Effects of canopy and trenching around Azadirachta indica A. Juss on soil properties and herbaceous vegetation in the Indian desert.

摘要

Azadirachta indica A. Juss is an important multipurpose species used in a recent afforestation progam in the Indian dry zone. This investigation aims to identify the changes in soil resource by which A. indica influences vegetation composition, productivity, and vegetation nutrient status, and effective management strategies to improve productivity and restore degraded community pasturelands. Tree lopping and/or trenching around the trees were used to reduce competition between the trees and vegetation. The five treatments were: intact trees without trench (intact T-), intact trees and trench (intact T+), lopped trees without trench (lopped T-), lopped trees and trench (lopped T+), and a control without trees. There were 19 herbage species in total across all treatments and the number was greater with intact trees. The soil under intact trees showed greater (p<0.05) concentrations of SOM, NH₄-N, NO₃-N, and PO₄-P facilitating species richness, diversity, population sizes and herbage biomass together with herbage nutrient status. Trenching around trees enhanced the positive influences, but tree lopping showed adverse effects on these variables. Drought adversely affected SOM and nutrients availability in 2002, but probably facilitated mineralization-enhancing soil nutrients and herbage biomass in 2003. Conclusively, intact trees and trench improved soil resource availability, herbage diversity, and productivity. However, density of A. indica may influence these variables and can be optimized for sustained productivity with improved soil health.