Growing short rotation woody crops in a tree-based intercropping system in southern Ontario, Canada

This study investigated the growth potential of three varieties of short rotation willow, used as bioenergy feedstock, on marginal land in both a conventional monocrop system and in an agroforestry intercropping system. Microclimatic differences between systems and their effects on willow growth were compared during the 2006 and 2007 growing seasons. Willow yields were significantly higher in the agroforestry field during both years of the study, with 3.0 and 1.1 odt ha-1 for the agroforestry and control fields, respectively, in 2007. Daily average photosynthetically-active radiation (PAR) was 210 mumol m2 s-1 (16%) lower in the agroforestry system, and PAR was correlated with soil temperatures that were on average 0.4°C--2.7°C lower in the agroforestry field. Soil temperatures were negatively correlated with soil moisture values that were on average 1.4%--1.9% higher in the agroforestry field, and soil moisture content was positively correlated with willow yields. Results of this study suggest that moderate shading in an intercropping setup can result in a buffering effect on microclimate conditions, where there is less variation in soil moisture content and soil temperature across a range of weather conditions.