The response of native oaks from California and Israel to drought

Abstract

California and Israel are both characterized by Mediterranean climates, and the native oaks growing in these two locales occupy similar ecological niches. However, in California certain oak species are having difficulty regenerating adequately, while in Israel this is not a problem. From 2004 to 2006, a series of greenhouse studies were conducted in both Israel and California to sort out the role of evolutionary history in influencing species regeneration rates and strategies. These studies have evaluated survival and growth, as well as the response of the species to disturbance including simulated browsing and fire. In 2006, an out-planting study was initiated at the University of California Sierra Foothill Research and Extension Center in Yuba County to determine how the species respond under normal field conditions. Three California oak species, including Quercus agrifiolia, Q. douglasii and Q. berberidifolia, as well as two Israeli oak species (Q. ithaburensis and Q. calliprinos) were planted in a common garden. This latter study was designed to evaluate phenology, growth rates, and how seedlings respond to summer drought in terms of pre-dawn plant moisture stress (PMS). Unfortunately, high field mortality prevented assessing plant moisture stress or field growth rates so the results reported here include only initial size, bud burst date and survival. Results indicate that the deciduous species from both locations (Q. douglasii and Q. ithaburensis) break bud far earlier than their evergreen counterparts. Growth in containers varied greatly by species, with Q. agrifolia from California and Q. ithaburensis from Israel growing far more rapidly that the other species. Finally, a comparison of the survival of evergreen and deciduous species from Israel with those from California suggests that California species tended to die earlier. These results are consistent with results from the greenhouse studies that found that the California species were generally less water-use efficient and might be less adapted to drought stress than Israeli species.

Parent Publication

• Proceedings of the sixth California oak symposium: today's challenges, tomorrow's opportunities

Citation

McCreary, Douglas; Gruzweig, Jose M.; Carmel, Yohay; Flather, Curtis H. 2008. The response of native oaks from California and Israel to drought. In: Merelender, A.; McCreary, D.; Purcell, K. L., tech. eds. Proceedings of the Sixth California Oak Symposium: Today's Challenges, Tomorrow's Opportunities; October 9-12, 2006; Rohnert Park, CA. Gen. Tech. Rep PSW-GTR-217. U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. p. 293-300.