Novel approaches to linking above and belowground networks
Classical food web theory once limited to trophic relationships has evolved to embrace a variety of network interactions such as mutualisms and indirect effects. Ecologists are now tasked with understanding linkages between different network types (trophic and otherwise) and assessing their functional consequences. Linkages between plants above-ground and soils below-ground serve as a useful framework for merging different network types including: trophic, mutualistic, direct and indirect relationships. The challenge of understanding how these essentially connected but very different habitats interact is an ongoing question in terrestrial and community ecology. In my talk, I will provide the conceptual framework for this symposium by introducing the current state of research linking above-ground and below-ground interactions. In so doing, my talk will review the most recent empirical research as well as novel modeling approaches to resolve linkages between the above- and below-ground.
In addition to reviewing the field of above-ground and below-ground interactions, I will present recent results from my own research group. Results from our experiments have been mixed with respect to connections between microbial communities in the soil and above-ground plant communities. Differences in connectivity vary with abiotic factors. In an urban brownfield, we find soil metal contamination drives the distribution of mycorrhizal communities in the soil, but has less of an effect on the distribution of plant taxa. In contrast, across a riparian transect, plant and fungal community compositions are closely linked, but plant and bacterial community compositions are not. Further, this linkage varies between the floodplain of the river and the upland habitat. These patterns are likely affected by network interactions that have yet to be described. To address this knowledge gap, I am working with presenting members of this symposium to develop mathematical approaches, using plant and soil interaction networks as model systems. The framework and experimental results I present will support the need for empirical and modeling efforts that include non-trophic interactions in resolving connections between above- and below-ground systems.