Nutrient Relations of the Evergreen Shrub, Adenostoma fasciculatum, in the California Chaparral

Abstract

Seasonal changes in biomass, nitrogen, and phosphorus contents in plant parts of the evergreen shrub, Adenostoma fasciculatu1n, indicate that the shoot of this plant takes up nutrients during the winter rainy season prior to any above-ground growth. Such a nutrient uptake pattern would result in a possible conservation of nutrients that would otherwise be lost to the plant through decomposition and leaching from the litter during the rainy season that follows the long summer drought. A similar uptake pattern has been noted in shrubs of the Australian mediterranean-climate region. M7e propose that evergreen leaves are efficient in providing a high photosynthetic return per unit of nutrient invested and also provide a sink for nutrients taken up from the soil during nongrowth periods. Primary production as well as nutrient pool sizes and fluxes of ildenostoma are similar to those found in scrub communities of other mediterraneanclimatic regions. The shrubs nere predominately resprouts from a 1950 fire. After sorting, drying, and uTeighing, the branch components w ere pooled into three subsamples and used for the determination of total nitrogen and phosphorus. Total nitrogen uTas determined by the Kjeldahl method and total phosphorus bsr the molsTbdate method. A Technicon Autoanal=zer II nas used for both methods. Old stems, roots, litter, and soil ^=ere collected at the same site during 1976-77 and analyzed for nitrogen and phosphorus by the soil-testing laboratory of the