When groundwater is conserved, soil carbon in wetlands recovers up to a point. At severe cutback in groundwater use, returns to wetlands are marginal and uncertain.
Check out our recent paper on restoring wetland carbon sequestration when water is conserved!!!
Climate change and water pollution. What causes them? At a fundamental level, these and other undesirable changes to our environment result from the mobilization of particular chemical elements. Accelerated delivery of carbon to the atmosphere, for instance, is the direct cause of climate change. Nature’s ecosystems do have one powerful way to slow down the mobilization and cycling of many elements, and that is to store them in soil organic matter, which is the partially decayed remains of plants, microorganisms, and organic materials exuded by all life forms.
Wetlands are quite impressive reservoirs for soil organic matter and the chemical elements that it stores. Because wetland soil is flooded for long periods of time, organic matter decomposes slowly, and wetlands thus have the capacity to sequester large quantities of carbon and other elements. Unfortunately, voracious water consumption by humans has lowered water tables and dried out wetlands in many areas, resulting in a loss of soil organic matter, and the release of carbon and other polluting elements to the atmosphere, rivers, and seas.
So what might happen if humans appropriated less water. Could wetland soil carbon recover as well? This is a difficult question to answer because there are many steps—each rife with uncertainty—between conserving water and restoring carbon cycles. In this recent paper, the Lewis Lab used an approach called error propagation to investigate whether one could detect changes in wetland soil carbon storage, amid all the noise and uncertainty, when human reliance on a groundwater aquifer was reduced. It appears that increased amounts of carbon in wetland soils may be detectable in the initial stages of water conservation, but that severe cutbacks in aquifer use to the point of human privation may be marginally less helpful for wetland soils.
Bert in a Juncus needlerush salt marsh near Tampa Bay
Congratulations to lab member Bert Anderson! Bert is a PhD candidate who received this year’s Outstanding Teaching Assistant award for the Department of Integrative Biology. Bert set the bar high for excellence in teaching. He more than just assisted, but helped innovate by creating new material and better learning experiences for our undergraduate students. Bert contributed to course design, and developed a feedback system so that student perspectives on courses could be used in solutions for course improvement. He has improved biology education in our department. Great job!
See our recent paper that links increases in urban water use with impaired ecosystem service provided by rural wetlands located in the water-extraction zone.
Cities use water…lots of water. Urban water demand is one of the most confounding issues of our time, because a city can demand so much water that supplies are stretched thin. “Water wars” erupt, as cities are pitted against each other and against other economic sectors like agriculture and extractive industries in scrambles to get dwindling water resources. The losers in these wars are often out-of-sight natural ecosystems, from which excessive amounts of water are extracted in an effort to satisfy all competitors. In a recent publication by the Lewis Lab, we shine a light on these ecosystems. We document how increases in water demand by a large metropolis (the Tampa Bay region of Florida) diminishes the water balance of rural wetlands, as well as the amount of carbon and nitrogen stored in the soils of those wetlands. Typically, wetland soils hold huge reserves of carbon and nitrogen, and the impairment of this “storage” service results in carbon and nitrogen pollution of air, streams, and bays.
A cypress swamp, one of many wetland types. Resulting from groundwater extraction, this swamp is degraded, as indicated by falling cypress trees and the loss and subsidence of organic soil. (Photo: TF Rochow)
Congratulations to Kirsti Martinez! Kirsti is one of only 260 undergraduate sophomores and juniors in the United States to receive the prestigious Barry M. Goldwater Scholarship for the 2015-2016 academic year. Congratulations are especially in order because this award does not simply recognize merit. Applicants had to write a competitive, rigorous research proposal, as well. Kirsti is a member of the Lewis Lab working on her Honors thesis, which investigates how leaf litter inputs from forest trees affect soil properties in upland and wetland habitats. Additionally, she is a member of Dr. Luanna Prevost’s lab, also in our department, where Kirsti participates in biology education research that investigates how biology and ecology are taught at the undergraduate level. Read the press release.
Prairie pothole wetlands in central North America. Credit: Ducks Unlimited. Taken from the National Science Foundation website.
Wetlands come in all shapes and sizes, and one form is the “geographically isolated wetland,” or GIW. Often, GIWs occur in complexes that reach across broad expanses, such as the prairie potholes shown here, which span the central plains of North America. Vernal pools in California, cypress domes in Florida, and pocosins in the Carolinas also occur as vast numbers of small basins scattered across broad landscapes. Wetlands perform many valuable services, such as filtering sediment and pollutants, and thereby protecting lakes, rivers, and bays situated further downhill. But recently, GIWs have come under attack based on the assumption that because they are “isolated,” they do not provide these valuable services. This attack has been so sweeping that the US Supreme Court recently stripped GIWs of many protections, ruling that they don’t fall within the scope of the Clean Water Act. The Lewis Lab participated in a review article, led by John Marton of Indiana University, emphasizing that GIWs are anything but isolated, as they communicate with their surroundings through the movements of organisms and flows of nutrients and groundwater. Our article discovered that GIWs indeed provide services that should place them within the scope of the Clean Water Act. Read it here.
Kristen Langanke, Jeannie Mounger, and Sandy Voors at the USF Undergraduate Research Colloquium.
Great job to the undergraduate researchers in the Dept of Integrative Biology at USF, who presented their posters yesterday at the USF Undergraduate Research Colloquium! Members of our lab presented three posters with authors including Sandy Voors, Kirsti Martinez, Kristen Langanke, and Jeannie Mounger. Thanks to faculty members Christina Richards and Luanna Prevost, and PhD student Bert Anderson, for mentoring these works!!
Congratulations to Bert Anderson, who just passed the PhD proposal examination, and has advanced to the status of PhD candidate. Bert’s research will examine how biogenic habitat modification alters organic matter dynamics in hypersaline coastal salt pans. Now the real work begins!
Viviana…from MS on to PhD.
Congratulations to Viviana Penuela! She recently defended her Master’s degree research, and has now deposited her approved thesis, thus successfully completing her M.S. degree. Viviana’s research addressed the link between land management policy and soil biogeochemistry. In particular, she examined how soil organic matter and nutrient pools in residential lawns were affected by different lawn system management strategies. These different strategies arise from an interaction between municipal-level policies and the yard-care behaviors of individual home residents. Distinct high-amendment and low-amendment strategy types were evident, and corresponded with the use of reclaimed water. Viviana’s work identified important implications for soil chemistry and microbiology, and contributes to understanding ecological variability in urban systems. Good work Viviana!
How do ecosystems change as they age? It’s a question we address in our most recent article – read it here! We identify how ecosystems might continue accumulating nitrogen even after they stop growing.
Oak forests in Pennsylvania. Young forest stand (about 10 years old) on the left, and older forest stand (over 100 years old) on the right. The older forest has accumulated abundant soil organic matter, and has great potential for capturing nitrogen and holding it in a stable form.
Succession, or the progressive change in ecological systems as they age, has long been an important concept in ecology that helps organize the discipline. For example, ecologists who focus on the cycling of energy and essential nutrients might investigate how these cycles change as an ecosystem ages. Ecologists know that young, growing ecosystems can increase their stockpile of nutrients (such as nitrogen) by storing it in accumulating plant matter. We also know that soils are a huge reservoir for storing nitrogen, and that even old ecosystems can continue to accumulate nitrogen in soil even after the plants have stopped growing. Our research, conducted with Jason Kaye at Penn State and Michael Castellano at Iowa State, suggests a couple mechanisms by which nitrogen can continue to accumulate in the soil of old forests. First, we show that new inputs of nitrogen are captured by soil organic matter much faster than are released, meaning the soil must accumulate nitrogen over time. Second, we found that the potential for this accumulation was greater in older forests because those forests had more soil organic matter. This research helps us understand the link between ecosystem succession and the nutrient economy of ecosystems, and highlights a significant ecosystem service—the capture of nitrogen, which can severely impair air and water quality—of mature ecosystems.
As we move into the second half of the semester, members of the lab are preparing to take important steps forward in their careers as ecologists. PhD student Bert Anderson will be defending his dissertation proposal in efforts to move forward to candidacy status. Likewise, Viviana Penuela will be defending her Master’s thesis that reports her studies of urban soil responses to the use of reclaimed water. Best wishes to them!!!