Areas of Expertise (4)
Coastal Wetland Sustainability
Global Change Ecology
Dr. Langley is the source to turn to for expertise on how ecosystems respond to, and may play a part in, global and environmental change. The future of ecosystems is extremely complex and uncertain, but Dr. Langley is working to predict changes through novel isotopic and gas exchange techniques that measure carbon and nutrient cycling. He has also done extensive research on the marshes in the Chesapeake Bay and can comment on the sustainability of coastal wetlands.
Northern Arizona University: PhD
Northern Arizona University: MS
North Carolina State University: BA
Select Accomplishments (1)
• Smithsonian Visiting Scientist Fellowship (professional)
- Smithsonian Environmental Research Center
- Ecological Society of America, Society for Wetland Scientists
- Merriam Powell Center for Environmental Research in Flagstaff, AZ
Select Media Appearances (7)
Rapid effects of climate change on plants and their ecosystems
An international team of researchers led by two Villanova University biologists has found that climate change is dramatically altering terrestrial plant communities and their ecosystems at such a rapid pace that having a stable baseline from which to conduct experiments is becoming increasingly difficult.
SEA-LEVEL RISE: Warmer temperatures could help wetlands keep pace
Climate change may be causing many challenges in wetlands, but it could also give them a fighting chance.
As sea levels rise, warmer temperatures could help coastal wetlands build height and expand, according to new
The study, published last week in the Journal of Ecology, found that warmer temperatures doubled mangrove
plants' height and accelerated their expansion.
Mangroves can't handle harsh winter freezes. As climate change makes more areas hospitable for these wetland
plants, they are expected to expand north and south into salt marshes. The woody plants would protect coasts
from storm surges and provide additional carbon storage.
"Mangroves coming in could be a part of that solution in a warmer world," said study author Adam Langley.
New study asks why some American forests are moving West
The Christian Science Monitor online
Climate change has begun to shift weather patterns in the US, likely affecting the envelope in which these trees are able to live. But while it's tempting to blame the shift entirely on climate change, there are other factors at play as well, according to Villanova University biology professor Adam Langley, who was not involved in the study.
"Introduced tree pests, such as the emerald ash borer and hemlock woolly adelgid, are clearly a huge deal in changing forest composition. One could imagine trees population centers moving west as individuals on the eastern front die from diseases, which are commonly introduced at the coast," he tells the Monitor via email.
Invasive Sedge Protects Dunes Better Than Native Grass, Study Finds
Charbonneau collaborated on the study with Louise S. Wootton of Georgian Court University, John P. Wnek of the Marine Academy of Technology and Environmental Science and J. Adam Langley and Michael A. Posner of Villanova University, where Charbonneau earned her master's degree, with this study at the heart of her thesis ...
Penn Doctoral Student Studies Coastal Dune Management and Erosion Prevention
In the second study published in the Journal of Environmental Management, Charbonneau and colleagues Wnek, J. Adam Langley and Ronald Balsamo of Villanova and Gina Lee of Boston University looked at how much structure two plant species provided a dune. They compared a species native to the Mid-Atlantic region, American beachgrass, to an invasive species, Asiatic sand sedge. The researchers found a surprisingly stark difference between the two species ...
Climate Change Policy
WHYY, Radio Times with Marty Moss-Coane radio
Appeared live on hour- long panel on Climate Change,
Don’t Feel Bad About Getting a Christmas Tree
Mother Jones online
Adam Langley remembers starting his high school summer days at 5 a.m. to work on Harry Yates’ Christmas tree farm. In a fertile, North Carolinian corner of southern Appalachia, he and his friends would pack into a decrepit truck and roll up remote mountainsides armed with clippers, shears, and knee guards. At the top, in a plot where Yates specialized in Fraser fir, Langley and his crew spent their formative years pruning trees destined for hundreds of living rooms across the country that winter.
Langley, now an ecologist and professor at Villanova University, has worked over the past four years with his wife and fellow professor Samantha Chapman through a USDA grant to examine how North Carolina Christmas tree farms might mitigate climate change. Their results, taken from 27 sites across nine farms and published in a paper in November, show that certain techniques can allow the tree plots to act like natural sponges for atmospheric carbon. The potential, they say, lies in the dirt.
Research Grants (4)
The influence of mangrove invasion and rising temperatures on belowground processes in coastal ecosystems.
National Science Foundation
Twenty-nine years of tidal marsh response to environmental change
National Science Foundation
Supplement: Twenty-three years of tidal marsh response to environmental change
National Science Foundation
Mangroves Marching Northward
National Aeronautics and Space Administration
Select Academic Articles (5)
Pastore MA, Megonigal JP, Langley JA
Wetlands have an inordinate influence on the global greenhouse gas budget, but how global changes may alter wetland contribution to future greenhouse gas fluxes is poorly understood. We determined the greenhouse gas balance of a tidal marsh exposed to nine years of experimental carbon dioxide (CO2) and nitrogen (N) manipulation. We estimated net carbon (C) gain rates by measuring changes in plant and soil C pools over nine years. In wetland soils that accrete primarily through organic matter inputs, long-term measurements of soil elevation, along with soil C density, provide a robust estimate of net soil C gain. We used net soil C gain along with methane and nitrous oxide fluxes to determine the radiative forcing of the marsh under elevated CO2 and N addition. Nearly all plots exhibited a net gain of C over the study period (up to 203 g C m−2 year−1), and C gain rates were greater with N and CO2 addition. Treatment effects on C gain and methane emissions dominated trends in radiative forcing while nitrous oxide fluxes in all treatments were negligible. Though these soils experience salinities that typically suppress methane emissions, our results suggest that elevated CO2 can stimulate methane emissions, overcoming positive effects of elevated CO2 on C gain, converting brackish marshes that are typically net greenhouse gas sinks into sources. Adding resources, either CO2 or N, will likely increase “blue carbon” accumulation rates in tidal marshes, but importantly, each resource can have distinct influences on the direction of total greenhouse forcing.
Fatichi, S, Leuzinger S, Paschalis A, Langley JA, Barraclough AD
Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation and evapotranspiration (ET), ultimately driving changes in plant growth, hydrology, and the global carbon balance. Direct leaf biochemical effects have been widely investigated, whereas indirect effects, although documented, elude explicit quantification in experiments. Here, we used a mechanistic model to investigate the relative contributions of direct (through carbon assimilation) and indirect (via soil moisture savings due to stomatal closure, and changes in leaf area index) effects of elevated CO2 across a variety of ecosystems. We specifically determined which ecosystems and climatic conditions maximize the indirect effects of elevated CO2. The simulations suggest that the indirect effects of elevated CO2 on net primary productivity are large and variable, ranging from less than 10% to more than 100% of the size of direct effects. For ET, indirect effects were, on average, 65% of the size of direct effects. Indirect effects tended to be considerably larger in water-limited ecosystems. As a consequence, the total CO2 effect had a significant, inverse relationship with the wetness index and was directly related to vapor pressure deficit. These results have major implications for our understanding of the CO2 response of ecosystems and for global projections of CO2 fertilization, because, although direct effects are typically understood and easily reproducible in models, simulations of indirect effects are far more challenging and difficult to constrain. Our findings also provide an explanation for the discrepancies between experiments in the total CO2 effect on net primary productivity.
Invasive plants can influence ecosystem processes such as greenhouse gas (GHG) emissions from wetland systems directly through plant-mediated transfer of GHGs to the atmosphere or through indirect modification of the environment. However, patterns of plant invasion often co-vary with other environmental gradients, so attributing ecosystem effects to invasion can be difficult in observational studies. Here, we assessed the impact of Phragmites australis invasion into native shortgrass communities on methane (CH4) emissions by conducting field measurements of CH4 emissions along transects of invasion by Phragmites in two neighboring brackish marsh sites and compared these findings to those from a field-based mesocosm experiment. We found remarkable differences in CH4 emissions and the influence of Phragmites on CH4 emissions between the two neighboring marsh sites. While Phragmites consistently increased CH4 emissions dramatically by 10.4 ± 3.7 µmol m−2 min−1 (mean ± SE) in our high-porewater CH4 site, increases in CH4 emissions were much smaller (1.4 ± 0.5 µmol m−2 min−1) and rarely significant in our low-porewater CH4 site. While CH4 emissions in Phragmites-invaded zones of both marsh sites increased significantly, the presence of Phragmites did not alter emissions in a complementary mesocosm experiment. Seasonality and changes in temperature and light availability caused contrasting responses of CH4 emissions from Phragmites- versus native zones. Our data suggest that Phragmites-mediated CH4 emissions are particularly profound in soils with innately high rates of CH4 production. We demonstrate that the effects of invasive species on ecosystem processes such as GHG emissions may be predictable qualitatively but highly variable quantitatively. Therefore, generalizations cannot be made with respect to invader-ecosystem processes, as interactions between the invader and local abiotic conditions that vary both spatially and temporally on the order of meters and hours, respectively, can have a stronger impact on GHG emissions than the invader itself.
Coastal wetlands are commonly exposed to hydrocarbon pollutants derived from extraction disasters like the Deepwater Horizon oil spill. Naturally occurring microbes can degrade oil, but the rate of oil degradation depends heavily on the key chemical and biological factors. The goal of this study was to determine the influence of interactions between marsh plants and nitrogen (N) on the degradation of oil from the Deepwater Horizon oil spill. Oil disappearance was measured with gas chromatography (GC) focusing on the change in C18 n-alkane-to-phytane ratio of oil, and instantaneous oil degradation rates were measured using an instantaneous carbon isotopic partitioning method. N addition often stimulates oil decomposition in soil slurries, but the effect of N in our mesocosms depended on plant species. N addition accelerated oil degradation in Spartina alterniflora mesocosms but slowed oil degradation in Spartina patens mesocosms. Across all plant and N treatments, oil degradation related to plant root growth. In many ecosystems including marshes, N addition has been shown to diminish root growth by reducing the need for nutrient foraging. Where N addition reduces root growth, N may ultimately exacerbate oxygen scarcity in marsh soils possibly negating or reversing the positive, direct effects that N has on oil degradation. Based on these findings, fertilization strategies that maximize marsh plant root growth will be the most effective at increasing the microbial degradation of oil and will have the greatest potential to mitigate the impacts of oil in marsh ecosystems.
Langley JA, Megonigal JP
Terrestrial ecosystems gain carbon through photosynthesis and lose it mostly in the form of carbon dioxide (CO2). The extent to which the biosphere can act as a buffer against rising atmospheric CO2 concentration in global climate change projections remains uncertain at the present stage1, 2, 3, 4. Biogeochemical theory predicts that soil nitrogen (N) scarcity may limit natural ecosystem response to elevated CO2 concentration, diminishing the CO2-fertilization effect on terrestrial plant productivity in unmanaged ecosystems3, 4, 5, 6, 7. Recent models have incorporated such carbon–nitrogen interactions and suggest that anthropogenic N sources could help sustain the future CO2-fertilization effect8, 9. However, conclusive demonstration that added N enhances plant productivity in response to CO2-fertilization in natural ecosystems remains elusive. Here we manipulated atmospheric CO2 concentration and soil N availability in a herbaceous brackish wetland where plant community composition is dominated by a C3 sedge and C4 grasses, and is capable of responding rapidly to environmental change10. We found that N addition enhanced the CO2-stimulation of plant productivity in the first year of a multi-year experiment, indicating N-limitation of the CO2 response. But we also found that N addition strongly promotes the encroachment of C4 plant species that respond less strongly to elevated CO2 concentrations. Overall, we found that the observed shift in the plant community composition ultimately suppresses the CO2-stimulation of plant productivity by the third and fourth years. Although extensive research has shown that global change factors such as elevated CO2 concentrations and N pollution affect plant species differently11, 12, 13 and that they may drive plant community changes14, 15, 16, 17, we demonstrate that plant community shifts can act as a feedback effect that alters the whole ecosystem response to elevated CO2 concentrations. Moreover, we suggest that trade-offs between the abilities of plant taxa to respond positively to different perturbations may constrain natural ecosystem response to global change.