The Lokern Grazing Study Project:
Effects of Livestock Grazing on a Community of
Species at Risk of Extinction in the San Joaquin Valley, California.
Principal Investigators: Dr. David Germano, Dr. Ellen Cypher, Dr. Galen Rathbun, Larry Saslaw, Sam Fitton.
large areas of desert, dominated
by salt bushes (Atriplex spp.).
What used to be relatively bare ground between the salt bushes has become choked with a dense growth of grass and accumulated thatch.
The southern San Joaquin Valley historically included large areas of desert, dominated by salt bush scrub (Atriplex spp.). Agricultural, oil, and urban development have displaced most of this habitat. What remains is being changed by the invasion of numerous species of annual grasses, most notably the genus Bromus, that have been introduced from the Mediterranean area of Europe over the last 200 years. What used to be relatively bare ground between the salt bushes has become choked with a dense growth of grass and accumulated thatch.
Some of the native annual forbs (wildflowers) in the southwestern San Joaquin Valley are disappearing because they can not effectively compete with the exotic grasses. The Kern mallow (Eremalche parryi ssp. kernensis), which is endemic to the region, has been listed by the US Fish and Wildlife Service as endangered.---->>
Blunt-nosed leopard lizard.
Giant kangaroo rat.
Some of the terrestrial vertebrates endemic to the southwestern San Joaquin Valley are also declining, and have been declared threatened or endangered. These include the blunt-nosed leopard lizard (Gambelia sila), giant kangaroo rat (Dipodomys ingens), and San Joaquin antelope squirrel (Ammospermophilus nelsoni). These animals, which rely on rapid locomotion across relatively bare ground to catch food and escape predators, are being adversely affected by the disappearance of open ground as exotic grasses invade the desert.
More information on Endangered Animals at:
http://arnica.csustan.edu/speciesprofiles
Cow grazing in study area.
Aerial photograph of the Lokern
Study Area.We are carrying out an experiment to see if well-managed herds of cattle can be used to reduce the amount of accumulated grass, and thus benefit the declining plants and animals. Our experiment includes four pastures that are about a square mile each where cattle are grazed (treatments - T), and four pastures about 60 acres each, where no grazing occurs (controls - C).
STUDY SITE:
Our experiment
is located on the Lokern Natural Area in western Kern County, California. In
February 1998 we started grazing the pastures. By August, after the cattle
were removed for the year, we had achieved a significant grazing effect on
the treatment pastures (see below). The aerial photograph above shows the control and
treatment plots within the four square-mile pastures. The diagonal straight
lines running through the plots are pipeline roads.
View looking down the fence line.
RADIO - TRACKING STUDIES;
In conjunction
with plot studies, we started gathering home range and habitat use
information on Blunt-nosed leopard lizards and
San Joaquin
antelope squirrels in 2002. Adult lizards are followed from May through
early August, and squirrels are tracked from August through early October.
The San
Joaquin antelope squirrel and Blunt-nosed leopard lizard with transmitters.
Home ranges of
blunt-nosed leopard lizards in sec. 27 and 33 in 2003.
RECENT SUMMARY:
The Lokern Study Area received less precipitation by the end of June 2006 than the previous rainfall year, but the total was near average for the site. Summer vegetation structure and biomass (residual dry matter) were high enough to once again have cattle graze the treatment plots. Plant studies continued with fairly low abundance of Kern mallow and no significant effect of treatment visible. The numbers of animal species studied were generally higher than in 2005 and mostly were more abundant in treatment plots than control plots. Numbers of short-nosed kangaroo rats and giant kangaroo rats were relatively high, but Heermann’s kangaroo rat numbers remained fairly low. McKittrick pocket mice continued their yearly fluctuation in abundance, with 2006 being a year of low numbers. The numbers of San Joaquin antelope squirrel caught were the second highest ever recorded and were much greater on treatment plots than controls. The numbers of sage sparrows, horned larks, and western meadowlarks continued to climb in 2006 and horned larks reached their greatest numbers in treatment plots. All lizards increased in abundance in 2006 compared to 2005, and blunt-nosed leopard lizards were found in greatest abundance on plots since the study started. Leopard lizards were found in all four treatment plots, where they were much more abundant than on control plots. Numbers of grasshoppers were the highest recorded for the study and no differences were seen between treatment and control plots. Ground invertebrates captured in pitfall traps were relatively high, especially in treatment plots, but these numbers were mainly due to high abundances of ants.
COOPERATORS:
The main
supporters and participants in the research include:
Aera Energy
Bureau of Land Management
Bureau of Reclamation
California Cattlemen's Association
California Department of Fish and Game
California State University, Bakersfield
Center for Natural Lands Management
Chevron/Texaco Exploration & Production Company
Endangered Species Recovery Program
Eureka Livestock Company
Great Valley Center
National Fish and Wildlife Foundation
Occidental Oil, Elk Hills
US Fish and Wildlife Service
Western Ecological Research Center, U.S. Geological Survey
- The following
scientists have been responsible for implementing the different aspects of
the Lokern research:
- Dr. Ellen Cypher
- Regional Botanist, San Joaquin Valley-Southern Sierra Region, California Department of Fish and Game, 1234 East Shaw Avenue, Fresno, CA 93710. ecypher@ca.dfg.gov. Vegetation and rare plant studies.
- Mr. Sam Fitton
- Wildlife Biologist, Bureau of Land Management, 20 Hamilton Court, Hollister, CA 95023. sfitton@blm.gov. Bird studies.
- Dr. David Germano
- Professor, Department of Biology, California State University, Bakersfield, CA 93311. dgermano@csub.edu. Lizard, mammal, and invertebrate studies. Report coordination and preparation.
- Dr. Galen Rathbun
- Fellow and Research Associate, California Academy of Sciences (San Francisco), c/o P.O. Box 202, Cambria CA 93428-0202. grathbun@calacademy.org. Mammal and invertebrate studies.
- Mr. Larry Saslaw
- Wildlife
Biologist, Bureau of Land Management, 3801 Pegasus Drive, Bakersfield,
CA 93308. lsaslaw@blm.gov.
Plot and cattle studies.
- PRODUCTS
Germano, D. J, G. B. Rathbun, and L. R. Saslaw. 2001. Managing exotic grasses and conserving declining species. Wildlife Society Bulletin 29:551-559.
Germano, D. J. 2001. Salvadora hexalepis (western patchnose snake). Herpetological Review 32:61.
Andreasen, K., E.A. Cypher, and B.G. Baldwin. 2002. Sympatry between desert mallow, Eremalche exilis, and Kern mallow, E. kernensis (Malvaceae): molecular and morphological perspectives. Madrono 49(1):22-24.
Germano, D. J., and J. Brown. 2003. Gambelia sila (Blunt-nosed leopard lizard) Predation. Herpetological Review 34:143-144.Germano, D. J., P. T. Smith, and S. P. Tabor. 2007. Food habits of the blunt-nosed leopard lizard (Gambelia sila). The Southwestern Naturalist 52:319-324.