CGRG Bibliography of Canadian Geomorphology
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Author : Dykstra, P.R.; and Curran, M.P.
Date : 2000.
Title : Tree growth on rehabilitated skid roads in southeast British Columbia.
Publication : Forest Ecology And Management
Issue : 133(1-2):
Page(s) : 145-156.
Abstract
Implementation of The Forest Practices Code of British Columbia Act (FPC) in 1995 made skid road rehabilitation mandatory on many sites effective immediately and on all sites by December, 1999. This requirement implies that skid road rehabilitation will restore slope hydrology and site productivity. These assumptions require verification. Tree growth on excavated and bladed trail (skid road) rehabilitation was examined at 10 sites in the East and West Kootenays of southeast British Columbia. Height and diameter growth of lodgepole pine (Pinus contorta), Engelmann spruce (Picea engelmannii), and Douglas-fir (Pseudotsuga menziesii) trees were monitored at retrospective and new research sites established between 1984 and 1994. The study examined several `worst case' scenarios with regard to soil and climatic conditions, and rehabilitation techniques. Soil conditions included fine and coarse textured material; a number of these sites have unfavourable subsoils such as calcareous, high pH parent materials. Site climates ranged from relatively dry and warm to cold and wet. Older rehabilitation techniques resulted in the subsoil mixed with the forest floor during excavation and recontouring, and the original running surface not decompacted prior to recontouring the slope. In contrast, newer techniques involve separate topsoil handling during excavation and rehabilitation, and decompacting of the skid road running surface. Growth on four disturbance types was compared: the undisturbed area adjacent to the skid road and three recontoured road locations equivalent to the previous inner track, midroad, and berm/sidecast. Data was analyzed using ANOVA and disturbance type contrasts in regional and biogeoclimatic groupings. The trees growing on the berm and undisturbed treatments commonly displayed better growth than the trees growing on the inner track and midroad treatments. For example, in the analysis of all 10 blocks for three year height increment, trees growing on the berm were either the leading or second ranked treatment in seven out of 10 blocks, with differences in growth relative to the undisturbed ranging from 89 to 161%. Height growth of trees growing on the berm, and on the berm and undisturbed together, was also significantly better in the biogeoclimatic analysis. Diameter and volume growth followed the same trend as height for all analyses. Poorer growth on inner track and midroad trees was similar to but not as pronounced as in previous studies on unrehabilitated skid roads, suggesting that characteristics of the original skidroad are still affecting the growth of trees on recontoured slopes. However, the results suggest that, for the site conditions studied, rehabilitated skid roads will support trees of merchantable quality, particularly with improved rehabilitation techniques.
Bibliography of Canadian Geomorphology