Root carbon flow from an invasive plant to belowground foodwebs
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- Bradford, M.A., Strickland, M.S., DeVore, J.L. et al. Plant Soil (2012) 359: 233. doi:10.1007/s11104-012-1210-y
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Soil foodwebs are based on plant production. This production enters belowground foodwebs via numerous pathways, with root pathways likely dominating supply. Indeed, root exudation may fuel 30–50 % of belowground activity with photosynthate fixed only hours earlier. Yet we have limited knowledge of root fluxes of recent-photosynthate from invasive plants to belowground foodwebs.
Using stable isotopes, we quantify the proportion of recent-photosynthate transferred belowground from the invasive grass Microstegium vimineum A. Camus, a widespread invader of forest understory. Given its minimal root biomass (∼8 % of individual mass), we expected exudation to contribute little to belowground foodwebs.
Within 2 days of 13C-labeling, we recover ∼15 % of photosynthate carbon in microbial biomass. Recovery in root and dissolved organic carbon pools is consistently low (<2 %), suggesting these pools operate as ‘pipelines’ for carbon transport to soil microbes. The recovery of the label in wolf spiders – forest floor predators that feed on soil animals – highlights that root inputs of recent photosynthate can propagate rapidly through belowground foodwebs.
Our results suggest that root carbon-exudation, an unexplored process of invasive grass inputs to forest foodwebs, may be an important pathway through which invasive species affect the structure and function of recipient ecosystems.