Canadian Forest Service Publications
The role of aggregated forest harvest residue in soil fertility, plant growth, and pollination services. 2014. McCavour, M.J.; Paré, D.; Messier, C.; Thiffault, N.; Thiffault, E. Soil Sci. Soc. Am. J. 78:S196-S207.
Available from: Laurentian Forestry Centre
Catalog ID: 35681
CFS Availability: PDF (request by e-mail)
While post-harvest residue (“slash”) is increasingly viewed as a source of biofuel, few studies have considered the potential ecological impact of the spatial distribution of forest harvest residue. We hypothesized that slash piles create islands of high soil fertility and light, leading to greater abundance, growth, and reproduction of plants. In 6-yr-old intensively managed hybrid poplar (Populus balsamifera L. x P. maximowiczii A. Henry) plantations, we showed that soluble organic N, NO3–N, NH4–N, and P decreased as a negative exponential function with distance from the pile. Pin cherry (Prunus pensylvanica L. f.) relative growth rate was fastest near piles in the first few years after harvest. We found significantly greater stem size, flowers per plant, and foliar P near piles for cherry, and this inverse gradient sharpened in a 16-yr-old white spruce [Picea glauca (Moench) Voss] plantation. For the two other flowering species, strawberry (Fragaria virginiana Mill.) and raspberry (Rubus idaeus L.), flower and fruit abundance were also significantly and strongly negatively correlated with distance to the pile. Further, directly correlating soil nutrient availability with plant traits, we found significant positive relationships between plant growth, reproductive output, and N availability. Partial correlation analysis indicated that more of the variance in plant traits was explained by distance than by soil nutrition. We conclude that in industrial forests, piles replace canopy gaps as sites where understory plant species can episodically reproduce and are therefore important for many plant species as well as the pollinators and frugivores dependent on them.
Plain Language Summary
This study demonstrates that putting cutting residues into large piles on cutover areas creates pockets near the piles (0 to 14 m) where the soil is more fertile (higher nitrogen and phosphorus contents) and where the light is more abundant.
These conditions promote plant growth and the early production of flowers and fruits on cutover areas. The presence of stacked residues may therefore have a beneficial effect on pollinating insects and fruit eating mammals. This effect should be taken into consideration in landscapes with very few flowering and small fruit bearing plants.
Many studies have focused on the quantity of cutting residues that should be left on site to ensure environmental sustainability of biomass harvesting. However, the impact of the distribution of residues left on site has not been studied to any great degree until now. Other research projects are under way to verify the effect on plantations.
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