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Effects of Biomass Removals on Site Carbon and Nutrients and Jack Pine Growth in Boreal Forests
Author(s) -
Hazlett P.W.,
Morris D.M.,
Fleming R.L.
Publication year - 2014
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2013.08.0372nafsc
Subject(s) - environmental science , nutrient , biomass (ecology) , forest floor , productivity , taiga , agronomy , nutrient cycle , logging , soil carbon , forestry , soil water , ecology , soil science , biology , macroeconomics , economics , geography
As international demand for renewable energy and forest biomass increases, there is considerable debate about the effect of increased removals on long‐term soil productivity. Carbon and nutrient contents of the aboveground biomass, forest floor, and mineral soil were determined at 14 boreal forest sites in northern Ontario. At each site, three treatments were performed: tree‐length harvesting (OM 0 ), full‐tree harvesting (OM 1 ) and full‐tree harvesting plus forest floor removal (OM 2 ). Theoretical and actual estimates of biomass removal for OM 0 and OM 1 were determined. Jack pine ( Pinus banksiana Lamb.) dominant height increments from Years 10 to 15 ( H D10‐15 ) were determined as a measure of site productivity. A nutrient budget approach was used to estimate C and nutrient removal and retention and to calculate stability ratios (i.e., ratio of nutrient removed during harvest to post‐harvest nutrient reserve) and nutrient replacement times. The OM 1 treatment removed 65% of the potentially available biomass; on average 27 Mg ha −1 of unutilized biomass was burned in slash piles. The OM 1 harvesting residue retention values coincided with guidelines of jurisdictions that recommend retaining one‐third of residues on site after bioenergy harvesting. The OM 0 and OM 1 C and nutrient removals were more similar than estimated in previous studies. Base cation stability ratios and nutrient replacement times gave opposite interpretations in terms of which sites were more sensitive to biomass removal treatments. For sandy sites with thin forest floor horizons H D10–15 responded positively to increased post‐harvest soil C reserves, but for sites with thick forest floors, organic matter accumulation became a detriment to increased growth.