Soil properties and tree growth on rehabilitated forest landings in the interior cedar hemlock biogeoclimatic zone: British Columbia

We studied operational landing rehabilitation programs in three forest districts of interior British Columbia (BC). Winged subsoiling and grass/legume seeding, followed by planting of lodgepole pine (Pinus contorta var. Latifolia) generally resulted in successful re-establishment of forest cover on landings. In the Boundary district, fifth year tree heights on landings were not significantly different from those in adjacent plantations, and fifth year growth increments were also similar despite evidence of delayed seedling establishment caused by cattle grazing damage. Trees on landings in the Kalum district were shorter than those in plantations, but fifth year increments were similar. Landings in the Kalum with >20% clay had lower stocking densities, tree heights, and probe depths compared to landings with <20% clay content. In the Kispiox district, average fifth year tree heights and fifth year increments were lower on landings than those on plantations. In the Kispiox district, landings with >20% clay content had shorter trees growing on them when compared to tree heights on landings with <20% clay. Landings in the Kispiox had the least probe depth of the three districts, and the greatest difference in height and increments between landings and plantations, supporting field reports of poor decompaction effectiveness there. In all districts, there was no forest floor present on landings 7 years after subsoiling, and cover of non-coniferous vegetation was lower than for plantations. Higher soil temperatures and lower soil moisture contents were recorded on landings relative to plantations in all districts during the growing season of 1998. Landing soils also had lower total C, N and mineralizable-N (min-N) than plantation soils in the Boundary and Kispiox, but such differences were not statistically significant in the Kalum. Reduced levels of total C, N and min-N on landings did not appear to have affected current foliar nutrient status of trees growing on these sites, as most nutrients appeared in concentrations considered adequate or only slightly deficient, except for foliar S on all sites. Average concentrations of N, P, K and S in foliage were either similar to or significantly higher for trees on landings relative to plantations, but these differences were attributed to dilution in plantation foliage rather than deficiency. Our results support the conclusion that operationally feasible techniques for soil rehabilitation can create conditions suitable for establishment of a new forest on sites that otherwise would be considered non-productive. Stocking levels and tree growth rates observed in our study are consistent with the conclusion that a commercial forest may be produced on some of the rehabilitated areas.