Urban tree species composition and diversity in Zomba city, Malawi: Does land use type matter?

摘要

Urban landscapes do harbour trees despite being predominantly built-up areas. These trees are increasingly becoming a depository of tree species diversity. Even so, little is known about such potential in developing countries. This study therefore sought to establish tree species composition and diversity, and their variations across six land use types of Zomba city, Malawi. The study results revealed that Zomba city harbours 168 tree species, belonging to 47 families. Of these species, 63.6% were indigenous. Mangifera indica, an exotic fruit tree, is found among the top three most abundant tree species in three land use types: Roads, residential areas, and institutional land. Shannon diversity index values were different across six land use types, with high values observed in institutional areas (H'=4.08). Species evenness was high in graveyards (E-Q=0.31) and low in residential areas (E-Q=0.15). Bray-Curtis index revealed high dissimilarity of species composition in all pairs except a pair of institutional land and residential areas (0.67). The pattern was also confirmed using detrended correspondence analysis. The discrepancies in species composition between land use types was associated with difference in their levels of anthropogenic activities. Overall, the study results confirm that urban landscapes in Africa are important depository of tree species composition and diversity that differ with land use type. The influence of other factors to species heterogeneity and importance of such diversity in providing ecosystem services to the urban landscapes needs further investigation.