NSF Award
2423861
The growth of desert plants starts with rainfall, and yet the amount, variability and seasonality of rainfall is changing around the globe. As with many other ecosystems, to understand how changes in rainfall will affect drylands in the future requires long-term measurements and experiments. Continued funding for this Long-Term Research in Environmental Biology (LTREB) project will allow the PI to continue four long-term experiments in the Sevilleta National Wildlife Refuge, New Mexico. Taken together, these four experiments assess how changes in rainfall amount, timing and variability will affect plant and soil biodiversity, plant productivity and storage of carbon. To date, long-term data from the first five years of this project show that plant species characteristic of the Chihuahuan Desert are gradually replacing the economically important Great Plains grassland at the study site as the climate gets warmer and dryer. In addition, a widespread native desert shrub, creosotebush, is invading these grassland communities, causing what some refer to as “desertification,” a process that further reduces the economic value of grassland ecosystems. This research addresses both the causes and consequences of these ongoing changes in plant communities that are driven by changes in climate. Because the work takes place in a national wildlife refuge, the research is directly applicable to refuge management decisions and actions. More broadly, grasslands cover >240 million hectares (33% of land area) in the US and they are commercially important for livestock, and provide many ecosystem services, including wildlife habitat, water resources, recreation, and carbon storage. Yet grasslands are increasingly vulnerable to global environmental change, especially changes in climate. This long-term research will continue to shed new light on the roles of air pollution (nitrogen deposition) and changes in the amount and seasonality of rainfall on these important grassland ecosystems. Public outreach and education on biodiversity and ecology will be important aspects of the project. <br/><br/>Water is the most limiting resource in dryland ecosystems, followed by nitrogen availability. Continued funding of this LTREB project will allow the PI and his team to continue four long-term experiments in the Sevilleta National Wildlife Refuge, New Mexico, that together, assess how nitrogen availability coupled with changes in rainfall amount, timing and variability will affect plant and soil biodiversity, biomass production and carbon sequestration. One of these on-going experiments imposed a chronic severe drought in Chihuahuan Desert and Great Plains grassland for seven years after which the researchers have been assessing the ability of these ecosystems to recover once rainfall returns to normal. A second long-term experiment changes rainfall timing (less in summer, more in fall) but not amount in these two grasslands. Together, results from these two experiments thus far suggest that as Chihuahuan Desert grassland increases at the expense of Great Plains grassland, this ecosystem will become more vulnerable in a warmer, dryer climate. A third experiment manipulates nitrogen addition and winter (El Niño) rainfall in the area where Chihuahuan Desert and Great Plains grassland intersect. The fourth experiment alters nitrogen availability along with the size and frequency of summer rain events in Chihuahuan Desert grassland, which is most likely to experience future invasion by creosotebush. Support for these long-term experiments will fill important knowledge gaps regarding the effects of reordering among dominant species on ecosystem processes under multiple global change scenarios. This long-term research is conducted in dryland ecosystems, which cover ~45% of continental land area globally and have measurable impacts on the global C budget. Drylands are changing rapidly in response to droughts, air pollution, and increased rainfall variability. Community reordering may be key to advancing researchers' understanding of how different global change factors will affect dryland ecosystems in the southwestern United States and elsewhere. The PI and his team are committed to making their data publically available through the Environmental Data Initiative. The University of New Mexico is a certified Hispanic Serving Institution, and the lead investigators will continue mentoring minority undergraduate students in STEM careers as part of the project. Public outreach activities will be conducted through the Visitors Center at the headquarters of the Sevilleta National Wildlife Refuge. Undergraduates supported on this project will be mentored as part of a summer undergraduate research experiences program (60% minority student participation).<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
