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<p><i>Cordia africana</i> and <i>Terminalia brownii</i>, indigenous Ethiopian multipurpose trees of high ecological and socioeconomic value, are increasingly threatened by overexploitation and climate change. Understanding how climatic and anthropogenic factors shape their distribution is critical for sustainable management and conservation. This study identified key environmental drivers, predicted suitable habitats under current and future climates, and assessed shifts in distribution, geographic range, and niche overlap. Future climate projections were assessed under two scenarios: the medium-emission scenario (SSP2-4.5) and the high-emission scenario (SSP5-8.5), for two time horizons: the 2050s and 2070s. An ensemble modeling framework was applied using seven algorithms: boosted regression trees, random forest, generalized linear model, generalized additive model, maximum entropy, support vector machine, and multivariate adaptive regression splines. Each model was run with ten sub-sampled replicates. We evaluated model performance using the area under the curve (AUC) for <i>C. africana</i> (0.84) and <i>T. brownii</i> (0.82), and the true skill statistic (TSS), which was 0.60 for both species. Predicted suitable habitat for <i>C. africana</i> (20.1%) was concentrated in the western, central, and southwestern regions, while <i>T. brownii</i> (19.9%) was mainly distributed in the northern, eastern, and southeastern lowlands. Under future climate scenarios, suitable areas are projected to decline sharply, shrinking to 8.68% and 2.07% of Ethiopia’s land area, respectively, by the 2070s. Suitable habitats for both species are expected to contract, with potential refugia for <i>C. africana</i> shifting toward highland areas. Geographic and environmental overlap between the two species was minimal. Given their multipurpose use, increasing vulnerability, and limited niche and geographic overlap, our results show that the projected habitat contraction, the marked decline of <i>T. brownii</i> within its natural range, and the upslope shift of <i>C. africana</i> refugia require species-specific conservation actions. <i>C. africana</i> needs refugia protection and climate-adapted management, while <i>T. brownii</i> requires targeted measures to support its long-term viability. Conservation efforts should focus on safeguarding existing habitats, regulating harvesting, strengthening community-based forest management, and maintaining ecological connectivity. Both species will also require stricter control of human use under future climate change.</p>

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Climate-driven habitat shifts And niche overlap of overexploited trees Cordia africana Lam. and Terminalia brownii Fresen in Ethiopia

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月30日

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  • Daniel Melese,
  • Muluye Asnakew,
  • Ashebir Awoke,
  • Atnafu Tesfaw,
  • Yibeltal Meslie,
  • Yibelu Yitayih Hailie

摘要

Cordia africana and Terminalia brownii, indigenous Ethiopian multipurpose trees of high ecological and socioeconomic value, are increasingly threatened by overexploitation and climate change. Understanding how climatic and anthropogenic factors shape their distribution is critical for sustainable management and conservation. This study identified key environmental drivers, predicted suitable habitats under current and future climates, and assessed shifts in distribution, geographic range, and niche overlap. Future climate projections were assessed under two scenarios: the medium-emission scenario (SSP2-4.5) and the high-emission scenario (SSP5-8.5), for two time horizons: the 2050s and 2070s. An ensemble modeling framework was applied using seven algorithms: boosted regression trees, random forest, generalized linear model, generalized additive model, maximum entropy, support vector machine, and multivariate adaptive regression splines. Each model was run with ten sub-sampled replicates. We evaluated model performance using the area under the curve (AUC) for C. africana (0.84) and T. brownii (0.82), and the true skill statistic (TSS), which was 0.60 for both species. Predicted suitable habitat for C. africana (20.1%) was concentrated in the western, central, and southwestern regions, while T. brownii (19.9%) was mainly distributed in the northern, eastern, and southeastern lowlands. Under future climate scenarios, suitable areas are projected to decline sharply, shrinking to 8.68% and 2.07% of Ethiopia’s land area, respectively, by the 2070s. Suitable habitats for both species are expected to contract, with potential refugia for C. africana shifting toward highland areas. Geographic and environmental overlap between the two species was minimal. Given their multipurpose use, increasing vulnerability, and limited niche and geographic overlap, our results show that the projected habitat contraction, the marked decline of T. brownii within its natural range, and the upslope shift of C. africana refugia require species-specific conservation actions. C. africana needs refugia protection and climate-adapted management, while T. brownii requires targeted measures to support its long-term viability. Conservation efforts should focus on safeguarding existing habitats, regulating harvesting, strengthening community-based forest management, and maintaining ecological connectivity. Both species will also require stricter control of human use under future climate change.