pdf

P hoto G allery
All photographs in this section are provided
by authors of papers in our scientific journals
and are used by permission.
All copyrights reserved.
SPATIAL SYNCHRONY IN CALIFORNIA OAKS
Walter D. Koenig and Johannes M. H. Knops
Photo 1. A valley oak (Quercus lobata) at Liebre Mountain in Los Angeles
County at the southern end of its range. Acorn production by 250 individual
valley oaks and 256 individual blue oaks at 12 sites located throughout California
were surveyed annually from 1994 to 2011 to quantify spatial synchrony in acorn
production by these species. Photo by W. Koenig.
Photo Gallery
January 2013
89
Photo Gallery
Photo 2. Valley oak
acorns. Acorn production
was estimated using
visual surveys, whereby
t wo obser vers cou n t
as many acorns as they
can in different parts of
the tree for 15 seconds.
This technique allows
the rapid assessment of
relative acorn production
by a large number of
individual trees over large
geographic areas. Photo
by W. Koenig.
Photo 3. The study reported
in the article is part of the
larger, ongoing California Acorn
Survey initiated by the authors
in 1994. Here the senior author
downloads data from an iButton
located on one of the valley oaks
surveyed at Hastings Reservation
in Monterey County. Note the
dendrometer on the tree for
measuring annual radial growth.
Photo by J. Knops.
90
Bulletin of the Ecological Society of America
We investigated spatial synchrony in acorn production within and between two species of
oaks (genus Quercus) endemic to California, the valley oak (Quercus lobata) and blue oak (Quercus
douglasii), over an 18-year period. Acorn production was highly synchronized both within and
between the two species over distances of nearly 750 km. Patterns closely matched spatial
synchrony in the environmental factors known to correlate with acorn production, thus providing
strong support for the hypothesis that such environmental factors drive spatial synchrony (the
Moran effect).
Photo 4. The California Acorn Survey takes two weeks every September, during which
time the authors travel ~3500 km and count acorns on over 1100 individually marked trees
located at 22 sites throughout the state. In between counting acorns they survey various local
establishments. Here, for example, the authors take a break at the Pozo Saloon in San Luis
Obispo County after counting acorns at the nearby American Canyon Campground in 2009.
Photo by W. Koenig.
These photographs illustrate the article “Large-scale spatial synchrony and crosssynchrony in acorn production by two California oaks” by Walter D. Koenig and Johannes M.
H. Knops, published in Ecology 94:83–93, January 2013.
Photo Gallery
January 2013
91