British Columbia Mine Reclamation Symposium

Natural revegetation of disturbances in the Peace River Coalfield Meidinger, Dellis Vern, 1953- 1979

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Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 273 NATURAL REVEGETATION OF DISTURBANCES IN THE PEACE RIVER COALFIELD Paper presented by: D.V.   Meidinger Dept.   of   Biology University  of Victoria Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 275 NATURAL REVEGETATION OF DISTURBANCES IN THE PEACE RIVER COALFIELD INTRODUCTION Knowledge of the environmental factors influencing the natural revegetation of man-made disturbances can provide valuable information which can be applied to reclamation procedures.  The environmental factors influencing natural revegetation were examined on areas disturbed by coal exploration in the Peace River Coalfield.  The factors found to be significantly corre- lated with the total vascular plant cover on a site (used as a measure of revegetation success) are discussed and suggestions are made regarding how this information may be of use to those responsible for reclamation. DESCRIPTION OF STUDY AREA The Peace River Coal Block is located on the eastern slope of the Rocky Mountains and runs in a northwest to southeast band within the Rocky Mountain Foothills Physiographic Region (Void, 1977) and extends from Williston Lake in the north to the Alberta border in the south.  The topographic relief within this region ranges from about 600 metres in some valley bottoms, to approximately 1900 metres at the top of some foothills. The foothills are underlain by faulted and folded sandstones, shales, conglomerates, and of course, coal. Natural vegetation in the area can be classified into four biogeoclimatic zones (Krajina, 1965).  The Boreal White and Black Spruce Zone to the west and the Subboreal Spruce Zone to the east occur in the valley bottoms and extend in height to approximately 1,000 metres.  The Engelmann Spruce -Sub- alpine Fir Zone is located between about 1,000 metres and 1,600 metres, while the Alpine Tundra Zone occurs at highest elevations.  At the upper levels of the treeline, where the Engelmann Spruce - Sub-alpine Fir Zone meets the Alpine Tundra Zone, there is an area where stunted Engelmann Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 276 Spruce and/or Sub-alpine Fir patches are found in mosaic with alpine vege- tation.  This area is referred to as the krummholz, due to the straggling, krummholz form of the trees, and is given a subzone designation by Harcombe (1978) in his biophysical treatment of the vegetation in the area.  Coal exploration has occurred in all four biogeoclimatic zones, but has been con- centrated in the Englemann Spruce - Sub-alpine Fir Zone and the Alpine Tundra Zone.  Thus, the sampling sites were concentrated in these two zones. STUDY METHODS Data Collection Data for this study were collected during the summers of 1977 and 1978 in conjunction with a study of the native species invasion of distur- bances in the Peace River Coalfield.  The main sampling areas were Bullmoose Mountain, Mount Chamberlain, Babcock Mountain, McAllister Creek - Carbon Creek, and Mount Johnson, which were selected because of the wide range of disturbances found in these areas and their relative ease of access. Sampling sites were chosen on disturbances that had been left to reve- getate naturally.  Plots were located in sections of disturbances where there was uniformity in species composition, community physiognomy, parent material, and adjacent vegetation, as well as consistency in such physical factors as slope and aspect.  Plot size varied from 25 to 40 square metres depending upon the site dimensions.  For each plot, in addition to an estimate of the total vascular plant cover, a list of all species with an estimate of their individual cover was made. Information recorded included the date of the observation; plot location; year of site abandonment; and the physical environmental parameters such as slope, aspect, elevation, moisture condition, micro-relief, exposure type and magnitude, and position on slope.  In addition features of the soil such as texture, colour, pH, drainage, compaction, degree of erosion and origin of surficial material were noted, as were the features of the adjacent undisturbed vegetation community including slope, aspect, dominant plants in each layer, and the biogeoclimatic zone.  At all sites during 1978, a soil sample was Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 277 collected which was analyzed to determine the levels of nitrate, phosphorus, potassium, magnesium and calcium concentration, per cent organic matter and electrical conductivity by the B.C. Ministry of Agriculture, Soils Lab, Kelowna.  Data Analysis Total vascular plant cover in a plot was used as a measure of the "revegetation success" on a particular site which within the age range of the sites sampled, was considered to be a valid approach.  The rela- tionship of the environmental variables to the "revegetation success" on a site was determined by calculating correlation coefficients between each of the environmental variables and the total vascular plant cover (expressed as per cent cover). Product-moment correlationcoefficients(Zar, 1974) were calculated to determine the relationship between total cover and the continuous variables of age, elevation, site slope, adjacent site slope, site exposure, adjacent site exposure, pH, nitrates, phosphorus, potassium, calcium, magnesium, organic matter content, salt level per cent erosion, compaction, and the texture of coarse fragments (Table 1). Spearman rank correlation coefficients (Zar, 1974) were calculated to determine the relationship between total cover and the ordinal variables of magnitude of wind exposure, heat index, site moisture regime, degrees of compaction, erosion intensity index, extent erosion, texture index, and soil colour (Table 2). To determine if there were any different factors affecting revegetation above and below the treeline, the data set was divided into two subsets and the previously described analysis was performed on each subset. The rates of revegetation on identifiable subsets of the data were determined by performing linear regression analysis (Zar, 1974) using the variable of age versus cover for each subset.  The subsets chosen were similar to the vegetation units described in the British Columbia Ministry of Mines and Petroleum Resources, Reclamation Program, Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 278 TABLE 1 EXPLANATION OF CONTINUOUS VARIABLES MEASURED  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 279 TABLE 2:  EXPLANATION OF CODING OF ORDINAL VARIABLES VARIABLE Wind exposure magnitude Heat index EXPLANATION 0 - Wind exposure not important 1 - strong wind exposure 2 - very strong wind exposure 3 — extreme wind exposure Exposure of site determines "heat index" as follows  Site moisture regime  1 - very xeric 2 - xeric 3 - subxeric 4 - submesic 5 - mesic  6 - subhygric 7 - hygric 8 - subhygric 9 - hygric  Compaction magnitude Erosion intensity index 0 - material on site less compacted than adjacent natural site 1 - material on site compacted about the same as adjacent site 2 - moderately compacted relative to adjacent site 3 - highly compacted relative to adjacent site Number of channels in plot times the depth of the channels in centimetres  Erosion magnitude Texture index  0 - no visible erosion 1 - sheet erosion 2 - rill erosion 3 - gully erosion  1 - sand, loamy-sand 2 - sandy-loam 3 - loam, silt-loam 4 - silt, sandy-clay-loam, clay-loam, silty-clay- loam 5 - sandy-clay, clay, silty-clay, heavy clay 6 - organic  Soil colour Value plus chroma using 10YR Munsell Colour Chart Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 280 Northeast Coal Block, 1977 report.  The units are based on broad physiognomic and edaphic criteria, and include Dry Alpine, Mesic Alpine, Wet Alpine, Dry Forest, Mesic Forest, and Wet Forest.  The regressions were forced through zero, as there was not adequate sampling on the young sites, and it was assumed that the cover would be zero at time zero. RESULTS Environmental Factors Affecting Natural Revegetation Summary statistics for both the continuous and ordinal variables are shown in Tables 3 and 4, respectively.  The maximum and minimum values recorded for the continuous variables give some idea of the range of sites sampled.  As can be seen, cover varied from 0 to 100% on sites ranging in age from one to nine years.  Almost the entire possible range for the variables of slope, exposure, compaction, and texture of coarse fragments were sampled.  The elevation of the sites sampled ranged from 632 metres to 1935 metres.  Although the erosion on a site varied from 0 to 35%, the mean value was quite low (2.6%), as most sites had very little erosion.  All of the macronutrients sampled covered a good range of possible values from low to high except the nitrate concentration, which was very low at all sites.  The variables of pH, compaction, and organic matter content cover a wide range of possible values.  All the measured values for electrical conductivity (salts) were quite low. All of the ordinal variables covered the full range of possible values with the exception of the Erosion Intensity Index.  Since most sites had no rill or gully erosion, there were a lot of zeros for this mea- sure.  The maximum value was ninety-nine. The correlation coefficients for the relationship between total Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 281 TABLE 3 SUMMARY STATISTICS FOR CONTINUOUS VARIABLES MEASURED AT ALL SITES  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation  282 TABLE 4 SUMMARY STATISTICS FOR ORDINAL VARIABLES MEASURED AT ALL SITES SAMPLES STANDARD VARIABLE SIZE MEAN DEVIATION Wind Exposure Magnitude 141 0.61 0.87 Heat Index 141 2.9 1.30 Site Moisture Regime 141 4.8 12 Compacting Magnitude 141 1.8 0.76 Erosion Intensity Index 141 5.7 15.06 Erosion Magnitude 141 0.8 0 89 Texture Index 141 2.8 0.84 Soil Colour 141 7.6 1.95 Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 283 vascular plant cover and the continuous and ordinal environmental variables are given in Tables 5 and 6.  These are the correlation coef- ficients for the maximum number of sites sampled for each variable. Significant positive correlations, at the 99% level of significance occur with the variables of age, site moisture, and texture.  Negative correlations are significant with the variables of elevation, texture of coarse fragments, wind exposure, and compaction as measured by two methods. Due to the major macroclimatic difference between the forested zones and the alpine zone, the data were divided into these two categories to determine if the environmental factors influencing natural revegetation would be the same. Forested Zones.  The summary statistics for the continuous and ordinal variables measured from sites in the forested zones are shown in Tables 7 and 8, respectively.  The range of values measured for each variable was very close to the ranges found when all the sites sampled were included in the analysis.  The main differences occurred with eleva- tion, which now ranged from 632 metres to only 1745 metres and site slope, which had a maximum of 24°.  The mean values were very similar, except for elevation and wind exposure, which were both lower in the forested zones. The correlation coefficients for total cover versus the various environmental variables are shown in Tables 9 and 10.  Highly signifi- cant positive correlations occur with the variables age, magnesium con- centration, site moisture and texture and negative correlations are found with the variables compaction, compaction magnitude and texture of coarse fragments. Alpine Zone.  The statistics for the continuous and ordinal variables measured from sites sampled in the Alpine Zone are summarized in Tables 11 and 12.  The mean cover was much lower in the Alpine Zone and, as expected, the mean elevation was higher.  Of the nutrients sampled, the Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 284 TABLE 5 CORRELATION COEFFICIENTS FOR TOTAL COVER VERSUS CONTINUOUS ENVIRONMENTAL VARIABLES AT ALL SITES MEASURED  PRODUCT-MOMENT        DEGREES OF VARIABLE CORRELATION COEFFICIENT    FREEDOM     SIGNIFICANCE  Age (years) 0.331 140 * Elevation (metres) -0.247 140 * Site Slope (degrees) 0.072 140 N.S. Adjacent Site Slope (degrees) 0.076 140 N.S. Site Exposure (degrees) -0.005 140 N.S. Adjacent Site Exposure (degrees) 0.035 140 N.S. pH 0.145 140 N.S. Nitrates (pounds/acre) -0.050 102 N.S. Phosphorus (pounds/acre) -0.120 102 N.S. Potassium (pounds/acre) 0.075 102 N.S. Calcium (pounds/acre) 0.095 102 N.S. Magnesium (pounds/acre) 0.187 102 N.S. Salts (mmhos/centimetre) 0.091 102 N.S. Organic Matter (%) 0.207 102 N.S. Erosion (%) -0.041 102 N.S. Compaction (Kilograms/ centimetre2) -0.299 102 * Coarse Fragment Texture (%)      -0.261 140 * *     correlation significant at probability <0.01 N.S.   not significant Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 285 TABLE 6 CORRELATION COEFFICIENTS FOR TOTAL COVER VERSUS ORDINAL ENVIRONMENTAL VARIABLES MEASURED AT ALL SITES SAMPLES SPEARMAN RANK VARIABLE                     SIZE   CORRELATION COEFFICIENT     SIGNIFICANCE Wind Exposure Magnitude      141 -0.304 * Heat Index                  141 -0.002 N.S. Site Moisture Regime         141 0.574 * Compaction Magnitude         141 -0.331 * Erosion Intensity Index      141 -0.003 N.S. Erosion Magnitude           141 -0.096 N.S. Texture Index               141 0.379 * Soil Colour                 141 0.147 N.S. *    correlation significant at Probability <0.01 N.S.  not significant Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 286 TABLE 7 SUMMARY STATISTICS FOR CONTINUOUS VARIABLES MEASURED AT SITES IN FORESTED ZONES SAMPLE STANDARD COEFFICIENT OF VARIABLE SIZE MEAN DEVIATION MIN.MAX.  VARIATION (%) Cover (%) 102 45.0 27.63 0 100 61.39 Age (years) 102 6.3 1.68 2 9 26.81 Elevation (metres) 102 1328.1 281.85 632 1745 21.22 Site Slope (degrees) 102 6.8 5.15 0 24 75.56 Adjacent Site Slope (degrees) 102 11.6 8.54 0 37 73.91 Site Exposure (degrees) 102 87.6 55.43 0 180 63.27 Adjacent Site Exposure (degrees) 102 88.5 55.10 0 180 62.24 pH 102 6.1 1.18 4.5 8.0 19.17 Nitrates (pounds/acre) 78 1.7 0.95 1.0 6.0 54.82 Phosphorus (pounds/acre) 78 42.2 47.84 2.0 258.0 113.39 Potassium (pounds/acre) 78 53.0 47.20 25.0 335.0 89.08 Calcium (pounds/acre) 78 2482.2 2245.19 500.0 10,000 90.45 Magnesium (pounds/acre) 78 290.3 213.79 25.0 1000 73.65 Salts (mmhos/centimetre) 78 0.11 0.07 0.1 0.32 62.12 Organic Matter (%) 78 4.2 3.99 0.5 30 94.73 Erosion (%) 78 2.7 5.98 0.0 35 225.24 Compaction (Kilograms/ centimetre2) 78 2.0 1.10 0.1 4.5 54.65 Coarse Fragment Texture (%)   102 31.2 19.62 0 95 62.83 Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 287 TABLE 8 SUMMARY STATISTICS FOR ORDINAL VARIABLES MEASURED AT SITES IN FOREST ZONES STANDARD VARIABLES MEAN DEVIATION N Wind Exposure Magnitude 0.2 0.515 102 Heat Index 3.0 1.27 102 Site Moisture Regime 4.9 1.05 102 Compaction Magnitude 1.8 0.75 102 Erosion Intensity Index 5.0 13.95 102 Erosion Magnitude 0.8 0.92 102 Texture 2.9 0.89 102 Soil Colour 7.9 1.85 102 Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 288 TABLE 9 CORRELATION COEFFICIENTS FOR TOTAL COVER VERSUS CONTINUOUS ENVIRONMENTAL VARIABLES MEASURED AT SITES IN FORESTED ZONES  PRODUCT-MOMENT DEGREES OF VARIABLE               CORRELATION COEFFICIENT    FREEDOM     SIGNIFICANCE Age (years)                  0.283 101 * Elevation (metres)          -0.147 101 N.S. Site Slope (degrees)          0.026 101 N.S. Adjacent Site Slope N.S. (degrees)          0.048 101 N.S. Site Exposure (degrees)       0.008 101 N.S. Adjacent Site Exposure (degrees)         0.098 101 N.S. pH                          0.201 101 N.S. Nitrates (pounds/acre)       -0.124 77 N.S. Phosphorus (pounds/acre)     -0.223 77 N.S. Potassium (pounds/acre)       0.096 77 N.S. Calcium (pounds/acre)         0.156 77 N.S. Magnesium (pounds/acre)       0.299 77 * Salts (mmhos/centimetre)      0.126 77 N.S. Organic Matter (%)            0.212 77 N.S. Erosion (%)                  0.011 77 N.S. Compaction (Kilograms/ centimetre2)     -0.325 77 * Coarse Fragment Texture (%)   0.299 101 * *     correlation significant at p < 0.01 N.S.   not significant Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 289 TABLE 10 CORRELATION COEFFICIENTS FOR TOTAL COVER VERSUS ORDINAL ENVIRONMENTAL VARIABLES MEASURED AT SITES IN THE FORESTED ZONES SAMPLES       SPEARMAN RANK VARIABLE SIZE   CORRELATION COEFFICIENT    SIGNIFICANCE Wind Exposure Magnitude 102 -0.167 N.S. Heat Index 102 0.008 N.S. Site Moisture Regime 102 0.602                   * Compaction Magnitude 102 —0.326                   * Erosion Intensity Index 102 -0.191 N.S. Erosion Magnitude 102 0.023 N.S. Texture Index 102 0.412                    * Soil Colour 102 0.241 N.S. *    correlation significant at p <0.01 N.S.  not significant Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 290   TABLE 11 SUMMARY STATISTICS FOR CONTINUOUS VARIABLES MEASURED AT SITES IN THE ALPINE ZONE SAMPLESTANDARD             COEFFICIENT OF VARIABLE                  SIZE MEAN DEVIATION MIN.MAX.   VARIATION (%) Cover (%) 39 30.8 24.87 3 80 80.75 Age (years) 5.8 2.00 1 9 34.54 Elevation (metres) 39 1672.0 112.81 1480 1935 6.75 Site Slope (degrees) 39 8.9 10.02 0 39 112.99 Adjacent Site Slope (degrees) 39 15.3 10.44 3 38 68.10 Site Exposure (degrees) 39 88.9 54.70 8 180 61.52 Adjacent Site Exposure (degrees) 39 101.0 46.57 10 180 46.11 pH 39 6.7 1.24 4.5 8.0 18.59 Nitrates (pounds/acre) 25 3.0 1.87 1.0 9 62.36 Phosphorus (pounds/acre) 25 18.0 17.99 2 68 100.19 Potassium (pounds/acre) 25 55.2 27.67 25 112 50.16 Calcium (pounds/acre) 25 4127.2 2993.45 500 9728 72.53 Magnesium (pounds/acre) 25 522.8 297.94 25 1000 56.99 Salts (mmhos/centimetre) 25 0.1 0.06 0.1 0.26    48.46 Organic Matter (%) 25 7.2 7.21 1.5 29 100.14 Erosion (%) 25 2.5 4.52 0 15 182.24 Compaction (Kilograms/ centimetre2) 25 1.6 1.10 0.2 4.2 68.27 Coarse Fragment Texture (%) 39 30.9 17.09 5 80 55.30 Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 291 TABLE 12 SUMMARY STATISTICS FOR ORDINAL VARIABLES MEASURED ATALL SITES (Alpine Zone) SAMPLES STANDARD VARIABLE                     SIZE MEAN DEVIATION Wind Exposure Magnitude       39 1.5 0.82 Heat Index                   39 2.9 1.38 Site Moisture Regime         39 4.3 1.18 Compaction Magnitude          39 1.8 0.78 Erosion Intensity Index       39 7.6 17.70 Erosion Magnitude             39 0.9 0.83 Texture Index                39 2.7 0.686 Soil Colour                 39 6.9 2.04 Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 292 mean phosphorus concentration was much lower in the alpine, whereas the calcium and magnesium mean concentrations were higher than in the forested zones.  The range of values was less for potassium, although the mean was about the same.  The mean values for nitrates con- centration and organic matter content were slightly higher in the alpine.  Of course, the mean value for the wind exposure was much higher in the Alpine Zone.  The other variables showed similar trends to those observed in the forested zones.  The correlation coefficients shown in Tables 13 and 14 are for the relationship between total cover and the environmental variables measured.  In the Alpine Zone, only the variables of age and site moisture showed siginificant positive correlations, and the Erosion Intensity Index was the only variable displaying a significant negative correlation. Rates of Revegetation The linear regressions showing the rate of revegetation in the dif- ferent broad vegetation units are shown in Figures 1 to 6.  Figures 1, 2 and 3 show the revegetation rate for the first nine years in the Dry Forest, Mesic Forest, and Wet Forest units respectively, and Figures 4, 5 and 6 show the same for the Dry Alpine, Mesic Alpine and Wet Alpine units.  All regressions were significant at P <0.001. A comparison of the regression coefficients gave some idea of the rela- tive rates of revegetation, for example, the regression coefficient for Dry Forest was 4.283, compared to 6.111 in the Mesic Forest unit.  A ranking of the regression coefficients in order of increasing magnitude would put the vegetation units in the following order of increasing rate of revegetation:  Dry Alpine, Dry Forest, Mesic Alpine, Mesic Forest, Wet Alpine, and Wet Forest.  From this ranking, it appears that moisture is more important than elevation in the areas sampled. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 293 TABLE 13 CORRELATION COEFFICIENTS FOR TOTAL COVER VERSUS CONTINUOUS ENVIRONMENTAL VARIABLES MEASURED AT SITES IN THE ALPINE ZONE PRODUCT-MOMENT DEGREES OF VARIABLE               CORRELATION COEFFICIENT    FREEDOM     SIGNIFICANCE Age (years)                   0.391 38             * Elevation (metres)            -0.222 38            N.S. Site Slope (degrees)           0.250 38            N.S. Adjacent Site Slope (degrees)           0.311 38            N.S. Site Exposure (degrees)         0.013 38             N.S. Adjacent Site Exposure (degrees)          -0.065 38            N.S. pH                            0.204 38             N.S. Nitrates (pounds/acre)          0.325 24             N.S. Phosphorus (pounds/acre)        0.215 24            N.S. Potassium (pounds/acre)         0.001 24             N.S. Calcium (pounds/acre)           0.176 24             N.S. Magnesium (pounds/acre)         0.296 24            N.S. Salts (mmhos/centimetre)        0.072 24             N.S. Organic Matter (%)              0.430 24             N.S. Erosion (%)                   -0.302 24             N.S. Compaction (Kilograms/ centimetre2)       -0.396 24            N.S. Coarse Fragment Texture (%)    -0.173 38            N.S. *   correlation significant at P < 0.001 N.S. not significant Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 294 TABLE 14 CORRELATION COEFFICIENTS FOR TOTAL COVER VERSUS ORDINAL ENVIRONMENTAL VARIABLES MEASURED AT SITES IN THE ALPINE ZONE SAMPLE       SPEARMAN RANK VARIABLE SIZE    CORRELATION COEFFICIENT     SIGNIFICANCE Wind Exposure Magnitude 39 -0.277 N.S. Heat Index 39 -0.048 N.S. Site Moisture Regime 39 0.418 * Compaction Magnitude 39 -0.389 N.S. Erosion Intensity Index 39 -0.420 * Erosion Magnitude 39 -0.391 N.S. Texture Index 39 0.238 N.S. Soil Colour 39 -0.145 N.S. *    correlation significant at Probability <0.01 N.S.  not significant Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 295 FIGURE 1 REVEGETATION    RATE   -     DRY    FOREST  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 296 FIGURE 2 REVEGETATION      RATE  -  MESIC    FOREST  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 297  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 298  cc 01 O    40 Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 299 FIGURE   5 REVEGETATION     RATE -  MESIC    ALPINE  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 300 FIGURE 6 REVEGETATION RATE – WET ALPINE  COVER Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 301 DISCUSSION Environmental Factors Affecting Natural Revegetation Table 15 provides a summary of the significant correlations found bet- ween total cover on a site and the measured environmental variables. Age of a site was found to be positively correlated with total cover in all three analysis.  This result was expected and has been confirmed. Increasing elevation results in decreasing cover when all sites are considered, but when the data set is divided into the two zones, the relationship is not significant.  Therefore, elevation is not as impor- tant a factor within a zone as it is between the two zones. Magnesium was the only macronutrient measured which showed a significant relationship with cover.  This occurred only in the forested zones, such that increasing magnesium concentrations correlated with increasing cover.  The reason that none of the other nutrients showed a relationship with cover may have been due to the very low nitrate con- centrations in the soils, in conjunction with the principle of limiting factors.  That is, the other nutrients were not allowed to "express" themselves because of the very low nitrate levels limiting the growth. Increasing compaction of a site was correlated with decreasing cover both when all sites were considered and when only sites in the forested zone were analyzed.  There was also a fairly strong negative correlation between compaction and total cover for the Alpine Zone, but it was only significant at the 95% level, consequently it was not included in the summary table.  Highly compacted soils would primarily influence plant establishment by inhibiting root penetration.  Compaction also results in decreased pore space for a particular soil, and this decreases the porosity of the soil to air and water, which could also affect growth. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 302 TABLE 15 SUMMARY TABLE OF SIGNIFICANT CORRELATIONS* VARIABLE ALL SITES      FORESTED ZONES       ALPINE ZONES Age + + + Elevation - Magnesium + Compaction - - Compaction Magnitude - - Texture of coarse - - fragments Texture Index         + +  Wind Exposure  - Magnitude Site Moisture Regime   + + + Erosion Intensity Index - * Only variables with at least one significant correlation are summarized in this table. + Significant positive correlation (P <0.001)  - Significant negative correlation (P <0.001)  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 303 Both the texture of the coarse fragments (2 millimetres) and the fine fragments were significantly correlated with cover.  As the volume of coarse fragments in a soil increased, the cover decreased.  As the tex- ture of the fine fragments changed from coarse to fine textured materials, the cover increased.  Therefore, in both cases, the coarse textured soils were correlated with lower cover.  Coarse textured soils have a relatively low water holding capability and do not have the capacity to absorb nutrients as well as finer textured soils.  Thus, they tend to show reduced potential for plant growth compared to finer soils  Magnitude of wind exposure was only significant when all the sites were considered.  It was thought that this factor would be important within the Alpine Zone even if elevation was not important, but apparently it is not.  When all the sites are pooled together, this variable could be considered as just another measure of elevation.  Site moisture regime was consistently and significantly correlated with the total cover on a site.  Moisture regime is a composite index which takes into account a number of site factors such as the position on slope, drainage characteristics, texture and depth of the parent material, and the slope and exposure.  Increasing moisture is highly correlated with increasing cover in all cases.  This would indicate that moisture is a limiting factor for revegetation on some sites in the Peace River Coalfield.   Although three different measurements of erosion on a site were used in this study, only the Erosion Intensity Index showed any significant correlation.  As erosion increased in the Alpine Zone, as measured by the index, the cover increased.  This resulted basically from the direct removal of a "habitable" ground.  In rills and gullies it is very difficult for young plants to become established after they have formed, due to the continuous erosion which occurs in such topography. The lack of any relationship between erosion and cover in the forested regions was probably because very few sites had a large amount of erosion.  Most of the road  samples had erosion bars installed, even though they had not been seeded. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 304 All the other variables measured did not show a significant correlation with the cover on a site.  In some cases, this could have been the result of only a narrow range of possible values being sampled due to the geographical area of the study and the nature of the sites, but in other cases, there may not be a simple relationship between the variables and total cover. In considering the variables found to be correlated with cover, only two can be practicably managed in the reclamation of coal-exploration disturbances in the Peace River Coalfield.  These are the compaction magnitude and the magnesium levels.  By "ripping" any roads or drill sites that have become compacted after abandoning an area, the success of revegetation on that site can be enhanced.  Also, if soil samples are taken on some of the disturbances in the forested zones, those sites which have low magnesium levels may be identified and then limed using a dolomitic limestone.  Organic matter content on a site was also very important.1   The methods and problems of adding organic matter to a site are too numerous to be expanded upon in this paper, but they could include adding wood chips or wood fibre to large areas, or sewage sludge or manure to smaller areas. Rates of Revegetation The rates of revegetation of the broad vegetation units sampled during the first nine years following abandonment of the site, showed that moisture seemed to be more important than elevation.  The regression coefficient for Mesic Alpine was less than that for the Mesic Forest - Wet Alpine pairs were very close.  It may be that revegetation occurs at about the same rate in the Alpine Zone as it does in the forested zones on sites having similar moisture conditions.   —————————— 1Organic matter content was consistent significantly at the 95% level of significance, but the 99% level was chosen for this study in order to reduce the alpha- error (Zar, 1074). Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 305 The revegetatlon rates for the Alpine units were based on small samples - very small in the case of the Wet Alpine unit - so more data will be required before a strong conclusion can be made. Also, a close inspection of the Dry Alpine and Mesic Alpine graphs showed that there were more points clustered below the line than above, so that if more sampling is undertaken the rates could be somewhat lower than that determined during this study.  Therefore, these results must be considered preliminary. Two more observations must be made regarding the revegetation graphs. The wide scatter of points about the line in all of the graphs is a result of the nature of the areas sampled.  As discussed previously, moisture, age and elevation are not the only factors that influence revegetation on a site.  For example, variations in compaction and texture of the sites within a broad vegetation unit are also going to influence revegetation. The rates of revegetation in these graphs may be considered as representative of the "average" site, with considerable variability occurring on individual sites.  Also, no attempt has been made to predict when 100% cover would occur on the "average" site in each unit.  A prediction of cover beyond the range of ages which were measurable would produce invalid results, as the relationship between total cover and age may change.  The total cover predicted at the end of nine years for the "average" site within each broad vegetation unit is summarized in Table 16.  As the table indicates, the "average" Wet Forest and Wet Alpine sites were almost totally revegetated after nine years of growth.  An inspection of Figure 3 shows that some Wet Forest sites had greater than 90% cover as early as six years after site abandonment, and that some sites had a cover of only 50% after nine years.  Therefore, although the revegetation graphs now approximate relative rates of revegetation on different sites, it should be recognized that the rate of revegetation on an individual site can vary considerably, depending on the growth limiting factors of a particular site. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 306 TABLE 16 PREDICTED TOTAL COVER ON "AVERAGE" SITE AFTER NINE YEARS GROWTH BROAD VEGETATION UNIT    REGRESSION EQUATION TOTAL COVER (%) IN NINE YEARS ON "AVERAGE" SITE Dry Forest               Y = 4.283 X 39  Mesic Forest              Y = 6.111 X 55 Wet Forest               Y = 9.997 X 90 Dry Alpine                Y = 4.238 X 38 Mesic Alpine              Y = 4.672 X 42  Wet Alpine               Y = 9.071 X 82  Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 307 CONCLUSION The results of this study indicate that a number of factors are important influences on the potential success of revegetation on a particular site. The most important factors include elevation, age, moisture, texture and compaction of the site.  Of the site factors found to be significantly correlated with cover, only the compaction and the magnesium level can be modified easily.  Although the rate of revegetation of an individual site may vary, these relative rates of revegetation within broad vegetation units may be compared.  From the comparisons, it appears that moisture is more important than elevation in determining the revegetation rate. Proceedings of the 3rd Annual British Columbia Mine Reclamation Symposium in Vernon, BC, 1979. The Technical and Research Committee on Reclamation 308 LITERATURE   CITED  Harcombe, A.P., 1978.  Vegetation Resources of the Northeast Coal Study Area 1976-77.  Resource Analysis Branch, Ministry of the Environment Report,  approx. 175 pp. Krajina, V.J., 1965.  Biogeoclimatic Zones and Classification of British Columbia.  Ecology of Western North America 1:1-17. Void, T., 1977.  Biophysical Soil Resources and Land Evaluation of the Northeast Coal Study Area, 1976-77.  Volume One.  Resource Analysis Branch, Ministry of the Environment Report.  69 pp. Zar, J.H., 1974.  Biostatistical Analysis.  Prentice-Hall Inc., New Jersey.  620 pp.

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