Decomposition and nitrogen transformation rates in a temperate grassland vary among co-occurring plant species

Decomposition of organic matter varies depending upon interactions between the composition of the organic matter and the source of the microbial community, with differences in these interactions among vegetation types leading to the Home Field Advantage (HFA) hypothesis whereby decomposition of litters is faster in soils previously conditioned by them. It is possible that HFA operates on smaller scales within plant communities with ecosystem processes responding to subtle changes of plant community dominance. Using field measurements and laboratory incubations, we found a strong plant species effect on nitrogen availability and transformations and the relative importance of autotrophic and heterotrophic processes to nitrification. We found that the origin of the soil microbial community had little influence on litter decomposition when litter quality was high but was important with low-quality litter, most of which was root material. Our results demonstrate that plant species identity has a substantial impact on both litter decomposition and N cycling even within a single vegetation type and on an extremely local scale via both litter chemistry and specificity of the associated soil microbial community. Therefore, changes in botanical composition could alter decomposition and nutrient release altering ecosystem productivity and carbon sequestration potential.