Canadian Forest Service Publications
Effects of biomass harvest intensity and soil disturbance on jack pine stand productivity 15 year results. 2014. Fleming, R.L.; Leblanc, J.D.; Hazlett, P. W.; Weldon, T.; Mossa, D.S. Canadian Journal of Forest Research 44:1566-1574.
Issued by: Great Lakes Forestry Centre
Catalog ID: 35853
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Rising demands for forest biomass have raised concerns that the increased removal of organic residues and harvest impacts may reduce longer term site productivity. Replicated field experiments examining the effects of stem-only harvest with disc trenching (SOT), whole-tree harvest with (WTT) and without (WT) disc trenching, whole-tree harvest with forest-floor removal by blading (WTB), and blading followed by compaction (WTBC) were installed on nine sandy jack pine (Pinus banksiana Lamb.) sites in northern Ontario. At year 5, planted-tree diameters, dominant tree heights (HD), and stand aboveground biomass (jPPBio) were smaller without soil disturbance (the WT), but were otherwise similar among treatments. At year 15, planted-tree size and stand yield rankings were WTT = SOT = WT > WTB = WTBC. Biomass production by natural regeneration and total stand aboveground biomass (TotBio) treatment rankings were SOT ≥ WTT ≥ WT > WTB = WTBC. HD, jPPBio, and TotBio showed increasing divergence over time in WTB vs. WTT – SOT response, whereas statistical equivalence of the WTT and SOT treatments was shown for most tree and stand growth responses. There was some evidence of increasingly negative impacts of WTB as site index declined. Overall, negative WTB effects on tree and stand productivity have become increasingly apparent.
Plain Language Summary
Organic matter removal and soil compaction are two key soil properties related to forest productivity that are readily influenced by harvest-related activities. Rising demands for forest biomass, including bioenergy uses, have raised concerns that increased removal of organic residues may reduce longer-term site productivity. We examined effects of increasing levels of harvest-related forest biomass removal (operational stem-only harvest (SOH), operational whole--tree harvest (WTH) and whole-tree harvest with forest floor removal by blading (FFR)) on nine sandy Northern Ontario jack pine sites. After 15 yrs, individual tree and stand growth were similar with WTH and SOH but greater than with FFR. Negative FFR effects on site productivity became increasingly apparent over time, particularly on less productive sites. In contrast, operational WTH and SOH have produced equivalent effects to date on most productivity measures. We conclude that there is no evidence of operational full-tree harvesting leading to declines in stand productivity on these jack pine sites 15 yrs after harvest. Nevertheless stand development and nutrient cycling considerations suggest treatment impacts on site productivity will continue to evolve over the next 1-2 decades.