Population structure, harvesting rate and regeneration status of four woody species in Kimboza forest reserve, Morogoro region - Tanzania

Abstract

Kimboza forest reserve is recognized as an IUCN category IV-habitat and species management area, but the information on population structure, harvesting rate and regeneration status of four commercial woody species, namely; Khaya anthotheca, Milicia excelsa, Pterocarpus angolensis and Dalbergia melanoxylon in the forest are lacking. This study, therefore, aims to fill this gap. A total of five transects were established in the forest whereby within each transect, five nested quadrats of 20 m × 20 m were placed at 200 m distance for sampling stems with diameter at breast height (DBH) ≥ 10 cm and stumps of the target species. Stems with DBH <10 cm were counted in a quadrat of 5 m × 5 m placed within the big quadrat. The findings show that density of stems & harvesting rate for Khaya anthotheca, Milicia excelsa, Pterocarpus angolensis and Dalbergia melanoxylon were 4.8 stems ha-1 & 6.6 stumps ha-1, 12.6 stems ha-1 & 3.4 stumps ha-1, 16.0 stems ha-1 & 2.8 stumps ha-1, and 5.6 stems ha-1 & 1.2 stumps ha-1, respectively. The DBH class distribution for Khaya anthotheca, Milicia excelsa and Pterocarpus angolensis displayed a good regeneration pattern, however, the last two were interrupted in high size classes. The Dalbergia melanoxylon revealed a poor regeneration pattern. The study recommends that illegal harvest of the species should be controlled, environmental education be provided to locals, and stringent measures be institutionalized against illegal loggers.