Faecal nutrient deposition of domestic and wild herbivores in an alpine grassland.

ABSTRACT

The contribution of herbivores to ecosystem nutrient fluxes through dung deposition has the potential to, directly and indirectly, influence ecosystem functioning. This process can be particularly important in nutrient-limited ecosystems such as alpine systems. However, herbivore dung content (carbon, C; nitrogen, N; phosphorus, P; potassium, K) and stoichiometry (C/N) may differ among species due to differences in diet, seasonality, body type, feeding strategy, and/or digestive system with consequences for soil biogeochemistry. Here we explore how species, body size, and seasonality may result in differences in dung stoichiometry for four alpine herbivores (chamois, sheep, horse, and cattle). We found that herbivore dung nutrient content often varies among species as well as with body size, with the dung of small herbivores having larger C, N, and P faecal content. Seasonality also showed marked effects on faecal nutrient content, with a general pattern of decreasing levels of faecal P, N and an increase of C/N as the summer progresses following the loss of nutrient value of the vegetation. Moreover, we showed how herbivores play an important role as natural fertilizers of C, N, and P in our study area, especially cattle. Our study highlights the importance of considering the relative contribution of different herbivores to ecosystem nutrient fluxes in management practices, especially with ongoing changes in wild and domestic herbivore populations in alpine ecosystems.