title: Seasonal changes of fine root density in the Southern Californian chaparral.
abstract: Fine root extractions from soil cores of a south facing slope in the Southern Californian chaparral were used to study the dynamics of feeder root growth in a summer-dry area. The studies were concentrated on the root systems of Adenostoma fasciculatum, Arctostaphylos glauca, Ceanothus greggii, and Rhus ovata. The total fine root biomass of Adenostoma fasciculatum increased from 0.6 g dm-3in early spring to 3.6 g dm-3in late summer. Considering the specific soil conditions at this site and earlier gained information on fine root distribution with depth, the value of 3.6 g dm-3converts to 1.58 kg m-2of ground shaded by the shrub canopy. The observed seasonal biomass increase is mainly due to the accumulation of dead root material in the soil when low soil moisture contents presumably inhibited decomposition processes. The total length of living fine roots also increased during the season, e.g. from 0.8 m dm-3to more than 5 m dm-3(0.35 km m-2to 2.2 km m-2) in A. fasciculatum. Unusual summer rains in the research year stimulated vigorous fine root growth at a time when the normally low soil moisture would prohibit further fine root growth. The average fine root diameters and total lengths of fine roots beneath one square meter of ground surface allowed an estimate of root area indices (RAI) analogous to the leaf area indices (LAI). The data provide evidence for a significant fine root turnover in the chaparral.
authors.affiliation: Botany Department, San Diego State University, 92182, San Diego, CA, USA.
authors.forename: Jochen
authors.initials: J
authors.lastname: Kummerow
authors.affiliation: Botany Department, San Diego State University, 92182, San Diego, CA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Krause
authors.affiliation: Botany Department, San Diego State University, 92182, San Diego, CA, USA.
authors.forename: William
authors.initials: W
authors.lastname: Jow