Spatial Analysis Of Trees Outside Forests As Influenced By Land Use Categories In River Sio Basin, Kenya

Increasing population in the developing world and associated needs for agricultural production, human settlement and industrialization have led to massive destruction of tree resources through deforestation and degradation of tree landscape. Countries have restricted access to forest resources by establishing forest reserves, causing communities to depend widely on Trees Outside the Forest (TOF). Therefore, TOF are diminishing and with them their protective and productive functions due to over exploitation. TOF include stands smaller than 0.5 hectare, tree cover on agricultural land, home gardens, orchards, trees in urban environments, along roads, riverine trees and those scattered on the landscape. This study was aimed at analysing the spatial distribution of TOF, in Sio river basin, Kenya in different land use categories (LUC) in relation to distance from the river as they play an important role in wetland conservation. The analysis helps in understanding the relations between TOF and its environment in order to achieve a sustainable management of the resource. Within this context, TOF assessment was carried out using basal area (BA/ha), number of trees (NT/ha), number of tree stumps (NS/ha) and tree products. In the study area, TOF information was collected using stratified random sampling method, and data collection involved tree counts, measuring of diameter at breast height (DBH) and an informal interview for socio-economic survey. The collected data were categorized into four river distance zones and into 6 Land Use Categories (LUC). Data analysis was carried out in SPSS version 11.0 software which involved testing the relations between TOF, LUC and distance from the river. Results indicate that TOF BA/ha and NT/ha significantly correlate with LUC. This means that Land use systems affect the distribution of TOF. However, the distribution of TOF is not dependent on the distance from the river except in bush, pasture/fallows and sugarcanes LUC. Damage to TOF is predominant in areas closer to the river. Results from socioeconomic survey revealed that the competitive nature of trees with food crops is the main reason refraining farmers from planting trees on their fields. Other factors include lack of enough land and tree seedlings. The survey on tree products depicts that farmers rely on TOF mainly for building followed by fuel. Out of the identified TOF species 54.7% are native to the area while 45.3% are exotic. The study recommends that efforts of tree planting practices should be strengthened among farmers. Farmers are encouraged to plant fast growing exotic trees which will provide products such as income, building and fuel wood. However, such species should not be grown close to the river as they drain away water. The study also recommends to the National Environmental Management Authority (NEMA) to ensure through the Environmental Impact Assessment (EIA) that areas closer to the river are protected from over exploitation.