Gosling Cleo M, Cromsigt Joris P G M, Mpanza Nokukhanya, Olff Han
Community and Conservation Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, PO Box 11103, 9700 CC Groningen, The Netherlands ; Leopard Ecology and Conservation, Private Bag BR 7, Gaborone, Botswana.
Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066, Blindern, 0316 Oslo Norway.
Ecosystems. 2012;15(1):128-139. doi: 10.1007/s10021-011-9497-8. Epub 2011 Nov 2.
A key aspect of savannah vegetation heterogeneity is mosaics formed by two functional grassland types, bunch grasslands, and grazing lawns. We investigated the role of termites, important ecosystem engineers, in creating high-nutrient patches in the form of grazing lawns. Some of the ways termites can contribute to grazing lawn development is through erosion of soil from aboveground mounds to the surrounding soil surface. This may alter the nutrient status of the surrounding soils. We hypothesize that the importance of this erosion varies with termite genera, depending on feeding strategy and mound type. To test this, we simulated erosion by applying mound soil from three termite genera (, , and ) in both a field experiment and a greenhouse experiment. In the greenhouse experiment, we found soils with the highest macro nutrient levels (formed by ) promoted the quality and biomass of both a lawn () and a bunch () grass species. In the field we found that soils with the highest micro nutrient levels (formed by ) showed the largest increase in cover of grazing lawn species. By linking the different nutrient availability of the mounds to the development of different grassland states, we conclude that the presence of termite mounds influences grassland mosaics, but that the type of mound plays a crucial role in determining the nature of the effects.
稀树草原植被异质性的一个关键方面是由两种功能性草地类型形成的镶嵌体，即丛生草地和放牧草坪。我们研究了白蚁（重要的生态系统工程师）在以放牧草坪形式创造高营养斑块方面的作用。白蚁促进放牧草坪发育的一些方式是通过将土壤从地上蚁丘侵蚀到周围土壤表面。这可能会改变周围土壤的养分状况。我们假设这种侵蚀的重要性因白蚁属而异，这取决于取食策略和蚁丘类型。为了验证这一点，我们在田间试验和温室试验中通过施用来自三个白蚁属（ 、 和 ）的蚁丘土壤来模拟侵蚀。在温室试验中，我们发现宏量养分水平最高的土壤（由 形成）促进了一种草坪（ ）和一种丛生（ ）草种的质量和生物量。在田间，我们发现微量养分水平最高的土壤（由 形成）显示放牧草坪物种的覆盖度增加最大。通过将蚁丘不同的养分可用性与不同草地状态的发育联系起来，我们得出结论，白蚁丘的存在影响草地镶嵌体，但蚁丘类型在决定影响的性质方面起着关键作用。
