Muylaert Renata L, Stevens Richard D, Ribeiro Milton C
Department of Ecology, Universidade Estadual Paulista (UNESP), 24A Av., 1515, 13506-900, Rio Claro, Brazil.
Department of Natural Resources Management, Museum of Texas Tech University, Lubbock, Texas, 79409, USA.
Ecol Appl. 2016 Sep;26(6):1854-1867. doi: 10.1890/15-1757.1.
Understanding how animal groups respond to contemporary habitat loss and fragmentation is essential for development of strategies for species conservation. Until now, there has been no consensus about how landscape degradation affects the diversity and distribution of Neotropical bats. Some studies demonstrate population declines and species loss in impacted areas, although the magnitude and generality of these effects on bat community structure are unclear. Empirical fragmentation thresholds predict an accentuated drop in biodiversity, and species richness in particular, when less than 30% of the original amount of habitat in the landscape remains. In this study, we tested whether bat species richness demonstrates this threshold response, based on 48 sites distributed across 12 landscapes with 9-88% remaining forest in Brazilian cerrado-forest formations. We also examined the degree to which abundance was similarly affected within four different feeding guilds. The threshold value for richness, below which bat diversity declines precipitously, was estimated at 47% of remaining forest. To verify if the response of bat abundance to habitat loss differed among feeding guilds, we used a model selection approach based on Akaike's information criterion. Models accounted for the amount of riparian forest, semideciduous forest, cerrado, tree plantations, secondary forest, and the total amount of forest in the landscape. We demonstrate a nonlinear effect of the contribution of tree plantations to frugivores, and a positive effect of the amount of cerrado to nectarivores and animalivores, the groups that responded most to decreases in amount of forest. We suggest that bat assemblages in interior Atlantic Forest and cerrado regions of southeastern Brazil are impoverished, since we found lower richness and abundance of different groups in landscapes with lower amounts of forest. The relatively higher threshold value of 47% suggests that bat communities have a relatively lower resistance to habitat degradation than other animal groups. Accordingly, conservation and restoration strategies should focus on increasing the amount of native vegetation of landscapes so as to enhance species richness of bats.
了解动物群体如何应对当代栖息地丧失和破碎化对于制定物种保护策略至关重要。到目前为止，关于景观退化如何影响新热带蝙蝠的多样性和分布尚未达成共识。一些研究表明，受影响地区的蝙蝠种群数量下降和物种丧失，尽管这些影响对蝙蝠群落结构的程度和普遍性尚不清楚。经验性破碎阈值预测，当景观中剩余的栖息地面积不到原始面积的30%时，生物多样性将急剧下降，尤其是物种丰富度。在本研究中，我们基于分布在巴西塞拉多 - 森林地貌的12个景观中的48个地点进行测试，这些景观中剩余森林比例为9% - 88%，以检验蝙蝠物种丰富度是否表现出这种阈值响应。我们还研究了四种不同食性类群内蝙蝠数量受影响的程度。蝙蝠多样性急剧下降的丰富度阈值估计为剩余森林的47%。为了验证蝙蝠数量对栖息地丧失的响应在不同食性类群之间是否存在差异，我们使用了基于赤池信息准则的模型选择方法。模型考虑了河岸森林、半落叶林、塞拉多、人工林、次生林以及景观中森林的总量。我们证明了人工林对食果蝙蝠的贡献具有非线性效应，塞拉多面积对食蜜蝙蝠和食虫蝙蝠具有积极效应，这两类蝙蝠对森林面积减少的响应最为明显。我们认为巴西东南部内陆大西洋森林和塞拉多地区的蝙蝠群落数量减少，因为我们发现在森林面积较少的景观中，不同类群的丰富度和数量较低。相对较高的47%阈值表明，蝙蝠群落对栖息地退化的抵抗力相对低于其他动物群体。因此，保护和恢复策略应侧重于增加景观中的原生植被数量，以提高蝙蝠的物种丰富度。
