COS 216-5 - Agricultural management alters wetland multifunctionality in a subtropical agroecosystem

Abstract: Geographically isolated wetlands (GIWs) are disproportionately important landscape elements that provide diverse ecosystem services. However, in agroecosystems, these wetlands are experiencing direct and indirect impacts from surrounding agricultural management, which may threaten their service supply and long-term sustainability. Prior research has focused on effects of individual agricultural practices on wetlands’ capacity to provide single or a few services. Yet studies that take a systematic and multifunctional approach considering consequences of multiple management practices for a broad suite of organisms and services are scarce. Therefore, we aim to investigate how three management practices interact to affect multiple ecosystem services from GIWs in subtropical agroecosystems. These practices include upland agricultural intensification (i.e., semi-natural – SN vs. intensively managed – IM pastures, which varied in fertilization, drainage, exotic forage grass introduction), cattle grazing, and prescribed fire. We synthesized decade-long datasets (2008-2020) from 40 experimental wetlands at the Archbold Biological Station’s Buck Island Ranch in south-central Florida, including >30 indicators that characterize seven major ecosystem services, and then calculated a multifunctionality index of each wetland. Management effects were analyzed using linear mixed-effects models.



Our results demonstrated that among all three agricultural practices, upland agricultural intensification was the dominant driver to most services. Intensification strongly enhanced forage quality (with higher P content and lower C:P and N:P ratios), but reduced biodiversity (reflected in lower total and native plant richness). Cattle grazing exerted individual effects on a few regulating and supporting services, including improving both water quality and ectothermic vertebrate richness. But more commonly, cattle grazing interacted with prescribed fire to affect wetland carbon sequestration, nutrient retention, and habitat suitability. For example, grazing promoted soil carbon and nutrients storage only in burned wetlands. Fire seldom exhibited significant individual effects on any service, but interacted with grazing and intensification to alter carbon sequestration, water quality, and soil microbial diversity. For instance, fire increased primary productivity and water P in fenced wetlands within IM pastures but exerted negative effects on these indicators in fenced wetlands within SN pastures. Furthermore, a three-way interaction among management practices reflected on wetland overall multifunctionality. Fenced-burned wetlands embedded within SN pastures showed the highest multifunctionality, whereas fenced-burned wetlands within IM pastures had the lowest multifunctionality. Collectively, our results suggested that upland intensification promoted provisioning but reduced supporting services, and interacted with grazing and fire to affect regulating services. Our findings are important to inform regional sustainable management strategies in subtropical agroecosystems.