@article {JRN54846,
	title = {Groundwater recharge in desert playas: current rates and future effects of climate change},
	journal = {Environmental Research Letters},
	volume = {13 014025},
	year = {2018},
	month = {01/2018},
	pages = {10 pp.},
	abstract = {<p class="rtejustify">Our results from playas, which are topographic low areas situated in closed-catchments in drylands, indicated that projected climate change in Southwestern USA would have a net positive impact over runon and groundwater recharge beneath playas. Expected increased precipitation variability can cause up to a 300\% increase in annual groundwater recharge beneath playas. This increase will overshadow the effect of decreased precipitation amount that could cause up to a 50\% decrease in recharge beneath playas. These changes could have a significant impact on groundwater and carbon storage. These results are important given that groundwater resources in Southwestern USA continue to decline due to human consumption outpacing natural recharge of aquifers. Here, we report on groundwater recharge rates ranging from less than 1 mm to greater than 25 mm per year beneath desert playas. Playas located in larger and steeper catchments with finer-textured soils had the highest rates of recharge. Vegetation cover had no effect on recharge beneath playas.We modeled catchment runoff generation and found that the amount of runon a playa receives annually strongly correlated to the rate of groundwater recharge beneath that playa. Runon occurred during precipitation events larger than 20 mm and increased linearly with events above that threshold.</p>
},
	keywords = {climate change, desert playas, groundwater recharge, Jornada LTER, precipitation variability, runoff modeling, watershed ecology},
	doi = {https://doi.org/10.1088/1748-9326/aa9eb6},
	url = {/files/bibliography/18-001.pdf},
	author = {Owen P. McKenna and O. E. Sala}
}
@article {JRN54899,
	title = {Playa-wetlands effects on dryland biogeochemistry: space and time interactions},
	journal = {Journal of Geophysical Research - Biogeosciences},
	year = {2018},
	abstract = {<p class="rtejustify">Playas are ephemerally flooded wetlands found in hydrologically closed dryland catchments. Recent research showed how upland-catchment biophysical characteristics control the amount of organic carbon and nutrients that accumulates in playas from upland grasslands and shrublands. Here we further explored the role of allochthonous and autochthonous processes in fixing carbon and accruing soil nutrients in playas across a desert basin. We assessed whether playas contribute soil nutrient, organic-carbon stocks, and primary productivity rates in amounts disproportionately higher or lower than upland grasslands and shrublands. We found that playas had higher soil carbon and nutrient storage but no difference in mean annual primary production. Playas, on average, had similar primary productivity than upland systems, because they exhibited lower productivity during extremely wet years that offset the larger productivity during average or below average precipitation years. These results suggest that playas contain higher carbon and soil nutrient stocks because of runoff-mediated allochthonous inputs, rather than autochthonous sources, since long-term average productivity was similar to upland ecosystems. We also used the precipitation-aboveground net primary production (ANPP) relationships to accurately measure run-on in playas using differences between playa and upland grassland ANPP. The dependence of playa ANPP on surface-water inputs from upland catchments makes them susceptible to future changes in extreme precipitation events.</p>
},
	keywords = {climate change, desert playas, groundwater recharge, Jornada LTER, organic carbon, precipitation variability, soil nutrients, watershed ecology},
	doi = {10.1029/2017JG004176},
	url = {files/bibliography/JRN54899.pdf},
	author = {Owen P. McKenna and O. E. Sala}
}
