I am broadly interested in the patterns and mechanisms of biogeochemical cycling among ecosystems, how this drives ecosystem structure and function, and how disturbances interact with both to influence ecosystem services. As an ecosystem ecologist, my research integrates spatiotemporal scales of biogeochemical cycling and organic matter processing, focusing on the interface (ecotone) between ecosystems where community transitions and exchanges of materials occur. I use theory, empiricism, and modeling to test general questions in ecology.
Over the past 10 years, my lab has worked to understand spatiotemporal patterns of biogeochemistry, organic matter processing, and disturbances among ecosystems by (i) integrating experimental manipulations that have revealed mechanisms of carbon and nutrient cycles, (ii) using long-term, large-scale data and time-series analyses, (iii) integrating functional traits and climate and hydrologic data, and (iv) expanding disturbance and ecosystem development theories. My research to date, collaboratively funded by state (Florida and Texas Sea Grants) and federal agencies (National Oceanic and Atmospheric Administration, National Science Foundation, National Park Service), has contributed to our understanding of how (i) changes in water chemistry drive ecosystem carbon storage, (ii) changes in climate and hydrology influence spatiotemporal patterns in ecology, and (iii) disturbances influence long-term patterns in ecosystems.
Changes in water chemistry drive ecosystem carbon storage: We conducted long-term nutrient enrichment studies in forest streams, discovering that added nitrogen (N) and phosphorus (P) reduces terrestrial carbon residence time (Rosemond et al. 2015 Science), enhances microbial respiration (Kominoski et al. 2015 Ecological Applications) and litter breakdown (Manning et al. 2015 Ecology, Manning et al. 2016 Ecological Applications), and elevates whole-stream respiration (Kominoski et al. 2018 Limnology and Oceanography). Our meta-analysis of 184 published studies (885 experiments, 3497 biotic responses) found that experimentally increased N or P concentrations in streams and rivers causes widespread increases in organismal biomass and abundance and rates of ecosystem processes across multiple trophic levels (Ardón et al. 2021 Biological Reviews). Using national datasets of dissolved and particulate N and P, we found that most U.S. streams and rivers have nutrient concentrations exceeding those considered protective of ecological integrity, retain dissolved N less efficiently than P, which is retained proportionally more in particles, and thus transport and export high N:P streamwater to downstream ecosystems on a continental scale (Manning et al. 2020 Ecological Applications).
My lab has conducted multiple long-term field and mesocosm experiments, and short-term laboratory experiments manipulating the concentrations of salinity and phosphorus contained in seawater to assess autotrophic and heterotrophic subsidy-stress responses and net effects on ecosystem carbon storage. This research discovered critical salinity concentration and exposure thresholds that induce soil elevation and carbon losses caused by decreased root biomass (Wilson et al. 2018 Ecological Applications, Charles et al. 2019 Estuaries and Coasts, Servais et al. 2018 Geoderma, Servais et al. 2019 Estuaries and Coasts). Salinity legacies persist for years causing reduced net ecosystem carbon storage in freshwater marshes despite restoration of fresh water for more than a year (Lee et al. 2021 Restoration Ecology).
Changes in climate and hydrology influence spatiotemporal patterns in ecology: Our global synthesis of leaf litter breakdown rates in streams and rivers, from n = 169 published studies, spanning absolute latitudes of 0° – 60°, quantified the temperature dependence of leaf litter breakdown and examine how macroinvertebrate density and leaf quality affect it. Breakdown rates may increase by 11-16% with a 2-3°C average global increase in water temperature, but the balance of microbial and metazoan contributions to leaf litter processing is unlikely to change (Follstad Shah et al. 2017 Global Change Biology). Through a NSF Urban SRN grant, we assessed the relative vulnerability of urban systems that span gradients in climate, green and grey infrastructure, and extreme event risks (McPhillips et al. 2018 Earth’s Future). We found that in coastal urban waterways, rainfall and tidal flooding interact with seasonal groundwater levels to influence dissolved organic matter sources and contaminates (Smith et al. 2021 Journal of Geophysical Research-Biogeosciences).
Through a NSF Water Sustainability & Climate grant, we developed an interdisciplinary framework incorporating societal feedbacks and adaptations for freshwater sustainability under near-term change and human population growth (Arumugam et al. 2017 Earth’s Future). We also used long-term (65 years) of streamflow data from streams and rivers of the American Southeast and Southwest coupled with native fish species traits to quantify resilience (adaptability to flow variation) and vulnerability (extinction) to climate and human changes in hydrology (Kominoski et al. 2018 Global Change Biology). Our synthesis of N = 4138 ecosystem time series from n = 26 tropical storms in the Northern Hemisphere compared various responses across multiple ecosystem types to reveal a pattern of trade-offs between resistance and resilience to wind speeds and rainfall levels, suggesting that evolutionary adapations govern ecosystem vulnerability to tropical cyclones (Patrick et al. 2022 Science Advances).
Disturbances influence long-term patterns in ecosystems: We synthesized findings from the US LTER Network to advance disturbance ecology theory (Gaiser et al. 2020 BioScience, Gaiser et al. 2022 Ecosphere) and ecosystem development theory (Kominoski et al. 2018 BioScience). We developed the first study to experimentally manipulate and test rapid and ongoing mangrove encroachment into salt marshes, using measurements across large spatial (ten 24 ´ 42 m plots) and temporal scales (> 10 years and ongoing). We identified thresholds and non-linearities in microclimates and ecosystem responses (Guo et al. 2017 Ecology, Charles et al. 2020 Ecology), as well as compared how a major hurricane altered plant identity effects on soil physical and chemical properties (Kuhn et al. 2021 Ecosphere, Pennings et al. 2021 Ecology, Deng et al. 2022 Ecology, Kominoski et al. 2022 Ecosphere).
Direction of Future Research: My lab will continue to address theoretically driven ecological questions that test how long-term changes in hydroclimate drivers affect organic matter dynamics and nutrient cycling. I am co-leading an effort to train others in time-series analyses to quantify and compare pulse drivers and responses among ecosystems of the US LTER Network. I currently co-lead three synthesis working groups (NSF RCN, NSF DISES, and US OCB) that study carbon loss and disturbances.
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