Dung of domestic grazing animals: characteristics and role for grassland function

Abstract

Three main factors underlie the physico-chemical characteristics of domestic grazing animal dung: the species of animal, the physiological state of the animal and quality of ingested herbage (driven by plant community composition and climatic conditions). Given that animals use only a small proportion of the nutrients they ingest, dung represents significant transfers of organic matter and nutrients to the pasture, promoting spatial heterogeneity in soil nutrients and nutrient cycling via uneven returns. This heterogeneity has cascading effects on both plant and animal diversity at the local scale. Dung degradation and time to disappearance depends on both climatic factors and coprophagous invertebrate activity. These invertebrates play a key role in modifying the properties of both animal dung and soil (aeration, water porosity), which in turn promotes microbial activities. In general, large dung patches have an adverse effect on vegetation immediately below the dung, and lead to local rejection of herbage by grazing animals. In the longer term, dung has a positive effect on surrounding pasture growth which may last up to two years after dung disappearance. Whilst the chemical transformations of dung and effects on flora and fauna are relatively well-described, further work is needed to assess the importance of coprophagous insects for ecosystem services.