Fire is common in seasonally dry areas in many parts of the world, and its effects on vegetation in these areas have been well studied. In riparian forests of the Pantanal, where fuel accumulation (dead plants) in the dry season can be a substantial driver of fire occurrence, little is known about the role of bark traits to fire protection in woody plants. Herein we evaluated some physical, chemical and anatomical bark traits to determine if they are associated with fire tolerance in tree riparian species of the Pantanal. To accomplish this, we selected three fire-sensitive species and seven fire-tolerant species in riparian forest of the Paraguay River. Bark samples were analyzed for relative total, outer and inner bark thickness, bark density, concentration of phenolic compounds and tannins, thermogravimetric behavior and their anatomical structure. We observed higher concentration of phenol and tannins and higher percentage of sclerenchyma in bark from fire-tolerant species than fire-sensitive species. Bark of fire-tolerant species also showed more sclerenchyma cells near vascular cambium and higher temperatures of thermal decomposition. In contrast, relative total, outer and inner bark thickness, and bark density did not differ between species groups. The high concentration of phenol and tannins, combined with higher percentage of sclerenchyma in secondary phloem, appear as the major bark traits that could mitigate fire damage in species from riparian forest of the Brazilian Pantanal.

火灾在世界许多地区的季节性干旱地区很常见，火灾对这些地区植被的影响已得到充分研究。在潘塔纳尔湿地的河岸森林中，旱季的燃料积累（枯死的植物）可能是火灾发生的重要驱动因素，但人们对树皮特性对木本植物防火的作用知之甚少。在此，我们评估了一些物理、化学和解剖学树皮特性，以确定它们是否与潘塔纳尔河沿岸树种的耐火性有关。为了实现这一目标，我们在巴拉圭河的河岸林中选择了三种火敏树种和七种耐火树种。对树皮样品进行了相对总、外层和内层树皮厚度、树皮密度、酚类化合物和单宁的浓度分析，热重行为及其解剖结构。我们观察到，与火敏感物种相比，耐火物种的树皮中苯酚和单宁的浓度更高，厚壁组织的百分比更高。耐火物种的树皮也显示出在维管形成层附近有更多的厚壁细胞和更高的热分解温度。相比之下，相对总、外部和内部树皮厚度以及树皮密度在物种组之间没有差异。高浓度的苯酚和单宁，加上次生韧皮部中较高比例的厚壁组织，是可以减轻巴西潘塔纳尔河沿岸森林物种火灾损害的主要树皮特性。我们观察到，与火敏感物种相比，耐火物种的树皮中苯酚和单宁的浓度更高，厚壁组织的百分比更高。耐火物种的树皮也显示出在维管形成层附近有更多的厚壁细胞和更高的热分解温度。相比之下，相对总、外部和内部树皮厚度以及树皮密度在物种组之间没有差异。高浓度的苯酚和单宁，加上次生韧皮部中较高比例的厚壁组织，是可以减轻巴西潘塔纳尔河沿岸森林物种火灾损害的主要树皮特性。我们观察到，与火敏感物种相比，耐火物种的树皮中苯酚和单宁的浓度更高，厚壁组织的百分比更高。耐火物种的树皮也显示出在维管形成层附近有更多的厚壁细胞和更高的热分解温度。相比之下，相对总、外部和内部树皮厚度以及树皮密度在物种组之间没有差异。高浓度的苯酚和单宁，加上次生韧皮部中较高比例的厚壁组织，是可以减轻巴西潘塔纳尔河沿岸森林物种火灾损害的主要树皮特性。树皮密度在物种组之间没有差异。高浓度的苯酚和单宁，加上次生韧皮部中较高比例的厚壁组织，是可以减轻巴西潘塔纳尔河沿岸森林物种火灾损害的主要树皮特性。树皮密度在物种组之间没有差异。高浓度的苯酚和单宁，加上次生韧皮部中较高比例的厚壁组织，是可以减轻巴西潘塔纳尔河沿岸森林物种火灾损害的主要树皮特性。