Louchouarn, Patrick: Texas A&M University, Galveston (Project Lead)
Project Funding:
2011 - 2014
NRA: 2010 NASA: Carbon Cycle Science
Funded by NASA
Abstract:
Our proposed study will examine the relationship between land use change, wetland vegetation shift/loss, and carbon (C) sequestration on the coast of the Gulf of Mexico (GOM). By combining field calibration with analysis of remote sensing imagery to detect land cover change, we aim to better understand the amount of carbon sequestration capacity lost from the alteration of naturally occurring estuarine wetlands over the last decade.
Carbon sequestration is an important ecosystem function in all vegetated habitats, and increasing evidence suggests that tidal wetlands may play a particularly key role in regional to global C budgets. Although tidal wetlands store ~10% of worldwide soil C pools (Schlesinger, 1995; Chmura et al., 2003), we know very little about the mechanisms that control this storage process. In the conterminous U.S., and over the next 20 years, the total burial flux of C in tidal wetlands (4.0-4.4 Tg/yr; Chmura et al., 2003; Brigham et al., 2006) could represent from as little as ~3-18% to as high as ~75-80% of the potential soil C sink estimated over the same period in agricultural soils (0.5-1.1 to 2.8 Pg; Cole, 1996; IPCC, 2001; Van Oost et al., 2007), despite comprising <0.5% of their surface area. Furthermore, estimates of C accumulation rates (fluxes) in wetlands are usually derived from large-scale simplifications (Chmura et al., 2003; Brigham et al., 2006) and thus need further revisions to accurately quantify C sequestration potential in these habitats.Our proposed study will examine the relationship between land use change, wetland vegetation shift/loss, and carbon (C) sequestration on the coast of the Gulf of Mexico (GOM). By combining field calibration with analysis of remote sensing imagery to detect land cover change, we aim to better understand the amount of carbon sequestration capacity lost from the alteration of naturally occurring estuarine wetlands over the last decade.
Carbon sequestration is an important ecosystem function in all vegetated habitats, and increasing evidence suggests that tidal wetlands may play a particularly key role in regional to global C budgets. Although tidal wetlands store ~10% of worldwide soil C pools (Schlesinger, 1995; Chmura et al., 2003), we know very little about the mechanisms that control this storage process. In the conterminous U.S., and over the next 20 years, the total burial flux of C in tidal wetlands (4.0-4.4 Tg/yr; Chmura et al., 2003; Brigham et al., 2006) could represent from as little as ~3-18% to as high as ~75-80% of the potential soil C sink estimated over the same period in agricultural soils (0.5-1.1 to 2.8 Pg; Cole, 1996; IPCC, 2001; Van Oost et al., 2007), despite comprising <0.5% of their surface area. Furthermore, estimates of C accumulation rates (fluxes) in wetlands are usually derived from large-scale simplifications (Chmura et al., 2003; Brigham et al., 2006) and thus need further revisions to accurately quantify C sequestration potential in these habitats.
Because the large-scale C stocks in the surface meter of tidal estuarine wetlands, substantial losses or alterations of these ecosystems could rapidly offset any management of croplands even at its highest efficiency. Despite localized restoration efforts, estuarine wetland loss continues at a rate of at least 5,700 acres/year, with the majority of that loss occurring on the GOM Coast (Dahl, 2006). Furthermore, in some areas, marsh grasses are being displaced by mangrove trees, possibly as a result of changes in local climate patterns. Analysis of remote sensing imagery over time can quantify the magnitude of past changes in wetland type and areal extent, due primarily to population growth and development along the coast, but requires field calibration to assess changes in the ability of these wetland systems to effectively sequester C.
The goal of this proposal is to calibrate NASA satellite imagery to characterize C storage within diverse estuarine wetland ecosystems (tidal marshes, mangroves), as well as the influence that land-use change and climate-induced ecosystem shifts (salt marsh to mangrove succession, wetlands to open water) may have on both the pools and fluxes of C in these systems. Following quantification of C sequestration potential on the Texas coast, we will be able to scale up to estimate C storage potential in tidal estuarine wetlands throughout the entire GOM region.
Our specific research objectives are to:
1) Quantify C sequestration in coastal wetlands with special emphasis on marsh and mangrove plant communities along the Texas coast.
2) Identify and measure the shift in vegetation structure that has occurred in estuarine wetlands over the last decade.
3) Identify and measure the loss of naturally occurring estuarine wetlands over the last decade from land use change along the coast.
4) Measure the amount of carbon sequestration capacity lost due to recent human-induced changes in the landscape.
Our proposed research is an ideal fit for the Carbon Cycle Science investigations within the NASA Earth Science Program because it will improve understanding of the global C cycle and quantify changes aquatic C storage “in response to land use and land cover change, and other human activities and natural events.” By investigating the interactions between land use/land cover change and the C cycle, we seek to develop applications that directly inform resource management, policy development, and decision-making.
More details may be found in the following project profile(s):
