Jornada Trails

Contents:

• Jornada Site Hosts Wildland Shrub Symposium
  
• Jornada LTER Featured in Discover Magazine
  
• Huenneke Represents Jornada LTER at Recent Scientific Meetings
  
• Undergraduates Get Hands-On Field Experience with Jornada Scientists
  
• Featured Investigator: Peter Herman of New Mexico State University
  
• Welcome to New LTER Investigators at the Jornada Program
  
• Duke Grad Student Awarded ESA Grant
  

Jornada Site Hosts Wildland Shrub Symposium

In late May 1995, the Las Cruces Hilton was the scene of the 9th Wildland Shrub Symposium, sponsored by the Shrub Consortium, New Mexico State University, the USDA Agricultural Research Service, and the Jornada LTER program. More than 150 scientists from the southwestern U.S. gathered to exchange current ideas regarding the management of arid and semiarid ecosystems, especially desert shrublands. The meeting included a mid-week tour of the Jornada Experimental Range, where USDA, NMSU and LTER researchers described current field studies in southern New Mexico and participants enjoyed an evening barbecue under the setting Sun.

Among featured speakers of the symposium, Julio Betancourt of the U.S. Geological Survey (Tucson) showed how climate fluctuations in the Holocene have controlled the frequency of fire in natural ecosystems of the Southwest.

Kris Havstad (Jornada Experimental Range, ARS) described his recent efforts to salvage and preserve historic data sets that describe the distribution of vegetation on quadrats established at the Jornada in the early part of this century. LTER Principal Investigator William Schlesinger (Duke University) showed how changes in arid lands are important feedbacks to climate change--both regionally and globally-- and Herman Mayeux (USDA) discussed some of the potential responses of desert shrubs to rising atmospheric carbon dioxide.

The proceedings of the entire symposium will be published by the U.S. Forest Service as a Technical Report from the Intermountain Station.

Jornada LTER Featured in Discover Article

Research at the Jornada was featured in the February 1995 issue of Discover magazine. In "How To Make a Desert," senior science editor Carl Zimmer summarized the cooperative efforts between the LTER scientists and staff researchers of the USDA Jornada Experimental Range.

Zimmer spent several intensive days with LTER researchers last summer, followed by a photographer on assignment for the magazine.

Discover is a national magazine covering science and technology news for adults without a scientific background. It has a circulation of one million.

As Zimmer's article shows, the basic hypothesis for long-term research at the Jornada is that the ongoing desertification process is accompanied by changes in the spatial distribution of water and soil nutrients--from a uniform distribution in grassland to a patchy distribution in shrublands.

The article quotes Kris Havstad, director of the Jornada Experimental Range, on the historic impacts that humans inflicted on the landscape of New Mexico: "After water was brought to the surface in the 1880s, there were 20,000 head of cattle out here. This place just got hammered." LTER principal investigator William Schlesinger is quoted as believing that cattle helped spur the spatial redistribution of soil resources, leading to the invasion of shrubs.

The Discover article describes how the LTER research at the Jornada is relevant to the current controversy concerning grazing rights and the management of western lands.

A new experiment, established cooperatively with researchers from the Environmental Protection Agency, will subject areas of desert grassland to intense grazing by cattle at different seasons. The goal is to assess the rate of shrub invasion and changes in the distribution of soil resources. Despite droughty conditions at the site, USDA personnel were able to initiate the first grazing treatment in February, and they hope to conduct the summer treatment this month.

Huenneke Represents Jornada LTER at Recent Scientific Meetings

LTER coinvestigator Laura Huenneke has represented the Jornada at a variety of recent meetings held to assess the importance of biodiversity to ecosystem function. Laura's own work at the Jornada indicates no clear relationship between the number of species present in a particular community and levels of ecosystem function, such as net primary productivity (see figure). Thus, Laura shows that the invasion of semiarid grasslands by desert shrubs is accompanied by a loss of species, without a loss of regional net primary production.

Working with Ian Noble (Australian National University), Laura has coauthored recent chapters in the United Nations Environmental Program's (UNEP) assessment of the global importance of biodiversity. With William Schlesinger (Duke University) she has represented the Jornada at meetings of The Americas Interhemispheric Geo-Biosphere Organization (AMIGO) and the InterAmerican Institute (IAI) for Global Change Research--both of which seek to foster cooperative studies between the South America, Latin America and the United States in global change research.

REU Program: Undergraduates Get Hands-On Field Experience with Jornada Scientists

Summer l995 brought a number of undergraduate students to the Jornada Experimental Range as part of the Research Experience For Undergraduates (REU) program of the National Science Foundation.

Kevin Gross (Duke University) and Josh Mooney (Dartmouth College) examined the comparative rates of decomposition of shrub litter as a function of experimental manipulations of soil moisture in rainout shelters.

Scott McCabe (SUNY-Buffalo) is developing a model to predict overland flow on irregular desert hillslopes under different rainfall regimes. He is working in cooperation with Dr. Athol Abrahams in the Department of Geography.

Visiting scientific teams also contributed to the REU program at the Jornada. Working with Jim Winsor of Penn State University (Altoona), Shani Peretz examined the pollination biology of the desert "buffalo" gourds as a function of herbivory and the timing of flowering relative to the onset of summer drought conditions.

Featured Investigator: Peter Herman of New Mexico State University

Each issue of Jornada Trails will highlight the work of an LTER investigator. New Mexico State University Associate Professor of Biology Peter Herman is our first featured investigator.

Recently, Peter's article in Applied and Environmental Microbiology was selected for special mention in the July Newsletter of the American Society of Microbiology. In his paper, Peter shows that the guild of soil microbes is distributed relatively uniformly in desert grassland soils, but very heterogeneously in adjacent shrublands. Peter's paper not only provides basic support for the underlying hypothesis of desertfification at the Jornada, but also illustrates the importance of local-scale heterogeneity that has been ignored by many soil microbiologists.

Expanding his work to new horizons, Peter will spend the 1995-96 academic year at the Swedish University of Agricultural Sciences, where he will examine the spatial distribution of soil microbial activity in pastures that are being invaded by shrubs. He has recently been awarded $40,000 from the National Science Foundation to further his comparative work on soil microbial processes at the Jornada and in Sweden.

Welcome to New LTER Investigators at the Jornada Program

The Jornada LTER welcomes these new investigators, who joined us in 1995:
Athol Abrahams, State University of New York at Buffalo (Studies of hydrologic transport in the Jornada basin)

Dale Gillette, NASA, Research Triangle Park, N.C. (Studies of soil crusts as determinants of wind erosion in the Jornada Basin)

Vince Gutschick, New Mexico State University (Studies of atmos-phere-vegetation interactions)

David Lightfoot, University of New Mexico, Albuquerque (Studies of small mammals as agents of soil heterogeneity in desert environments)

Curtis Monger, New Mexico State University. (Studies of soil development in Quaternary environments of the Jornada basin)

Duke Grad Student Wins ESA Award

Roberto Fernandez, a Duke graduate student working with James Reynolds, has been granted a $1,000 Forrest Shreve Desert Research Award by the Ecological Society of America.

The title of Roberto's proposal was "why has grass cover in the Northern Chihuahuan Desert decreased over the past 150 years? A test of the xero-phytism vs. palatability hypothesis." Roberto began field work at the Jornada in June of this year.

The newsletter Jornada Trails is published twice annually, in March and September. If you would like to contribute story ideas, or for more information on how to receive the printed newsletter, contact Bill Schlesinger.