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Air pollution and changes in forest nitrogen status: Fog and rain deposition and nitrogen losses from forested watersheds in the San Bernardino Mountains. Final report

Technical Report ·
OSTI ID:679047
The primary objective of this project was to examine the effects of N deposition on mixed conifer forests in southern California. Studies were conducted at selected sites an air pollution gradient in the San Bernardino Mountains (SBM). The main tasks were: (1) to measure N deposition to the forest in fog and throughfall, (2) to determine spatial and temporal patterns of nitrate export in stream water, and (3) to quantify trace gas fluxes from soil at sites with high and low N deposition. Fog was found to be an important N source at the western end of the SMB due to his high frequency and presence at elevated concentrations. N deposition from throughfall was found to be similar to levels in forests where adverse effects have occurred. Annual fluxes of N from soil were 18-times higher at the western end of the SBM than at the eastern end. The data provide evidence of forest nitrogen saturation caused by the deposition of anthropogenic pollutants over a multi-decade period in the SBM.
Research Organization:
Pacific Southwest Forest and Range Experiment Station, Riverside, CA (United States); California State Air Resources Board, Research Div., Sacramento, CA (United States)
Sponsoring Organization:
California State Air Resources Board, Sacramento, CA (United States)
OSTI ID:
679047
Report Number(s):
PB--99-160202/XAB; CNN: Contract ARB-95-329
Country of Publication:
United States
Language:
English