Investigation of effect of Alnus acuminata tree species on soil biochemical properties in Silvopasture around Gishwati forest western Rwanda

Abstract

This research examined the effect of landscape restoration on ecosystem functioning using forestry around Gishwati natural forest in western Province of Rwanda. It specifically examined changes in soil-litter arthropods and soil chemical properties in silvopastoral landscapes dominated by Alnus acuminata tree species planted by Landscape Approach to Forest Restoration and Conservation project. Data were collected in the sites dominated by Alnus acuminata and in control sites dominated by Desmodium intortum (Greenleaf desmodium), Pennisetum clandestinum (Kikuyu grass) and Urtica dioica (stinger/nettle). Leaf-litter arthropods were collected by pitfall traps and hand sampling methods and analysed to the family level using dichotomous keys. Further, soil cores were collected and analysed for soil pH, soil total nitrogen, total phosphorus, soil available phosphorus and soil organic carbon. 1,065 individuals of soil-litter arthropods grouped in 6 orders and 8 families were found in treatment sites, and 864 individuals grouped in 6 orders and 7 families were found in control sites. Higher levels of soil total nitrogen (0.2±0.0%), available phosphorus (11.0±0.9ppm), organic carbon (19.6%) and leaf-litter arthropods (24.6±4) were found in treated plots compared to control sites. The study concluded that Alnus acuminata biomass contributes in maintenance of soil biological and chemical properties, and hence the ecosystem functioning. It is therefore recommended that Alnus acuminata can be a valuable agroforestry tree to plant in pastoral land along with other tree species.