BETA DIVERSITY OF BIRDS (Passeriformes, Linnaeus, 1758) IN SOUTHERN AMAZON

Abstract The importance of estimating the biological diversity and understanding how ecological specialization of species changes with spatially-organized habitats in undeniable. High beta diversity between neighboring places means an elevated number of species living within small distances, which usually are adapted to local conditions and highly vulnerable to anthropogenic actions as deforestation and burning. We investigated beta diversity of birds from the order Passeriformes in Southern Amazon, within landscapes with a large heterogeneous vegetation cover (habitats with flooded forest, dry forest, and marsh palm) through sound, observational, and photographic censuses. We marked 126 points in equidistant transects. A total of 148 species of birds were identified, distributed in 27 families. We found that 97% of the species foraged in flooded forest, 77% in dry forest and 19% in marsh palms, and only 18% foraged in the three habitats. An ordination analyses revealed which species showed the strongest preference to each habitat. The analysis for the Global beta diversity showed that this value is high (Whittaker: 7.7405), and the same pattern was obtained with the measure of pairwise dissimilarity. An influence of spatial distance was clearly observed in the cluster analysis and confirmed with a partial Mantel analysis; however, this was not observed at points that coincided with the transition and substitution of species. The influence of spatial distance in the dissimilarity index (beta diversity) was significant (r: 0.0608, p: 0.0049). The assemblage of species in small local populations with high beta diversity may be at risk if deforestation, selective logging, and poaching continue. In summary, this study provides important information on specific habitats with high beta diversity that may be at risk of destabilization of its populations due to continuing environmental changes imposed by humans.摘要 评估生物多样性并阐明物种的生态特化如何随空间结构化生境发生变化，其重要性毋庸置疑。相邻生境间的高β多样性（beta diversity）意味着小尺度范围内栖息的物种种数更高，这些物种通常适应了局地环境，且极易受到森林砍伐、焚烧等人为活动的威胁。本研究针对亚马逊南部区域的雀形目（Passeriformes）鸟类开展β多样性研究，该区域的景观拥有丰富的异质植被覆盖，涵盖泛滥林、旱生林与沼泽棕榈林三类生境，调查采用鸣声普查、目视观测与摄影计数三种方式。研究团队在等距样带上共布设126个调查点，最终鉴定出隶属于27个科的148种鸟类。调查结果显示，97%的物种会在泛滥林内觅食，77%的物种利用旱生林，19%的物种活动于沼泽棕榈林，仅有18%的物种会同时利用这三类生境。排序分析揭示了对各类生境具有最强偏好的物种类群。整体β多样性分析结果显示该数值较高（惠特克指数：7.7405），基于成对相异性指数的分析也得到了一致的结果。聚类分析中可明显观测到空间距离的影响，且经偏曼特尔检验得到了验证；但在物种更替与过渡的样点中，并未发现该规律。空间距离对相异性指数（即β多样性）的影响具有统计学显著性（r=0.0608，p=0.0049）。若森林砍伐、选择性采伐与偷猎活动持续发生，这类以小局域种群为特征且具有高β多样性的物种集合体将面临生存风险。综上，本研究为具有高β多样性的特定生境提供了重要的基础数据——这类生境的种群可能因人类持续施加的环境变化而面临种群稳定性受损的风险。