Biosyst. Divers., 2023, 31(4) Biosystems Diversity ISSN 2519-8513 (Print) ISSN 2520-2529 (Online) Biosyst. Divers., 2023, 31(4), 460–469 doi: 10.15421/012355 Functional diversity along disturbance and environmental gradients in Ethiopian moist Afromontane forest F. A. Jeldu, M. Tolera, T. Woldeamanuel Hawassa University, Wondo Genet, Ethiopia Article info Received 25.09.2023 Received in revised form 01.11.2023 Accepted 12.11.2023 Hawassa University, Wondo Genet, P. O. Box 128 Shashemene, Ethiopia. Tel: +251-046-211-001. E-mail: feredeabuye@gmail.com Jeldu, F. A., Tolera, M., & Woldeamanuel, T. (2023). Functional diversity along disturbance and environmental gradients in Ethiopian moist Afromontane forest. Biosystems Diversity, 31(4), 460–469. doi:10.15421/012355 Considering multiple measures to fully capture functional diversity is important. However, the effects of disturbance gradients on diver- sity have been controversial, as species diversity alone may not fully capture these effects. This study aimed to evaluate trait-based diversity across disturbance gradients in the moist Afromontane forest of Ethiopia, Yayu Coffee Forest Biosphere Reserve (YCFBR). Vegetation data and relevant traits related to plant-life strategies, competition, and responses to disturbances were collected. A multiple regression model was used to test the response of functional diversity to disturbances and environmental gradients. The results revealed functional diversity in plant communities, including dendrogram-based functional diversity for plot-based (FDp), functional richness (FRic), functional evenness (FEve), functional divergence (FDiv), functional dispersions (FDis), and community-weighted mean of maximum tree height (CWM.Hmax), showed decreasing patterns with increasing disturbance intensity in the YCFBR. Additionally, the findings highlighted that FDis and Hmax are the most vulnerable functional traits to anthropogenic factors and are less tolerant in disturbed ecosystem environments. Therefore, reduc- ing disturbances is crucial to maintaining higher levels of these functional diversities. For example, the results showed that the CWM.Hmax declined from 27.25 m to 15 m, indicating a shift towards shorter plant species. In contrast, the community-weighted mean of woody density (CWM.WD), the community-weighted mean of specific leaf area (CWM.SLA), and the community-weighted mean of seed mass (CWM.SM) increased significantly with an increase in disturbance intensity. For instance, CWM.SM and CWM.SLA changed from 5 to 14.25 (g) and 90 to 130 (cm 2 /g), respectively. These indices may serve as indicators of ecosystem resilience at disturbed forest ecosystem sites. Furthermore, the regression results indicated that FDp, FRic, FEve, FDiv, FDis, CWM.WD, and CWM.Hmax showed increasing patterns with increasing species richness, which suggests that protecting and promoting species diversity can contribute to maintaining high levels of functional diversity. The mixed effects model revealed that anthropogenic disturbance and elevational gradients had significant effects on functional diversity in the YCFBR. Therefore, when managing and conserving biodiversity in heterogeneous environments, both anthropogenic factors and environmental variables need to be considered. Species with low SLA and SM are recommended for the restora- tion of disturbed ecosystems. Overall, this study demonstrates that trait-based functional diversity is useful for predicting the adaptation potentials of species in heterogeneous environments and disturbance gradients. Keywords: heterogeneous environments; ecosystem resilience; low specific leaf area; patterns of functional diversity; species richness. Introduction The total area under forests across the globe is estimated to be 4.06 billion hectares (ha), which is 31 percent of the total land area and equiva- lent to 0.52 ha per person (FAO and UNEP, 2020). Forests provide a ple- thora of ecosystem services that include biodiversity conservation, socio- cultural benefits, nature experiences and climate regulation. Unfortunately, these pristine natural resources are under tremendous threat both from na- tural and anthropogenic stresses (Sasidharan & Kavileveettil, 2023). Many of the world’s most biodiverse regions are found in Africa; a continent facing exceptional challenges due to increasingly severe climate change and environmental conflict, all of which will ravage biodiversity (Chapman et al., 2022). Forty-five percent of the world’s forested areas are in the tro- pics, and they are among the most important regulators of regional and global climate, natural carbon sinks and the most significant repositories of terrestrial biomass (Griggs, 2023). This implies that they are of immeasu- rable value to biodiversity, ecosystem services, social and cultural identi- ties, livelihoods, and climate change adaptation and mitigation. Tropical forests are also the most biodiverse ecosystems in the world, yet their eco- system functions, such as carbon sequestration for climate change mitigation and the provisionary services, are threatened by anthropogenic disturbances and climate change (Aguirre‐Gutiérrez et al., 2022; Smit et al., 2023). Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface tempera- ture reaching 1.1 °C above 1850–1900 in 2011–2020 (IPCC, 2023). Fur- thermore,over 420 million ha of forest were lost to deforestation from 1990 to 2020; more than 90% of that loss took place in tropical areas, threatening biodiversity, environmental services, the livelihoods of forest communities, and resilience to climate shocks (Griggs, 2023). For exam- ple, the Global Forest Resources Assessment (GFRA) revealed that Africa had the largest annual rate of net forest loss in 2010–2020, at 3.9 million ha, followed by South America, at 2.6 million ha (Lee & Ha, 2022). Defo- restation, climate change, and land use change are the major factors posing threats to forest sustainability (Akram et al., 2023). Following this, much attention has been paid in recent years to the massive loss of ecosystem services and biodiversity worldwide due to forest clearance. Similarly, these rapid environmental changes are putting species at risk, and such changes in species composition can have strong effects on ecosystem processes and functions (Singh, 2021). Forest loss and degradation have been the main causes of tropical biodiversity loss and this continues rapidly at regional or global scales due to increasing intensity of disturban- ces such as overexploitation of species, destruction of habitats and climate change (Griggs, 2023). Therefore, protecting tropical forests has become increasingly important given the recognition that the loss of these forests accounts for between 6% and 17% of global carbon dioxide emissions (Baccini et al., 2017). Ethiopia has a diverse climate of various ecological regions, and no- vel habitats with different topography have driven the establishment of diverse vegetation types, which range from afroalpine vegetation to semi- arid and arid vegetation types (Lemessa & Teka, 2017; Zerihun et al., 460