Patterns of Woody Species Diversity Along Disturbance Gradient in Gumdri Abo Natural Forest, Dangila District, North Western Ethiopia

摘要

The study was conducted in Gumdri Abo natural forest along the three disturbance gradients which is located in Dangila Woreda Amhara Region Ethiopia. The aim of the study was to determine woody species diversity and stand structure within the three forest strata that were classified based on human induced forest disturbance level. For vegetation analysis, the forest was stratified in to three disturbance classes, i.e. Heavily Disturbed Forest (HDF), Moderately Disturbed Forest (MDF) and Low Disturbed Forest (LDF). Data were collected from nested circular plots of 11.28m (400m 2 ) for trees and 5.64m (100m 2 ) plots for seedlings and saplings that are laid down systematically along six transect lines. Equal sample plots were allocated for each forest strata. Woody species diversity was analyzed using Shannon Diversity Index (H’). Woody species density and diversity were assessed for each disturbance classes. One-way ANOVA was used to test significances differences among disturbance classes. A total of 72 woody species belonging to 40 families and 62 genera were recorded. Trees, shrubs and lianas account 44.4%, 45.8% and 9.7% respectively. Richness and diversity of woody species decreased from LDF to HDF. The diversity and density of woody species in the three forest strata were significantly different at 95% confidence interval. Stand structure from diameter class distribution for trees and shrubs revealed trends of normal J shape in the three forest strata. The findings of the study indicated that woody species diversity and density in HDF and MDF were significantly lower than LDF. Thus, collaborative form of forest conservation by the government aimed at woody species conservation should be geared towards protecting Gumdri Abo natural forest from excessive human disturbance.