We know that genetic variation exists within plant populations, but we know little regarding how this genetic variation is important to the ecosystem processes that influence all species. Recent work has shown that plant genotypic variation can influence ecosystem functioning directly through leaf litter decomposition and indirectly through herbivore-mediated ecosystem responses. For instance, in aspen forests, decomposition rates vary widely according to plant genotype. Similarly, the manner in which herbivores alter the quantity and quality of organic inputs to the soil is dependant on the plant genotype upon which they feed. In both direct and indirect pathways, genotypic variation in plant chemistry plays a pivotal role in determining ecosystem responses. Large amounts of intraspecific variation in polyphenolic tannins have significant afterlife effects on leaf litter decomposition and associated detrital communities. Despite the growing body of literature, very little work as been done to elucidate the feedbacks between aboveground plant genotypes and belowground microbial communities. In addition, we are just beginning to explore the spatial extent to which plant genotype can influence belowground processes. We use a combination of manipulative litter transplant studies and large-scale observational studies to better understand the relationship between aboveground plant genotypic variation and belowground nutrient cycling.
Results/Conclusions
We demonstrate two key points. First, microbial communities beneath aspen stands are determined, at least in part, by aboveground aspen genotypes. In addition, a slight homefield advantage exists whereby detrital communities process litter from familiar genotypes faster than they process litter from foreign genotypes. Secondly, across regional scales plant genotypes create genetic mosaics of ecosystem functioning with distinct patches of microbially-mediated nutrient cycling. How these patches respond to global changes may be largely determined by the identity of the aboveground plant genotype.
