Project at a Glance

Title: Vegetation process studies : California Air Resources Board integrated watershed project

Principal Investigator / Author(s): Rundel, Philip W. (Philip Wilson)

Contractor: Laboratory of Biomedical and Environmental Sciences, UCLA

Contract Number: A3-097-32

Research Program Area: Ecosystem & Multimedia Effects

Topic Areas: Acid Deposition, Ecosystem Impacts


This work was undertaken to supply baseline data about ecosystem processes that might be affected by acid deposition and air pollution. The project encompasses seven subtopics: stand data and dynamics, lichens studies, tree ring analysis, above ground biomass and production for two dominant Abies species and for non-Abies species, analytical work related to nutrient pools, below ground production, and population studies.

The work performed included evaluation of thallus morphology of a dominant lichen species, analysis of 25 elements in three important lichens species, analysis of potentially toxic elements in tree rings, the establishment of regressions and evaluation of published regressions for estimating net annual above ground production, determination of element concentrations in plant tissues, quantification of below ground production, and resampling of l0-15-year-old permanent plots.

Results included the finding that Hypoqymnia imshaugii at our site is somewhat convolute, that certain elements were in significantly higher concentrations in H. imshauqii than in two other lichen species, that Abies concolor tree rings showed a sharp decline in calcium levels in the pastxears. Above ground production of two Abies species is high. Regressions were found for estimating biomass and productionof the non-Abies species. A substantial body of data was amassed on nutrient pools. Foliar levels of magnesium are low and of aluminum are high in older needles of A. magnifica growing on skeletal soils with low pH's, but not on richer soils. This may indicate an sensitivity in such habitats to soil leaching. Below ground biomass was 970 g/m < 2 > and 2785 g/m < 2 > in October 1984 and May 1985, respectively. Production of the < 2 mm size class was 158 g/m < 2 > during the same period. Mycorrhital colonization was determined and a conversion factor used to estimate production. Burned stands of mixed-conifer forest experienced mortality, shifts in species composition, and changes in basal area. Sequoiadendron giganteum reproduced slowly, but had very low mortality and generally increased in basal area. Calocedrus decurrens grew and reproduced with surprising rapidity. Pinus ponderosa showed relatively high mortality.

Conclusions of the work include the subtle effects of pollution potentially acting in the mixed-conifer forests, as indicated by lichen studies. Foliar levels of magnesium and aluminum may indicate potential sensitivity of A. magnifica to pollution on poor soils. Below ground production is rather low and above ground production is high in these forests.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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