When first introduced to the preserve in 2009, I was astounded by the wide diversity of oaks found at Pepperwood. Within the preserveâ€™s 3117 acres, one can
expect to encounter evergreen species such as the coast live oak (Quercus agrifolia), interior live oak (Q. wislizenii), the less common canyon live oak (Q. chrysolepis), as well as deciduous species such as blue oak (Q. douglasii), California black oak (Q. kelloggii), valley oak (Q. lobata), and Oregon white oak (Q. garryana). The serpentine outcrops scattered throughout the Preserve create a less competitive environment for the leather oak (Q. durata), a shrubby evergreen tolerant of, and abundantly found in, serpentine conditions. One species in particular, grabbed my attention - the Oregon white oak. The populations of Q. garryana found at Pepperwood are unique; extensive stands exist throughout the Northern California Coast Ranges with Pepperwood lying at the southern edge of the speciesâ€™ range. There is concern that climate change will ultimately affect trees found at this southern border because they will
no longer be living within their current known climatic tolerance. As a dominant species in oak woodlands, Q. garryana plays a critical role in community structure. This species is an essential habitat and food resource for wildlife,
providing nesting sites for many species of bird, as well as nutritious acorns,
leaves, pollen, wood, roots and sap for a variety of insects, birds and mammals. Oregon white oaks also strongly influence ecosystem processes that influence
plant community assemblages. In other words, many plant and animal species at risk of local or global extinction are associated with Oregon white oak communities.
During the past year, I tested and established methods to begin a longitudinal study of Q. garryana at Pepperwood investigating how physiological and climatic responses affect patterns of acorn production within the species. This project
will ultimately assist future restoration and preservation projects and benefit acorn-dependent wildlife species in California. Between August 2010 and January 2011, with help from three very dedicated volunteers, I tested and established
methods for monitoring acorn production in oak populations found at Pepperwood. The goal was to design an acorn sampling protocol that was precise, while remaining efficient to construct and install. In order to test our acorn
catchment structures, it was necessary to locate an actively fruiting population of Q. garryana. However, due to the population-level synchronous production of a large acorn crop, referred to as masting, we were unable to find a population of Q. garryana that met our research criteria at the time of our study. Instead, we tested our completed acorn trap design and visual survey methods on an actively
fruiting population of Q. kelloggii located just off the trail to Redwood Canyon, NE of the parking area between September 17 and December 17, 2010. We constructed and tested 14 seed traps (2 traps for each tree sampled) randomly located beneath the treeâ€™s canopy. After several revisions, I designed an acorn catchment structure that successfully caught acorns while limiting acorn predation. The traps were checked and emptied weekly, and the collected acorns were sorted into one of two groups: 1) Viable, or 2) Non-viable. Any acorn caps collected from the trap were counted as viable, and recorded accordingly. This
year I plan on installing three traps per tree sampled to provide a more evenly distributed sampling protocol. Due to the density of the tree canopy at the sampling site, the visual acorn surveys were difficult to perform. Therefore, to
accurately utilize visual survey techniques, I will be selecting populations with a sparser canopy cover for my future research efforts.
A phenological study requires the collaboration of many observant individuals. Quercus species produce cyclically at the individual level, which strongly implies that a long- term phenological study is needed. In addition to providing a longer historical baseline than instrumental measurements, phenological observations provide high temporal resolution of ongoing changes related to global warming. By monitoring the timing of physiological events and the number of acorns
produced by both individual trees, and entire populations, we can get closer to determining masting patterns of Q. garryana populations found at Pepperwood
Preserve. By determining masting patterns, we can better predict the effect of climate change on acorn production, and the consequences on oak population dynamics and larger ecosystem processes.
Since this is a long-term monitoring project I am looking for assistance from
Pepperwood stewards and volunteers who may be interested in oak woodland management with projects beginning in April. I am looking for approximately
10 enthusiastic, and physically fit, adults to assist with the construction and installation of 75 acorn traps. We will be out in the field approximately one day per week. Once the trees begin to produce acorns, I am also looking for
volunteers to help with the collection, counting, and sorting of acorns. We have a great time out in the field, and I have been known to bring donuts and coffee! Please contact Michelle Jensen (email@example.com) if you
are interested in helping me with my study.
Thank you to Michael Golas, Pam Horton, and Sophia Porter. Without your help last year, this study would not be possible. Also, a huge thank you to my advisors on this projectâ€”Shawn Brumbaugh and Steve Barnhart. I have learned so much from the two of you.