Fire plays a crucial role in shaping plant communities in South American savannas. However, the impact of biotic interactions on tree communities still needs to be better explored. In this study, we evaluated the influence of tree-on-tree interactions and abiotic conditions on the structure and diversity of woody communities in savannas of Central Brazil. We used plots of 10 × 10 m in three preservation areas of savanna to assess the abundance and composition of juveniles and adults in woody communities associated with two Apocynaceae tree species: Hancornia speciosa, postulated to show negative interactions with the associated tree community, and Himatanthus obovatus, postulated to show positive interactions. Our results revealed that while abiotic factors, represented by the altitude, are more critical in shaping the community of juvenile trees, tree-on-tree interactions have a stronger influence on adult tree populations, driving community dynamics during plant recruitment. Specifically, Hancornia speciosa reduces the abundance of adults, whereas Himatanthus obovatus enhances their relative abundance; both shape the composition of tree communities. Consequently, tree-on-tree interactions create distinct mosaics at various stages of regeneration, contributing to savanna dynamics and conservation.

中文翻译：

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树与树之间的相互作用和非生物条件对巴西稀树草原木本群落的影响

火在塑造南美稀树草原植物群落方面发挥着至关重要的作用。然而，生物相互作用对树木群落的影响仍需要更好地探索。在这项研究中，我们评估了树与树之间的相互作用和非生物条件对巴西中部稀树草原木本群落结构和多样性的影响。我们在三个稀树草原保护区使用 10 × 10 m 的地块来评估与两种夹竹桃科树种相关的木本群落中幼体和成体的丰度和组成：花花花，假设显示出与相关树木群落的负面相互作用，并且卵形喜花，假设显示出积极的相互作用。我们的结果表明，虽然以海拔为代表的非生物因素在塑造幼树群落方面更为关键，但树与树之间的相互作用对成年树种群有更大的影响，在植物补充过程中推动群落动态。具体来说，花花花减少了成年人的数量，而卵形喜花提高它们的相对丰度；两者都塑造了树木群落的组成。因此，树与树之间的相互作用在再生的各个阶段创造出独特的马赛克，有助于稀树草原的动态和保护。