A Preliminary Yield Model for Natural Yushania Alpina Bamboo in Kenya

Abstract

Natural bamboo resources in Kenya are about 150,000 ha and they are mainly found on the mountain slopes in the high potential areas in Mt Kenya, Aberdares ranges, Mau escarpment, Cherangani hills and Mt Elgon at high elevations between 2300 and 3200 meters above sea level.  There is only one indigenous bamboo species, Yushania alpina (formerly Arundinaria alpina). It grows in single culms grouped into clumps. The main use of Y. alpina bamboo in Kenya is construction and fencing. There is high demand for bamboo for use in horticulture farming, handcraft, residential fencing, and cottage industry for making furniture, baskets, tooth picks and match sticks. Some companies have expressed interest in using large amounts of bamboo for bio-energy, panels, particle boards and pulp. However, bamboo raw material is not available for use because of a Presidential ban imposed on harvesting bamboo resources in all Government and Trust lands. But even if the ban was lifted, harvesting of bamboo in the natural forests cannot be prudent because there is very little information on the quantity, quality and geographical distribution of the available amount. Many entrepreneurs have continued to request the Government through Kenya Forest Service (KFS) to be allowed to extract natural bamboo for various uses. On the other front Kenya Forestry Research Institute (KEFRI) has vigorously continued to promote growing and intensive use of bamboo. These two noble ideas cannot be realized in the absence of the bamboo resource data. The objective of this study was to develop a yield model that can be used to estimate total bamboo culms biomass in a given area and the proportion that can be harvested on a sustainable basis. This study used bamboo data from 25 rectangular temporary sample plots of 10 m x 20 m in natural stands of Y. alpina and trees at Kieni, Kamae and Kinale in Kiambu County to estimate density and model the dependence of culms merchantable green weight and oven dry weight on diameter at breast height. The culms mean stoking density was 21000 culms ha^-1. The coefficient of determination (R²) for green weight model is 0.82 and the root mean square error (RMSE) is 1.45 kg. The model calculates mean weight of old Y. alpina culm as 9.6 kg.

Keywords: Bamboo, stocking, yield, weight, culms, green weight model