INFLUENCE OF VARIATION IN BIOPHYSICAL FACTORS ON TREE SPECIES STRUCTURE AND COMPOSITION IN KAPSERET FOREST, UASIN GISHU COUNTY, KENYA

Abstract

Forests are important for survival and development of human and other fauna. However, they are under degradation due to changes in biophysical factors which affects tree species structure and composition. Understanding these variations and their influence on tree species structure and composition guides conservation of forest. This study aimed at assessing the influence of variation in biophysical factors on tree species structure and composition. Ecological survey was used whereby, tree species and soil samples were studied from 12 sample plots identified through stratified sampling techniques within Kapseret forest. Tree species were enumerated and recorded by species name and Diameter at Breast Height (DBH), those with ≥3m height and DBH > 9.5 cm were classified as trees, while those with ≤3m height and less than DBH ≤ 9.5cm were recorded as saplings. Tree species attributes assessed included: tree DBH and diversity, while biophysical variables measured were: soil organic carbon (SOC), soil texture, phosphorous and potassium. A total of 148 tree species were identified with 62.16% being saplings while 35.14% were mature trees. The CCA results indicated positive correlation between tree species diversity with variation in biophysical factors, the presence of gaps with high P levels were associated with majority of the saplings, however, the DBH class distribution did not indicate an inverse J-shape portraying high degradation. The tree species-biophysical factors should therefore be utilized with other environmental factors such as topography,light intensity,temperature and wind when planning and choosing species for rehabilitation and restoration of degraded landscapes.