Vertical root separation and light interception in a temperate tree-based intercropping system of Eastern Canada
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- Bouttier, L., Paquette, A., Messier, C. et al. Agroforest Syst (2014) 88: 693. doi:10.1007/s10457-014-9721-6
We analysed the spatial distribution of fine roots and light availability in a tree-based intercrop system (TBI) composed of Quercus rubra L. (QUR), hybrid poplar (Populus deltoides × Populusnigra—HYP) and hay (CROP) in southern Québec (Canada) to evaluate interactions between trees and crop. Trees in the 8-year-old TBI system had superficial fine root profiles, which is common in tree species grown in conventional plantations and natural forests. More than 95 % of fine roots were found within the first 25 and 45 cm for QUR and HYP, respectively, and 35 cm for CROP. However, vertical separation between the fine root systems of QUR and CROP was evident, as QUR allocated less fine roots to the top 10 cm of soil, and more to depths between 10 and 30 cm, as opposed to CROP which had a greater proportion of fine roots in the top 10 cm. HYP fine roots showed no adaption when intercropped with hay. High tree fine root length density (FRLD) in the top soil layer was observed near the tree stems while hay FRLD was reduced by 45 %, suggesting strong competition for resources. Hay yield analysis revealed significant reduction near trees, particularly HYP. However, light did seem to be the main driver of intercrop yield, as it not only accounted for the effect of competition by roots (being correlated), but also had a singular effect.