Effect of tree inclination and the distance from tree row on fine root biomass and soil organic carbon in the milpa intercropped with fruit trees agroforestry system
摘要
Agroforestry systems contribute to climate change mitigation through carbon (C) sequestration, but the design and management affect their capacity for above- and below-ground biomass and soil C accumulation. The milpa intercropped with fruit trees (MIFT) is an alley cropping agroforestry system that combines fruit trees in rows and annual crops (corn and beans) in alleys, where trees are inclined to alternate sides to harness more photosynthetically active radiation. However, the effect of tree inclination and distance from the tree row on the distribution of fine root biomass and soil organic carbon (SOC) is not clear in the MIFT agroforestry systems. We evaluated the SOC and fine root distribution (≤ 2 mm) towards and against tree inclination at different distances from the tree row to 50 cm soil depth, at an interval of 10 cm, in a MIFT agroforestry system in southern Mexico. The average SOC content was higher under the tree crown (2.6 kg m−2) compared to farther distances (1.9–1.6 kg m−2). Tree inclination did not influence SOC content, but a higher fine root biomass (253 g m−3) was found on the opposite side of the tree inclination than towards it (189 g m−3). Crop fine root biomass was distributed more to the shallow soils, whereas tree roots were distributed more in the deeper soil profiles. The results regarding the complementarity or niche segregation between tree and crop fine root distribution have important implications in designing agroforestry systems to optimize belowground resources and mitigate atmospheric CO2 through C sequestration in soils.