Litter-fall and nutrient returrn in Gmelina arborea short rotation woodlot: Implications for site productivity

Abstract

The amount of litter produced and nutrients returned to the forest floor in Gmelina arborea (Roxb) short rotation woodlot were monitored for 12 months. The trials were planted with 400-25 trees within treatment plots, each measured 12m x 12m or 27,777 – 1,736 trees/ha and harvesting was done after the litter-fall monitoring. The results showed that litter-fall and the subsequent amount of nutrients returned to the forest floor, increased with increasing planting density. The differences in both cases were significant (P<0.001). The annual litter-fall ranged from 1.2 to 8.1 t/ha of which leaves were the dominant components with the proportions of other components being insignificant. Total N, P, K, Ca and Mg returned were 106, 11, 117, 76 and 32 kg/ha respectively. Over 60% of total annual litter-fall occurred during the dry season. The pattern of nutrient retranslocation from the leaves showed that all nutrients except calcium were significantly retranslocated. Therefore, to reduce the impact of tree harvesting on site nutrient status and also to ensure sustainable production of wood, harvesting should be done at a period of low nutrient levels in the leaves. The reason being most of the nutrients might have been transferred into storage organs like the roots through processes like retranslocation. This, it is believed, could ensure a sustainable production system, and also efficiency of the nutrient cycling process.

Keywords: Afram headwaters, derived savanna, nutrient content, retranslocation,spacing, West Africa

Ghana Journal of Forestry Vol. 17 & 18 2005: pp. 44-55