Skip to Main Content
Response of Subalpine Conifers in the Sierra Nevada, California, U.S.A., to 20th-Century Warming and Decadal Climate VariabilityAuthor(s): Constance I. Millar; Robert D. Westfall; Diane L. Delany; John C. King; Lisa J. Graumlich
Source: Arctic, Antarctic, and Alpine Research, Vol. 36(2): 181-200
Publication Series: Scientific Journal (JRNL)
PDF: Download Publication (0 B)
DescriptionFour independent studies of conifer growth between 1880 and 2002 in upper elevation forests of the central Sierra Nevada, California, U.S.A., showed correlated multidecadal and century-long responses associated with climate. Using tree-ring and ecological plot analysis, we studied annual branch growth of krummholz Pinus albicaulis; invasion by P. albicaulis and Pinus monticola into formerly persistent snowfields; dates of vertical branch emergence in krummholz P. albicaulis; and invasion by Pinus contorta into subalpine meadows. Mean annual branch growth at six treeline sites increased significantly over the 20th century (range 130–400%), with significant accelerations in rate from 1920 to 1945 and after 1980. Growth stabilized from 1945 to 1980. Similarly, invasion of six snowfield slopes began in the early 1900s and continued into snowfield centers throughout the 20th century, with significantly accelerated mean invasion from 1925 to 1940 and after 1980. Rate of snowfield invasion decreased between 1950 and 1975. Meadow invasion and vertical leader emergence showed synchronous, episodic responses. Pinus contorta invaded each of ten subalpine meadows in a distinct multidecadal pulse between 1945 and 1976 (87% of all trees) and vertical release in five krummholz P. albicaulis sites also occurred in one pulse between 1945 and 1976 (86% of all branches). These synchronies and lack of effect of local environments implicate regional climate control. Composite weather records indicated significant century-long increases in minimum monthly temperature and multidecadal variability in minimum temperature and precipitation. All ecological responses were significantly correlated with minimum temperature. Significant interactions among temperature, precipitation, Pacific Decadal Oscillation (PDO) indices, and multiyear variability in moisture availability further explained episodic ecological responses. Four multidecadal periods of the 20th century that are defined by ecological response (<1925; 1925–1944; 1945–1976; >1976) correlate with positive and negative PDO phases, as well as with steps in the rate of temperature increase. These diverse factors in spatially distributed upper-montane and treeline ecosystems respond directionally to century-long climate trends, and also exhibit abrupt and reversible effects as a consequence of interdecadal climate variability and complex interactions of temperature and moisture.
- You may send email to email@example.com to request a hard copy of this publication.
- (Please specify exactly which publication you are requesting and your mailing address.)
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationMillar, Constance I.; Westfall, Robert D.; Delany, Diane L.; King, John C.; Graumlich, Lisa J. 2004. Response of Subalpine Conifers in the Sierra Nevada, California, U.S.A., to 20th-Century Warming and Decadal Climate Variability. Arctic, Antarctic, and Alpine Research, Vol. 36(2): 181-200
- Height growth determinants in pines: A case study of Pinus contorta and Pinus monticola
- Natural range of variation of red fir and subalpine forests in the Sierra Nevada Bioregion
- Reconstructing fire history of lodgepole pine on Chagoopa Plateau, Sequoia National Park, California
XML: View XML