 11 11 11 12 12  Statistical Analysis  13  Results  15  Site Similarity  15  Crown Volume Index Herb Layer Shrub Layer Deciduous Tree Layer Coniferous Tree Layer  15 15 21 22 23  Species Richness  24  Species Turnover Herb Layer Shrub Layer Tree Layer  26 26 26 28  Species Diversity Herb Layer Shrub Layer Tree Layer  29 29 29 29  Structural Diversity Herb Layer Shrub Layer Tree Layer Total (herb, shrub, and tree layers combined)  31 31 31 34 34  iv  Discussion  Experimental Design Crown Volume Index Herb and Shrub Layers Deciduous Tree Layer Coniferous Tree Layer  Species Richness Species Turnover Herb Layer Shrub Layer Tree Layer  Species Diversity Herb and Shrub Layers Tree Layer  Structural Diversity Herb Layer Shrub Layer Tree Layer Total (herb, shrub, and tree layers combined)  Conclusions  35  35 36 36 38 39  42 43 43 44 45  45 46 48  49 49 50 51 51  52  Literature Cited  53  Appendix 1  63  Appendix 2  66  Appendix 3  68  List of Tables  Table 1. Repeated measures analysis of variance (RM-ANOVA) model used for investigating plant volume, species diversity, and structural diversity  14  Table 2. Statistical results (RM-ANOVA)  16  Table 3. Crown volume indices (m /0.01 ha) of prominent herbs, shrub, and trees  17  VI  List of Figures  Figure 1. Design of strip-transects used to sample vegetation  10  Figure 2. Mean total crown volume index (m /0.01ha) for herb, shrub, deciduous tree, and coniferous tree layers among control, manually, and cut-stump treated plantations 20 3  Figure 3. Mean species richness for herb, shrub, and tree layers among control, manually, and cut-stump treated plantations  25  Figure 4. Mean species turnover for herb, shrub, and tree layers layers within control, manually, and cut-stump treated plantations . 27 Figure 5. Mean species diversity indices (Simpson's and Shannon-Wiener) for herb, shrub and tree layers among control, manually, and cut-stump treated plantations .. 30 Figure 6. Mean Simpson's structural diversity indices for herb, shrub, tree, and combined total layers among control, manually, and cut-stump treated plantations 32 Figure 7. Mean Shannon-Wiener structural diversity indices for herb, shrub, tree, and combined total layers among control, manually, and cut-stump treated plantations. 33  vii  Acknowledgements  I thank the British Columbia Ministry of Forests, Research Branch, Victoria, B.C., and the Salmon Arm Forest District for financial and logistical support. Additional funding was provided by the Natural Sciences and Engineering Research Council of Canada. For their assistance with field work, I also thank S. Allen, M. Burwash, B. Hammond, C. Houwers, S. Milne, C. Nowotny, G. Ozawa, M. Porter, D. Ransome, E. Roberts, G. Ryznar, and C. von Trebra. And finally, I thank L. Zabek, P. Marshall, and M . Pitt for assistance with statistics.  viii  Introduction  Vegetation management is increasingly important in temperate forests of North America as a means to increase the survival and growth rates of crop trees, and to more quickly achieve free-to-grow status for regenerating stands (Newton and Comeau, 1990). If allowable annual cut levels are to be maintained, accelerated development of new plantations, as well as rehabilitation of backlog sites is required. Intensive silviculture programs must deal with the problem of reducing competing herbs, shrubs, hardwoods, and other non-commercial species to increase production of merchantable trees (McDonald and Radosevitch, 1992). Vegetation management is, therefore, a tool which can help provide rates of tree growth necessary to sustain the forest industry.  To accelerate the development of a second-growth stand of crop trees, vegetation management is particularly important during the first few years following planting. This is the time when a site is naturally dominated by pioneer species which, depending on the objectives established for the site, may be considered as non-crop species. Species often considered as non-crop competitors with coniferous crop trees are species of the genera Betula (birch), Alnus (alder), Populus (poplars and aspens), Acer (maple), Prunus (cherry), and Rubus (raspberry and thimbleberry). There are several methods for reducing the competition created by these non-crop species such as 1) manual (hand-held chain saws, brush saws, and girdling tools), 2) mechanical (machinery that mow, rake,  1  crush, and chip), 3) burning, 4) biological (use of grazing livestock and pathogens), and 5) herbicides.  Because the goal of vegetation management is to modify the plant community to favor the rapid development of crop trees, it undoubtedly has profound effects on the abundance of some plant species inhabiting treated areas (Santillo et al., 1989). Although the benefits of vegetation management treatments on the growth and survival of coniferous crop trees is well documented (Reukema, 1964; Crossley, 1976; Brix, 1981; Berry, 1982; Harrington and Reukema, 1983; MacLean and Morgan, 1983; Maguire, 1983; Lavigne, 1988; Yang, 1991, Wang etal, 1995; Simard and Heineman, 1996a, 19966, and 1996c, and others), its effects on non-timber plant community attributes are still not well understood (Wagner, 1993).  Because of growing public concern about the environment, forest managers are no longer charged with only regenerating forests (Lautenschlager, 1986; McGee and Levy, 1988; Freedman, 1991; Brand, 1992; Lautenschlager, 1993; Halpern and Spies, 1995). Today, in addition to regenerating forests for future harvest, the conservation of biodiversity is becoming an integral part of forest management. For example, the recent development of the Forest Practices Code of British Columbia and the publication of a series of guidebooks such as the Biodiversity Guidebook (B.C. Ministry of Forests, 1995), are indications of this change within B.C.'s forest industry. However, as outlined by Wagner (1993), there is a serious lack of information about the effects that vegetation management has on the environment. Therefore, if forest management is to encompass  2  both timber production and the conservation of biodiversity, vegetation management procedures must be critically examined within the context of both of these objectives.  The most common form of vegetation management within Canadian forests is aerial spraying of the herbicide glyphosate (Vision®, commercial formulation containing glyphosate, 356 g/L present as an isopropylamine salt) (Campbell, 1990). At prescribed rates, glyphosate poses minimal toxicological risks, in terms of mortality and reduced reproduction in wildlife, and does not accumulate in the environment (Morrison and Meslow, 1983; Newton et al., 1984; Freedman 1991), however, public opinion about the use of any forest herbicides is often very negative (Mitchell, 1990; Turpin, 1990; Freedman, 1991; Glover, 1994). Research has shown that glyphosate does not have a direct effect on the survival or reproduction of small mammals (Sullivan and Sullivan, 1981; Sullivan, 1990a; Sullivan et al., 1997). In addition, several studies have shown that small mammal population responses to aerial application of this herbicide have ranged from an overall increase in population density (Anthony and Morrison, 1985), to no change in density (Sullivan and Sullivan, 1982; D'Anieri et al, 1987; Sullivan, 19906), to others which have reported a decrease in abundance (Clough, 1987; Santillo et ah, 1989). Other studies have also reported that glyphosate does not have any significant long-term effects on the survival or health of ungulates (Sullivan and Sullivan, 1979; Cambell et al, 1981; Jones and Forbes, 1984). However, more information is still needed to assess the effects that vegetation management treatments, particularly alternative treatments (Campbell, 1990), have on both the timber resource and non-timber values such as habitat quality.  3  One such alternative vegetation management treatment is the ground-based method of applying glyphosate to the cut-stump surface of manually-cut deciduous trees. The nonbroadcast and species-specific approach of this treatment suggests that it may be an effective and environmentally sensitive method of vegetation management. One study reported that this cut-stump method, although significantly reducing crown volume index of the targeted deciduous tree layer, had no apparent effect on the abundance of herbs, shrubs, and coniferous trees, and did not affect the survival or reproduction of small mammals (Runciman and Sullivan, 1996).  Studies designed to investigate the effects of vegetation management on biodiversity often monitor changes in plant abundance and diversity (Tomkins and Grant, 1977; Pollack ef al, 1990; Freedman et al, 1993; Sullivan, 1994; Sullivan et al, 1996; and others). However, a habitat attribute that is frequently ignored by such studies is structural diversity. Because of the well documented direct relationship between the structural diversity of a habitat and the diversity of species that live there (MacArthur and MacArthur, 1961; MacArthur, 1964; MacArthur, 1965; Balda, 1969; Sutton and Hudson, 1980; Adler, 1987; Harney and Dueser, 1987, Hunter, 1990; and others), structural diversity should be carefully examined to determine the effects of vegetation management treatments on habitat quality.  This study was designed to test the hypothesis that vegetation management treatments (manual spacing and cut-stump applications of glyphosate) applied in young mixed-  4  conifer plantations would adversely affect the plant community (herbs, shrubs, and trees) by decreasing 1) plant abundance, 2) species richness, 3) species turnover, 4) species diversity, and 5) structural diversity.  5  Study Areas  This study was conducted within two similar areas in the Shuswap Highlands of southcentral British Columbia, Canada. The Eagle Bay (50° 55' N, 119° 11' W) and Sicamous (50° 52' N, 118° 59' W) sites are both located within the Thompson Moist Warm variant of the Interior Cedar-Hemlock biogeoclimatic zone (Lloyd et al., 1990). These areas are characterized by similar topography, elevation, climate, and climax vegetation. The topography of this area is hilly to steeply sloping and elevation ranges from 550 to 1237 m. Summers are generally warm and dry and winters cool and wet. Mean annual temperatures range from 2 to 8.7° C and precipitation ranges from 500 to 1200 mm, with as much as 50% falling as snow (Ketcheson et al., 1991). Climax forests on mesic sites are characterized by western redcedar (Thuja plicata Donn ex D. Don) and western hemlock (Tsuga heterophylla (Raf.) Sarg.), while interior Douglas-fir (Pseudotsuga menziesii var. glauca (Beissin.) Franco), lodgepole pine (Pinus contorta Dougl. Ex Loud, var. latifolia Engelm.), and paper birch (Betulapapyrifera Marsh.) are common serai species. Nomenclature for all plant species follows Hitchcock and Cronquist (1973).  Nine plantations, ranging from 16 to 47 ha in area, and 2 to 9 years in age when selected, were chosen in conjunction with the Salmon Arm Forest District silvicultural staff on the basis of operational scale, proximity, and initial similarity in requiring vegetation management treatments. The six plantations found at the Eagle Bay site were located on a north to north-east facing slope. These areas were logged between 1978 and 1986 and  6  planted predominantly to lodgepole pine between 1985 and 1990. Site inspections indicated that Douglas-fir, western larch (Larix occidentalis Nutt), and hybrid spruce {Picea engelmannii Parry X P. glauca (Moench) Voss) were also present. The remaining three plantations at the Sicamous site were located on a southeast slope. These areas were logged between 1977 and 1988 and planted between 1982 and 1989, largely with Douglas-fir. Inspections of these sites indicated that lodgepole pine was also present with lesser amounts of hybrid spruce and western white pine (Pinus monticola Dougl.).  Materials and Methods  Experimental Design  This study follows a randomized-block design. Study plots were established in eight of the nine plantations during September 1991, and in the ninth during April 1992. Assignment of control and vegetation management treatments was done subjectively among these nine plantations due to logistical and economic constraints. The first of these constraints was related to the close proximity of the Eagle Bay plantations to a residential community. To facilitate the approval of the herbicide application permits, the cut-stump herbicide treatments had to be applied to the two plantations furthest from these residents. The second constraint was related to a minimum acceptable outcome anticipated for the cost of the vegetation management treatments. This required that the more expensive treatment, the cut-stump herbicide treatment, be applied to the Sicamous plantation that was most dominated with deciduous trees.  The nine plantations were stratified into three blocks on the basis of 1) location and 2) elevation. Consequently, plantations A , B, and C (Sicamous site) formed Block 1, and the remaining six plantations from the Eagle Bay site (D to I) were stratified into Blocks 2 and 3, on the basis of elevation.  In addition to untreated controls, the vegetation management treatments used in this study were applied in the following manner. Manually treated plantations had all trembling aspen (Populus tremuloides Michx.), paper birch, and black cottonwood (Populus trichocarpa T. & G.) cut with power saws, except for a few individual stems that were left in the openings of the plantation. A l l stems of willow (Salix spp.), Douglas maple (Acer glabrum Ton .), bitter cherry (Prunus emarginata (Dougl.) Walp.), and speckled -  alder (Alnus incana (L.) Moench) that were within 1 m of a crop tree were also cut. A l l other vegetation was left uncut.  Cut-stump treated plantations were treated in a similar manner as those receiving the manual treatment, with the additional application of the herbicide glyphosate, diluted 2:1 in water, to the cut stump surfaces of the felled deciduous trees. A small amount of Basacid Blue® dye was added to the herbicide mixture to mark the treated stumps. Most maple, cherry, and alder stems were left uncut. These prescriptions were applied between September 25 and October 22, 1992.  8  Vegetation Sampling Vegetation was assessed annually within each plantation to determine the presence and abundance of individual species for the purpose of monitoring the plant community's composition and structure. Five permanent 5 x 25-m strip-transects, each consisting of five contiguous 5 x 5-m subplots with nested 3 x 3-m and 1 x 1-m subplots (Figure 1), were established within each of the nine plantations (as outlined in Stickney, 1980; 1985). Transects were randomly placed within each plantation as long as they were at least 50 m from the nearest stand edge and they did not cross any roads, skid-trails, or landings.  Within a strip-transect, each of the 3 different sized subplots were used to sample 2  2  different plant forms: the 5 x 5-m (25-m ) subplots for sampling trees, the 3 x 3-m (9-m ) subplots for sampling shrubs, and the 1 x 1-m (1-m ) subplots for sampling herbs (as outlined in Ritchie and Sullivan, 1989). In addition, trees, shrubs, and herbs were each sampled within 6 height classes of 0-0.25, 0.25-0.50, 0.50-1.0, 1.0-2.0, 2.0-3.0, and 3.04.0 m (Walmsley et al, 1980). Species abundance was estimated within each of the 6 height classes that the plants occurred in by a visual estimate of percent cover. Individual plants were only measured once within the height class containing the topmost growth of that plant. All plants can be classified into one of three life forms: herb, shrub, or tree. However, these classes can be further subdivided or, conversely, grouped together, to create additional classes of plants. For example, the tree layer may be subdivided into deciduous and coniferous tree classes. Also, herbs, shrubs, and trees are sometimes  9  grouped together to form a class including all plant forms. Hereafter, the tree class w i l l include both deciduous and coniferous trees and the total class w i l l include all plant forms.  5 x 25 m Transect  Trees  Shrubs  Herbs  Figure 1. Design o f strip-transects used to sample vegetation.  10  Crown Volume Index  A crown volume index was calculated for each species within each of the five nested subplots of a transect by multiplying the percent cover values by the top of the corresponding height class (Stickney, 1985). The product of these values gives the volume of a cylindroid representing the space occupied by the plant in m /0.01 ha. 3  Species Richness  Species richness (S) was calculated as the total number of species of a given plant form (herb, shrub, or tree) sampled within a transect (Krebs, 1989).  Species Turnover  Species turnover (TO) was also calculated for herb, shrub, and tree layers. TO is defined as the number of species lost and gained during a set time period, divided by the total number of species sampled during the same period (Schoonmaker and McKee, 1988), and is calculated as follows:  TO =  / (A + B)  where: L is the number of species lost and G is the number of species gained during a defined time period from ti to t2 and A and B are the total number of species sampled during times ti and t2, respectively. Because a species turnover calculation requires a  11  minimum of two sample periods, this measure is undefined for the first year of sampling (pre-treatment year).  Species Diversity  Two diversity indices are reported within this paper: Simpson's index, which is sensitive to changes in abundant species (Simpson, 1949) and the Shannon-Wiener index, which is sensitive to changes in rare species (Pielou, 1966a; Peet, 1974). Simpson's index of species diversity is the probability of picking two organisms at random that are different species, and ranges from 0 to almost 1. The Shannon-Wiener index of diversity is based on information theory and the degree of difficulty in predicting correctly the next individual sampled. As such, this index increases with number of species sampled, and ranges from 0 to approximately 5 for biological communities.  Structural Diversity  The above definition of Simpson's and Shannon-Wiener diversity indices, although referring to species diversity, applies equally to structural diversity. While species is the object of a species diversity index, height class is the object of a structural diversity index. The indices are calculated as follows:  Simpson's diversity index (D) D = l-[Z( f] Pl  Shannon-Wiener diversity index (H') H' =  -I( )(log ) Pi  2Pi  12  where: p, = proportion of mean total crown volume index (Pielou, 1966a) belonging to the i' species (for species diversity indices) or h  height class (for structural diversity  indices).  Pre-treatment vegetation sampling was initiated in late July 1992. The first posttreatment sampling of vegetation was conducted in July 1993 and was conducted annually to July 1996, when the study was terminated.  All plant community attributes (e.g., crown volume index, diversity indices) were calculated on a subplot basis, and then averaged across the five subplots of a transect. Consequently, each transect represents one datum.  Statistical Analysis  A repeated measures analysis of variance (RM-ANOVA, SPSS Institute Inc., 1997) was used to test for significant differences among treatment means, as shown in Table 1. Both pre- and four post-treatment years were analyzed together, resulting in five levels (years) for the within-subjects factor (time). Both treatment and block were assigned as between-subjects factors. Before performing any analyses, data not conforming to properties of normality and equal variance were subjected to various transformations to best approximate these assumptions required by any ANOVA (Zar, 1984). Mauchly's W test statistic was used to test for sphericity (independence of data among repeated measures) (Littel, 1989; Kuehl, 1994). For data found to be correlated among years, the Huynh-Feldt correction was used to adjust the degrees of freedom of the within-subjects  13  F-ratio. The Bonferroni post-hoc test (adjusted for multiple contrasts) was used to locate differences among treatment means within each sample year (Rosenthal and Rosnow, 1985). Significance levels for all analyses (i.e., RM-ANOVA and Bonferroni significance tests) was set at a = 0.10. Although conclusions made from statistical results with the more standard significance level of 0.05 may be stated with more confidence than those resulting from tests with a probabilty of 0.10, significance tests with P-0.10 are likely biologically significant and deserve comment. Tests regarding data properties, such as Leven's homogeneity test and Mauchly's W sphericity test, were made with a significance level of a = 0.05.  Table 1. Repeated measures analysis of variance (RM-ANOVA) model used for investigating crown volume, species richness, species turnover, species diversity, and structural diversity. Source of variation  Factor type  Level  Degrees of freedom  Block Treatment Error I Time Time X Treatment Error II  Random Fixed  n=3 k=3  Fixed  t= 5  n-l=2 k-l=2 (n-l)(k-l)=4 t-l=4 (t-l)(k-l)=8 k(n-l)(t-l)=24  a  F-test (d.f.)  MS-Treat. / MS-Err. I (2,4)  MS-T.xTreat. / MS-Err. II (8,24)  " There are five levels of time (t = 5) for all plant attributes except species turnover. Because species turnover is not defined for the pre-treatment year, there are only four levels (t = 4) for this attribute.  14  Results  Site Similarity There were no statistical differences among the treatment and control plantations for any of the plant attributes (crown volume index, species richness, species diversity indices, and structural diversity indices) during the pre-treatment year (Table 2; Figures 2, 3 and 5 to 7).  Crown Volume Index Herb Layer  Prominent herb species found within the study area included fireweed (Epilobium angustifolium), white hawkweed (Hieracium albiflorum), common dandelion {Taraxacum officinale), wild strawberry (Fragaria virginiana), and pearly everlasting (Anaphalis margaritacea). The crown volume index of these and other prominent herbs are provided, by treatment and sample year, in Table 3.  Although the mean total crown volume index (m /0.01 ha) of the herb layer changed over time (Figure 2), differences among control and treatment plantations were not significant (F2,4 = 1.26; P = 0.38). Both the control and treatment groups showed similar trends during the four post-treatment years. The mean total crown volume index of the herb layer for the control, manually, and cut-stump treated plantations peaked during the  15  Table 2. Statistical results obtained from repeated measures analysis of variance (RMANOVA) conducted on several plant community attributes. Five years of data (one pretreatment year and four post-treatment years) were included in these analyses. Treatment Effects  Attribute  r(2.4>  P  Herbs Shrubs Deciduous trees Coniferous trees  1.26 0.86 40.63 0.99  0.38 0.49 0.002 0.45  Herbs Shrubs Trees (decid. and conif.)  3.29 2.75 1.17  0.14 0.18 0.40  0.72 1.66 2.14  0.54 0.30 0.23  3.34 1.26 1.49  0.14 0.38 0.33  Species Diversitv - Shannon's Herbs Shrubs Trees (decid. and conif.)  2.78 1.17 1.22  0.18 0.40 0.39  Structural Diversitv - Simpson's Herbs Shrubs Trees (decid. and conif.) Total (herbs, shrubs, and trees)  0.09 0.05 3.68 6.34  0.92 0.95 0.12 0.06  Structural Diversitv - Shannon's Herbs Shrubs Trees (decid. and conif.) Total (herbs, shrubs, and trees)  0.16 0.09 3.70 7.09  0.85 0.92 0.12 0.05  Time X Treatment Interaction P  Volume Index F(6,19) = F (8,24)  =  F(6,19) = F(8,24)  =  0.73 1.15 9.94 0.33  0.63 0.37 < 0.001 0.94  1.77 0.31 0.85  0.13 0.95 0.57  0.37 1.24 1.06  0.89 0.33 0.42  0.34 0.29 2.66  0.93 0.95 0.04  0.24 0.36 2.70  0.97 0.92 0.03  0.24 0.62 1.73 2.39  0.97 0.75 0.15 0.05  0.30 0.70 1.73 1.60  0.96 0.69 0.15 0.19  Species Richness F(8,24)  =  F(8,24)  =  F(8.24)  =  F(6,18)  =  Species Turnover Herbs Shrubs Trees (decid. and conif.) Species Diversity - Simpson's Herbs Shrubs Trees (decid. and conif.)  F(6,18) = Fr6.i8i  F  =  a,22)=  F(7,22)  =  F(7.22)  =  F(7,22)  =  F(7,21) = F(7.23) =  F(8,24)  =  F(8,24)  =  F(7,23) = F(7,23) =  F(8,24) = F(8,24)  =  F(7,23) = F(7.22) =  Degrees of freedom for tests of Time x Treatment interactions are 8 and 24 (or 6 and 18 for species turnover) when the data are not correlated among years. Correlation among repeated measures data is a violation of ANOVA assumptions and requires an adjustment (Huynh-Feldt correction) which decreases the df from those mentioned above. Note: Significant P-values (a = 0.10) are indicated in bold text. a  16  CO  CO x f 0 0 xf CO m xin" c n xr CM T - O CM O o o o o CM o ci p o p d o O o d P o p o p  xf x f IO X -  CM N~  o p m  CO  in  xf  CM CM  T~  2  s U ro  in  00 o o o ) x in OO;-^ i n 01 x~ c\i p  cn  CM CO CM CO -<-- m CM  in  CM c o CM K CD N. T- CNJ CM O O p  T - CO c o x f XT xp T- P O  co  CM  cn oo  CO C O  cn to xf o P o p 00  CO  CO  CO X -  o p  d  in  O  p  CM  cn o o i ^ t  in  o p  CO  xr m  i n co h- x~ CM p i d P  CD CO  o p  oo i n  CO X CO CM  d  p  p  d  CO CD x- c n xtxr c o c o oo CD CM O CM x- o o t- 0 0 CD x— o p d p d p o p XT p CO O i CD CO CM 0 0 CD P d p  m oo CD 0 0 d XT P  in  in c o  oo XJc o oo  p  T-  in ^ cn c o m in m x~  cu OH CO  s  .a-QO on -*-»  o  Spe  cie ani  CM  5  p  xf  T-  CM N -  d  p  x~  o o p d p  CO  in  XJ-: P i  d  p  CM  co O  d  p  Xf  p  co x-  d  p  d  p  CO  c  CD CM CM c n  p ^ P  o o in in p CM  d  CM  co  in  d  CO xf i n x~ xr  p  d  m  CM  d  •<- c o CO  p  CM  d  CO 0 0 xf CM 0 0  p  CD  d  CM  in CM d  .co £  g  s§  S8M3H  co d  CD CM c o m  o o p d p  p  d  CM  p CO  x~  in p  i -  d  CM  P  p  ^_ Xf  ° P cn o p  CO* CD x? CM 00 o d o d  CO*  p  co CO  d  in  p  o  ^* m CO* p CM cn* CO o o o d o d  C  3  CD  w ro  CO £  oo oo CM O d p  CO CO  CO  d  CO CM* m CM CM  in o  00  CO J ~  co m cn P  O  d  o p  CO*  00  CM  Xt-  o  d  p  NCM <o CM CM P d p  00 CM  cn oo oo cn P  c o oo  p  CO  CO* c o ^ " o o ~XJ-ICO t~  ^  ^ - c o  0  1  oo  00 f > C M o > T - | ^ i o o oo CM CM d p  CM  CM  XJ-  CO* CO  o Xf p_ d p  1  CM*  -<  T-: & o o  oo  !ci o p  co x}- CM in;CM c o cn c o CM' ^ i t M P T- CM o P  S2  m  p  co co x~ d  in  in o  co co p  cn o  S  0 0 oo c o CM oo oo oo CM x~ CD x~ T- P d p d p d p d p  TO  O  oo d  oo d  CO N -  co  xr  CM  CM  I-  CO  .CO  o  O  T -  T -  O d  p  m x f T— 1^ 00 CO 00 oo xf x~ o o 00 CM d p d p d p  CO  p  xf cn o> P CM t~ p d p  oo oo xr oo oo o o o o p d p d p d p  CO  d  m o  o o o o o o p d p d p d p  d  d  CM  CO T~  p  d  iri  ^—•  CM CO  c o CO* CO oo 00  i  p;  c o i n oo 00 00  o co o o d p d p T-  U  P  d  p  00 N . CM CM  CO  CM  x~  O  xr  m in  CO  CM;  d  CM CM CM  o o 0|T- P o o p d p d pd p  in  2 -  p  T— X-  CM Xf m CM o P o T- p d p d d p  CD CO oo xjT- 0 0 c o c o CD oo xf x- CM P CN <M CM xT O T- C j d p d p d p d p d  00  in  xf oo c o oo o CM x- i n o p d p d  oo P  CO  CO*  CM  o o o o o po p  CD 0 0 O P d p  c o oo CO c o x- o d p d  P  o p  CO  T-  CD x— 00 l O : N 'SICM x- CO x - | o Pi o O P o p o pi d  CO C O CM C O  CM  CO CM CD CM CO CM c o  CO  p  CO  o in  o P  h - 00 co  o p o po p  oo  Xf i n CMCM 0 0 O O o O p  •r- Xf CO f~  o p o po p  o P 3  CO T~  1  CM  •r- CO CD Xf xf j - ;  5)•^3- m  CM* c o  ^  CO* CO 00* oo oo f ^ i C M CO xf c n T- C i 00 X f  K  T - CO cn oo CM  CO 0 0 h - CO xf CM  p c^iSS io p ^  co oo  00  52.°' S. in CM  xf  ,m  i-  cn °° inicn m CM p CM 5SJ°' S m  — I CD  0  0  00  . CM;CM CM 00 CM oo 1^- Xf ;cO o 00 co p CM P OOi CM CM  in  cn oo o in p  i n Nin o  CM  S .-2 ^ ci co  5; to  CO  j g : CO CO ."3 co; 3 ^ i ? c >< >Ci-Q £ i - Q CD 3 r~o i " ~^ CO ^ " 3 c 3 im 2 2  P  0. EjQ:  IB  3  QiQ;  B  Lt  SflflHHS  17  co co <o £ > o• coco• C\ i CD o 0\ — CO i d o ~p CSI T ~ d o p CO CO X t - C O xjOi CN I ^ T - ; x f i o O v - O c o T- p ; - * - p o p ' ; 0 P 1  co  iO  ro co  CN xj* C D IO T - 0> O CO P O  co" in oJ o CO P d p  5J  R  5?  1  g j | 0 0 COCO LO •<-  d  CMT-  cn  p  1  O  o d  p  CM CO CM CM o O  1  P_ d  x~;o  3"  o  —  d  •"tcoT-cd^mio CM co co c o i i - o in co C M X ~ 00 o ioi o co j ^ d p d p ' i d c i d o_ d o i : co CN  io  d  CM xp  d  co  P CT) oo;co x~ p o p d  o  !  m  m x-  h - O i CO C N CO x- O P  d  T f  p  oo  CO COjCO T -  a  d p'id p ° ? LO  0\  d  p  d P_ d o d  CD O IO  m  d  O *H  p  3!<  co x-  5^  p  o>  CO  o  d  p'i  co l O i c o co C N ^ :  pidS.  P  in  "3 CD  cb  00 CM  cd co d  co P  CD  p  m  d  CM m co m o o p'id p o P i n Oi  CO  p  co" S  p  p  T-  CM t~  d p'id p w  ^•8  5 !fl w « a: cB oc -a <c  O-.S O  (panunuoD)  *  CO ^ ;  c^£^=^?  io~ oo  P2 c o i c o . O i O CM i°  P  CD CM  .  d  F0 T -  p  t—  co  NC\| CM J ~  r - O  j-"  oTi CD ?J IOOOSO) oi m CO CO  II co" C D co d  ,  T-  d  p  p  6T  2 S N  r~- c o h~ o o i m c*51io •^•in N- CD c o i m o i c o t o c o C D CM d p C N v - ^ i d p  CM  ^i^H  roi-<3-  O) CD CSliT- oo - S M I O co co T !CD CNitn CN  o o  co  co  to  T t CO CM <M  w o o CM  T f  00 OO  co  CM  Pio  o p  lOi^ T-:  i n CO . CCO O 1  uo  in p  °  00 N . ; CD i o :  co Oi  T-  CO CO  co  K  CN  1  p  R  oo CO O i T~  o  1  p  0  o_  T— T—  p^  pi  o  CO T ? CO  co cd~ oo  T T Oi l e d CN  T f T f  <3' oo co*  CO; to i  Q  Q; <.Q DC .CD  0>;CO Xh! C O j T - x~ CD CO  P  CD CO T— IO  T f  • P: • P  J -  CD 00 CO X f ° ^ co °^CO CD c o O xf T f CO xt-OO ^ ; 0 0 N . C D O)! ° ? CO CN x" p i d p 10  0 0  -  2ii°2  52Jv^  p  co ^  LO  CD  .to  •2 CO CD £ 3 O Q O « '55 - 3 3  saHMHS  _  g o  O  CM  S  CM  in io p  L  5? CO •IO* J ; I ^ CN : CD CO uu 00 CO CNicO CD CO" 00 CO T J - i r - T f : ! ^ . LO OR LO 00 CO o 1^ 00 x f r - l T f C\j CD co ICN m CM  CO CNi  co  g  T f  o p o p P  T  co~i co CO CO > ^ io T-^  ,r  P  CD  oo  CN -<-;co c o : O  a  od in -  T- ,~  CM C D co CN O 00  . °H OiCD 1^  co" "f  CO  co~i io" CM "!HCD •y-iCD CN  1  2  io oo  co  T™• to CO C  CD CN m CO o  £  u  ^ S ^  CO CN CN 00 T f WJ CN l ^ C N IO iri iri N - i o c o m  co  p  ^  C0 o  co  CO .CO  0  idi ^  .  CD \ h CD co  p  o p  d  *  p  d  in r-  d  d o d co  1  p'i£^!  ^ CD CM  CD oo  o  i c o in i c o c o CO • )V i^f t~ CN f~c o  :  rP CN  CO CM" CN CO CO  CD  S  CO  .  ;  cn c o  CN co  CN  o P  CM  U  d  •CM CJ)  CO  t - CO CO co CN lOi^f r-i  ro  CO M- CO O O T-  UO  OS  R o p  CM co  in  o p  d  CN  T f  CN  CO in C N <=>. v. r-~ <°.  p  c o M - m c o CM c o oV; in 5 T x r N . in ^ ; c o |^ C0;^f 'TfiCM d p oo c o cd co i cd d  ^  C N C D x ~ o o M- CN CM C D X } T f CO CM xo d p d p p  CM IO CM P  co x~ TT CN d p  CD  O x~ TJ- C N i O co x - - i d p ' i d  CM  O  XJ-  • CM  „ :  CN  i^-  T f  x-  s  X f  P : d p'  co  T f  o  *~.  CN  ° p  • 5°  o p  o p o p  1  a.  E  x - CN r - io g Ri^r Inxr C Q C D ifj CN K. CD xCD •«-•  p  5 ct  3 o o y Q, S  to CD -2 CD  s;i=  -2  3 CO  •c; X o, i" co  to o  co P CD  ,to o  CD  S33HI 18  LO  R*  XT C O CN X—•  CN  CO"  CN o o o d ci_ oj d  cn* T—  c/3  00 N -  IO  CO  CD  m x- o o d d p'  a E  co = 2CN 00 CN  X f in xf T—  p d  p  •— C O * m CO* xf < o o xf Xf CN Csi d o d oj d oj —  CO* CO  •xf  5>* x f  CO  o o C N X— T— V pj d oj d oj d pj > o co; oo*i S co*cn K. co g 3* § cn ^ CSj o O csi j ~ | _; p d p d p xf  CN CO p pj  o d  c o fl"  o o o CD ,fl  fl  3 T3  O Oj  CN co* CN 00 o P o o p j in coj d P j CN  5 .5  =5 «2  a  CN x O O  CN x~  p  o o d p  o o d p  o o d p  d  CN CO  CO  9 o o d p  x- CO  S* C D C O * o N - CN x-^ oj  CN  O  £ x*  eg! o— U  in  CO  CO  x--  o oo  o  o  o o d p CN  o d  O C N co* o O Oj T ~ x-^  o d  55* C O oo* CO oo C O o x-^ d c j  o d  CO*  r- x f x - in o P o N. d p T- P .CO CD O  1  c < o £ .x S u C O •S o CO o C/5 -J o Q: S  CO 3  s  iS CD ,co (panuiiuoD) saajxcf  19  Control  Manual  Cut-stump  Mean Total Crown Volume Index  Herbs  Shrubs  40 <?30 1 20  '92 |  '93  '94 Yea  '95  '96  '92  '93  '94  '95  '96  Yea  Mean total crown volume index (m /O.Olha) for herb, shrub, deciduous tree, and coniferous tree layers among control, manually, and cut-stump treated plantations. No statistical differences (a = 0.10) were observed for herb, shrub, or coniferous tree volume, however, the deciduous tree layer was significantly affected by the treatments. Arrow on horizontal axis indicates timing of treatments. * P < 0.10, **P< 0.05, *** P < 0.01; significance by Bonferroni post-hoc test. Figure 2.  20  second post-treatment year (1994) and then gradually decreased during thefinaltwo years of the study. Both the manually and cut-stump treated plantations showed a decrease in volume of herbs in the first post-treatment year, in contrast to the increase in herb volume observed within the control during this same period, although differences were not significant (Figure 2).  Shrub Layer  Prominent shrub species found within the study area include falsebox (Pachistima myrsinites), thimbleberry (Rubus parviflorus), red raspberry (Rubus idaeus), bitter cherry  (Primus emarginatd), and willow (Salix spp.). The crown volume index of these and other prominent shrubs are provided, by treatment and sample year, in Table 3.  Although the mean total crown volume index of the shrub layer changed over time (Figure 2), differences among control and treatment plantations were not significant (F24 ;  = 0.86; P = 0.49). The control plantations showed a steady increase in mean total crown volume index of shrubs throughout the five years of the study. Both the manually and cut-stump treated plantations also increased in shrub volume during the post-treatment years. Like the herb layer, the shrub layer experienced a slight decrease in volume during thefirstpost-treatment year within the treated plantations; however, differences were not significant (Figure 2).  21  Deciduous Tree Layer  The three deciduous tree species that were found within the study area were paper birch, black cottonwood, and trembling aspen. The crown volume index of these deciduous tree species are provided, by treatment and sample year, in Table 3.  The mean total crown volume indices of deciduous trees were not statistically different (Bonferroni; P = > 0.17) among the control and treatment plantations during the pretreatment year. The treatments resulted in siginificant (F2,4 = 40.63; P < 0.002) decreases in deciduous tree volume during the first post-treatment year (Table 2; Figure 2). In the first post-treatment year, the mean total crown volume index of deciduous trees decreased by 87% (106.5 to 13.5 m /0.01ha) and 95% (46.8 to 2.2 m /0.01ha) within the manually 3  3  and cut-stump treated plantations, respectively. This decline was in direct contrast to the control plantations, which experienced an increase in mean total crown volume index of 38% (53.2 to 73.3 rrrVO.Olha) during this same period (Figure 2). Consequently, both the manually and cut-stump treated plantations had significantly less (Bonferroni; P = 0.05 and P < 0.01, respectively) deciduous tree volume than that of the control during the first post-treatment year. In addition, during the first post-treatment year, the cut-stump treated plantations had significantly less (Bonferroni; P = 0.02) deciduous tree crown volume than those treated manually (Figure 2).  Both the control and cut-stump treated plantations showed a gradual increase in mean total crown volume index of deciduous trees throughout the four post-treatment years. The dramatic suppression of deciduous tree volume observed one year after treatment is  22  maintained during the post-treatment years for the cut-stump treatment. As a result, deciduous tree volume within the cut-stump treatment is less (Bonferroni; P < 0.02) than that of the control during all four post-treatment years. The suppression of deciduous tree volume within the manually treated plantations was, however, only short-lived. There was a rapid increase in growth by the second post-treatment year (1994), resulting in deciduous crown volumes becoming similar (Bonferroni; P = 1.00) to that of the control during the 1994 sample year, and thereafter (Figure 2).  Coniferous Tree Layer  Prominent coniferous tree species sampled within the study area included interior Douglas-fir, western redcedar, lodgepole pine, western hemlock, hybrid spruce, and western white pine. Western larch, subalpine fir (Abies lasiocarpa), and western yew (Taxus brevifolia) were also found within the study area, but were much less common than the coniferous tree species listed above. The crown volume index of these coniferous tree species are listed, by treatment and sample year, in Table 3.  Although the mean total crown volume index of the coniferous tree layer changed over time (Table 3, Figure 2), differences among control and treatment groups were not significant (F2,4 = 0.99; P = 0.45). The control plantations showed only a slight increase in mean total crown volume index of coniferous trees throughout the five years of this study. However, both the manually and cut-stump treated plantations exhibited accelerated growth rates of coniferous tree volume relative to that of the control during  23  the post-treatment years. During the four post-treatment years, the mean annual percentage increment of coniferous crown volume (see formula below) was 5%, 44%, and 29% for control, manually, and cut-stump treated plantations, respectively.  Mean annual percentage increment of crown volume  where: A  is the crown volume at time 1, B is the crown volume at time 2, and C is the  number of years between time 1 and 2.  Although the differences in coniferous tree crown volume among treatment and control plantations were not statistically significant, increased coniferous growth rates of 5 to 8 times that of control plantations suggested a biologically and likely economically significant treatment effect.  Species Richness During this study, a total of 75 herb, 37 shrub, and 12 tree species were sampled. A list of these herb, shrub, and tree species is provided in Appendices 1, 2, and 3, respectively.  There was no statistical difference in mean species richness among the control and treatment plantations for herbs (F , = 3.29; P = 0.14), shrubs (F 2  4  2>4  = 2.75; P = 0.18), or  trees (F2,4 = 1.17; P = 0.40), at any time during this study (Table 2; Figure 3). Some time trends, common to both control and treatment groups did occur. Although not  24  Control  Manual C U  Cut-stump  Species Richness Herbs  Shrubs  '94  I  '95  '96  Year  Trees  Figure 3. Mean species richness for herb, shrub, and tree layers among control, manually, and cut-stump treated plantations. No statistical differences (a = 0.10) in species richness were observed among the control and treatment plantations for any of the plant forms (herbs, shrubs, or trees) during any of the five sample years. Arrow on the horizontal axis indicates timing of treatments.  25  statistically significant, the observed peak in mean herb species richness two years posttreatment (1994), was followed by a gradual decline until the completion of the study (Figure 3). The mean species richness of the shrub layer, although more static than that of the herbs, also peaked in the second and third post-treatment years (1994 and 1995) (Figure 3). The mean species richness of the tree layer was the most static of all, with only very minor differences observed from the start to the end of this 5-year study (Figure 3).  Species Turnover Herb Layer  There were no significant (F2,4 = 0.72; P = 0.54) differences in herb species turnover observed among control and treatment plantations during any consecutive year intervals (Table 2; Figure 4). The lowest species turnover was observed between the pre-treatment and first post-treatment year (1992 to 1993), and the highest was observed the next year (1993 to 1994). Control, manual, and cut-stump treatments all showed similar time trends throughout the study.  Shrub Layer  There were no significant (F2,4 = 1.66; P = 0.30) differences in shrub species turnover observed among control and treatment plantations during any consecutive year intervals (Table 2; Figure 4). Although not statistically significant, differences in shrub species turnover among treatment and control plantations do suggest some trends. Both manual  26  Control I  I  Manual CZ] Cut-stump  Species Turnover  Herbs  Shrubs  o H  Trees  0.1 0.08 0.06 0.04 0.02 0 '92-'93 t  '93-'94  '94-'95  '95-'96  Time interval (years)  Figure 4. Mean species turnover for herb, shrub, and tree layers within control, manually, and cut-stump treated plantations. No statistical differences (a = 0.10) in species turnover were observed among the control and treatment plantations for any of the plant forms (herbs, shrubs, or trees) during any of the five sample years. Arrow indicates timing of treatment.  27  and cut-stump treated plantations experienced the highest species turnover during the pretreatment and first post-treatment time interval (1992 to 1993) and then declined thereafter. This is in contrast to the shrub species turnover observed to be its lowest within the control plantations during this same time period, followed by an increase during consecutive years, peaking during the 1994 to 1995 time interval.  Tree Layer  There were no significant (F2,4 = 2.14; P = 0.23) differences in tree species turnover observed among control and treatment plantations during any consecutive year intervals (Table 2; Figure 4). The small changes in tree species turnover observed during the course of this study were caused by a single species being gained or lost within a given time interval. An exception to this was observed during the pre-treatment to first posttreatment year interval (1992 to 1993) when, within one of the three manually treated plantations, two tree species were gained.  By the final post-treatment year (1996), no tree species present during the pre-treatment year had been lost within any of the control or treatment plantations. However, during this same time interval, some species were gained. Western yew, western white pine, and western larch were gained within the control, manually, and cut-stump treated plantations, respectively (Table 3).  28  Species Diversity Herb Layer  At no time during this study did either the Simpson's ( F ^ = 3.34; P = 0.14) or ShannonWiener (F2,4 — 2.78; P = 0.18) mean species diversity of the herb layer differ statistically among the control and treatment plantations (Table 2; Figure 5). Both Simpson's and the Shannon-Wiener index of diversity showed similar time trends among the control and treatment plantations. Specifically, the species diversity of the herb layer appeared to peak one year post-treatment (1993) and then gradually decline during the remaining three years of the study (Figure 5).  Shrub Layer  At no time during this study did either the Simpson's (F  4  2>  = 1.26; P = 0.38) or Shannon-  Wiener (F2 4 = 1.17; P = 0.40) mean species diversity of the shrub layer differ statistically j  among the control and treatment plantations (Table 2; Figure 5). Both control and treatment plantations demonstrated the highest level of shrub species diversity during the pre-treatment year and showed a gradual decline in diversity thereafter.  Tree Layer  At no time during this study did either the Simpson's ( F ^ = 1.49; P = 0.33) or ShannonWiener (F2 4 = 1.22; P = 0.39) mean species diversity of the tree layer differ statistically ;  among the control and treatment plantations (Table 2; Figure 5). The greatest change in both Simpson's and Shannon-Wiener tree species diversity indices occurred between the pre-treatment and first post-treatment year and accounts for the significant (¥7,22 = 2.66; P  29  Control  Manual E 3  Cut-stump  Species Diversity Simpson's Index  Shannon-Wiener Index  Herbs  Herbs  2 1.5  1 0.5  0 '92  '93  '94  '95  '96  Year  Trees  Trees  '92 |  '93  '94  '95  '96  Year  Figure 5. Mean species diversity indices (Simpson's and Shannon-Wiener) for herb, shrub and tree layers among control, manually, and cut-stump treated plantations. No statistical differences (a = 0.10) in species diversity were observed among the control and treatment plantations for any of the plant forms (herbs, shrubs, or trees) during any of the five sample years. Arrow on horizontal axis indicates timing of treatments.  30  = 0.04 and F7 23 = 2.70; P = 0.03, respectively) Time x Treatment interactions reported in Table 2.  Structural Diversity Herb Layer  The mean structural diversity of the herb layer for both the Simpson's (F 2 4 = 0.09; P = 0.92) and Shannon-Wiener (F2,4 = 0.16; P = 0.85) indices were statistically similar among the control and treatment plantations throughout the study (Table 2; Figures 6 and 7). The control plantations were observed to peak in herb structural diversity in the first post-treatment year (1993) and gradually decreased thereafter. Similarly, the plantations that received treatments were also observed to peak in structural diversity, however, this peak lagged behind that of the control by one year (i.e., peaked during the second posttreatment year).  Shrub Layer  The mean structural diversity of the shrub layer for both the Simpson's (F2,4 = 0.05; P = 0.95) and Shannon-Wiener (F2,4 = 0.09; P = 0.92) indices were similar among the control and treatment plantations throughout the study (Table 2; Figures 6 and 7). The structural diversity indices of the shrub layer changed very little during the five year course of this study. The only notable exception was a slight decrease in structural  31  Control [ZD  Manual  Cut-stump  Simpson's Structural Diversity Herbs  Trees  Shrubs  Total  Mean Simpson's structural diversity indices for herb, shrub, tree, and combined total layers among control, manually, and cut-stump treated plantations. Bonferroni post-hoc tests indicated no statistical differences (a = 0.10) in structural diversity among any of the control and treatment plantations within the herb and shrub layers, pre- and post-treatment. However, some statistical differences among the treatment and control groups were observed within the combined total layer. Arrow on horizontal axis indicates timing of treatments. * P < 0.10, ** P < 0.05, *** P < 0.01; significance by Bonferroni post-hoc test. Figure 6.  32  Control  Manual I  I Cut-stump • •  Shannon-Wiener Structural Diversitv  Mean Shannon-Wiener structural diversity indices for herb, shrub, tree, and combined total layers among control, manually, and cut-stump treated plantations. A Bonferroni post-hoc test suggested no statistical differences (a = 0.10) in structural diversity among any of the control and treatment units within the herb, shrub, and tree layers, pre- and post-treatment. However, some statistical differences among the treatment and control groups were observed within the combined total layer. Arrow on horizontal axis indicates timing of treatments. * P < 0.10, ** P < 0.05, *** P < 0.01; significance by Bonferroni post-hoc test. Figure 7.  33  diversity observed immediately following treatment within both manually and cut-stump treated plantations.  Tree Layer  The mean structural diversity of the tree layer for both the Simpson's ( F ^ = 3.68; P = 0.12) and Shannon-Wiener (F2,4 = 3.70; P = 0.12) indices were similar among the control and treatment plantations throughout the study (Table 2; Figures 6 and 7). The structural diversity of the tree layer decreased for both the control and cut-stump treated plantations from the pre-treatment year through to the final year of sampling. The manually treated plantations increased slightly in tree layer structural diversity in the first post-treatment year, followed by a gradual decline during the final three years of sampling. The rate of decrease in tree layer structural diversity (both Simpson's and Shannon-Wiener) was greatest for the control and least for the cut-stump treated plantations.  Total (herb, shrub, and tree layers combined)  The mean total structural diversity indices (both Simpson's and Shannon-Wiener) for the control and treatment plantations gradually declined following a single peak. However, the year in which this peak occurs differs among control, manual, and cut-stump treated plantations (1992, 1993, and 1994, respectively) (Figures 6 and 7). Differences in total structural diversity among control and treatment plantations were indicated by a significant (F2,4 = 7.09; P = 0.05) treatment effect for total Shannon-Wiener structural diversity (Table 2). During the second post-treatment year, total Shannon-Wiener structural diversity within both manual (Bonferroni; P = 0.08) and cut-stump treated  34  plantations (Bonferroni; P = 0.01) was greater than that of the control plantations (Figure 7).  A significant Time X Treatment interaction for mean total Simpson's structural diversity (F723  = 2.39; P = 0.05) made it difficult to comment on the significant main treatment  effect. However, a significant treatment effect ( F ^ = 7.37; P = 0.04) without interaction (F6,i8  = 1.63; P = 0.20) was observed when a RM-ANOVA was performed on the post-  treatment years only. This suggested that the interaction was caused by a change in total Simpson's structural diversity among control and treatment plantations from the pre- to post-treatment year and that a treatment effect did exist during the post-treatment years. Post-hoc tests indicated that, as with the Shannon-Wiener index, total Simpson's structural diversity was significantly greater than that of the control within both the manual (Bonferroni; P = 0.02) and cut-stump treated plantations (Bonferroni; P < 0.01), during the second post-treatment year (Figure 6).  Discussion  Experimental Design The subjective allocation of the cut-stump herbicide treatment was a potential concern because this was not consistent with a randomized-block design. However, although natural variation was apparent among the plantations, the statistical similarity of control and treatment units during the pre-treatment year (Figures 2 to 7) suggested that the  35  subjective allocation of cut-stump treatments did not significantly bias the experimental design of this study. In addition, treatment allocation was well interspersed among the nine plantations (and among the three blocks), a condition that is considered by some to be more important than randomization. Hurlbert (1984) states that ".. .interspersion is the more critical concept or feature; randomization is simply a way of achieving interspersion in a way that eliminates the possibility of bias and allows accurate specification of the probability of a type I error". This is especially true when replication is low, as is often the case with large-scale ecological studies.  Crown Volume Index  Herb and Shrub Layers  Because the manual and cut-stump treatments targeted only specific deciduous tree species, it is not surprising that there was not a significant effect on the crown volume index of herbs or shrubs (Table 2; Figure 2). However, these treatments appeared to temporarily depress the growth of these plant forms, relative to the control. Within the control plantations, during the first post-treatment year (1993), the mean crown volume index of the herb layer increased by 59% from the pre-treatment year (12.3 to 19.6 m /O.Olha). Whereas, during the same period, decreases of 24% (10.8 to 8.2 m /O.Olha) and 17% (13.2 to 11.0 m70.01ha) were observed for the manual and cut-stump treatments, respectively. Similarly, from 1992 to 1993, the mean volume index of the shrub layer increased by 11% (26.6 to 29.6 m /O.Olha) within the control plantations. The shrub layer decreased in volume by 50% (36.7 to 18.5 m /0.01ha) and 19% (28.5 to 3  36  23.1 m /0.01ha) within the manual and cut-stump treatments, respectively, during this 3  period.  The small and temporary decrease in abundance of understory vegetation (both herbs and shrubs) noted in response to treatments during this study was in contrast to the significant decreases in understory biomass reported in several studies treated with broadcast applications of glyphosate (Pollack et al., 1990; Sullivan, 19906; MacKinnon and Freedman, 1993; Sullivan, 1994; Simard and Heineman, 1996a; 19966; 1996c; Sullivan et al, 1998; Whitehead and Harper, 1998; and others). This suggested that, relative to the more commonly prescribed broadcast applications of herbicides, the species-specific approach of cut-stump herbicide applications appeared to have minimal effects on the understory vegetation biomass.  From the second post-treatment year (1994) to the final year of sampling (1996), both herb and shrub crown volume indices fluctuated in a similar manner among the control and treatment plantations presumably in response to natural successional processes.  The deciduous tree slash resulting from the vegetation management treatments likely resulted in the short-term decrease in herb and shrub volume observed one year after treatment. The physical obstruction caused by the deciduous tree slash may have 1) impeded the growth of both herbs and shrubs, and 2) damaged some perennial shrubs. The expected recovery of both herb and shrub volume observed by the second post-  37  treatment year (1994) was likely due to plants taking advantage of the increased resources (light and moisture) created by the treatments.  Deciduous Tree Layer  Because treatments targeted the deciduous tree layer, the dramatic decrease in mean deciduous crown volume was expected in the first post-treatment year (Figure 2). Both the manually and cut-stump treated plantations had significantly less (Bonferroni; P = 0.05 and P < 0.01, respectively) deciduous tree volume than that of the control during this first post-treatment year. However, rapid regrowth of paper birch and trembling aspen trees via prolific stump sprouts occurred within manually treated plantations. Consequently, by the second post-treatment year (1994), deciduous tree volume within the manually treated plantations had returned to levels similar to that of the control. Other trials have also recorded the vigorous sprouting ability of paper birch and other hardwood species following manual cutting (Hart and Comeau, 1992; Simard and Heineman, 1996a). As reported in other studies (Johansson, 1985; Marrs, 1985), the treatment of cut-stumps with the systemic herbicide glyphosate limited the sprouting behavior of hardwoods, resulting in continued suppression of the deciduous tree layer for the four post-treatment years of this study. Relative to the volume of deciduous trees within the control plantations, the manually treated plantations had a treatment effect which lasted only one year.  38  My findings and those of other studies (Christensen, 1984; Lund-Heie, 1984; Johansson, 1985; Marrs, 1985; Wall, 1990), suggest that treatments with the objective of suppressing deciduous tree species capable of growing prolific stump sprouts, such as paper birch and trembling aspen, should employ measures to impede this sprouting behavior. My results indicate that the application of glyphosate to cut-stumps of paper birch and trembling aspen is an effective approach to reduce competition of these species with coniferous crop trees. In addition, the species-specific nature of the cut-stump method appeared to benefit the growth of coniferous crop trees and had no significant effects on other plant community attributes, such as species richness, species turnover, species diversity, and structural diversity.  Coniferous Tree Layer  Although the sampling methods employed during this study did not measure specific attributes of coniferous tree growth (such as diameter at breast height and exact heights), the mean crown volume index did measure the growth response of the entire coniferous tree (branches and bole). Therefore, the crown volume index of the coniferous tree layer is likely directly related to coniferous bole production, which is of primary importance to the silviculturalist gauging the success of vegetation management treatments.  Although no statistical differences in coniferous crown volumes were observed among control and treatment plantations, pre or post-treatment, trends in growth response during the post-treatment years do suggest a treatment effect (Figure 2). The mean annual  39  percentage increment of coniferous tree volume (accumulation of volume) within the control units was very gradual during the four post-treatment years (5% annual increase). This was in contrast to the 44% and 29% mean annual percentage increment of coniferous tree volume observed during this same period among the manually and cutstump treated plantations, respectively. This suggests that the coniferous tree layer did benefit from the vegetation management treatments in terms of an increased rate of growth.  Differences in coniferous tree growth within treated plantations may increase relative to that of the control with time. Simard (1996a) reported that responses of Douglas-fir height growth to vegetation management treatments were not fully expressed even nine years after treatment. Also, a more sensitive measure to determine the treatment effects on crop tree growth may have been possible if the sampling method had included measurements of stem diameter. Simard (1990, 1996a) reported that stem diameter was the most sensitive measure of early response of lodgepole pine to release from competing vegetation.  The slight decrease in coniferous tree volume observed in the first post-treatment year among the manually and cut-stump treated plantations can likely be attributed to a phenomenon known as "thinning shock" (Reukema, 1964; Brix, 1981; Harrington and Reukema, 1983; Maguire, 1983). Thinning shock, of course, does not actually reduce the stem volume of an affected tree, but rather it temporarily reduces the rate of tree growth due to increased exposure (e.g., sunscald) and increased physical damage (e.g., wind,  40  snow, and ice) (Harrington and Reukema, 1983). The decrease in coniferous tree cover observed within the treated plantations during the first post-treatment year was consistent with the effects of thinning shock.  In addition to the short-term negative effects associated with thinning shock, vegetation management treatments may have a more serious long-term effect on a stand's productivity. In deciduous/coniferous mixedwood stands, the potential for deciduous trees to function as nurse trees for a coniferous crop suggests that a stand may experience a decrease in production following treatments that suppress the deciduous tree layer (Man and Lieffers, 1999). Several studies have indicated that deciduous trees can have positive effects on coniferous tree growth by improving nutrient cycling, interplant transfer of nutrients and carbon through mycorrhizae, decreasing competition, reducing pest attack, and by offering physical protection from snow and wind (Navratil et al., 1991; Lieffers and Beck, 1994, Man and Lieffers, 1999). These studies have all been conducted within boreal forests and it is not clear how well their results apply to the milder conditions of the Interior Cedar-Hemlock biogeoclimatic zone. It is clear, however, that no vegetation management prescription should be chosen without considering the natural ecology of the area and the non-timber resource values. In addition, the bias towards coniferous production is not always appropriate with the growing importance of hardwoods in today's wood products (Man and Lieffers, 1999).  41  Species Richness Because differences in herb, shrub, and tree species richness observed among control and treatment plantations were not significant, and time trends were similar among all plantations, the observed fluctuations can be assumed to be associated with naturally occurring environmental and successional events. Other studies have also reported no significant differences in species richness among control plantations and these treated with manual methods or glyphosate applications (Boyd et al, 1995; Simard and Heineman, 1996a; 19966; Sullivan etal, 1996; and others).  The sampling method used during this study recorded the presence of a plant, no matter how small a plant was. Even a plant covering less than 1% was recorded as having trace coverage within a given sample plot. With this fine-filter approach for vegetation sampling, a common scenario might be for a small and/or rare species to be sampled during year 1 and 3, but not during year 2, due to mortality and later germination of that particular species. This does not imply that this species was necessarily lost from the site, nor should the reappearance of this species the following year suggest that this species was gained. Therefore, it was difficult to comment on which species were lost or gained as changes in species composition, especially for the herb and shrub layers, were often only temporary.  42  Species Turnover  Herb Layer The similarity in herb species turnover among control and treatment plantations, as well as similar trends over time, suggested that herb turnover was not affected by treatments and that changes may have been the result of naturally occurring successional events. The number of herb species gained was always greater than species lost during the first two or three years of the study within control and treatment plantations. The contrary was true for the final years of the study, when more herb species were lost than gained. This suggested that the five-year sampling period of this study may have captured a transition period for the herb layer, perhaps changing from a community of shadeintolerant to more shade-tolerant herbs in association with increased canopy closure of the tree layer. The greater number of species gained early in the study may have represented the last wave of shade-intolerant herbs invading the sites while light conditions still permitted germination, and the greater number of species lost during the final years of this study may have represented the loss of shade-intolerant species as light conditions declined.  The peak in herb species richness observed midway through this study further supported the hypothesis that the peak in herb species turnover may have been associated with a period of overlapping herb assemblages (one shade-intolerant and the other more shadetolerant), as one would expect greater species richness during such transitions, before species are lost. Schoonmaker and McKee (1988) reported similar findings during such transitional periods in a study of secondary succession within coniferous forests of the  43  western Cascade Mountains. They described the transition period from one plant assemblage to another as a time of unresolved competition.  Unfortunately, I can only speculate as to the cause of the changes in herb species turnover during this study. Moreover, the lack of statistical difference, within and between years, suggested that the observed changes in herb species turnover may have been the result of random variation and not that of the suggested successional progression of plant species. An analysis that groups herb species into classes of shade-tolerance, as well as a sampling method that specifically measures canopy closure and light conditions beneath the forest canopy, would be important for testing this hypothesis (Halpern and Spies, 1995).  Shrub Layer The similarity in shrub species turnover among control and treatment plantations suggested that shrub turnover was not affected by treatments and that changes may have been the result of naturally occurring successional events. However, a weak trend of increasing shrub turnover within control plantations and a decrease in shrub turnover within the treated plantations over the 5-year period of this study suggested a possible treatment effect. Number of species gained and lost within manually and cut-stump treated plantations remained relatively low and constant throughout the study (average of 0 to 3 species lost and gained within consecutive year intervals). Whereas control plantations experienced a slightly greater and more variable gain and loss of species (average of 1 to 4 species lost and gained within consecutive year intervals). Perhaps the  44  treatments have maintained a more stable shrub community by delaying the canopy closure of the tree layer. The contrary being the case for the control plantations which may have experienced a more rapid change in shrub community due to the decreasing light conditions associated with the closing canopy of the tree layer. The decrease in shrub species turnover observed within both the manual and cut-stump treatments during the final two years of this study suggested that the delay in canopy closure was only temporary and that the shrub community within the treated plantations may have begun to change at this point. As with the herb layer, an analysis that groups shrub species into classes of shade-tolerance, as well as a sampling method that specifically measures canopy closure and light conditions beneath the forest canopy, would have been useful for testing this hypothesis.  Tree Layer  The lack of difference in tree species turnover among control and treatment plantations, as well as among years, suggested that the treatments did not affect tree species turnover and that observed changes were likely the result of naturally occurring successional events.  Species Diversity Two diversity indices were calculated (Simpson's and Shannon-Wiener) because of the different interpretations possible from each type of index. However, because time trends were similar for both indices within the herb, shrub, and tree layers (Figure 5),  45  interpretations of the two diversity indices would also be similar. Therefore, to avoid redundancy, both Simpson's and Shannon-Wiener indices are discussed together.  When interpreting species diversity results, it is important to consider the two components that define diversity: 1) the number of species sampled, or species richness, and 2) the frequency distribution, or relative abundance, of these species. For this study, crown volume index was used to calculate the proportions of species sampled within an area. Therefore, crown volume index is useful for inferring information about the proportion component of a diversity index.  Herb and Shrub Layers  The lack of statistical difference and similar time trends observed among the treatment and control groups, pre- and post-treatment, suggested that the fluctuations in species diversity within the herb and shrub layers may be the result of naturally occurring successional events, and not to the treatments.  Herb species diversity began to decline in 1994, even though this was the year that experienced the greatest species richness of any of the sample years. However, when combined with the fact that the greatest herb volume of any of the sample years was also observed during 1994 (Figure 2), it follows that a few herb species thrived (causing the increased herb volume) and dominated the herb layer during this time, causing the observed decline in herb species diversity. Domination was observed to increase from  46  the first to second post-treatment years for several herb species within control and treatment plantations. In particular, during 1993, the combined crown volumes of fireweed and grass made up 44, 62, and 63% of the total crown volume of the common herbs (Table 3) within control, manual, and cut-stump treated plantations, respectively. In the following year (1994), these same two herbs had increased in dominance and made up 57, 80, and 67% of the total crown volume of the common herbs within control, manual, and cut-stump treated plantations, respectively.  The shrub layer species diversity gradually declined from the pre-treatment year (1992) to the end of the study (1996) among the control, manually, and cut-stump treated plantations (Figure 5). Although shrub species richness was relatively constant throughout all five sample years, shrub volume generally increased during the four posttreatment years. This inverse relationship between shrub species diversity and shrub volume suggested that a few shrubs became increasingly dominant, causing the observed decline in diversity, as was concluded for the herb layer. Domination was observed to increase from the first to second post-treatment years for several shrub species within control and treatment plantations. In particular, during the first post-treatment year (1993), the combined crown volumes of thimbleberry, bitter cherry, and willow made up 77, 83, and 63% of the total crown volume of the common shrubs (Table 3) within control, manual, and cut-stump treated plantations, respectively. By the final year of sampling (1996), these same three shrub species had increased in dominance so that their combined volumes made up 86, 91, and 70% of the total crown volume of the common shrubs within control, manual, and cut-stump treated plantations, respectively.  47  Tree Layer The manual treatment increased tree species diversity while the cut-stump treatment resulted in a decrease in diversity from the pre-treatment to post-treatment year period. Tree species diversity within the control plantations remained relatively unchanged during this same period. The different treatment effects on tree species diversity between these two years (1992 and 1993) accounts for the significant Time X Treatment interaction observed in Table 2, and was confirmed by the nonsignificant interaction (F , = 0.68; P = 0.66 and F i = 0.87; P = 0.53 for Simpson's and Shannon-Wiener 6j  8  6>  8  indices, respectively) that resulted from a RM-ANOVA without the pre-treatment year.  Once again, the two components of diversity (number of species (species richness) and relative proportions of these species (inferred via crown volume index)) must be investigated to interpret and explain the observed response in tree species diversity.  Because tree species richness was relatively constant and coniferous tree volume changed little in the first post-treatment year, the dramatic changes in deciduous tree volume were suspected to be the cause of changes in tree species diversity within the manual and cutstump treatments. The dramatic reduction of deciduous tree volume observed within the cut-stump treated plantations (95% decrease relative to pre-treatment year), while not eliminating any deciduous species, increased the relative dominance of the coniferous trees. Of the total crown volume index for the tree layer, coniferous trees made up 50% during the pre-treatment year. During the first post-treatment year, the proportion of  48  coniferous trees had increased to 94% within plantations receiving the cut-stump treatment. Moreover, during this first post-treatment year, 88% of the total tree crown volume was made up of only 4 of the 12 tree species found within the cut-stump treated plantations, all coniferous (Douglas-fir, western redcedar, lodgepole pine, and western hemlock). Conifer dominance is, therefore, the most likely cause for the decline in tree species diversity during the first post-treatment year.  Manually treated plantations also had the deciduous tree layer volume significantly reduced (87% decrease relative to pre-treatment year). During the pre-treatment year, 76% of the total tree volume was made up of just 3 of the 11 tree species found within the manually treated plantations, all deciduous (paper birch, black cottonwood, and trembling aspen). During the year following treatment, these three deciduous tree species comprised only 37% of the total tree volume. The removal of a substantial proportion of this deciduous tree layer resulted in a more evenly distributed, and therefore, more diverse tree layer during the first post-treatment year within manually treated plantations. Pielou (19666) described this type of increase in species diversity (i.e., one caused by the thinning of a dominant tree layer) as resulting from an increase in pattern-diversity.  Structural Diversity Herb Layer  The similar structural diversity (both Simpson's and Shannon-Wiener) of the herb layer observed among control and treatment plantations, pre- and post-treatment, suggested  49  that changes in structural diversity may have been caused by naturally occurring successional events, and not by the treatments. The gradual decline in structural diversity of the herb layer within control and treatment plantations was likely correlated with increasing canopy closure of the tree layer. By removing a substantial portion of the tree canopy, the time to canopy closure was delayed within plantations that received treatments. The observed delay for the herb layer to reach peak structural diversity within the manual and cut-stump treated plantations further suggested that structural diversity of the herb layer was related to the overstory canopy closure.  I predicted that the treatments should not significantly alter the structural diversity of the herb layer. This was because of the annual nature of herbs which allow this plant layer to respond quickly to changing environmental conditions, growing into many of the same height classes as it had the year before. In contrast, perennial plants such as shrubs, because of their interdependence on the previous year's growth, were predicted to take a little longer, as a group, to respond to new environmental conditions.  Shrub Layer  The lack of statistical difference among the control and treatment plantations for structural diversity of the shrub layer suggested that the minor fluctuations in diversity may have been caused by naturally occurring successional events. However, the slight decrease and increase in structural diversity observed within treated and control plantations, repectively, during the first post-treatment year suggested a possible treatment effect. By felling a substantial portion of the deciduous tree layer during  50  treatment, it is speculated that the obstruction and physical damage caused to the shrub layer (particularly the taller height classes) may have temporarily simplified the structural diversity of this layer.  Tree Layer  As a stand of trees ages, shading created by increasing canopy closure begins to thin out and simplify the understory height classes (Pielou, 19666). By removing a substantial portion of the canopy, the manual and cut-stump treatments had effectively delayed the onset of canopy closure within the treated plantations. The result was that the plantations receiving treatments had greater structural diversity than the control plantations, although this difference was not significant. The control plantations moved quickest towards canopy closure, and as such, decreased in structural diversity faster than either of the two treatment groups.  Total (herb, shrub, and tree layers combined)  Because overstory shading, to a large extent, governs what can grow in the understory, canopy closure is a driving force that will largely determine the total (herb, shrub, and tree layers combined) structural diversity of a stand. Therefore, as the control plantations grew unimpeded towards canopy closure, there was a steady decline in structural diversity throughout all five years of this study. Treatments, on the other hand, temporarily opened the overstory canopy, and consequently the total structural diversity, although decreasing through the post-treatment years, was statistically more structurally diverse than that of the control in 1994.  51  Conclusions  This study suggested that conifer release from deciduous trees (capable of stump sprouts) was best achieved with a cut-stump application of herbicide, such as glyphosate. Methods that do not employ some means of impeding stump sprouts, such as the manual cutting method, are not likely to maintain suppression of deciduous trees for extended periods following treatment.  Although the cut-stump herbicide application of glyphosate significantly reduced deciduous tree volume for four post-treatment years, this treatment had little effect on species richness, species diversity, and structural diversity of the plant community (herb, shrub, and tree layers). In fact, reduced dominance of the deciduous tree layer and opening of the tree canopy created by both treatments appeared to increase the total structural diversity (all layers combined) during the post-treatment years, relative to that of the control.  This study appears to be the first to analyze a plant community's response to alternative vegetation management treatments applied to young mixed-conifer plantations. Results suggested that the species-specific approach of the cut-stump herbicide treatment should achieve its objective of conifer release without adversely affecting the species richness, species diversity, or structural diversity of the plant community, while suppressing the targeted deciduous tree layer volume.  52  Literature Cited  Adler, G.H. 1987. Influence of habitat structure on demography of two rodent species in eastern Massachusetts. Can. J. Zool. 65: 903-912. Anthony, R.G. and M.L. Morrison. 1985. Influence of glyphosate herbicide on small mammal populations in western Oregon. Northwest Sci. 59:159-168. B.C. Ministry of Forests. 1995. Forest practices code of British Columbia: Biodiversity guidebook. Ministry of Forests and Ministry of Environment. 99 p. Balda, R.P. 1969. Foliage use by birds of the oak-pine juniper woodland and ponderosa pine forest in southeastern Arizona. Condor. 7 1 : 399-412. Berry, A.B. 1982. Response of suppressed conifer seedlings to release from aspen-pine overstory. For. Chron. 58: 91-92. Boyd, R.S., J.D. Freeman, J.H. Miller, and M.B. Edwards. 1995. Forest herbicide influences on floristic diversity seven years after broadcast pine release treatments in central Georgia, USA. New Forests 10. 1:17-37. Brand, D.G. 1992. The use of vegetation management in Canadian forest regeneration programs. Aspects of Appl. Bio. 29:113-124. Brix, H. 1981. Effects of thinning and nitrogen fertilization on branch and foliage production in Douglas-fir. Can. J. For. Res. 1 1 : 502-511. Cambell, D.L., J. Evans, G.D. Lindsey, and W.E. Dusenberry. 1981. Acceptance by black-tailed deer of foliage treated with herbicides. USDA For. Serv., Pacific Northwest Forest and Range Experiment Station; Portland, OR: USDI, Fish and  Wildlife Service, Forest-Animal Damage Control Research Project. Olympia, WA. Res. Pap. PNW-290. 31 p. Campbell, R.A. 1990. Herbicide use for forest management in Canada: where we are and where we are going? For. Chron. 66: 355-360. Christensen, P. 1984. Review of Danish results from chemical/mechanical control of deciduous vegetation. Aspects of Appl. Bio. 5:135-142. Clough, G.C. 1987. Relations of small mammals to forest management in northern Maine. Can. Field-Nat. 101:40-48. Crossley, D. I. 1976. Growth response of spruce and fir to release from suppression. For. Chron. 52: 189-193. D'Anieri, P., Leslie, D.M., Jr., and M.L. McCormack, Jr. 1987. Small mammals in glyphosate-treated clearcuts in northern Maine. Can. Field-Nat. 101: 547-550. Freedman, B. 1991. Controversy over the use of herbicides in forestry, with particular reference to glyphosate usage. J. Environ. Sci. Health. C8: 277-286. Freedman, B., R. Morash, and D. MacKinnon. 1993. Short-term changes in vegetation after the silvicultural spraying of glyphosate herbicide onto regenerating clearcuts in Nova Scotia, Canada. Can. J. For. Res. 23:2300-2311. Glover, P. 1994. Reducing forest herbicide use in Northwestern British Columbia: Public pressure gets results. J. Pest. Reform. 14: 2-4. Halpern C B . and T.A. Spies. 1995. Plant species diversity in natural and managed forests of the Pacific Northwest. Ecological Applications. 5:913-934. Harney, B.A. and R.D. Dueser. 1987. Vertical stratification of activity of two Peromyscus species: an experimental analysis. Ecology. 68: 1084-1091.  54  Harrington, C A . and D.L. Reukema. 1983. Initial shock and long-term stand development following thinning in a Douglas-fir plantation. For. Sci. 29: 33-46. Hart, D. and P.G. Comeau. 1992. Manual brushing for forest vegetation management in British Columbia: a review of current knowledge and information needs. B.C. Min. For., Victoria, B.C., Land Manage. Handb. No. 7. Hitchcock, C.L. and A. Cronquist. 1973. Flora of the Pacific Northwest. University of Washington Press, Seattle. Hunter, M.L., Jr. 1990. Vertical structure (Chapter 11). In Wildlife, forests, and forestry: principles of managing forest for biological diversity. Prentice Hall, Englewood Cliffs, N.J. pp 181-199. Hurlbert, S. H. 1984. Pseudoreplication and the design of ecological field experiments. Ecol. Monogr. 54: 187-211 Johansson, T. 1985. Herbicide injections into stumps of aspen and birch to prevent regrowth. Weed Res. 25: 39-45. Jones, R. and J.M. Forbes. 1984. A note on effects of glyphosate and quinine on the palatability of hay for sheep. Animal Production. 38:301-303. Ketcheson, M.V., Braumandl, T.F., Meidinger, D., Utzig, G., Demarchi, D.A., and B.M.Wikeem, 1991. Interior Cedar-Hemlock zone. In Ecosystems of British Columbia. Edited by D. Meidinger and J. Pojar. B.C. Ministry of Forests, Victroria. pp 167-181. Krebs, C.J. 1989. Ecological Methodology. Harper and Row, New York, New York, USA.  Kuehl, R.O. 1994. Repeated measures designs (Chapter 15). In Statistical principles of research design and analysis. Duxbury Press, Belmont, California, pp 499-528. Lautenschlager, R.A. 1986. Forestry, herbicides, and wildlife. In Is good forestry good wildlife management? Edited by J.A. Bissonette. Maine Agric. Stn. Misc. Publ. 689. pp. 299-308. Lautenschlager, R.A. 1993. Response of wildlife to forest herbicide applications in northern coniferous ecosystems. Can. J. For. Res. 23: 2286-2299. Lavigne, M.B. 1988. Growth and net assimilation rates in thinned and unthinned stands of balsam fir. Can. J. For. Res. 18: 1205-1210. Lieffers V.J. and J.A. Beck Jr. 1994. A semi-natural approach to mixedwood management in the prairie provinces. For. Chron. 70: 260-264. Littel, R.C. 1989. Statistical analysis of experiments with repeated measures. HortScience. 24: 36-40. Lloyd, D.A., Angove, K., Hope, G., and C. Thompson, 1990. A guide for site identification and interpretation of the Kamloops Forest Region. Vols. 1 and 2. B.C. Ministry of Forests, Victoria. Land Manage. Handb. 23. Lund-Haie, K. 1984. Growth response of Norway spruce (Picea abies L.) to different vegetation management programmes - preliminary results. Aspects of Appl. Bio. 5: 127-133. MacArthur, R.H. 1964. Environmental factors affecting bird species diversity. Am. Nat. 98: 387-397. MacArthur, R.H. 1965. Patterns of species diversity. Biol. Rev. 40:510-533.  MacArthur, R.H. and J.W. MacArthur. 1961. On bird species diversity. Ecology. 42: 594-598. MacKinnon, D.S. and B. Freedman. 1993. Effects of silviculture use of the herbicide glyphosate on breeding birds of regenerating clearcuts in Nova Scotia, Canada. J. Appl. Ecol. 30 395-406. MacLean, D.A. and M.G. Morgan. 1983. Long-term growth and yield response of young fir to mechanical and chemical release from shrub competition. For. Chron. 59: 177-183. Maguire, D.A. 1983. Suppressed crown expansion and increased bud density after precommercial thinning in California Douglas-fir. J. For. Res. 13: 1246-1248. Man, R. and V.J. Lieffers. 1999. Are mixtures of aspen and white spruce more productive than single species stands? For. Chron. 75: 505-513. Marrs, R.H. 1985. Birch control by the treatment of cut stumps with herbicides. Arbor. J. 9: 173-182. McDonald, P.M. and S.R. Radosevitch. 1992. General principles of forest vegetation management. In Silvicultural approaches to animal damage management in Pacific Northwest forests. Technical Editor: H.C. Black. USDA For. Serv. Gen. Tech. Rep. PNW-GTR-287. pp 67-91. McGee, A.B. and E. Levy. 1988. Herbicide use in forestry: communication and information gaps. J. Environ. Manage. 26: 111-126. Mitchell, W. 1990. Vegetation management and public concerns in British Columbia. In Vegetation management: An integrated approach - Proceeding of the fourth annual  57  vegetation management workshop, Nov. 14-16, 1989. Vancouver, B.C. Compiled by E. Hamilton. Ministry of Forests, Research Branch, pp. 8-9. Morrison, M.L. and E.C. Meslow. 1983. Impacts of forest herbicides on wildlife: toxicity and habitat alteration. Trans. N. Am. Wildl. Nat. Resour. Conf. 48: 175-185. Navratil, S., K. Branter and J. Zasada. 1991. Regeneration in the mixedwoods. pages 32-48. In A. Shortreid, Ed. Northern mixedwood '89. Proc. Symp., Sept. 12-14, 1989. Fort St. John, B.C. Pacific Forestry Centre. Victoria, B.C. FRDA Rep. 164. Newton, M. and P.G. Comeau. 1990. Control of competing vegetation, irc Regenerating British Columbia's forests. Edited by D.P. Lavender, R. Parish, C M . Johnson, G. Montgomery, A. Vyse, R.A. Willis, and D. Winston. University of British Columbia Press, Vancouver, pp. 256-265. Newton, M., Howard, K.M., Kelpsas, B.R., Danhaus, R., Lottman, C M . , and S. Dubelman. 1984. Fate of glyphosate in an Oregon forest ecosystem. J. Agric. Food Chem. 32: 1144-1151. Peet, R.K. 1974. The measurement of species diversity. Annu. Rev. Ecol. Syst. 5: 285307. Pielou, E.C. 1966a. The measurement of species diversity in different types of biological collections. J. Theor. Biol. 13:131-144 Pielou, E.C. 19666. Species-diversity and pattern-diversity in the study of ecologial succession. J. Theor. Biol. 10: 370-383. Pollack, J.C, P. LePage, and F. van Thienen. 1990. Some effects of different forest herbicides on upland Salix spp. Can. J. For. Res. 20: 1271-1276.  Reukema, D.L. 1964. Crown expansion and stem radial growth of Douglas-fir as influenced by release. For. Sci. 10:192-199. Ritchie, R. T., and T. P. Sullivan. 1989. Monitoring methodology for assessing the impact of forest herbicide use on small mammal populations in British Columbia. FRDA report no. 081. Rosenthal, R. and R.L. Rosnow. 1985. Contrast analysis: focused comparisons in the analysis of variance. Cambridge University Press. London. Runciman, J. B. and T. P. Sullivan. 1996. Influence of alternative conifer release treatments on habitat structure and small mammal populations in south central British Columbia. Can. J. For. Res. 26: 2023-2034. Santillo, D.J., Leslie, D.M., Jr., and P.W. Brown. 1989. Response of small mammals and habitat to glyphosate application on clearcuts. J. Wild. Manage. 53: 164-172. Schoonmaker, P. and A. McKee. 1988. Species composition and diversity during secondary succession of coniferous forests in the western Cascade Mountains of Oregon. For. Sci. 34: 960-979. Simard, S.W. 1990. A retrospective study of competition between paper birch and planted Douglas-fir. Can. For. Serv. and B.C. Min. For., Victoria, B.C. FRDA Rep. No. 147. Simard, S.W. and J. Heineman. 1996a. Nine-year response of Douglas-fir and the mixed-hardwood-shrub complex to chemical and manual release treatments on an ICHmw2 site near Salmon Arm. Can. For. Serv. and B.C. Min. For., Victoria, B.C., FRDA Rep. No. 257.  59  Simard, S.W. and J. Heineman. 19966. Nine-year response of lodgrepole pine and the dry alder complex to chemical and manual release treatments on an ICHmkl site near Kelowna. Can. For. Serv. and B.C. Min. For., Victoria, B.C., FRDA Rep. No. 259. Simard, S.W. and J. Heineman. 1996c. Nine-year response of Englemann spruce and the willow complex to chemical and manual treatments on an ICHmw2 site near Vernon. Kelowna. Can. For. Serv. and B.C. Min. For., Victoria, B.C., FRDA Rep. No. 258. Simpson, E.H. 1949. Measurement of diversity. Nature. 163:688. SPSS Institute Inc. 1997. Statistical Programs for the Social Sciences. Chicogo, IL. Stickney, P. F. 1980. Data base for post-fire succession, first 6 to 9 years, in Montana Larch-fir forests. USDA Forest Service General Technical Report, LNT-62, Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. Stickney, P. F. 1985. Data base for early post-fire succession on the Sundance Burn, northern Idaho. USDA Forest Service General Technical Report, INT-189, Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. Sullivan, T.P. 1990a. Influence of forest herbicide on deer mice and Oregon vole population dynamics. J. Wildl. Manage. 54: 566-576. Sullivan, T.P. 19906. Demographic responses of small mammal populations to a herbicide application in coastal coniferous forest: population density and resiliency. Can. J. Zool. 68: 874-883. Sullivan, T.P. 1994. Influence of herbicide-induced habitat alteration on vegetation and snowshoe hare populations in sub-boreal spruce forest. J. Appl. Ecol. 31: 717-730. Sullivan, T.P. and D.S. Sullivan. 1979. The effects of glyphosate herbicide on food preference and consumption in black-tailed deer. Can. J. Zool. 57: 1406-1412.  60  Sullivan, T.P. and D.S., Sullivan. 1981. Response of a deer mouse population to a forest herbicide application: reproduction, growth, and survival. Can. J. Zool. 59: 11481154. Sullivan T.P. and D.S., Sullivan. 1982. Responses of small mammal populations to a forest herbicide application in a 20-year-old conifer plantation. J. Appl. Ecol. 19: 95106. Sullivan, T.P., D.S. Sullivan, R.A. Lautenschlager, and R.G. Wagner. 1997. Long-term influence of glyphosate herbicide on demography and diversity of small mammal communities in coastal coniferous forest. Northwest Sci. 71: 6-17. Sullivan, T.P., R.A. Lautenschlager, and R.G. Wagner. 1996. Influence of glyphosate on vegetation dynamics in different successional stages of sub-boreal spruce forest. Weed Tech. 10:439-446. Sullivan, T.P., R.G. Wagner, D.G. Pitt, R.A. Lautenschlager, and D.G. Chen. 1998. Changes in diversity of plant and small mammal communities after herbicide application in sub-boreal spruce forest. Can. J. For. Res. 28:168-177 Sutton, S.L. and P.J. Hudson. 1980. The vertical distribution of small flying insects in lowland rainforests of Zaire. Zool. J. Linnaean Soc. 68:111-123. Tomkins, D.J. and W.F. Grant. 1977. Effects of herbicides on species diversity of two plant communities. Ecology. 58: 398-406. Turpin, T.C. 1990. Vegetation management and public issues in the Pacific Northwest. In Vegetation management: An integrated approach - Proceeding of the fourth annual vegetation management workshop, Nov. 14-16,1989. Vancouver, B.C. Compiled by E.Hamilton. Ministry of Forests, Research Branch, pp 4-7.  61  Wagner, R. G. 1993. Research directions to advance forest vegetation management in North America. Can. J. For. Res. 23: 2317-2327 Wall, R.E. 1990. The fungus Chrondrostereum purpureum as a silvicide to control stump sprouting in hardwoods. North. J. Appl. For. 7:17-19. Walmsley, M. E., G. Utzig, T. Void, and J. Van Barneveld. 1980. Describing ecosystems in the field. British Columbia Ministry of Environment and Ministry of Forests, Land Management Report Number 7. Wang, J.R., S.W. Simard, J.P. Kimmins. 1995. Physiological responses of paper birch to thinning in British Columbia. For. Ecol. Manag. 73: 177-184. Whitehead, R.J. and G.J. Harper. 1998. A comparison of four treatments for weeding Englemann spruce plantations in Interior Cedar Hemlock Zone of British Columbia: ten years after treatment. Information Report BC-X-379. Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. 21 p. Yang, R.C. 1991. Growth of white spruce following release from aspen competition: 35 year results. For. Chron. 67:706-711. Zar, J.H. 1984. Data transformations (Chapter 14). In Biostatistical analysis. 2 ed. nd  Prentice Hall, Englewood Cliffs, N.J. pp 236-243.  62  Appendix 1  Alphabetical list of all of the herb species that were sampled during the five years of this study (75 species in total). Nomenclature follows Hitchcock and Cronquist, (1973). Scientific (Latin) name Achillea millefolium L.  Common name  Actea rubra (Ait.) Willd.  Baneberry  Adenocaulon bicolor Hook.  Pathfinder  Anaphalis margaritacea L.  Pearly everlasting  Antennaria microphylla Rydb.  Rosy pussytoes  Apocynum androsaemifolium L.  Spreading dogbane  Aquilegia formosa Fisch.  Red columbine  Aralia nudicaulis L.  Wild sarsaparilla  Arnica cordifolia Hook.  Heart-leaved arnica  Asarum caudatum Lindl.  Wild ginger  Aster ciliolatus Lindl.  Lindley's aster  Aster foliaceus Lindl.  Leafy aster  Athyrium filix-femina (L.) Roth.  Lady fern  Calypso bulbosa (L.) Oakes.  Fairyslipper  Car ex spp. L.  Sedge  Castilleja miniata Dougl.  Common red paintbrush  Cerastium arvense L.  Field chickweed  Chrysanthemum leaucanthemum L.  Oxeye daisy  Cirsium arvense (L.) Scop.  Canada thistle  Cirsium vulgare (Savi) Tenore  Bull thistle  Clintonia uniflora (Schult.) Kunth.  Quene's cup  Cornus canadensis L.  Bunchberry  Disporum hookeri (Torr.) Nicholson  Hooker's fairybells  Epilobium angustifolium L.  Fireweed  Epilobium minutum Lindl.  Small-flowered willowherb  Yarrow  63  Appendix 1 Continued Common name  Scientific (Latin) name Epilobium watsonii  Purple-leaved willowherb  Barbey  Equisetum arvense L.  Common horsetail  Fragaria virginiana Duchesne  Wild strawberry  Galium triflorum  Sweet-scented bedstraw  Michx.  Geranium sp. L.  Geranium  Geum macrophullum Willd.  Large-leaved avens  Goodyera oblongifolia Raf.  Rattlesnake plantain  Gramineae spp.  Grass  Gymnocarpium dryopteris Habenaria unalescensis Hieracium albiflorum  (L.) Newm.  (Spreng.) Wats.  Hook.  Hieracium gracile  Alaska rein-orchid White hawkweed Orange hawkweed  Hieracium aurantiacum L. Hieracium cynoglossoides  Oak fern  Arv.-Touv.  Hook.  Hounds-tongue hawkweed Slender hawkweed  Hieracium umbellatum L.  Narrow-leaved hawkweed  Lactuca canadensis L.  Canadian wild lettuce  Lactuca muralis  (L.) Fresen.  Lactucapulchella (Pursh) DC. Lathyrus ochroleucus Lilium columbianum Lupinus latifolius  Hook.  Hanson  Blue lettuce Creamy peavine Tiger lily  var. subalpinus (Piper &  Robins) Smith Medicago sativa L. Melilotus alba  Wall lettuce  Desr.  .TA.1. C  1UU11IC  Alfalfa White sweet-clover  Melilotus officinalis (L.) Lam.  Yellow sweet-clover  Mentha arvensis L.  Field mint  64  Scientific (Latin) name Mitella nuda L.  Appendix 1 Continued Common name  Osmorhiza chilensis H. & A.  Osmorhiza purpurea (Coult. & Rose)  Suksd.  Common mitrewort Mountain sweet-cicely Purple sweet-cicely  Prunella vulgaris L.  Self-heal  Pteridium aquilinum (L.) Kuhn.  Bracken  Pyrola asarifolia Michx.  Pink wintergreen  Pyrola picta Smith  White-viened wintergreen  Pyrola secunda L.  One-sided wintergreen  Ranunculus sp. L.  Buttercup  Saxifraga occidentalis Wats.  Western saxifrage  Smilacina racemosa (L.) Desf.  False Solomon' s-seal  Smilacina stellata (L.) Desf.  Star-flowered false Solomon's-seal  Sonchus arvensis L.  Perennial sow-thistle  Streptopus amplexifolius (L.) DC.  Clasping twisted stalk  Streptopus roseus Michx.  Rosy twisted stalk  Streptopus streptopoides (Ledeb.) Frye &  Small twisted stalk  Rigg Taraxacum officinale Weber Tiarella trifoliata var. trifoliata L. Tiarella trifoliata var. unifoliata (Hook.)  Kurtz.  Common dandelion Three-leaved foamflower One-leaved foamflower  Tragopogon dubius Scop.  Yellow salsify  Trifolium pratense L.  Red clover  Trifolium repens L.  White clover  Verbascum thapsus L.  Great Mullein  Vicia americana Muhl.  American vetch  Viola spp. (L.)  Violet  65  Appendix 2 Alphabetical list of all of the shrub species that were sampled during the five years of this study (37 species in total). Nomenclature follows Hitchcock and Cronquist, (1973). Scientific (Latin) name Acer glabrum var. douglasii (Hook.)  Dippel Alnus incana (L.) Moench. Amelanchier alnifolia Nutt. Arctostaphylos uva-ursi (L.) Spreng. Berberis aquifolium Pursh Ceanothus velutinus Dougl. Chimaphila umbellata (L.) Bart. Cornus stolonifera Michx. Gaultheria ovatifolia Gray  Holodiscus discolor (Pursh) Maxim Linnaea borealis (L.) Lonicera ciliosa (Pursh) DC.  Lonicera involucrata (Rich.) Banks Lonicera utahensis Wats. Menziesia ferruginea Smith Pachistima myrsinites (Pursh) Raf.  Prunus emarginata (Dougl.) Walp. Rhamnus purshiana DC.  Ribes lacustre (Pers.) Poir. Ribes viscosissimum Pursh. Rosa acicularis Lindl. Rosa gymnocarpa Nutt. Rubus idaeus L. Rubus leucodermis Dougl. Rubus parviflorus Nutt.  Common name  Douglas maple Speckled alder Saskatoon Kinnikinnick Tall Oregon-grape Snowbrush Prince's-pine Red-osier dogwood Oregon wintergreen Ocean spray Twinflower Orange honeysuckle Black twinberry Utah honeysuckle False azalea Falsebox Bitter cherry Cascara Black gooseberry Sticky current Prickly rose Baldhip rose Red raspberry Black raspberry Thimbleberry  66  Scientific (Latin) name Rubus pedatus J. E . Smith  Appendix 2 Continued Common name  Five-leaved bramble  Rubus pubescens Raf.  Trailing raspberry  Salix spp. L.  Willow  Sambucus racemosa L.  Red elderberry  Sheperdia canadensis (L.) Nutt.  Soopolallie  Sorbus sitchensis Roemer  Sitka mountain-ash  Spiraea betulifolia Pall.  Birch-leaved spirea  Symphoricarpos albus (L.) Blake  Common snowberry  Vaccinium caespitosum Michx.  Dwarf blueberry  Vaccinium membranaceum Dougl.  Black huckleberry  Vaccinium ovalifolium Smith  Oval-leaved blueberry  Vaccinium parvifolium Smith  Red huckleberry  67  Appendix 3 Alphabetical list of all of the tree species that were sampled during the five years of this study (12 species in total). Nomenclature follows Hitchcock and Cronquist (1973). Scientific (Latin) name Common name Subalpine fir Abies lasiocarpa (Hook.) Nutt. Betula papyrifera Marsh.  Paper birch  Larix occidentalis Nutt. Picea engelmannii Parry X Picea glauca  Western larch  (Moench) Voss Pinus contorta Dougl. ex Loud. var. latifolia Engelm. Pinus monticola Dougl. Populus tichocarpa T. & G. Populus tremuloides Michx. Pseudotsuga menziesii var. glauca  (Beissin.) Franco Taxus brevifolia Nutt. Thuja plicata Donn ex D. Don  Tsuga heterophylla (Raf.) Sarg.  Hybrid spruce Lodgepole pine Western white pine Black cottonwood Trembling aspen Interior Douglas-fir Western yew Western redcedar Western hemlock  68  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0075409/manifest

Comment

Related Items