Research

Ongoing Projects

Understanding water relations of Joshua trees  essential to conservation planning

The Joshua tree (Yucca brevifolia) is under threat from climate change. Models predict that Joshua trees will be largely eliminated from Joshua Tree National Park by 2100. As water stress due to changes in temperature and precipitation will be the main cause of mortality for Joshua trees, a better understanding of the water relations of Joshua trees is essential to conservation planning efforts.

Michael Loik using the Portable IRGA on a Joshua tree.

My research seeks to understand the role of water storage in Joshua tree water budgets, the dynamics of precipitation pulse response, and the effects of Joshua tree root systems on soil moisture conditions. To this end, I have installed sap-flow sensors in Joshua trees at Burns Pinon Ridge Reserve to measure the volume of water moving through the trees every 15 minutes. This will give us a fine-scale picture of the water use of these trees. I have also installed soil moisture sensors in the ground below the trees and in an open area nearby to examine any effects of the Joshua tree root system on the soil moisture around the tree. Once a month, I use a portable infrared gas analyzer to quantify the amount of carbon dioxide the trees are taking up and making into sugar and the amount of water they lose to the air in the process. This detailed picture of the water use of these plants should give us new insight into how these plants survive in the difficult Mojave Desert environment.

Portable Infrared Gas Analyzer measurements of Joshua tree photosynthesis.

The Leaf Chamber of the IRGA on a joshua tree.

Joshua tree with sap flow sensor and laptop.

Plant Community Dynamics Across Spatial Gradients of Resource Availability – UC Irvine, Center for Environmental Biology, Sarah Kimball, Megan Lulow, Jordan Rainbow

Within a given area, the diversity and abundance of plant species and their respective functional traits are indicators of change in resource availability at multiple scales. We have established marked transects and quadrats on the Burns Piñon Ridge Reserve to study plant community dynamics over time and across areas expected to vary in solar radiation and soil moisture.

Three point-intercept transects have been established that are each 50 meters in length, with ten associated 1m x 1m quadrats adjacent to the transect line. On each transect the total number and average size of individuals per species is recorded. On two of the three transects, an extra 3 quadrats are located under randomly selected shrubs within 10 m of each transect line. Transects are replicated across flat areas, north-facing slopes, and south-facing slopes.

Vegetation transects among contrasting topographies. Phacelia campanularia and Emmenanthe penduliflora in bloom along piñon pine- juniper transect.

Dr. Jeff Lozier on a collection expedition to the Burns Pinon Reserve with the Essig Museum of Entomology, UC Berkeley, 2005.

Peer-Reviewed Papers

Chandler D.S. and M.S. Caterino. 2011. A taxonomic revision of the New World genus Oropodes Casey (Coleoptera, Staphylinidae, Pselaphinae). ZooKeys 147:425-477. Doi: 10.3897/zookeys.147.2072

Based on collections made in Oregon and California, the authors redescribe 7 beetle species, elevate 1 species from synonymy, and describe 10 new species. A portion of the collecting activities focused on the understudied Transverse Ranges of southern California. The holotype for one of the new taxa, Oropodes serrano Chandler & Caterino, sp. n., was collected at the Burns-Piñon Ridge Reserve.

Hopp, K.J. and M.S. Caterino. 2009. Seven new species of Cephennium Muller & Kunze (Coleoptera, Staphylinidae, Scydmaeninae, Cephenniini) from California with a key to native North American species. ZooKeys 24:31-54. Doi: 10.3897zookeys.24.247

The authors describe and illustrate seven new species of beetles collected from central to southern California. These collections increase the representation of the genus Cephennium in the Nearctic region and extend the genus’ geographic range from the San Francisco Bay region south to the eastern Transverse Ranges of southern California.

SEM image of Cephennium aridum from the Burns Piñon Ridge Reserve. Image provided by Mike Caterino.

Loik, M.E. 2008. The effect of cactus spines on light interception and Photosystem II for three sympatric species of Opuntia from the Mojave Desert. Physiologia Plantarum 134(1): 87-98.

Spines were removed from the stems of three species of cacti to determine the effect of spines on light interception, plant tissue temperature, and pigment content. Spines had no effect on stem temperatures of any species, and they substantially affected photosynthetic activity and pigment composition only in the cactus species with the greatest spine density.

Regus, J.U., C.E. Wendlandt, R.M. Bantay, K.A. Gano-Cohen, N.J. Gleason, A.C. Hollowell, M.R. O’Neill, K.K. Shajin, J.L.Sachs. 2016. Nitrogen deposition decreases the benefits of symbiosis in a native legume. Plant Soil Doi: 10.1007/s11104-016-3114-8.

The study examines effects of increased soil nitrogen concentrations via atmospheric N-deposition on legume-rhizobium symbioses. The researchers measured atmospheric N-deposition rates across a predicted deposition gradient, used isotopic analyses to assess the relative importance of mineral nitrogen and biologically-fixed nitrogen to the legume Acmispon strigosus, and exposed A. strigosus plants from contrasting depositional environments to a controlled nitrogen gradient. They found that (1) plants from higher-deposition environments have higher total nitrogen content, (2) plants in higher-deposition environments incorporate a larger percentage of nitrogen from mineral sources, and (3) the growth benefits of rhizobial nodulation to the plant are reduced under higher-nitrogen conditions.  

Smith-Downey, N.V., J.T. Randerson, and J.M. Eiler. 2008. Molecular hydrogen uptake by soils in forest, desert, and marsh ecosystems in California. Journal of Geophysical Research 11: G0307 (11 pages).

Masters and Doctoral Dissertations

Schakaraschwili, G.V. 1986. Flock Size, Foraging and Vigilance in Gambel’s Quail. Master of Science

Thompson, S.D. 1980. Microhabitat Use, Foraging Behavior, Energetics and Community Structure of Heteromyid Rodents. Doctoral Dissertation, Department of Ecology and Evolutionary Biology, University of California, Irvine.

UCNRS Burns Pinyon Ridge Reserve Brochure

Herring, M. August 1997. Burns Pinyon Ridge Reserve. University of California Natural Reserve System, Oakland, California. 4 pp.

Conference Proceedings and Technical Reports

Bowler, P.A. and S. Brown (eds.). 1987. Proceedings of the California Oak Heritage Conservation Conference, March 11, 1983. Published by the Sea and Sage Chapter of the Audubon Society, Santa Ana, California.

Bretz, W.L. 1987. The University of California Natural Reserve System: A partial collection of California Oak and Oak-Associated Natural Resources. Pp. 110-121 in Bowler, P.A. and S. Brown (eds.). 1987. Proceedings of the California Oak Heritage Conservation Conference, March 11, 1983.

Published by the Sea and Sage Chapter of the Audubon Society, Santa Ana, California.

Conkelton, S.1984. University of California Directory of Photographic Collections. Compiled for the California Museum of Photography, University of California, Riverside.

Vasek, F.C., H.B. Johnson, and W.W. Mayhew. 1975. Piñon Woodlands of the California Reserve System. A Report to the University of California, Natural Land and Water Reserve System as Part of a Resource Inventory. Department of Biology, University of California, Riverside 92502. Unpublished Report, 9 pp. Plus 2 Tables and 2 Appendices.

University of California, Systemwide Administration. July 1, 1975. University of California Property Atlas.

Please send citations for any new or unlisted publications to Peter Bowler pabowler@uci.edu or Megan Lulow mlulow@uci.edu

Last updated by Megan Lulow 2017