Forest–savanna mosaics exist across all major tropical regions. Yet, the influence of environmental factors on the distribution of these mosaics is not well explored, limiting our understanding of the environmental constraints on savannas especially in Southeast Asia, where most savannas exist in mosaics. Despite clear structural and functional characteristics indicative of savannas, most SE Asian savannas continue to be classified as forest. This designation is problematic because SE Asian savannas are threatened by both fragmentation and forest-centric management practices. By studying forest–savanna mosaics across SE Asia, we aimed to parse out how landscape mosaics of forest and savanna may be constrained by fire, climate and soil characteristics. We used remotely sensed data to characterize the distribution of tree cover and forest–savanna mosaics. Using regression models, we quantified the relative effects of precipitation, fire frequency, seasonality and soil characteristics on average tree cover and landscape patchiness. We found that low tree cover, indicative of savannas, occurs in drier, seasonal subregions that experience frequent fire. Further, our results demonstrate that fire and precipitation strongly shape landscape patchiness. Landscapes were patchiest in subregions with low precipitation and intermediate fire frequency. These results demonstrate that the environmental factors important in delineating the distribution of savannas globally shape the distribution of tree cover and landscape patchiness across SE Asia. Fire especially drives patterns of tree cover across scales. In a region where fire suppression is a common management strategy, our results suggest that further research studying vegetation response to fire and fire suppression is needed to improve management and conservation of these mosaic landscapes. More broadly, this work demonstrates a useful approach for studying the environmental drivers that influence the distribution of forest–savanna mosaics.

中文翻译：

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东南亚树木覆盖和森林-稀树草原镶嵌的环境驱动因素

森林-稀树草原马赛克存在于所有主要热带地区。然而，环境因素对这些马赛克分布的影响尚未得到很好的探索，这限制了我们对热带稀树草原的环境限制的理解，特别是在东南亚，大多数稀树草原存在于马赛克中。尽管有明确的结构和功能特征表明稀树草原，但大多数东南亚稀树草原仍被归类为森林。这种指定是有问题的，因为东南亚稀树草原受到碎片化和以森林为中心的管理实践的威胁。通过研究整个东南亚的森林-稀树草原镶嵌，我们旨在解析森林和稀树草原的景观镶嵌如何受到火灾、气候和土壤特征的限制。我们使用遥感数据来描述树木覆盖和森林-稀树草原马赛克的分布。使用回归模型，我们量化了降水、火灾频率、季节性和土壤特征对平均树木覆盖率和景观斑块性的相对影响。我们发现表明稀树草原的低树木覆盖率发生在经常发生火灾的干燥季节性次区域。此外，我们的研究结果表明，火灾和降水强烈地塑造了景观斑块状。在降水量少和火灾频率中等的次区域，景观最为斑驳。这些结果表明，在描绘全球热带稀树草原分布方面重要的环境因素决定了整个东南亚的树木覆盖和景观斑块分布。火尤其会推动跨尺度的树木覆盖模式。在一个灭火是一种常见管理策略的地区，我们的研究结果表明，需要进一步研究植被对火灾和灭火的响应，以改善这些马赛克景观的管理和保护。更广泛地说，这项工作展示了一种有用的方法来研究影响森林-稀树草原马赛克分布的环境驱动因素。