Annual allowable cut for merchantable woody species in a community managed forest in western Kenya.

摘要

Changes in stand density, basal area, off-take and annual increment were determined from 18 permanent sample plots established in 1997 in Got Ramogi Forest in western Kenya. The plots were assessed in 2003 and 2008. A total of 824 stems >=1.5 m in height were recorded from 43 woody species. Key merchantable woody species comprised 20% of the woody species and 67% of the overall stem density. There was a significant reduction in the overall stand density and in the stem density of key merchantable woody species, but not among other woody species between 1997 and 2008. The basal area decreased significantly among key merchantable woody species, but not for the overall forest. The basal area decreased from 22.6 to 9.7 m2 ha-1 for key merchantable woody species. The stand volume of key merchantable woody species decreased from 156 m3 ha-1 in 1997 to 61.7 m3 ha-1 in 2008. The mean annual off-take declined from 10.3 m3 ha-1 year-1 between 1997 and 2003 to 9.1 m3 ha-1 year-1 between 2003 and 2008, while the mean annual increment increased from 2.9 to 3.3 m3 ha-1 year-1. It was predicted that forest recovery would surpass the 1997 stand volume of 156 m3 ha-1 if off-take levels between 10% and 90% of the mean annual increment were adopted. We settled on an annual allowable cut of 80% of the mean annual increment as a compromise between consumptive and conservation interests. We identified over-harvesting as the main cause of the reduction in stem density among key merchantable woody species. A management plan with compartment registers indicating the diversity, abundance and distribution of each woody species was recommended to guide their utilization and monitor their population dynamics.