The California Acorn Survey

In collaboration with Dr. Jean Knops of the University of Nebraska and Bill Carmen of Mill Valley, the California Acorn Survey quantifies acorn production of over 1,000 trees at 19 sites throughout California each year as part of our continuing quest to understand patterns of acorn production in California oaks. This effort is currently funded by an LTREB grant from the National Science Foundation.

Our technique involves visual surveys during which two observers count as many acorns as they can in different parts of the tree, each for 15 seconds. These counts are added to yield an index of acorn production for the tree that year. This method is discussed in more detail in Koenig et al. (1994b).

We have monitored acorn production of five species of oaks at Hastings Reservation, Monterey County, California, since 1980. Starting in 1994, we expanded work to include several additional species and other sites throughout most of California (see map). These sites include several field stations (Hastings, Jasper Ridge, Hopland, Sierra Foothills, San Joaquin Experiment Station, James Reserve, Sedgwick Reserve), two Nature Conservancy sites (Dye Creek and the Santa Rosa Plateau), several parks (Yosemite and Palomar Mountain SP) as well as several other strategically-located sites scattered throughout the oak woodland areas of the state.

The California Acorn Survey has its own newsletter, the California Acorn Report; you can download this year's edition (vol. 15, 2011) here. Thanks to Mark Stromberg, prior editions are available at the Hastings Reservation website.

Eventually we plan on providing summaries of the California Acorn Survey data on this web site as well as publications and more information on the study. In the meantime, if data for a particular site are of interest to you, feel free to contact me at wkd4<at>cornell.edu.

A poster that talks about some of our work on acorn production in California oaks is available on the Hastings Reservation web site here. Notable publications of the California Acorn Survey include:

Koenig, W. D., R. L. Mumme, W. J. Carmen, and M. T. Stanback. 1994a. Acorn production by oaks in central coastal California: variation within and among years. Ecology 75: 99-109.pdf

Koenig, J. M. H. Knops, W. J. Carmen, M. T. Stanback, and R. L. Mumme. 1994b. Estimating acorn crops using visual surveys. Canadian Journal of Forest Research 24: 2105-2112. pdf

Koenig, W. D., J. M. H. Knops, W. J. Carmen, M. T. Stanback, and R. L. Mumme. 1996. Acorn production by oaks in central coastal California: influence of weather at three levels. Canadian Journal of Forest Research 26: 1677-1683. pdf

Koenig, W. D. and J. M. H. Knops. 1998. Scale of mast-seeding and tree-ring growth. Nature 396: 225-226.pdf

Koenig, W. D. and J. M. H. Knops. 2000. Patterns of annual seed production by northern hemisphere trees: a global perspective. American Naturalist 155: 59-69.pdf

Koenig, W. D. and J. M. H. Knops. 2005. The mystery of masting in trees. American Scientist 93: 340-347. pdf

Knops, J. M. H., W. D. Koenig, and W. J. Carmen. 2007. A negative correlation does not imply a trade-off between growth and reproduction in California oaks. Proceedings of the National Academy of Sciences (USA) 104: 16982-16985. pdf

Koenig, W. D., J. M. H. Knops, W. J. Carmen, and R. D. Sage. 2009. No trade-off between seed size and number in the valley oak Quercus lobata. American Naturalist 173: 682-688. pdf

Koenig, W. D., J. M. H. Knops, J. L. Dickinson, and B. Zuckerberg. 2009. Latitudinal decrease in acorn size in bur oak (Quercus macrocarpa) is due to environmental constraints, not avian dispersal. Botany 87: 349-356. pdf

Koenig, W. D., J. M. H. Knops, and W. J. Carmen. 2010. Testing the environmental prediction hypothesis for mast-seeding in California oaks. Canadian Journal of Forest Research 40: 2115-2122. pdf

Sage, R. D. W. D. Koenig, and B. C. McLaughlin. 2011. Fitness consequences of seed size in the valley oak Quercus lobata Née (Fagaceae). Annals of Forest Research 68: 477-484. pdf

Scofield, D. G., V. R. Alfaro, V. L. Sork, D. Grivet, E. Martinez, J. Papp, A. R, Pluess, W. D. Koenig, and P. E. Smouse. 2011. Foraging patterns of acorn woodpecker (Melanerpes formicivorus) on valley oak (Quercus lobata Née) in two California savanna-woodlands. Oecologia 166: 187-196. pdf

Abraham, S. T., D. N. Zaya, W. D. Koenig, and M. V. Ashley. 2011. Inter- and intraspecific pollination patterns of valley oak, Quercus lobata, in a mixed stand in central coastal California. International Journal of Plant Sciences 172: 691-699. pdf