Research

DUWC Research–Relationships Among Climate Change, Land Use, and Invasive Plants

Phase 3 of the DUWC Stream and Wetland Assessment Management Park (SWAMP) in Duke Forest will be the site for a field-based warming experiment, the first level of experimental study in the EPA-funded project exploring connections among climate change, land use, and invasive species. The water on one side of this uniquely designed treatment floodplain will be heated, and comparisons in the behavior of the two halves will be used to test for hypothesized shifts in species composition, diversity, and ecosystem thresholds. Above, the location of the six downstream wetland cells is indicated by the darker vegetation, while one edge of the settling pond is visible near the photo’s right edge. SWAMP, an ongoing project on the Duke campus, was designed to help improve regional water quality, provide research opportunities, and act as a teaching laboratory.

Photo by Mengchi Ho, DUWC

Duke University Wetland Center researchers Curtis Richardson, Neal Flanagan, and Song Qian have received an EPA STAR Grant of $598,000 in support of a research project entitled "Ecological impacts from the interactions of climate change, land use change and invasive species."

Future climate scenarios for the southeastern U.S. predict that surface water temperatures will rise as air temperature rises. Stream flows will probably decrease, with a greater proportion of annual watershed hydrologic yield coming from major storm events. Land use changes (for example, as forested areas become increasingly urban) have also been shown to raise water temperature and to increase pulsed water releases during storms.

The DUWC project's primary objective is to assess how these predicted changes of hydrologic flux and temperature regimes in floodplain ecosystems would affect the vulnerability of plant communities to the establishment and spread of invasive species. Another goal is to study how these changes will affect ecosystem functions and services. Studies of how an ecosystem responds to such disturbances have important implications for the development of management decisions.

North Carolina flood plain communities face a host of invasive plant species. Prominent among these are the semi-deciduous shrub species Chinese Privet (Ligustrum sinense) and the graminoid species Microstegium vimineum. These plants often form dense monocultures below the forest canopy, which reduces diversity and may suppress the regeneration of native canopy species as well as alter the hydrologic and nutrient cycling functions of floodplain systems.

Specifically, the project will focus on the relationships among native species composition, diversity, productivity, and invasibility of floodplain ecosystems affected by alterations of water temperature and annual hydrographs driven by climate change and land use change (urban, forested and agricultural). Researchers will use a combination of varying scale experimental studies and one novel large scale regional study to verify experimental and threshold modeling results.

There will be four distinct levels of experimental study, three of which will take place at the DUWC Stream and Wetland Assessment Management Park (SWAMP) in Duke Forest.

First, a field-based warming experiment will allow direct evaluation of treatment-effects of temperature and hydrology on species invasions, community composition, and ecosystem services of an experimental (restored) floodplain ecosystem.

Secondly, 99 diversity plots on a floodplain will be used to test how species richness effects species invasions.

The third experimental level will be 102 permanent vegetation plots distributed over 3 hydrogeomorphic zones in the floodplain (stream bank, low terrace, and high terrace). These will be used to assess how species invasions are affected by pulsed waters and flood inundation frequency.

Finally, a novel large-scale regional study of wetlands downstream of both surface-releasing and bottom-releasing dams will be used to assess pulsed water and temperature effects on invasive species. These data will be compared with analogous information from control rivers.

At each experimental level, the researchers will assess how feedbacks from invasive species alter ecosystems services such as flood control, sediment retention, and maintenance of water quality.

Nicholas School of the Environment

DUWC Research–Relationships Among Climate Change, Land Use, and Invasive Plants
		Phase 3 of the DUWC Stream and Wetland Assessment Management Park (SWAMP) in Duke Forest will be the site for a field-based warming experiment, the first level of experimental study in the EPA-funded project exploring connections among climate change, land use, and invasive species. The water on one side of this uniquely designed treatment floodplain will be heated, and comparisons in the behavior of the two halves will be used to test for hypothesized shifts in species composition, diversity, and ecosystem thresholds. Above, the location of the six downstream wetland cells is indicated by the darker vegetation, while one edge of the settling pond is visible near the photo’s right edge. SWAMP, an ongoing project on the Duke campus, was designed to help improve regional water quality, provide research opportunities, and act as a teaching laboratory. Photo by Mengchi Ho, DUWC
Duke University Wetland Center researchers Curtis Richardson, Neal Flanagan, and Song Qian have received an EPA STAR Grant of $598,000 in support of a research project entitled "Ecological impacts from the interactions of climate change, land use change and invasive species." Future climate scenarios for the southeastern U.S. predict that surface water temperatures will rise as air temperature rises. Stream flows will probably decrease, with a greater proportion of annual watershed hydrologic yield coming from major storm events. Land use changes (for example, as forested areas become increasingly urban) have also been shown to raise water temperature and to increase pulsed water releases during storms. The DUWC project's primary objective is to assess how these predicted changes of hydrologic flux and temperature regimes in floodplain ecosystems would affect the vulnerability of plant communities to the establishment and spread of invasive species. Another goal is to study how these changes will affect ecosystem functions and services. Studies of how an ecosystem responds to such disturbances have important implications for the development of management decisions. North Carolina flood plain communities face a host of invasive plant species. Prominent among these are the semi-deciduous shrub species Chinese Privet (Ligustrum sinense) and the graminoid species Microstegium vimineum. These plants often form dense monocultures below the forest canopy, which reduces diversity and may suppress the regeneration of native canopy species as well as alter the hydrologic and nutrient cycling functions of floodplain systems. Specifically, the project will focus on the relationships among native species composition, diversity, productivity, and invasibility of floodplain ecosystems affected by alterations of water temperature and annual hydrographs driven by climate change and land use change (urban, forested and agricultural). Researchers will use a combination of varying scale experimental studies and one novel large scale regional study to verify experimental and threshold modeling results. There will be four distinct levels of experimental study, three of which will take place at the DUWC Stream and Wetland Assessment Management Park (SWAMP) in Duke Forest. First, a field-based warming experiment will allow direct evaluation of treatment-effects of temperature and hydrology on species invasions, community composition, and ecosystem services of an experimental (restored) floodplain ecosystem. Secondly, 99 diversity plots on a floodplain will be used to test how species richness effects species invasions. The third experimental level will be 102 permanent vegetation plots distributed over 3 hydrogeomorphic zones in the floodplain (stream bank, low terrace, and high terrace). These will be used to assess how species invasions are affected by pulsed waters and flood inundation frequency. Finally, a novel large-scale regional study of wetlands downstream of both surface-releasing and bottom-releasing dams will be used to assess pulsed water and temperature effects on invasive species. These data will be compared with analogous information from control rivers. At each experimental level, the researchers will assess how feedbacks from invasive species alter ecosystems services such as flood control, sediment retention, and maintenance of water quality.
	Nicholas School of the Environment