Current theories on biodiversity-carbon sequestration relationship describe biodiversity as an important factor influencing carbon storage, either through complementarity effect or by mass ratio effect. So far, the expected form of biodiversity-carbon relationships in tropical ecosystems has not been known with certainty. Therefore, we explored the relationship between aboveground carbon stock and different biodiversity measurement indices (i.e., species richness, species diversity, species evenness, and functional diversity) in different land cover types of Eastern Ethiopia. A total of 48 plots were established using stratified random sampling. Vegetation parameters such as diameter at breast height, diameter at stump height, tree height, and species type were recorded. We found that the average aboveground carbon stock of the study area is 147.6 ± 17.2 t ha−1 (mean, SE) across land cover types. Species richness, Shannon index, and functional diversity together explained 73.5%, 61.4%, 58.9%, and 52.0% of the variation in aboveground carbon storage in woodland, riparian forest, bushland, and farmland, respectively. Functional diversity was a significant predictor explaining the total aboveground carbon stocks (26.7%) across the land cover types. The effects of biodiversity on aboveground carbon storage were mediated by functional diversity and presence and dominance of species. This shows that both the selection effects and the niche complementarity are important for carbon storage. However, the impact of functional diversity effects (niche complementarity) was higher than that of functional dominance effects (selection effects). Implementation of protected area-based ecosystem conservation practices in the country seems feasible to mitigate climate change and Reducing Emissions from Deforestation and Forest Degradation (REDD+) programme should emphasize on biodiversity conservation.

中文翻译：

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埃塞俄比亚东部热带生态系统中的地上碳储量与土地覆盖和木本物种多样性有关

当前关于生物多样性-碳固存关系的理论将生物多样性描述为通过互补效应或质量比效应影响碳储存的重要因素。到目前为止，还不确定地确定热带生态系统中生物多样性与碳之间关系的预期形式。因此，我们探索了埃塞俄比亚东部不同土地覆被类型中地上碳储量与不同生物多样性度量指标（即物种丰富度，物种多样性，物种均匀度和功能多样性）之间的关系。使用分层随机抽样共建立了48个样地。记录植被参数，例如胸高直径，树桩高直径，树高和物种类型。我们发现研究区域的平均地上碳储量为147。跨土地覆盖类型为6±17.2 t ha-1（平均值，SE）。物种丰富度，香农指数和功能多样性共同解释了林地，河岸森林，灌木丛和农田地上碳储量变化的73.5％，61.4％，58.9％和52.0％。功能多样性是解释整个土地覆盖类型地上碳总储量（26.7％）的重要预测指标。生物多样性对地上碳储存的影响是通过功能多样性以及物种的存在和优势来介导的。这表明选择效应和生态位互补性对于碳储存都很重要。但是，功能多样性效应（生态位互补性）的影响高于功能优势效应（选择效应）。