NPP Grassland: Jornada, U.S.A., 1970-1972


[PHOTOGRAPH]
Photograph: Jornada during the PROVE experiment, May 1997 (click on the photo to view a series of images from this site).

Data Citation

Cite this data set as follows:

Pieper, R. D. 1998. NPP Grassland: Jornada, U.S.A., 1970-1972. Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.

Description

Productivity of a desert grassland was monitored at the Jornada IBP study site from 1970 to 1972. Dynamics of above-ground plant biomass were monitored at roughly 2-week intervals during the growing season. Data on above ground live biomass, standing dead matter and litter are available, for two replications of a grazed and an "ungrazed" (relatively undisturbed) treatment. Total below-ground biomass was also sampled. Above-ground net primary production (ANPP) was estimated conservatively, by summing peak biomass of individual species, and below-ground net primary production (BNPP) estimated as the sum of positive increments in total root plus crown biomass.

Data were collected as part of a coordinated study over 1-3 years at ten grassland sites of the central and western United States, under the U.S. Grassland Biome Project of the International Biological Program (IBP).

The Jornada study site (32.60 N 106.85 W) is situated in the Basin and Range geomorphic province at the northernmost extent of the Chihuahuan Desert, near the city of Las Cruces, New Mexico, about 60 km north-west of El Paso, Texas. Climate is characterized by sunshine, wide diurnal temperature range, low humidity and extremely variable precipitation. About half the annual rainfall typically occurs in brief, local, but intense, convective thundershowers during July to September. Winter precipitation (derived from the Pacific Ocean) is more variable than summer, but is more effective in wetting the soil profile.

Over the past 100 years, various factors including over-grazing and fire suppression have resulted in large areas of former black grama grassland being replaced by shrubland communities dominated by creosotebush, mesquite and tarbush. This produces a patchy distribution of soil nutrients, with nutrient-rich areas under shrub canopies and soil resources lost from adjacent inter-shrub spaces by wind and water erosion, although there appears to be little change in NPP.

Field research is continuing on a variety of habitat types under the Jornada Long-Term Ecological Research (LTER) project, within the 26,000-hectare New Mexico State University Research Center and the adjacent 78,000-hectare U.S. Department of Agriculture Jornada Experimental Range (where the Jornada IBP Grassland Biome site is actually located).

Contact Information

Contact: Dr. W. K. Lauenroth
Natural Resource Ecology Laboratory
Colorado State University
Fort Collins, Colorado 80523
U.S.A.

Telephone: +1 (970) 491-7581
Fax: +1 (970) 491-1965
E-mail: billl@cnr.colostate.edu

Alternative Contacts: Dr. Rex D. Pieper/ Dr. Laura F. Huenneke
Department of Animal and Range Science/ Department of Biology
New Mexico State University
Las Cruces, New Mexico 88003-8001
U.S.A.

Telephone +1 (505) 646-4435/ 646-3933
Fax: +1 (505) 646-5665 (Huenneke)
E-mail: rpieper@nmsu.edu/ lhuennek@nmsu.edu

Alternative Contact: Dr. Kris M. Havstad, Research Leader
USDA-ARS Jornada Experimental Range
MSC 3JER
P.O. Box 30003, NMSU
Las Cruces, NM 88003-8003
U.S.A.

Telephone +1 (505) 646-4842
Fax: +1 (505) 646-5889
E-mail: khavstad@nmsu.edu

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