Comparison of wood basic density and basal area of 5-year-old Acacia crassicarpa, A. julifera, A. leptocarpa, Leucaena pallida and Senna siamea in rotational woodlots trials in western Tabora, Tanzania

Improvement and Culture of Nitrogen Fixing Trees

Introduction The term rotational woodlot connotes a technology which involves growing trees, normally N-fixing, with crops for 2-3 years until the trees out-compete the crops. The woodlot may then be used as a source of fuelwood, building poles or fodder. Soil fertility is also restored during this time until the farmers can cut the trees and start growing crops between the stumps, 4 to 5 years later. The technology was designed to mimic the traditional practice of shifting cultivation by introducing trees into the crop and shrub land with shortened fallow. The cropping and fallow phases take place concurrently. This allows the farmers to crop for an extended period without returning the land to bush fallow. The technology is flexible in the sense that it allows the farmers to adopt both the cropping phase and trees to suit individual needs which diversifies production base, enhances trees and crops productivity and allows a sustainable cropping system (Ramadhani et al. 2002). This technology is being promoted by the World Agroforestry Centre (ICRAF) in collaboration with farmers, Tanzania Forestry Research Institute (TAFORI), and the Agricultural Research and Development Institute (ARDI) Tumbi. The main objective is the provision of fuelwood for tobacco curing and other domestic uses to rural farmers and improvement of soil fertility in the tobacco-cereal land use system of Tabora, Tanzania. It reduces pressure on the 'miombo' woodlands. Despite the potential of this technology, there are few studies on wood basic density and basal area on trees currently used in rotational woodlots. Wood density is highly affected by woodlot manipulation through silvicultural and cultural practices. This study reports comparison of wood basic density and basal area of 5-year-old N-fixing trees of Acacia crassicarpa, A. julifera, A. leptocarpa, Leucaena pallida and Senna siamea grown in rotational woodlots both on-station and in farmers fields.