Ethiopia is land of geographical contrasts with elevations that range from 125 m below sea level in the Danakil Depression to 4533 m above sea level in the Semien Mountains, a world heritage site. The diverse climate of various ecological regions of the country has driven the establishment of diverse vegetation, which range from Afroalpine vegetation in the mountains to the arid and semi-arid vegetation type in the lowlands. The formation of Ethiopian vegetation is highly connected to the climate and geological history of the country. Highland uplift and rift formation due to volcanic forces formed novel habitats with different topography and climatic conditions that have ultimately become drivers for vegetation diversification. Due to Ethiopia's connection with the temperate biome in the north and the Arabian Peninsula during the dry glacial period, the biotic assemblage of Ethiopian highlands consists of both Afrotropical and palearctic biota. In general, eight distinct vegetation types have been identified in Ethiopia, based mainly on elevation and climate gradients. These vegetation types host their own unique species, but also share several common species. Some of the vegetation types are identified as centers of endemism and have subsequently been identified globally as the East African Afromontane hotspot. Ethiopia is biologically rich, with more than 6500 vascular plant species. Of these species, 12% are endemic mainly due to geographical isolation and unique climatic conditions. However, researchers have yet to extensively investigate the ecology, phenology, as well as the evolutionary, genetics, and conservation status of Ethiopian vegetations at community and species level over space and time. This lack of research is a barrier to achieving the goal of zero global plant extinctions. Taxa extinction risk assessment has not been extensively carried out for majority of Ethiopian species. Detailed research is needed to explore how vegetation and species respond to rapidly growing environmental change. Currently, human-induced climate change and habitat fragmentation are severely threatening the country's biodiversity, and the consequences of these effects have not been studied at large. Furthermore, we still lack scientific evidence on how micro- and macro-ecological and evolutionary processes have been shaping vegetation structures in this climatically, topographically, and geologically diverse country. These gaps in our knowledge represent an opportunity for ecologists, geneticists, evolutionary biologists, conservation biologists, and other experts to investigate the biodiversity status and the complex ecological processes involved in structuring vegetation dynamics so as to help take effective conservation actions.

Although elevational gradients of biodiversity have long been the topic of scientific research, information on patterns of, and processes that shape insect community structure across elevation is still lacking. Addressing this gap requires the use of both taxonomic and functional approaches when studying diversity across elevational gradients. In this study, we examined taxonomic and functional alpha and beta diversity of ant assemblages sampled along tropical, subtropical, and subalpine elevational transects in Yunnan Province, southwest China. Species richness was used to quantify taxonomic alpha diversity, and two indices (FD and FRic) were calculated using morphological measurements to quantify functional alpha diversity. Taxonomic and functional beta diversity were partitioned into their turnover- and nestedness-resultant components. Though temperature and functional alpha diversity decreased linearly with increasing elevation, taxonomic alpha diversity showed a significant logarithmic decrease, with few species present at elevations greater than 3000 m a.s.l. The turnover-resultant component of taxonomic beta diversity increased with increasing elevational distance, while the nestedness-resultant component of functional beta diversity increased with increasing elevational distance in the subtropical transect. The observed patterns of taxonomic and functional diversity reflected ants’ thermophilic nature, implying functional adaptations (i.e., nested functional diversity) at higher elevations where environmental conditions were unfavorable.

Elevational patterns of tree diversity are well studied worldwide. However, few studies have examined how seedlings respond to elevational gradients and whether their responses vary across climatic zones. In this study, we established three elevational transects in tropical, subtropical and subalpine mountain forests in Yunnan Province, southern China, to examine the responses of tree species and their seedlings to elevational gradients. Within each transect, we calculated species diversity indices and composition of both adult trees and seedlings at different elevations. For both adult trees and seedlings, we found that species diversity decreased with increasing elevation in both tropical and subalpine transects. Species composition showed significant elevational separation within all three transects. Many species had specific elevational preferences, but abundant tree species that occurred at specific elevations tended to have very limited recruitment in the understory. Our results highlight that the major factors that determine elevational distributions of tree species vary across climatic zones. Specifically, we found that the contribution of air temperature to tree species composition increased from tropical to subalpine transects, whereas the contribution of soil moisture decreased across these transects.