Jornada Basin LTER

desertification; grazing effects on ecosystem structure and function; factors affecting primary production; connectivity between wind, water, and animals; cross-scale interactions; groundwater recharge; triggers of ecosystem change; desert biodiversity; innovative approaches to k-12 education

The goal of the Jornada Basin LTER (JRN) is to understand and quantify the key factors and processes controlling ecosystem dynamics in Chihuahuan Desert landscapes, which exemplify the ecological conditions and management challenges in arid and semi-arid regions around the world. Many arid and semiarid ecosystems (“drylands”) of the world have experienced dramatic changes in vegetation structure and ecosystem function over the past several centuries in part due to extensive grazing and changes in climate. These changes, typically referred to as “desertification”, result in broad-scale conversion of perennial grasslands to landscapes dominated by unpalatable, xerophytic shrubs, and are often accompanied by soil erosion and loss of biological resources, including aboveground production and biodiversity (Barger et al. 2011, Archer et al. 2017).

However, dryland researchers are now challenging paradigms that the shift from grassland to shrubland in landscapes such as the Chihuahuan Desert are inevitable and irreversible. JRN LTER researchers are leading these efforts by demonstrating that triggers such as grazing or precipitation interact with wind, water and other resources across a geomorphic template to affect vegetation dynamics at multiple spatial scales. Complex feedbacks, the legacy of past disturbance, and a changing climate also drive vegetation dynamics. In addition to traditional desertification (grassland to shrubland), multiple alternative states can occur, including shifts from desertified shrublands back towards native grasslands, from one shrubland type to another, and from grasslands or shrublands to novel ecosystems dominated by non-native annual or perennial grasses (Allington and Valone 2010, Archer 2010, Wilcox et al. 2010, Peters et al. 2012).

Because drylands occupy >40% of the Earth’s land surface, and many dryland regions rely on grasslands for grazing of livestock, the ability to understand and predict these state changes has important long-term consequences for the provisioning of goods and services to the > 1 billion people who are directly linked to these landscapes (Reynolds and Stafford Smith 2002, Boone et al. 2018). The JRN continues to develop a comprehensive framework for dryland landscapes using multiple approaches including extensive short and long-term datasets, multi-scale pattern analyses, simulations, and experimental manipulations. Diverse temporal datasets (from long-term observations, sensor data, data from investigator-led studies) are combined with spatial data layers to improve our understanding, and to develop predictions for other locations. In the near future, online tools will allow for mapping and visualization of Jornada datasets by scientists and the public.

Field research at the Jornada LTER is conducted in various habitat types found within New Mexico State University's Chihuahuan Desert Rangeland Research Center (25,900 ha) and the adjacent lands of the USDA Jornada Experimental Range (78,266 ha). These lands, which form the Jornada del Muerto Basin in southern New Mexico, are found at the northern end of the Chihuahuan desert, which extends from southcentral New Mexico,USA to the state of Zacatec as, Mexico, comprising 36% of North American Desert land (MacMahon and Wagner 1985). The Jornada LTER focuses on five habitat types: black grama grassland (Bouteloua eriopoda), creosotebush shrubland (Larrea tridentata), mesquite duneland (Prosopis glandulosa), tarbush shrubland (Flourensia cernua) and playa.The playas, dominated by a variety of grasses, are found in low- lying, periodically flooded areas that receive drainage waters from the various upslope communities.

The climate of the northern Chihuahuan desert is characterized by high amounts of solar radiation, wide diurnal ranges of temperature, low relative humidity, extremely variable precipitation, and high potential rates of evaporation. The average maximum temperature of 36 °C (97 °F) is usually recorded in June; during January the average maximum temperature is 13 °C (55 °F). Precipitation averages 23 cm (9 inches) annually, with 52% typically occurring in brief, local, but intense, convective thundershowers during July to September.

Our research group includes faculty from both local (New Mexico State University-NMSU) and national-distributed universities (Arizona State University, University of Illinois, University of Texas El Paso (UTEP), University of California at Las Angeles (UCLA), as well as scientists from two agencies within USDA (ARS, NRCS). Each investigator has a clear role in the overall project, and participates in specific studies depending on his/her interest and the expertise needed for a question. Training opportunities are provided for a large number of graduate and undergraduate students, including year-long and summer internships, and REU and graduate fellowships. We also support a highly successful K-12 and teacher-training program, with more than 90,000 students, teachers, and other adults involved during our last funding cycle. The majority of participants are from underserved populations in southern New Mexico and west Texas. Interactions with resource management agencies occur via workshops, seminars, and events. Our annual research symposium is attended by > 100 scientists, educators, and land managers.

The profession of range science in the United States has its roots in the closing decades of the nineteenth century, when widespread overgrazing and severe droughts resulted in acute episodes of livestock mortality, accelerated soil erosion, and a deviant loss of native forage plants across much of the western United States. The crisis was worst in the Southwest—western Texas, New Mexico, and Arizona—and beginning in the 1890s the US Department of Agriculture sent a handful of special agents to the region to assess the damages, study the causes, and identify potential remedies. Among the institutional outcomes of these early assessments and reports were large experimental ranges, beginning with the Santa Rita Experimental Range south of Tucson, Arizona, in 1903, and followed in 1912 by the Great Basin Experimental Range in Utah and the Jornada Experimental Range (The Jornada) in south-central New Mexico.

The Jornada Experimental Range has served as a field research laboratory since its establishment in 1912. The creation of the International Biological Program (IBP) provided the impetus for an ecosystem framework for research. The Jornada Basin was the location for the desert-grassland site within IBP. As the IBP dissolved in the late 1970s, the Long-term Ecological Research (LTER) program emerged in the 1980s as its successor. The LTER, in its second decade, had five core research efforts: (1) pattern and control of primary production; (2) spatial and temporal distribution of populations selected to represent trophic structure; (3) pattern and control of organic matter accumulation in surface layers and sediments; (4) pattern of inorganic inputs and movements of nutrients through soils, groundwater, and surface waters; and (5) pattern and frequency of disturbances. Research in these core areas provided a basis for modeling at the JRN over the years.

The varied scientific activities on the range throughout this century have led to important discoveries about desert ecosystems that have been the basis for principles of land management that have application around the globe. This region is probably the most extensively studied desert on earth, and research activities both on-site and around the globe, continue to flourish in the 21st century. From microscopic-scale studies of soil microorganisms to synoptic-scale assessments of vegetation patterns detected from satellite-based sensors, the Jornada research group is addressing a multitude of research needs relevant to natural resource management issues.

Although the overall goal of the Jornada Basin LTER (JRN) is to identify key factors controlling ecosystem dynamics and biotic patterns in Chihuahuan Desert landscapes, the impetus for the work has certainly been influenced by the historical changes that have occurred in this region, and the uncertainty in the causes of those changes. In the beginning of the LTER (1982-1989), historic livestock grazing and periodic drought were thought to be the main drivers of vegetation change from grassland to shrubland. However, based on decades of research at the Jornada, the paradigm has evolved to recognize that the underlying geomorphic template, the legacy of past disturbance, and a changing climate all interact to drive vegetation dynamics. In addition to traditional desertification (grassland to shrubland), multiple alternative states can occur, including shifts from desertified shrublands back towards native grasslands, from one shrubland type to another, and from grasslands or shrublands to novel ecosystems dominated by non-native annual or perennial grasses (Allington and Valone 2010, Archer 2010, Wilcox et al. 2010, Peters et al. 2012). The current focus of the JRN is on developing a better framework for understanding the triggers of these changes, in order to inform management of drylands worldwide.