Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia.
PLoS One. 2012;7(6):e38800. doi: 10.1371/journal.pone.0038800. Epub 2012 Jun 7.
Urban landscapes are often located in biologically diverse, productive regions. As such, urbanization may have dramatic consequences for this diversity, largely due to changes in the structure and function of urban communities. We examined the influence of landscape productivity (indexed by geology), housing density and vegetation clearing on the spatial distribution of nocturnal insect biomass and the foraging activity of insectivorous bats in the urban landscape of Sydney, Australia. Nocturnal insect biomass (g) and bat foraging activity were sampled from 113 sites representing backyard, open space, bushland and riparian landscape elements, across urban, suburban and vegetated landscapes within 60 km of Sydney's Central Business District. We found that insect biomass was at least an order of magnitude greater within suburban landscapes in bushland and backyard elements located on the most fertile shale influenced geologies (both p<0.001) compared to nutrient poor sandstone landscapes. Similarly, the feeding activity of bats was greatest in bushland, and riparian elements within suburbs on fertile geologies (p = 0.039). Regression tree analysis indicated that the same three variables explained the major proportion of the variation in insect biomass and bat foraging activity. These were ambient temperature (positive), housing density (negative) and the percent of fertile shale geologies (positive) in the landscape; however variation in insect biomass did not directly explain bat foraging activity. We suggest that prey may be unavailable to bats in highly urbanized areas if these areas are avoided by many species, suggesting that reduced feeding activity may reflect under-use of urban habitats by bats. Restoration activities to improve ecological function and maintain the activity of a diversity of bat species should focus on maintaining and restoring bushland and riparian habitat, particularly in areas with fertile geology as these were key bat foraging habitats.
城市景观通常位于生物多样性丰富、生产力高的地区。因此，城市化可能会对这种多样性产生巨大影响，主要是因为城市社区的结构和功能发生了变化。我们研究了景观生产力（以地质为指标）、住房密度和植被清理对澳大利亚悉尼城市景观中夜间昆虫生物量的空间分布和食虫蝙蝠觅食活动的影响。从悉尼中央商务区 60 公里范围内的城市、郊区和植被景观中，代表后院、开放空间、灌木林地和河岸景观要素的 113 个地点，采样了夜间昆虫生物量（g）和蝙蝠觅食活动。我们发现，与营养贫瘠的砂岩景观相比，位于最肥沃页岩影响地质上的郊区灌木林地和后院元素中的昆虫生物量至少高出一个数量级（均 p<0.001）。同样，在郊区肥沃地质上的灌木林地和河岸元素中，蝙蝠的觅食活动最大（p=0.039）。回归树分析表明，同样的三个变量解释了昆虫生物量和蝙蝠觅食活动变化的主要部分。这三个变量是环境温度（正）、住房密度（负）和景观中肥沃页岩地质的百分比（正）；然而，昆虫生物量的变化并没有直接解释蝙蝠的觅食活动。我们认为，如果许多物种回避高度城市化地区，那么这些地区的猎物可能对蝙蝠不可用，这表明蝙蝠的觅食活动减少可能反映了它们对城市栖息地的利用不足。为改善生态功能和维持多种蝙蝠物种的活动而进行的恢复活动应侧重于维持和恢复灌木林地和河岸栖息地，特别是在具有肥沃地质的地区，因为这些地区是蝙蝠觅食的关键栖息地。
