Savanna tree communities occurring in confluence zones with other biomes likely experience different environmental pressures, resulting in shifts in the selection of individual traits, the combinations of such traits, and species composition. In seasonally dry fire-prone environments, plant survival is presumably associated with adaptive changes in bark properties related to fire protection and water storage. Here, we integrated the multiple functions of the bark to investigate whether different selective pressures could influence patterns of variation in bark structure and allocation across species in a broad geographical range. We measured thickness, density, and water content of the inner and outer bark in branches and the main stem of the 51 most abundant species in three savanna communities differing in climatic aridity, one located at the core region of Cerrado in Central Brazil and the other two at its periphery, in the transition zones with Amazonia and Atlantic forest biomes. We found no difference in outer bark thickness but markedly difference in inner bark thickness between the three plant communities. In the central region, where dry season is long and fire is frequent, branches and main stem showed thicker inner bark. Contrastingly, in the south periphery region, where dry season is short, species showed thinner inner bark in both branches and main stem. Species from the north periphery region, where mean annual precipitation is higher, but fire is frequent and the dry season is also long, showed similar main stem inner bark thickness, but thinner branch inner bark compared to core region species. Our findings support the idea that investing in inner bark thickness and bark moisture may be the most advantageous strategy in plant communities that suffer from high evaporative demand during a long period and are at a high risk of fire.

出现在与其他生物群落汇合区的稀树草原树群落可能会经历不同的环境压力，导致个体特征的选择、这些特征的组合和物种组成发生变化。在季节性干燥的火灾多发环境中，植物存活可能与与防火和储水相关的树皮特性的适应性变化有关。在这里，我们整合了树皮的多种功能，以研究不同的选择压力是否会影响广泛地理范围内树皮结构和物种分配的变化模式。我们测量了三个不同气候干旱的稀树草原群落中 51 种最丰富物种的枝条和主干的内部和外部树皮的厚度、密度和含水量，一个位于巴西中部塞拉多的核心区域，另外两个位于其外围，与亚马逊河和大西洋森林生物群落的过渡区。我们发现三个植物群落的外层树皮厚度没有差异，但内层树皮厚度有显着差异。在旱季长、火多的中部地区，枝条和主干的内皮较厚。相比之下，在干旱季节较短的南缘地区，物种的两个分支和主干的内部树皮都较薄。年平均降水量较高，但火灾频繁，旱季也长的北部外围地区的物种，与核心地区物种相比，主干内皮厚度相似，但分支内皮更薄。