I’m a third year PhD student in the Silver lab. My thesis examines the impact of anaerobic conditions and fluctuations in redox potential on greenhouse gas emissions and carbon cycling in tropical forest soils.
My previous research focused on the restoration of temperate and neotropical wetlands, where I evaluated impacts of altered disturbance regimes on plant communities and documented the potential of indigenous management to restore degraded systems. This led to an MS degree at the University of Wisconsin, advised by Joy Zedler in collaboration with Roberto Lindig-Cisneros at UNAM-CIEco in Mexico.
Hall, S.J., Silver W., and R. Amundson. Greenhouse gas fluxes from Atacama Desert soils: A test of biogeochemical potential at the Earth’s arid extreme. Accepted, Biogeochemistry.
Hall, S.J., and J.B. Zedler. 2010. Constraints on sedge meadow self-restoration in urban wetlands. Restoration Ecology: DOI: 10.1111/j.1526-100X.2008.00498.x
Hall, S.J. 2009. Cultural disturbances and local ecological knowledge mediate cattail invasion in Lake Pátzcuaro, México. Human Ecology 37:241-249 Open Access URL: http://www.springerlink.com/content/g304087p6472x520/
Hall, S.J., R. Lindig-Cisneros, and J.B. Zedler. 2008. Does harvesting sustain diversity in central Mexican wetlands? Wetlands 28:776-792.
Hall, S.J. 2009. Invasive species datasheets for Typha x glauca and Typha domingensis. CABI Invasive Species Compendium. Centre for Agricultural Bioscience International, Wallingford, UK.
Smith, S. D., P. R. Izquierdo S., S. J. Hall and D. A. Baum. 2008. Comparative pollination biology of sympatric and allopatric Andean Iochroma (Solanaceae). Annals of the Missouri Botanical Garden 95: 600-617.
I am broadly interested in how human activities are changing how natural
and managed ecosystems function and how ecosystem responses to global
change can feedback to drive or slow future global change. My research is
in terrestrial biogeochemistry and ecosystem ecology with a focus on
determining process rates and drivers of chemical transformations in the
environment. I am particularly interested in the controls on greenhouse
gas emissions, the effects of nitrogen deposition on soil nitrogen
retention and loss, the effects of plant community composition shifts on
soil nitrogen and carbon dynamics, and the coupling of biogeochemical
cycles beyond carbon and nitrogen. An important component of my research
is the development of novel methodological approaches using tracer and
natural abundance stable isotope techniques, in particular to quantify
soil dinitrogen emissions and gross fluxes of greenhouse gases.
My current research projects include: (1) investigating the controls on
iron reduction coupled to anaerobic ammonium oxidation (termed Feammox) in
upland soils, (2) exploring soil redox controls on gross production and
consumption of nitrous oxide and methane in temperate peatlands and
coastal salt marshes in California, and (3) characterizing patterns in
gross fluxes of greenhouse gases during the growing season in agricultural
land (e.g., corn fields).
Yang, WH, Weber, KA, Silver, WL (2012) Nitrogen loss from soil through anaerobic ammonium oxidation coupled to iron reduction. Nature Geoscience, 5, 538-541.
Yang, WH, Silver, WL (2012) Application of the N2/Ar technique to measuring soil-atmosphere N2 fluxes. Rapid Communications in Mass Spectrometry, 26, 1-11.
Yang, WH, Herman, DJ, Liptzin, D, Silver, WL (2012) A new approach for removing iron interference from soil nitrate analysis. Soil Biology and Biochemistry, 46, 123-128.
Yang, W.H., Y.A. Teh., and W.L. Silver. A test of a field-based 15N-nitrous oxide pool dilution technique to measure gross N2O production in soil. Global Change Biology, 17, 3577–3588.
Burgin, A.M, W. H. Yang, W.L. Silver, and S. Hamilton. 2011. Beyond C and N: How the microbial energy economy couples elemental cycles in diverse ecosystems. Frontiers in Ecology and the Environment 9:44-52.
Cusack, D.F., W.W. Chou, W.H. Yang, M.E. Harmon, W.L. Silver, and the LIDET Team. 2008. Controls on long-term root and leaf litter decomposition in netropical forests. Global Change Biology, doi:10.1111/j.1365-2486.2008.01781.x.
Liu, W.H., D.M. Bryant, L.R. Hutyra, S.R. Saleska, E. Hammond Pyle, D.C. Curran, and S.C. Wofsy, 2006. Woody debris contribution to the carbon budgets of selectively-logged and maturing mid-latitude forests. Oecologia 148:108-117.
Sack, L., P. Melcher, W.H. Liu, E. Middleton, T. Pardee, and N.M. Holbrook, 2006. How strong is intra-canopy leaf plasticity in temperate deciduous trees? American Journal of Botany 93:829-839.
I finished my doctoral research in the Silver lab in 2012. I am interested in the interaction between climate change and land management on biogeochemical processes, particularly in the storage of carbon. My dissertation research explored the potential for carbon sequestration in grazed annual grasslands with different management strategies. I use a combination of large-scale experimental field manipulations, laboratory incubations, and modeling to test the impacts of organic matter additions and keylining to ecosystem carbon pools and fluxes. This work is part of the Marin Carbon Project, a regional collaboration of scientists, managers, agricultural extension, and nonprofits who aim to enhance carbon sequestration in rangeland soils.
I graduated from Duke University with a Masters in Environmental Management with a focus in ecosystem management and climate policy. For my Master’s project, I investigated the potential for carbon sequestration in deep soils in at the Duke Free Air CO_2 Enrichment experiment, under the advisement of Dr. Rob Jackson. As an undergraduate, I conducted research on phytoremediation of methyl tertiary-butyl ether, a persistent groundwater pollutant from gasoline, with Dr. Deborah Hokien at Marywood University, where I earned a B.S. in Environmental Science.
I am currently postdoc at Brown University and the Marine Biological Lab, where I am investigating opportunities for reduction of soil greenhouse gas emissions and ecosystem nitrogen retention through sustainable poultry manure management. For more information, visit my website.
Ryals, R., M. Kaiser, M.S. Torn, A.A. Berhe, and W.L. Silver. Impacts of organic matter amendments on carbon and nitrogen dynamics in rangeland soils. In review.
Ryals, R. and W.L. Silver. 2013. Effects of organic matter amendments on net primary productivity and greenhouse gas emissions in annual grasslands. Ecological Applications 23:49-59.
Ackerely, D.D., R. Ryals, W.K. Cornwell, S.R. Loarie, W.L. Silver, and T.E. Dawson (2012) Potential impacts of climate change on biodiversity and ecosystem services in the San Francisco Bay Area. Chapter in Bay Area Climate Change Impacts Report, California Energy Commission. Available online.
Silver, W.L., R. Ryals, and V.E. Eviner (2010) Soil carbon storage in California rangelands. Rangeland Ecology and Management. DOI: 10.2111/REM-D-09-00106.1
Lichter, J., S.A. Billings, S.E. Zegler, D. Gaindh, R. Ryals, A.C. Finzi, R.B. Jackson, E.A. Stemmlerm W.H. Schlesinger (2008) Soil carbon sequestration in a pine forest after 9 years of atmospheric CO2 enrichment. Global Change Biology 14:2910-2922.
Williams, E., N. Greenglass, and R. Ryals (2007) Carbon capture, pipeline and storage: a viable option for North Carolina utilities? The Nicholas Institute for Environmental Policy Solutions and The Center on Global Change at Duke University. Working Paper. March 8, 2007. Available online.