Which urban trees support many tiny habitats in Greater Kumasi?

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Urban trees benefit city residents and host tree-related microhabitats (TreMs). These habitats enhance structural complexity, support the sustainable provision of ecosystem services, and strengthen resilience against climate change and environmental stressors. Yet many aspects of biodiversity remain understudied in rapidly urbanizing African cities facing climate change impacts.

Researchers examined the structure, composition, functional traits, and TreMs of the urban forest in Greater Kumasi, Ghana, a densely populated and rapidly growing city. From August to December 2022, they inventoried 644 trees across 236 plots, representing 93 species and 31 families. They compared tree species composition, functional traits, TreM abundance, and TreM type richness between land cover classes and identified critical drivers of TreM diversity.

Large-diameter trees were scarce and non-native species dominated, but native and large-diameter trees were crucial for supporting many TreMs, including ecologically valuable types such as those found in epiphyte habitats. TreM abundance and richness differed between palms and trees and between deciduous and evergreen species. The researchers also discovered new TreM types, such as those found in termite and ant nests on trees. They said these findings highlight the need for more research into the unique ecological factors influencing TreM abundance and richness in tropical Sub-Saharan African cities.

The results also showed human influence on species composition and size structures. To strengthen the biodiversity and resilience of African tropical urban forests, the researchers recommended management strategies that integrate socioeconomic perspectives, consider protecting mature trees, and monitor the spread of non-native species.