PARENT SESSION
Oral Session #104: Plant Communities: Vegetation Analysis.
Presiding: S. Will-Wolf
Friday, August 9. 9:00 AM to 12:00 PM. Grand Ballroom West, Radisson.
The importance of oaks in the restoration of California grasslands.
Yoshida, Toshihiko*,1, Quinn, Jessica2, Seabloom, Eric3, Harpole, Stan4, 1 University of California, Santa Barbara, Santa Barbara, CA2 University of California, Davis, Davis, CA3 National Center for Ecological Analysis and Synthesis, Santa Barbara, CA4 University of Minnesota, St. Paul, MN
ABSTRACT- Facilitation and interference in plant communities can complicate restoration efforts when the success of one suite of species is dependent on the presence or absence of another. These processes may alter the spatial structure of the plant community, an often-neglected component in restoration plans. Furthermore, plants can have strong effects on the abiotic environment of their community and these effects can alter the distribution and abundance of other species. The invasion of California grasslands by exotic annual species is one of the most extensive plant invasions worldwide. Here, we investigate the role of oak canopies in structuring restored California grasslands. Restoration of these grasslands is complicated by the strong effects of oak canopies on the distribution of native grasses because of the long-term decline of oak populations throughout the state. We used experimental seedings of five native perennial grasses in an abandoned agricultural field to determine the rate at which compositional gradients develop as a result of oak canopies. We compared the compositional and abiotic gradients in the restored grassland to those in relict natural oak-savannah communities. We found that in the restored grassland the spatial distribution of native grasses began to resemble natural populations after two years. In addition, total carbon and nitrogen levels were higher under the canopy, though these differences were weaker in the restored grassland. The abiotic environment formed by the presence of oaks in California grasslands has an effect on the compositional distribution of native species. Understanding the mechanisms of oak facilitation and interference in native California grasslands is critical when trying to design and implement realistic restorations of these communities.
KEY WORDS: oaks, grassland, restoration