Effect of fire under the soils on the organization of communities of three remnants of Amazonian savannas

ABSTRACT Areas of cerrado (Brazilian savanna) in the Amazon have been poorly studied from the perspective of fire impacts on environmental sustainability, especially with regard to disturbances to soil and vegetation structure. This study aimed to analyze the influence of edaphic variables and fire together on the composition and structure of tree and shrub vegetation of three cerrado remnants in the Amazon. Eight plots were systematically installed in burned and unburned environments in each remnant. Data were submitted to floristic diversity, similarity, and diametric and altimetric structural assessments. Phytosociological parameters were obtained and submitted to Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA). A total of 808 individuals (34 species, 30 genera, and 21 families) were recorded. The CCA indicated that the distribution of species is influenced by edaphic factors, as confirmed by the strong direct correlation of tree and shrub species with the reduced nutrition and high acidity of the soils common in the analyzed remnants. Our results support the hypothesis that fire plays a relevant role in structuring vegetation since it contributed to good indicators of soil properties and caused changes in the composition of woody species.

摘要 亚马逊流域内的塞拉多（Cerrado，巴西稀树草原）区域，从火对环境可持续性的影响维度，尤其是针对土壤与植被结构的干扰层面，相关研究仍较为匮乏。本研究旨在分析土壤因子与火的共同作用，对亚马逊地区三处塞拉多残存斑块的乔灌植被组成与结构的影响。在每个残存斑块的火烧与未火烧生境中，系统性布设8个样地。对采集的数据开展植物区系多样性、群落相似性，以及径级与株高结构特征评估。计算得到植物社会学参数，并开展主成分分析（Principal Component Analysis，PCA）与典范对应分析（Canonical Correspondence Analysis，CCA）。本研究共记录到808株个体，隶属于34种、30属及21科。典范对应分析结果显示，物种分布受土壤因子影响，该结论得到了木本植物与研究斑块内常见的低营养、高酸度土壤间存在强直接相关性的佐证。本研究结果支持"火在植被结构塑造中发挥关键作用"这一假说，因为火可作为土壤属性的良好指示因子，并引发木本植物组成的显著改变。