The Influence of Epiphytic Lichens on the Nutrient Cycling of a Blue Oak Woodland

Abstract

We evaluated the importance of epiphytic lichens in the nutrient cycling of a blue oak (Quercus douglasii) woodland in California. Each oak tree contained an average of 3.8 kg lichen biomass, totaling 590 kg per ha. For comparison, oak leaf biomass was 958 kg per ha. We compared tree growth, volume and composition of throughfall (rainfall falling though the tree canopy), litterfall, and soil nutrients under 20 trees from which we removed the lichens to 20 control trees. The removal of lichens had no effect on the growth of the oak trees, but it did influence nutrient cycling fluxes significantly. We calculated an enhanced atmospheric deposition for nitrogen of 2.85 kg/ha/yr and for phosphorus of 0.15 kg/ha/yr. This is caused by the presence of epiphytic lichens in the canopy where they act as an intercepting surface, enhancing dry deposition into the tree canopy. Thus, epiphytes can significantly influence nutrient fluxes in blue oak woodlands. This also supports the hypothesis that the tree canopy influences atmospheric deposition and that this, in turn, contributes to the observed “canopy effect” on the understory productivity in oak savannas.

Parent Publication

• Proceedings of a symposium on oak woodlands: ecology, management, and urban interface issues; 19–22 March 1996; San Luis Obispo, CA

Citation

Knops, Johannes M.; H. Nash III, Thomas H.; Schlesinger, William H. 1997. The Influence of Epiphytic Lichens on the Nutrient Cycling of a Blue Oak Woodland. In: Pillsbury, Norman H.; Verner, Jared; Tietje, William D., technical coordinators. 1997. Proceedings of a symposium on oak woodlands: ecology, management, and urban interface issues; 19–22 March 1996; San Luis Obispo, CA. Gen. Tech. Rep. PSW-GTR-160. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 75-82