Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales

Herbivores do not forage uniformly across landscapes, but select for patches of higher nutrition and lower predation risk. Macrotermes mounds contain higher concentrations of soil nutrients and support grasses of higher nutritional value than the surrounding savanna matrix, attracting mammalian grazers that preferentially forage on termite mound vegetation. However, little is known about the spatial extent of such termite influence on grazing patterns and how it might differ in time and space. We measured grazing intensity in three African savanna types differing in rainfall and foliar nutrients and predicted that the functional importance of mounds for grazing herbivores would increase as the difference in foliar nutrient levels between mound and savanna matrix grasses increases and the mounds become more attractive. We expected this to occur in nutrient-poor areas and during the dry season when savanna matrix grass nutrient levels are lower. Tuft use and grass N and P content were mea...

食草动物并非在整个景观中均匀觅食，而是会选择营养更丰富、捕食风险更低的斑块。大白蚁丘（Macrotermes mounds）的土壤养分浓度更高，支撑的草类营养价值也高于周围的稀树草原基质，因此吸引哺乳动物食草动物优先取食蚁丘上的植被。然而，关于白蚁对觅食模式影响的空间范围，以及这种影响在时空上的差异，目前仍知之甚少。我们在三种降雨和叶片养分含量不同的非洲稀树草原类型中测量了觅食强度，并预测：随着蚁丘与稀树草原基质草类之间叶片养分水平的差异增大、蚁丘吸引力增强，蚁丘对觅食食草动物的功能重要性将随之提升。我们推测这一现象会发生在养分贫瘠区域以及旱季（此时稀树草原基质草类的养分水平较低）。此外，我们还测量了草丛利用率以及草类的氮（N）和磷（P）含量……