Jornada Trails

Contents:

• Laura Huenneke of NMSU Will Head Jornada Basin LTER Renewal
  
• Talks on Remote Sensing, Long-Term Vegetation Studies Highlight the Annual Jornada Symposium
  
• Book Review: Encyclopedia of Deserts
  
• Wainwright Awarded Medal by BGRG
  
• Featured Investigator: Jeff Herrick
  

After ten years at the helm of the Jornada Basin LTER, William Schlesinger of Duke University will step down, and the renewal proposal will be prepared under the leadership of Laura Huenneke of New Mexico State University’s biology department. Laura has a long association with our LTER site, having joined the investigative team in 1988. She has been responsible for all studies of plant production since that time, and recently she initiated a major experiment in which plant biodiversity has been reduced to study consequent changes in ecosystem function.

While the Jornada Basin investigators are still refining the theme for the renewal proposal, it is clear that a major effort will be directed toward understanding linkages, transfers, and connections within the Jornada Basin. According to Schlesinger, "this is a logical next step, following a decade of study of plant and patch processes and soil heterogeneity. We need to understand the fate of the materials that are lost from the barren soils in the shrublands."

One goal of the next proposal will be to understand how the Jornada Basin has acted as either a source or a sink of atmospheric dust during the vegetation changes of the past century. Similarly, attention will be given to the movements of water across the landscape. Accumulations of water in local areas control the distribution and production of plant communities, which suffer disruption when the normal hydrologic pathways are blocked or disrupted.

Laura will be joined by Curtis Monger of the NMSU agronomy department, Deb Peters and Kris Havstad of the USDA, and a consortium of outside coinvestigators, including Schlesinger, in the preparation of the renewal proposal. The USDA’s Jeff Herrick will head an effort to translate the results of the Jornada Basin field studies to better management of semiarid lands throughout the southwestern United States.

The Jornada Basin is one of several LTER sites with renewal proposals due in February 2000.

Talks on Remote Sensing, Long-Term Vegetation Studies Highlight the Annual Jornada Symposium

by H. Curtis Monger

New Mexico State University

June 24, 1999 brought more than 100 researchers to the New Mexico State University campus to attend the annual Friends of the Jornada Symposium—a daylong series of presentations to kick off the summer field season.

Bill Schlesinger opened the morning session with a paper on the relationships between vegetation cover, albedo, and radiant temperatures in arid and semiarid lands of the Chihuahuan desert. Using satellite imagery, he showed how lower vegetation cover in Mexico, the result of overgrazing, resulted in increased temperatures and albedo south of the Arizona border.

Greg Okin, a doctoral candidate at the California Institute of Technology, described his studies using advanced remote sensing of semiarid grasslands at the Jornada to detect vegetation types, living versus dead vegetation, gravel-sand-clay content, iron oxidation, and land surface disturbance. High spectral resolution from AVIRIS can be used to recognize different ecosystems in the central Jornada Basin.

Also reporting on remote sensing studies, Al Rango described how the JORNEX project (see Jornada Trails 2:2) has produced detailed topographic maps of the morphology of mesquite dunes, using remote sensing techniques such as scanning laser and video data. His maps of coppice dunefields have a vertical resolution of ten centimeters and a horizon resolution of one meter.

Among other papers, Laura Huenneke described patterns of aboveground plant production in the Jornada from 1989 to 1999. Her data revealed three patterns: that shrublands and grasslands have similar amounts of aboveground biomass and net primary production (NPP), that biomass distribution is more patchy in shrublands than in grasslands, and that grasslands have greater temporal variability in NPP than shrubland.

Walt Whitford spoke on his long-term studies of the establishment of creosotebush in semiarid grasslands. He tracked the survival of creosotebush seedlings planted in control plots, in irrigated plots, and in irrigated plots with nitrogen. Early in the experiment (1984), many seedlings survived in the control and in the irrigated plots with nitrogen, but by 1986 no seedlings survived in either of the irrigated plots, and even the control contained few surviving seedlings. The high mortality rate was attributed to rabbits, other rodents, and damping-off.

Later, Dave Lightfoot spoke on the interactions between rodents, plants and ants. His research, which utilizes various animal exclosures, is conducted at the Sevilleta and Jornada LTER sites and the Mapimi Biosphere Reserve in Mexico. At several sites, more fluff grass is visible inside rodent exclosures because the plants reach greater heights when they are not grazed. This, in turn, gives rise to more seed-harvester ants because the fluff grass provides them with an abundant food source.

The Symposium closed with a presentation by Ed Fredrickson and Kris Havstad, who reviewed the history of livestock grazing in the Jornada basin. They considered the impacts of the Pleistocene megafauna, the Spanish introduction of grazing animals, and populations of grazing animals at the Jornada from the late 1800s to the present. They pointed out the economic difficulties facing ranchers, who must contend with fluctuations in forage biomass while making constant mortgage payments. They described how management practices in the future may include diversifying forage, decreasing forage demand, basing management on ecological principles, and developing economic flexibility.

The symposium closed with the traditional rangeland barbecue, served at the USDA Headquarters ranch that evening.

Book Review

by William H. Schlesinger

Duke University

Edited by Michael A. Mares (University of Oklahoma Press, 1999, $49.95)

This reference book will be of wide interest to both scientists and lay readers who frequent desert ecosystems. It contains more than 700 entries, on topics ranging from desert regions of the world (e.g., the Chihuahuan desert), to geographic places and parks, geomorphic processes and soil types, ecosystem functions (e.g., primary production), and a wide variety of plants and animals.

The coverage is somewhat biased toward North America and vertebrate animals, but topics specific to deserts on other continents and to international conservation efforts are included.

Prepared by 41 scientists from around the world, the entries are easily within the reach of new students and visitors to arid lands, and each entry is nicely cross-referenced to lead the reader to further information. Most entries also end with several references that are recommended for further reading. Some of these are somewhat general and dated, but still useful as additional sources of information.

For scientists, the book will be more useful for its diverse coverage of topics than for its in-depth coverage of current research. Nevertheless, I had great fun flipping through the volume, reading about subjects of my interest in the Chihuahuan (e.g., calcrete) and Mojave (e.g., runoff and stone pavement) deserts.

Wainwright Awarded Medal by BGRG

by Tony Parsons

University of Leicester

Jornada collaborator John Wainwright of King’s College, London, was awarded the Gordon Warwick medal by the British Geomorphological Research Group (BGRG) at its annual meeting in September. This prestigious award is given annually to a young geomorphologist (within 15 years of obtaining a Ph.D.) who has made an outstanding contribution to the discipline.

In his citation, the Chair of the BGRG drew attention to John’s work on hydrology and sediment transport in the semi-arid southwestern United States.

At the Jornada, John works closely with Tony Parsons, Athol Abrahams, and Bill Schlesinger on studies of sediment and nutrient transport during hillslope runoff. We look forward to seeing John at the Jornada next summer sporting his new medal! D

Featured Investigator: Jeff Herrick

With this issue of Jornada Trails, we recognize Dr. Jeff Herrick as our featured Jornada Basin LTER investigator. Jeff arrived at the Jornada in 1994 as a post-doctoral research associate funded by a competitive grant through the USDA’s National Research Initiative.

During his post-doctoral work on soil aggregate stability, Jeff developed interests in other scientific efforts at the Jornada, most notably in the environmental monitoring program conducted in collaboration with Walt Whitford and the Environmental Protection Agency. Jeff has continued that effort over the last few years, leading to the preparation of a manual on rangeland monitoring techniques that will be published by the Natural Resource Conservation Service this fall. Under Jeff’s leadership, the Jornada has conducted workshops to train rangeland managers in the use of these monitoring techniques on public and private lands.

In January 1998, Jeff formally joined the staff of the Agricultural Research Service at the Jornada Experimental Range. As a soil scientist, he quickly developed research collaborations with Deb Peters of the ARS, and Laura Huenneke with New Mexico State University’s department of biology. His primary research interests focus on soil quality on rangelands and understanding soil-vegetation linkages at landscape scales.

Jeff has been instrumental in developing K-12 education programs, including the LTER Schoolyard program, and delivering these programs to students and science teachers in this region. Along with Ed Fredrickson, Paul Hyder and others, Jeff interacted with more than 3,000 students during the 1998–99 academic year. Jeff and his collaborators have been instrumental in developing the Chihuahuan Desert Nature Park, a non-profit organization that administers the science education program for the Jornada Basin LTER with support from NSF, the World Wildlife Fund, and the ARS.

Jeff was named one of the eight outstanding early career scientists in the ARS in 1999.