562-568 Kairo.p65

Mangrove forests in Kenya have traditionally been used as a source of building poles and firewood (1–3). About 70% of the population along the Kenyan coast depend on mangrove poles for house construction (4), and the recent boom in tourism in the area over the last few decades has led to an increasing demand for mangrove poles for construction of restaurants, hotels and holiday resorts (5). The most harvested mangrove poles are the mazio and boriti sized poles with butt diameter ranging from 8.0 to 13 cm. These are used in construction (2, 3, 6). Larger poles of banaa (diameter above 30.5 cm) are of less economic value and are left standing in the forest (3, 7, 8). Excessive removal of boriti and mazio poles has created complex mangrove management problems in Kenya along the whole coast (3, 5, 6). The overgrowing banaa canopy shade out juveniles and young trees and cause them to be crooked, as they grow according to available space in the closed forest canopy (9). In order to achieve sustainable forest management there is a need to assess the trends in forest conditions over time. One way to characterize mangrove ecosystem, and to monitor changes is through the assessment of forest structure (10, 11), these aspects being closely linked to forest productivity (12). Some of the structural parameters used are: tree height, stem diameter, basal area, crown diameter and leaf area index (11, 13), from which other attributes like stand tables, regeneration rates, distribution patterns and complexity index can be derived. Structural studies have been used to describe the mangroves of Puerto Rico (14), and mangrove stands in Florida, Mexico and Costa Rica (15) among others. Past studies on mangrove forestry in Kenya tend to have concentrated on floristic composition and distribution of species (16– 18), economic utilization (2, 3) and regeneration strategies of the principal species (6, 19). Work on mangrove benthos has yielded results regarding resource partitioning (20), zonation (21, 22), feeding habits and propagule predation (23–26). Studies on nutrient cycling have also been carried out (27, 28). Quantitative data on mangrove vegetation structure, stocking rates and yield sustainability is lacking, an aspect which has been much neglected until recently for want of resources and personnel. The main objective of the present study was to investigate natural regeneration and timber potential of the mangrove forests of Mida Creek for better management, based on the principle of sustained yield.