Effects of mechanical disturbance on soil properties and lodgepole pine growth in British Columbia's central interior.

摘要

Forest landings are located adjacent to haul roads where the harvested trees that were skidded from the plantation are processed and loaded onto trucks. Soils on landings are excessively compacted by heavy timber harvesting machinery and may take many years to recover from such disturbance. The degraded land may be lost from the productive land base unless efforts are made to restore productivity. This study examines soil properties and tree growth on landings (unrehabilitated with and without natural regeneration) and plantations adjacent to the landings in the Central Interior of British Columbia. Landings had significantly greater soil bulk density, strength and water content than plantations. Water content at field capacity and wilting point were not significantly affected by the disturbance on the landings. Chemical analysis showed landings to have lower concentrations of C, N, P, and mineralizable-N but higher pH compared to plantations. Site index, as estimated using the growth intercept method, did not differ between naturally regenerated landings and plantations, suggesting that the soils were equally productive. A greenhouse experiment evaluated biomass and lodgepole pine (Pinus contorta Dougl. Ex. Loud. var. latifolia Engelm.) seedling growth on landing soil of varying levels of compaction and water contents. Seedling biomass and growth measurements responded mainly to water content levels although compaction had an effect when water content was low. Foliar N and P deficiencies occurred in all of the medium and high water content treatments. Soil water content had a greater impact than soil strength on seedling growth and nutrient uptake. This research shows that the interaction of soil properties may affect the growth of lodgepole pine and that soil water content is key in controlling the effects of compaction and plant nutrient uptake ability.