Litter functional trait diversity impacts decomposition dynamics: A riparian agroecosystem study

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Serra-Willow Buchanan and Marney E. Isaac, Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON, Canada, Marie Sauvadet, GECO, Univ Montpellier, Montpellier, France, Marie Sauvadet, CIRAD, UPR GECO, Martinique, France

Background/Question/Methods
Rehabilitation of agricultural landscapes with riparian systems is a transformative practice that achieves several ecosystem services, including carbon (C) storage. Yet, there is very little information on this plant community and its role in soil C storage in these critical transition zones. Plant litter plays a crucial role in soil C dynamics, via fresh C inputs and potential soil C loss through priming effects. However, the role of morphological litter traits and broad litter functional diversity in these C fluxes is not well known. In this study, we assessed C dynamics of riparian plant litter using CO2 flux and δ13C signatures. Drawing on a network of established riparian buffers within southern Ontario, Canada, we collected litter from plant communities which have significantly different community weighted functional leaf trait syndromes: a rehabilitated deciduous buffer (RDB), a mature coniferous buffer (MCB) and a grassland buffer (GRB). We employed a 95-day incubation experiment, comparing the C dynamic of soil with GRB, RDB or MCB litter mixtures and soil with no litter (control). We assessed two treatments of litter diversity: the original diversified litter mixture, a composition determined with field measurements, and single species, representing the dominant species of each plant community.
Results/Conclusions
We found significantly different rates of total C-CO2 between riparian type, where total C-CO2 emissions were highest for the GRB treatment after 95 days (354.7 ± 13.3 mg C-CO2 kg-1 soil), followed by RDB (266.1 ± 12.0 mg C-CO2 kg-1 soil) and MCB (208.9 ± 18.7 mg C-CO2 kg-1 soil). Litter diversity had a significant positive impact among all riparian types, with higher total C-CO2 emissions within litter mixtures as compared to single species treatments. The impacts of litter functional trait syndromes and litter functional diversity on priming effects will also be discussed.