No general edge effects for invertebrates at Afromontane forest/grassland ecotones
No general edge effects for invertebrates at Afromontane forest/grassland ecotones
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DOI：
10.1023/a:1016606209906
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发表时间：
2001-03-01
影响因子：
3.4
通讯作者：
Samways, MJ
中科院分区：
文献类型：
--
作者：
Kotze, DJ;Samways, MJ
南非的非洲山地地区的特点是在草原矩阵中有许多小的，残留的森林。森林和草原之间的边缘或生态交错带通常很尖锐（通常只有几米多），主要由自然火灾和最近的人为火灾维持。我们调查了非洲山地森林/草原交错带的表生端足类、步甲和蚂蚁的分布格局，发现几乎没有证据支持生物边缘效应。然而，52个采样物种中的5个物种在生态交错区的丰度确实显著增加。其中有一个非常独特的边缘物种，片脚类动物非洲龙。总体而言，步甲在森林中数量较多，种类丰富，而蚂蚁则在草原中。蚂蚁和步甲的数量和种类在春、夏两季均比秋、冬两季多。更有趣的是，整个生态交错带的丰度和物种丰富度模式并没有随着季节的推移而改变。我们认为，非洲山地森林斑块的保护战略也必须包括周围的草地。草原生境往往被认为不如森林有价值，因此受到许多人为干扰，如破碎化、放牧和植树造林。保护森林斑块周围的草地不仅可以保护丰富的蚂蚁多样性，而且可以保护森林和边缘的生物群，因此对非洲山地生物多样性的整体保护更有意义。
The Afromontane region of South Africa is characterised by numerous small, remnant forests in a grassland matrix. The edges, or ecotones between forests and grasslands are usually sharp (typically just over a few metres) and are mainly maintained by both natural and, more recently, anthropogenic fires. We investigated epigaeic amphipod, carabid and ant distribution patterns across Afromontane forest/grassland ecotones and found little evidence to support the biological edge effect. Five of the fifty-two sampled species however, did increase significantly in abundance at the ecotone. Among these was a very distinct edge species, the amphipod Talistroides africana. Overall, carabids were more abundant and species rich in forests while for ants it was in the grasslands. Ants and carabids were both more abundant and species rich in spring and summer than in autumn and winter. More interestingly, the abundance and species richness patterns across the ecotone did not change with the passing of the seasons. We argue that a conservation strategy for the Afromontane forest patches must also incorporate the surrounding grassland. The grassland habitat is often perceived as less valuable than forest and, as a consequence, is subject to many anthropogenic disturbances such as fragmentation, cattle grazing and afforestation. Protecting grasslands around forest patches not only conserves the rich ant diversity, but also conserves the biota in the forests and at the edges, and would therefore be more meaningful in terms of the overall conservation of Afromontane biodiversity.