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Control Number309819
Date and Time of Latest Transaction20150706094044.AM
General Information150706s |||||||||b ||00|||
Cataloging SourceSTII-DOST
Local Call NumberScienceDirect
Main Entry - Personal NameMeixner, T.
 F. Yuan
 Gimeno, B.S.
 Rao, L.E.
 Johnson, R.F.
 Tonnesen, G.S.
 Geiser, L.H.
 Jovan, S.
 Weiss, S.B.
 Allen, E.B.
 Fenn, M.E.
 Bytnerowicz, A.
Title StatementNitrogen critical loads and management alternatives for N- impacted ecosystems in California by M.E. Fenn and 11 others
Physical Descriptionpages 2404-2423 computer file; text; 2,986kb
Summary, Etc.Empirical critical loads for N deposition effects and maps showing areas projected to be in exceedance of the critical load (CL) are given for seven major vegetation types in California. Thirty-five percent of the land area for these vegetation types (99,639 km(2)) is estimated to be in excess of the N CL. Low CL values (3-8 kg N ha(-1) yr(-1)) were determined for mixed conifer forests, chaparral and oak woodlands due to highly N-sensitive biota (lichens) and N-poor or low biomass vegetation in the case of coastal sage scrub (CSS), annual grassland, and desert scrub vegetation. At these N deposition critical loads the latter three ecosystem types are at risk of major vegetation type change because N enrichment favors invasion by exotic annual grasses. Fifty-four and forty-four percent of the area for CSS and grasslands are in exceedance of the CL for invasive grasses, while 53 and 41% of the chaparral and oak woodland areas are in exceedance of the CL for impacts on epiphytic lichen communities. Approximately 30% of the desert (based on invasive grasses and increased fire risk) and mixed conifer forest (based on lichen community changes) areas are in exceedance of the CL. These ecosystems are generally located further from emissions sources than many grasslands or CSS areas. By comparison, only 3-15% of the forested and chaparral land areas are estimated to be in exceedance of the NO(3)(-) leaching CL. The CL for incipient N saturation in mixed conifer forest catchments was 17 kg N ha(-1) yr(-1). In 10% of the CL exceedance areas for all seven vegetation types combined, the CL is exceeded by at least 10 kg N ha(-1) yr(-1), and in 27% of the exceedance areas the CL is exceeded by at least 5 kg N ha(-1) yr(-1). Management strategies for mitigating the effects of excess N are based on reducing N emissions and reducing site N capital through approaches such as biomass removal and prescribed fire or control of invasive grasses by mowing, selective herbicides, weeding or domestic animal grazing. Ultimately, decreases in N deposition are needed for long-term ecosystem protection and sustainability, and this is the only strategy that will protect epiphytic lichen communities
Subject Added Entry - Topical TermEcology
 Climate Change -- California
 California ecosystems
 Epiphytic lichens
 Coastal sage scrub
 Nitrogen Cycle
LocationDOST STII ScienceDirect NONPRINTS NP 13-14785 1 13-14785 Online/Download 2010-11-30
  
     
 
Physical Location
Department of Science and Technology
Science and Technology Information InstituteScienceDirect
  
     
 
Digital Copy
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