Yekwayo Inam, Pryke James S, Gaigher René, Samways Michael J
School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit, South Africa.
Department of Conservation Ecology and Entomology, Stellenbosch University, Matieland, South Africa.
Oecologia. 2019 Sep;191(1):231-240. doi: 10.1007/s00442-019-04471-4. Epub 2019 Jul 27.
Fire is a natural feature of many ecosystems, with some vegetation types highly adapted to fire. However, very little is known about the effect of fire on spiders, especially as fires have become more frequent owing to human activity. We determine whether different spider functional guilds (web builders vs. wanderers) respond differently to fires in the sclerophyllous fynbos. We determine also the effect of rockiness as refuge for these guilds and whether it influences their post-fire recovery. There were three site categories of time-since-last fire: 3 months, 1 year, and 7 years. We found that fire caused a decline in spider richness and abundance, with the 3-month category supporting the lowest. In sites that were burned within 1 year, abundance of wanderers was as high as in sites that had 7 years to recover, whereas species richness and abundance of web builders in sites that were burned 1 year ago were as low as in recently burned sites. However, assemblages of wanderers differed among categories, while no differences were observed for web builders, highlighting that wanderers took longer time to recover than web builders. Species richness and abundance of both guilds were not affected by different levels of rockiness. However, rockiness is important in shaping assemblages of wanderers. The results emphasize that the assemblages of greatest conservation concern with increased fire frequencies are wanderers and are candidate surrogates for monitoring post-fire recovery. These results highlight the need to allow fynbos vegetation to recover fully between fire intervals and draws attention to the dangers of frequent unplanned fires.
火灾是许多生态系统的自然特征，一些植被类型对火灾具有高度适应性。然而，人们对火灾对蜘蛛的影响知之甚少，尤其是由于人类活动导致火灾变得更加频繁。我们确定了不同的蜘蛛功能类群（结网蜘蛛与游猎蜘蛛）对硬叶石南灌丛火灾的反应是否不同。我们还确定了岩石作为这些类群避难所的作用，以及它是否会影响它们火灾后的恢复情况。有三类自上次火灾以来的时间点：3个月、1年和7年。我们发现火灾导致蜘蛛的丰富度和数量下降，其中3个月这一时间段的蜘蛛数量最少。在1年内发生过火灾的地点，游猎蜘蛛的数量与有7年恢复时间的地点一样多，而1年前发生过火灾的地点，结网蜘蛛的物种丰富度和数量与最近发生火灾的地点一样低。然而，游猎蜘蛛的组合在不同时间段有所不同，而结网蜘蛛则没有差异，这突出表明游猎蜘蛛比结网蜘蛛需要更长的时间来恢复。两个类群的物种丰富度和数量均不受不同岩石程度的影响。然而，岩石程度在塑造游猎蜘蛛的组合方面很重要。结果强调，随着火灾频率增加，最需要保护的组合是游猎蜘蛛，它们是监测火灾后恢复情况的候选替代指标。这些结果凸显了在火灾间隔期让石南灌丛植被充分恢复的必要性，并提醒人们注意频繁发生的意外火灾的危险性。
