Changing relationships between tree growth and climate in Northwest China

Abstract

Recently, several studies have shown changing relationships between tree growth and climate factors, mostly in the circumpolar north. There, changing relationships with climate seem to be linked to emergent subpopulation behavior. Here, we test for these phenomena in Northwest China using three tree species (Pinus tabulaeformis, Picea crassifolia, and Sabina przewalskii) that had been collected from six sites at Qilian Mts. and Helan Mts. in Northwest China. We first checked for growth divergence of individual sites and then investigated the relationship between tree growth and climate factors using moving correlation functions (CF). Two species, Pinus and Sabina, from two sites clearly showed growth divergence, not only in the late twentieth century as reported in other studies, but also over nearly the whole record. In divergent sites, one chronology shows more stable relationships with climate factors (usually precipitation). In non-divergent sites, nearly all relationships either vary in strength or become non-significant at one point. While this might possibly be related to increased stress on some trees due to increasing temperature, the exact causes for this shift in sensitivity remain unclear. We would like to highlight the necessity for additional studies investigating possible non-stationary growth responses of trees with climate, especially at sites that are used for climate reconstruction as our sites in Northwest China.

Divergent responses to climate factors in the radial growth of Larix sibirica in the eastern Tianshan Mountains, northwest China

“…Since around the middle twentieth century, the evidences for reduced sensitivity of tree growth to temperature have been reported on Picea glauca (Alaska), Picea abies (Alps), Picea rubens (southern Appalachian Mountains), Fagus sylvatica (European Mediterranean Basin) and so on (Lloyd and Fastie 2002;Büntgen et al 2006;Tegel et al 2014;White et al 2014). And similar results had also been recorded by several dendroclimatic studies on Pinus tabulaeformis (Helan Mountains), Sabina przewalskii (Qilian Mountains), Picea crassifolia (northeast Tibet Plateau), Pinus koraiensis (Changbai Mountains) and so on in China (Zhang et al 2009;Zhang and Wilmking 2010;Gao et al 2013;Yu et al 2013). Combining these instances of unstable growth-temperature relationships, warming-induced drought stress might be a driving factor in recent decades (D'Arrigo et al 2008).…”

“…However, no divergence phenomenon was observed for Larix decidua in the European Alps (Büntgen et al 2008). Diverging growth trends were observed for Pinus tabulaeformis and Sabina przewalskii but not for Picea crassifolia in northwest China (Zhang et al 2009). While the 'divergence problem' has received greater attention and recognition in recent years, the explanation of the 'divergence problem' remains a topic of debate, focusing on the response threshold effect of climate change and environmental pollution (Barber et al 2000;Wilson and Elling 2004), the age effect of biological species heterogeneity (Wu et al 2013a), the end effect of inappropriate detrending method (Briffa and Melvin 2011) and other concepts.…”

Tree growth and time-varying climate response along altitudinal transects in central China

“…This decreased drought sensitivity may reduce the Rbar value of XLM03 and the lower correlations between XLM02 and XLM03. A number of previous dendrochronological studies have documented a loss in climate sensitivity in recent decades, a so-called divergence problem (e.g., Barber et al 2000;Briffa et al 1998;D'Arrigo et al 2007;Wilmking et al 2005;Wilson and Elling 2004;Vaganov et al 1999;Zhang et al 2008). Our study suggests that the shift in the climate-growth responses, for example, from negative to positive at XLM03, might be one potential cause.…”

Temporal instability of isotopes–climate statistical relationships – A study of black spruce trees in northeastern Canada

“…The phenomenon has been observed for ring width and density in several areas of the northern hemisphere (Büntgen et al, 2008;D'Arrigo et al, 2008;Driscoll et al, 2005;Pisaric et al, 2007;Zhang et al, 2009). The ensuing inability of tree-ring reconstruction to reflect high-frequency regional climate signals has been attributed to several regional causes like a non-linear response from trees to recent climate warming or threshold responses (Vaganov et al, 1999), increase of temperature inducing a drought stress (Barber et al, 2000;Jacoby and D'Arrigo, 1995), delayed snow-melt and seasonality changes (Driscoll et al, 2005;Vaganov et al, 1999) and differential response to maximum and minimum temperatures (Wilson and Luckman, 2003).…”