Early History of the Jornada Experimental Range
The Jornada Basin is located in the Southwestern United States where dynamic changes in ecosystems have occurred in response to extreme drought and livestock overgrazing. During the late nineteenth century, the native grasslands of the Chihuahuan Desert began a transition toward a woody plant-dominated landscape. These changes in ecosystems are often interpreted as “desertification”, the broad scale conversion of perennial grasslands to dominance by xerophytic woody plants and the associated loss of soils and biological resources, including biodiversity. Large numbers of domestic livestock in combination with extreme, multi-year drought were devastating to native grasses and allowed native, drought adapted, long-living shrubs to dominate large expanses throughout the region by the early 1900s. In response, two research sites were established in southern New Mexico: the US Department of Agriculture’s Jornada Experimental Range in 1912 and New Mexico State University’s College Ranch (currently Chihuahuan Desert Rangeland Research Center) in 1926. In 1982, the Jornada Basin LTER was funded by the National Science Foundation (NSF) to study the causes and consequences of desertification through long-term research. This funding led to a long-term collaboration with the USDA-ARS, NMSU, and scientists at other universities and federal agencies that continues to present day.
History of the Jornada Basin LTER Program
From 1982-2000, research at the Jornada Basin LTER focused on causes and consequences of desertification governed by processes at the plant-interspace scale. From 2000-2012, Jornada LTER researchers studied the role of redistribution of resources and organisms across multiple scales with a focus on patch structure and connectivity, and how pattern-process relationships can explain spatial variation in desertification dynamics. A conceptual framework for the role of cross-scale interactions in transitions from grassland to shrubland states was developed. From 2006-2012, LTER research tested and confirmed elements of this conceptual framework in the context of grassland to shrubland transitions, and was expanded to focus on the recovery of perennial grasses on desertified shrublands. In 2012, LTER research was expanded to examine additional types of transitions occurring in the region, including those: (a) between different types of shrublands, and (b) from grasslands or shrublands towards novel ecosystems involving invasive species. We focused on transitions in the five major ecosystem types in Chihuahuan Desert ecosystems: upland grasslands, playa grasslands, mesquite shrublands on the sand sheet, creosotebush shrublands on the upper bajada, and tarbush shrublands on the lower bajada.
From 2018 to present, we are exploring how landscape-level spatial heterogeneity evolves in response to the effects of disturbance triggers, connectivity-mediated feedbacks, and their interactions with the soil-geomorphic template. We are expanding our landscape linkages framework to contribute to emerging ecological theory on: (a) alternative states and resilience, (b) ecosystem sensitivity to global change, and (c) cross-scale interactions. Our recent observations indicate the need to conceptually and computationally integrate data and knowledge into a Data Science Integrated System (DSIS) of drylands that will allow Jornada results to be translated to other locations in the Chihuahuan Desert and to drylands globally. Our research is resulting in five major products: (1) new understanding of state changes, in particular in drylands, that lead to theory development, testable hypotheses, and new experiments; (2) accessible data, derived data products, and visualization tools applicable at multiple scales; (3) explanatory and predictive relationships among drivers, patterns, and processes that can be used to (4) predict dynamics of alternative states at new locations or future conditions with assessments of their impacts on ecosystem services; and (5) provide training, outreach and information transfer to broader audience locally, nationally and internationally.
By David Greenland and John Anderson.
From: “A Climatic Analysis Of Long-Term Ecological Research Sites”
Field research at the Jornada LTER is conducted in various habitat types found within the USDA Jornada Experimental Range (78,266 ha) and the adjacent lands of New Mexico State University’s Chihuahuan Desert Rangeland Research Center (25,900 ha). These lands, which form the Jornada del Muerto Basin in southern New Mexico, are found at the northern end of the Chihuahuan desert (MAP) . It extends from southcentral New Mexico, USA to the state of Zacatecas, Mexico (MacMahon and Wagner 1985).
Vegetation varies along the north-south axis of the Chihuahuan desert, and the habitat types studied at the Jornada are most representative of the northern Trans-Pecos subdivision of this region. 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, co-dominated by tobosa grass (Pleuraphis mutica), alkali sacaton (Sporobulus airoides), and vine-mesquite grass (Hopia obtusa), 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 is usually recorded in June; minimum temperatures occur in January when the average maximum temperature is l3 C. Precipitation averages 23 cm annually, with 52% typically occurring in brief, local, but intense, convective thundershowers from 1 July to 1 October. Winter precipitation during synoptic weather patterns that derive from the Pacific Ocean is more temporally variable than summer precipitation, but it is more effective in wetting the soil profile because it typically occurs as gentle rain showers.
Despite the fact that there is a summer maximum of precipitation, all of this precipitation is consumed in actual evapotranspiration under high daytime temperatures and low relative humidity. In the summer following convective storms, there can be adequate soil moisture that might last for several days. Runoff is produced during large winter storms and convective events during the North American monsoon, leading to streamflow in channels and ponding of playas in the basin floor.
Climatic Factors Affecting Flora and Fauna
The Jornada lies within the Basin and Range physiographic province, in which parallel north-south mountain ranges are separated by broad valleys filled with alluvial materials. This Basin and Range topography extends westward through Arizona and Nevada to the Mojave Desert of California. Throughout this region, soil development is strongly determined by topographic position, parent material, and climatic fluctuations during the Quaternary (Gile et al. 1981). Pleistocene-age alluvial materials form Aridisols with highly developed calcic/petrocalcic horizons, known as caliche, while Holocene alluvium is often poorly differentiated.
Extremes of moisture conditions affect the flora. The general dryness of the climate causes the xerophytic vegetation to adopt numerous strategies for water conservation. These strategies include deep root systems (Gibbens and Lenz 2001), and waxy, impermeable skin surfaces. The existence of a caliche layer in the soil acts as a barrier to moisture loss, giving rise to long term moisture availability to plants during dry seasons (Conley and Conley, 1984). Water conservation methods by the flora are important in light of the severe droughts that have occurred at the site in the last 100 years (Van Cleve and Martin, 1991). At the other extreme, occasionally a series of convectional storms can leave surface water in the playa. When this happens a number of species, not normally active, can take advantage of the moisture conditions and flourish for a short time. The high diurnal temperature range and the high radiation loads during the day cause many of the fauna to be nocturnal in their feeding habits.
Topographic position, soil development, and human impact interact to determine vegetation dynamics in the northern Chihuahuan desert, where dramatic changes in vegetation have been observed during the last 100 years (Buffington and Herbel 1965). Large areas of former black grama grassland have been replaced by shrubland communities dominated by creosotebush, mesquite and tarbush (Gibbens et al. 2005). This has led to changes in soil resources which have important consequences for ecosystem function, linking the ecosystem processes in deserts to changes in the global environment (Schlesinger et al.1990). Similar changes in vegetation and soils have occurred over large areas of the Chihuahuan desert and in other areas of the world, where semiarid grasslands have been replaced by shrubland vegetation. It is unclear how over-grazing, climatic change, fire suppression, or rising concentrations of atmospheric CO2 have acted solely or in concert to lead to these changes in vegetation. Although the shrubland communities show lower species diversity than the original grasslands, studies at the Jornada LTER show little change in the absolute level of net primary production as a result of these changes in vegetation (Peters et al. 2012).
Buffington, L.C . and C.H. Herbel. 1985. Vegetation changes on a semidesert grassland range from 1858 to 1963. Ecological Monographs 35: 139-164.
Conley, M.R. and W.C. Conley. 1984. New Mexico State University College Ranch and Jornada Experimental Range: A summary of Research, 1900 – 1983. Dept. of Fishery and Wildlife Sciences. New Mexico State University. Las Cruces, NM. 83 pp.
Gibbens, R.P. and J.M. Lenz. 2001. Root systems of some Chihuahuan Desert plants. Journal of arid Environments 49:221-263.
Gibbens, R.P., R.P. McNeely, K.M. Havstad, R.F. Beck, and B. Nolen. 2005. “Vegetation changes in the Jornada Basin from 1858-1998.” Journal of Arid Environments 61: 651-668.
Gile, L.H., J.W. Hawley, and R.B. Grossman. 1981. Soils and geomorphology in the Basin and Range area of southern New Mexico–Guidebook to the Desert Project. Memoir 36, N.M. Bureau of Mines and Mineral Resources, Socorro.
MacMahon, J.A. and F.H. Wagner. 1985. The Mojave, Sonoran and Chihuahuan deserts of North America. pp. 105-202. In M. Evenari et al., (eds.). Hot Deserts and Arid Shrublands. Elsevier Scientific Publishers, Amsterdam.
Peters D.P.C, J. Yao, O.E. Sala, and J.P. Anderson. 2012. Directional climate change and potential reversal of desertification in arid and semiarid ecosystems. Global Change Biology 18:151-163.
Schlesinger, W.H., J.F. Reynolds, C.L. Cunningham, L.F. Huenneke, W.M.Jarrell, R.A. Virginia and W.G. Whitford. 1990. Biological feedbacks in global desertification. Science 247: 1043-1048.
Van Cleve, K. and Martin, S. 1991. Long Term Ecological Research in the United States: A Network of Research Sites. LTER Network, University of Washington, College of Forest Resources, AR-10, Seattle, WA 98195. 178 pp.