Collaborative Research: Controls of Ecosystem Level Functions in a Lichen-Oak Woodland

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The hypothesis that canopy lichens, acting as keystone species, can control the conservation and retention of nutrients in forest ecosystems and affect nutrient cycling and primary production will be tested. In blue oak woodlands, a community that occupies 6.5% of California, biomass of the lichen, Ramalina menziesii, can exceed 700 kg/ha in the canopy. This proposed work seeks to demonstrate the importance of this non-nitrogen- fixing canopy epiphyte in net primary production and nutrient cycling throughout this oak woodland ecosystem. A replicated factorial experiment will be imposed by which canopy lichen and lichen litterfall are manipulated at two sites, representing different degrees of maritime influence in Monterey County, California. Manipulations of the canopy lichen biomass will test the hypothesis that Ramalina enhances nutrient inputs from the atmosphere. For instance, the catch of atmospheric aerosols, fog water and gases by Ramalina may enhance the input of nutrients to the entire woodland. Manipulations of the amount of Ramalina that is deposited as litterfall will test the hypothesis that the decomposition of this lichen controls the decomposition and cycling of nutrients to the oak trees. The growth efficiency and nutrient-use efficiency of the oak trees will also be examined in the experimental plots. The investigators will also develop a simple technique for extrapolating results to oak woodlands of differing density and to considerations at scales ranging to regional evaluations. The results will be significant to understanding the role of particular species in the functional properties of entire ecosystems, and to the understanding of canopy processes to other aspects of ecosystem function in oak woodlands. In addition, this study may be viewed as a case study for any lichen dominated canopy and will have implications for the function of epiphytes in general in ecosystems. The research project team is excellent. Institutional accommodations are quite good, and accommodations for the work at the Hastings Natural History Reservation will be adequate.