Climate response of Salix oritrepha growth along a latitudinal gradient on the northeastern Tibetan Plateau

Abstract

Shrubs are widespread at higher altitudes and latitudes. Dendrochronology of shrub growth has been intensively studied in the circumpolar Arctic, Mediterranean and Patagonia. However, relatively little is known about shrub growth responses to climate change on the Tibetan Plateau. Herein, we investigate climate sensitivity of Salix oritrepha growth along a north-south (35-39° N) latitudinal gradient on the northeastern Tibetan Plateau. Four S. oritrepha shrub sites were selected for dendrochronology study. Pearson and partial correlation analyses were used to estimate strength of the climate sensitivity of the growth time series at each site. We found that not all of the site chronologies show consistent variations. Despite of this, its radial growth was primarily limited by the July mean temperature across the latitudinal gradient, and warming summer climate tends to increase the growth of S. oritrepha on the northeastern Tibetan Plateau.

Warming‐induced shrubline advance stalled by moisture limitation on the Tibetan Plateau

“…To date, collecting annual-ring data is the only choice for the determination of the germination age of trees and shrubs in the studied remote regions. In the eastern TP, Salix shrub forms well-defined annual rings and can be used in dendroecological analyse (Lu et al 2019b). We sampled all Salix shrubs located in each plot (Supporting information), so we could reliably reconstruct the yearly variations of shrub recruitment.…”

“…Samples of wood were processed following standard dendrochronological procedures, including air-drying, sanding and the visual cross-dating of cores under a stereomicroscope (Stokes and Smiley 1996). Salix stems usually have circular cross sections (Lu et al 2019b). Series of annual ring widths from mature individuals can be cross-dated well if mean series correlations exceed 0.32.…”

“…This study 1) reconstructed the variations of Salix shrub recruitment and shrubline position in recent 80 years on the TP and 2) evaluated the relative influences of temperature, precipitation and moisture variables on Salix shrubline dynamics. The growth of Salix shrubs above the treeline is assumed to be mainly limited by low temperature (Lu et al 2019b), so our hypothesis was that infilling and shrubline advances of Salix shrubs would be driven by climatic warming but that the rate of these processes would be modulated by warming‐induced moisture stress.…”