Department of Plant and Soil Sciences, University of Pretoria, Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch, 7701, South Africa.
Sci Rep. 2019 Dec 18;9(1):19355. doi: 10.1038/s41598-019-55917-x.
The impacts of ecosystem engineers may be expected to vary along environmental gradients. Due to some resources being more limited in arid than in mesic environments, disturbances created by burrowing mammals are expected to have a greater ameliorating effect in arid environments, with larger differences in microhabitat conditions expected between burrows and undisturbed areas. The aim of this study was to test if the impacts of a medium-sized burrowing mammal, the aardvark, on soil properties (soil temperature, moisture and compaction) and vegetation characteristics (plant cover, species richness and species composition) are consistent across three biomes that differ strongly in annual rainfall. Burrowing affected soil and vegetation attributes, but the direction and magnitude of these biogeomorphological impacts were not consistent across the different biomes. For example, plant species composition was altered by burrowing in the arid scrubland and in the mesic grassland, but not in the semi-arid savannah. Contrary to expectations, the difference in the impacts of burrowing between biomes were not related to rainfall, with burrowing having strong, albeit different, impacts in both the arid scrubland and the mesic grassland, but weaker effects in the semi-arid savannah. It appears, therefore, that the impacts of these biogeomorphic agents may be site-specific and that it may be difficult to predict variation in their biotic and abiotic effects across environmental gradients. As a result, forecasting the impacts of ecosystem engineers under different conditions remains a challenge to management, restoration and conservation strategies related to these types of species.
生态工程师的影响预计会随环境梯度而变化。由于一些资源在干旱环境中比在湿润环境中更为有限，因此挖掘哺乳动物造成的干扰预计在干旱环境中会有更大的改善效果，在洞穴和未受干扰的区域之间，微生境条件的差异预计会更大。本研究的目的是测试一种中等大小的挖掘哺乳动物——土豚，其对土壤性质（土壤温度、湿度和紧实度）和植被特征（植物覆盖度、物种丰富度和物种组成）的影响是否在三个年降雨量差异很大的生物群落中一致。挖掘会影响土壤和植被属性，但这些生物地貌影响的方向和程度在不同的生物群落中并不一致。例如，在干旱灌丛和湿润草地中，挖掘会改变植物物种组成，但在半干旱稀树草原中则不会。与预期相反，挖掘对生物群落的影响差异与降雨量无关，在干旱灌丛和湿润草地中，挖掘都产生了强烈的影响，尽管在半干旱稀树草原中的影响较弱。因此，这些生物地貌因素的影响似乎是特定于地点的，并且很难预测它们在生物和非生物效应方面在环境梯度上的变化。因此，预测不同条件下生态工程师的影响仍然是管理、恢复和保护与这些物种相关的策略的一个挑战。
