Effects of diversionary feeding on abundance of microbes involved in soil nitrogen cycling on a Mediterranean mountain

Abstract

Soil microorganisms maintain soil functions, playing a key role in nutrient cycling. However, human activities may alter ecological processes through, for instance, wildlife management tools, which affect environment conditions. Some management tools, such as diversionary feeding, are a source of organic matter and promote high animal densities in small areas, which could affect soil properties and nutrient cycling. This study evaluated how diversionary food inputs that aim to manage an exotic wild ungulate (Ammotragus lervia) can affect the soil potential for microbial N cycling on a Mediterranean mountain in SE Spain. We quantified the functional genes involved in N cycling present in soil exposed to diversionary feeding and compared soil characteristics from three areas: feeding station soil, contour area soil (surrounding the feeding station) and a reference soil (not influenced by supplementary feeding). Our results showed that the amount of the amoA-arch gene (from ammonia-oxidising archaea), the nifH gene (associated with N-fixation), the nirK gene (associated with denitrification) and the ureC gene (associated with ureolysis) were smaller in the feeding stations than in other areas. However, the nirS and nosZ genes (associated with denitrification) were more abundant in soil from feeding stations than in the reference soil. Our results suggest that diversionary feeding modifies microbial abundance and alters nitrogen cycle dynamics because of nutrient inputs and biochemical changes in soil.