Fine root distribution of pruned trees and associated crops in a parkland system in Burkina Faso

Besides aboveground interactions, pruning of trees may also modify their rooting pattern for which a better understanding is needed for the optimisation of agroforestry systems. Thus, variation in fine root (d less than or equal to 2 mm) distribution of pruned trees and crops were assessed during three cropping seasons by sampling soil layers at 10 cm intervals up to 50 cm and at four distances from tree trunk. Three crown pruning treatments ( totally- pruning, half-pruning and no-pruning) were applied to karite ( Vitellaria paradoxa) and nere (Parkia biglobosa). In 1999, 59% (0.477 cm cm(-3)) and 69% (0.447 cm cm(-3)) of fine roots for karite and nere respectively occurred in the upper 20 cm with a significant decrease in root length density with soil depth. However, in 2000, totally- pruned trees of nere and karite showed 32% (0.051 cm cm(-3)) and 34% (0.078 cm cm(-3)) of their density in the upper 20 cm whereas root distribution in 2001 was similar to that of 1999. Thus, pruning to reduce belowground competition for the benefit of associated crops can be recommended in the light of the temporary reduction of root density in crop rooting zone and consequently the increase in crop production.