@article{25154e8e6bd948d795840fd7701af368,
title = "Invasive perennial forb effects on gross soil nitrogen cycling and nitrous oxide fluxes depend on phenology",
abstract = "Invasive plants can increase soil nitrogen (N) pools and accelerate soil N cycling rates, but their effect on gross N cycling and nitrous oxide (N2O) emissions has rarely been studied. We hypothesized that perennial pepperweed (Lepidium latifolium) invasion would increase rates of N cycling and gaseous N loss, thereby depleting ecosystem N and causing a negative feedback on invasion. We measured a suite of gross N cycling rates and net N2O fluxes in invaded and uninvaded areas of an annual grassland in the Sacramento-San Joaquin River Delta region of northern California. During the growing season, pepperweed-invaded soils had lower microbial biomass N, gross N mineralization, dissimilatory nitrate reduction to ammonium (DNRA), and denitrification-derived net N2O fluxes (P < 0.02 for all). During pepperweed dormancy, gross N mineralization, DNRA, and denitrification-derived net N2O fluxes were stimulated in pepperweed-invaded plots, presumably by N-rich litter inputs and decreased competition between microbes and plants for N (P < 0.04 for all). Soil organic carbon and total N concentrations, which reflect pepperweed effects integrated over longer time scales, were lower in pepperweed-invaded soils (P < 0.001 and P = 0.04, respectively). Overall, pepperweed invasion had a net negative effect on ecosystem N status, depleting soil total N to potentially cause a negative feedback to invasion in the long term.",
keywords = "Lepidium latifolium, Sacramento-San Joaquin River Delta, annual grassland, denitrification, dissimilatory nitrate reduction to ammonium, gross nitrogen cycling, invasive species, mineralization, nitrification, nitrous oxide, perennial pepperweed, soil nitrogen",
author = "Evan Portier and Silver, {Whendee L.} and Yang, {Wendy H.}",
note = "Funding Information: We appreciate laboratory and field assistance from Maya Almaraz, Steven Hall, Andrew McDowell, Jonathan Treffkorn, Michelle Wong, and Wendy Yang. This research was funded by National Science Foundation grants ATM-0842385 and DEB-0543558, and USDA National Institute of Food and Agriculture, McIntire Stennis grant CA- B-ECO-7673-MS to W. L. Silver. W. L. Silver was also supported by funds from Breakthrough Strategies & Solutions, and the V. Kann Rasmussen, Oak Creek, Jewish Community, Northern Trust, and Trisons Foundations. The Biology Fellows Program, McNair's Scholars Program, and the College of Natural Resources at the University of California, Berkeley supported E. Portier. E. Portier and W. H. Yang designed and conducted the experiments, performed statistical analyses, interpreted the data, and wrote the manuscript; W. L. Silver contributed to study design and manuscript preparation. The data sets from this study are available in the Illinois Data Bank repository at https://doi.org/10.13012/b2idb-1324977_v1 Funding Information: We appreciate laboratory and field assistance from Maya Almaraz, Steven Hall, Andrew McDowell, Jonathan Treffkorn, Michelle Wong, and Wendy Yang. This research was funded by National Science Foundation grants ATM-0842385 and DEB-0543558, and USDA National Institute of Food and Agriculture, McIntire Stennis grant CAB-ECO-7673-MS to W. L. Silver. W. L. Silver was also supported by funds from Break-through Strategies & Solutions, and the V. Kann Rasmussen, Oak Creek, Jewish Community, Northern Trust, and Trisons Foundations. The Biology Fellows Program, McNair{\textquoteright}s Scholars Program, and the College of Natural Resources at the University of California, Berkeley supported E. Portier. E. Portier and W. H. Yang designed and conducted the experiments, performed statistical analyses, interpreted the data, and wrote the manuscript; W. L. Silver contributed to study design and manuscript preparation. The data sets from this study are available in the Illinois Data Bank repository at https://doi.org/10.13012/ b2idb-1324977_v1 Publisher Copyright: {\textcopyright} 2019 by the Ecological Society of America",
year = "2019",
month = jul,
doi = "10.1002/ecy.2716",
language = "English (US)",
volume = "100",
journal = "Ecology",
issn = "0012-9658",
publisher = "Ecological Society of America",
number = "7",
}