生物多样性与濒危物种杂志

Community Structure and Mechanisms of Co-existence among Six Guild Insect Species in the Munessa Forests

Abstract

Solomon Ayele Tadesse

Anthropogenic disturbances are major factors influencing the ecological processes and spatial patterns of a landscape. Most studies which were conducted in the past in the field of landscape ecology were carried out based on the analyses of spatial patterns. However, considering only the spatial patterns is more of descriptive and incomplete. The present study utilized the analyses of both spatial patterns and ecological processes in a landscape scale. The objective of the study was to examine the impacts of logging and other human-induced disturbances on community structure and mechanisms of co-existence among six guild insect species in a landscape scale between 1970 and 2010 in the Munessa Forests. Mathematical model was employed to compute the index values of richness, patchiness, diversity, dominance, and contagion. Moreover, counting was done to determine the number of boxes in each habitat type using box fractal dimension technique. The box fractal dimension was analyzed by regressing the number of boxes counted versus caliber width. Survival and intrinsic rate of population growth for each coexisting species were determined. The results revealed that logging and other human-induced disturbances affected the index values of patchiness, diversity, dominance, and contagion, suggesting that the size of each habitat type and patterns of habitat patches differed between 1970 and 2010. Moreover, the box fractal analysis showed that there was a change in habitat size and patterns of species distribution resulted from the negative impacts of logging and other human-induced disturbances. The stochastic process results suggested that anthropogenic disturbances affected the survival, intrinsic rate of population growth, and co-existence among the six guild insect species through affecting the natural mosaics of habitats and also by aggravating the stochastic causes of species extinction rates. Generally, the combined results obtained from the change in spatial patterns and ecological processes are important to describe and better explain how logging and other human-induced disturbances affected the community structure and mechanisms of coexistence among the six guild insect species in a landscape scale between 1970 and 2010. The findings of this study are crucial to explain and increase our understanding and later predict how the impacts of logging and other human-induced disturbances affect the structure and coexistence of the six guild insect species in a landscape scale. The "Anti-fragmentation Authority" should properly work towards conserving and managing the patches of the four habitat types which are connected one another. Because connectedness increases the dispersal rates of individuals from one habitat patch to another. Edge effect will be also reduced when compacted habitat patches are connected for future conservation goals.