Removing Harvest Residues from Hardwood Stands Affects Tree Growth, Wood Density and Stem Wood Nutrient Concentration in European Beech (Fagus Sylvatica) and Oak (Quercus spp.)
Résumé
Background: Increased exportation of harvest residues from forests, to mitigate excessive demand for
woody biomass, have reportedly diminished soil mineral resources and may lead to degraded tree
nutrition and tree growth. However, as nutrients become less available in the soil, the remobilization of
nutrients in biomass tissues (plant internal cycling) helps sustain tree nutrition. Our study aims to
quantify the impact of Removing Harvest Residues and Litter (RHRL) during five years on tree growth,
wood density and stem wood nutrient concentrations in young beech and oak forest stands.
Result: Our study found that, RHRL significantly decreased the tree growth ring width, by 14%, and wood
density, by 3%, in beech trees, in the near bark rings. RHRL also significantly reduced the nutrient
concentration in the near bark and near pith areas of both species. Mg, Na and S were found lower by 44%,
76% and 56%, respectively, in the near bark area of beech trees, and K, Ca, Mg, Na, S and Fe were lower by
20%, 25%, 41%, 48%, 41% and 16%, respectively, in the near bark area of oak trees. K and Mg
concentrations decreased more strongly in the near pith area compared to the near bark area suggesting
internal translocation of these two elements.
Conclusion: In beech trees, wood density proved to be an important factor while quantifying the effect of
removing harvest residuals on tree growth and biomass. Soil nutrient loss intensified the
remobilization of nutrients contained in older tree rings (close to the pith) towards newly formed rings
(close to bark). In our study, in beech trees, K was found to be the most recycled major nutrient. These
results demonstrate the potential of such analysis for providing valuable insight into the effect of RHRL
in premature stands on the physiological adaptive strategies of trees and an indication of soil fertility and
acidity status.
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