Growth response of the alpine shrub, Linanthus pungens, to snowpack and temperature at a rock glacier site in the eastern Sierra Nevada of California, USA

摘要

Annual ring chronologies in high-elevation and high latitude plants have numerous, but largely unexplored, climatic, ecological and geomorphologic applications. This paper presents the first shrub-ring chronology of Linanthus pungens (Torr.) J.M. Porter and LA. Johnson at the above-treeline Barney Lake (BL) rock glacier (37.56466N, 118.96554W) on the eastern crest of the Sierra Nevada, USA, The L pungens chronology is 77 years in length with sufficient sample replication (expressed population signal, EPS, ＞0.75) to capture a robust common signal from 1946 through 2007. Marker years in the BL chronology correspond to drought (wide rings) and persistent snowpack (narrow rings). Response function analysis indicates significant associations with July temperature maxima and previous years' November precipitation (PPT). Radial taproot growth has varied little over the past century and is significantly and positively correlated with temperature during the early portion of the chronology period and significantly and negatively correlated with both snowpack and PPT during the latter half of the chronology period. Predictions of decreasing snowpack and increasing temperatures for the alpine Sierra Nevada would therefore be expected to result in increased shrub growth and possible increases in shrub abundance and range expansion if unprecedented drought does not limit growth in the future.