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稀树草原（Cerrado）区域，针对火灾对环境可持续性影响的研究仍较为匮乏，尤其是关于其土壤与植被结构受干扰的相关研究。本研究旨在探讨土壤因子（edaphic variables）与火灾的共同作用，对亚马逊境内三处塞拉多稀树草原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，均系统布设了8个样地。研究数据被用于开展植物区系多样性、群落相似性以及径级与高度级结构评估。通过分析得到植物社会学参数，并将其应用于主成分分析（PCA）与典范对应分析（CCA）。本次研究共记录到808株个体，隶属于34种、30属、21科。典范对应分析结果显示，物种分布受土壤因子调控，乔灌物种与研究区域常见的低营养、高酸性土壤呈现极强的直接相关性，这验证了土壤因子的重要影响。本研究结果支持“火灾在植被结构塑造中发挥关键作用”这一假说，因为火灾可作为土壤属性的良好指示因子，并引发木本植物物种组成的显著改变。