B.C. Ministry of Forests Forest Science Program
				Abstract for LTSPS Research Note 04

		Nutrient Removals in Woody Biomass: Preliminary Estimates from the Sub-Boreal Spruce Long-Term Soil Productivity Study
		Author: P. Sanborn, M. Kranabetter, and B. Chapman
		Branch: Research
		Subject:  Soil Conservation
		Series:  LTSPS Research Note
		Other details:  Published by Prince George, Prince Rupert and Cariboo Forest Regions - March 2000.

Abstract

The Long-Term Soil Productivity (LTSP) Study (Ministry of Forests E.P.1148) seeks to understand the long-term impacts of organic matter removals and soil compaction on tree growth and other ecosystem processes (Powers et al.,1990). The core LTSP experimental design includes 3 levels of organic matter removal:
•OM1: merchantable boles only (Photo 1)
•OM2: merchantable boles + logging slash (Photo 2)
•OM3: merchantable boles + slash + forest floor

The OM1 treatment is comparable to conventional bole-only harvests in which de-limbing occurs at the stump, while the more intensive OM2 treatment simulates whole-tree harvesting (WTH)2 .

Since the early 1970 ’s, numerous studies have considered whether the higher utilization levels involved in WTH are a threat to sustained site productivity (e.g. Kimmins, 1977;Weetman and Webber, 1972). The removal of additional biomass components increases the potential site nutrient loss from harvesting because foliage and fine branches have higher nutrient concentrations than the bole. For areas with considerable winter harvesting, this would be a greater concern for evergreen than deciduous species, since the latter would shed their foliage before the winter harvesting season. As noted by Wiensczyk (1992), the likely impact of WTH-related nutrient removals depends on site-specific factors such as natural rates of nutrient replacement (e.g. atmospheric deposition, chemical weathering of minerals) and the relative size of other nutrient pools n the forest floor and mineral soil. Other things being equal, sites with thin forest floors and/or coarse-textured parent materials are expected to be much more sensitive.

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Updated September 2002

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