Data from: Interactions between C:N:P stoichiometry and soil macrofauna control dung decomposition of savanna herbivores

1. Although dung of mammalian herbivores is an important pathway for nutrient return in savanna ecosystems, differences in dung decomposition rates among species have been little studied. 2. We measured rates of dung deposition and decomposition for various herbivores in a moist Tanzanian savanna, and related differences among species to nutrient concentrations and the activities of soil macrofauna (e.g., different mesh sizes of decomposition bags, or presence and absence of dung beetles). 3. Dung C:N:P stoichiometry varied widely among species, which could in part be explained by differences in feeding strategy (browsers vs. grazers) and digestive physiology (ruminants vs. non-ruminants). Rates of both decomposition and nutrient release were influenced by the C:N:P stoichiometry of dung, with lower relative losses of the least abundant nutrient. Surprisingly, soil macrofauna increased relative losses of the least abundant nutrient, thereby stabilizing the ratio of N loss to P loss. Dung beetles increased rates of N and P release from wildebeest dung significantly and also increased N availability in the soil. 4. We conclude that rates of nutrient return in dung depend not only on where herbivores deposit their dung, but also on its C:N:P stoichiometry, the activity of soil macrofauna, and interactions between these factors. These factors may therefore influence the relative availabilities of N and P in the soil and hence the functioning of savanna ecosystems.1. 尽管哺乳类草食动物粪便乃是稀树草原（savanna）生态系统中养分归还的重要途径，但不同物种间粪便分解速率的差异却鲜有研究。 2. 本研究在一处湿润的坦桑尼亚稀树草原中，测定了多种草食动物的粪便沉积与分解速率，并将物种间的速率差异与养分浓度及土壤大型动物群（soil macrofauna）的活动相关联——例如采用不同孔径的分解袋，或是设置蜣螂存在与缺失的对照组。 3. 不同物种的粪便碳-氮-磷（C:N:P）化学计量比差异显著，这在一定程度上可由其取食策略（食叶动物与食草动物之分）以及消化生理特征（反刍动物与非反刍动物之分）解释。粪便分解与养分释放速率均受其C:N:P化学计量比的调控，含量最低的养分其相对流失量更低。值得注意的是，土壤大型动物群会提升含量最低养分的相对流失量，进而稳定氮（N）流失与磷（P）流失的比值。蜣螂可显著提升角马粪便的氮、磷释放速率，同时提升土壤中的氮有效性。 4. 本研究得出结论：粪便介导的养分归还速率不仅取决于草食动物的粪便沉积位置，还与其粪便的C:N:P化学计量比、土壤大型动物群的活动以及这些因素间的交互作用密切相关。因此，上述因素可通过调控土壤中氮、磷的相对有效性，进而影响稀树草原生态系统的功能运转。