On the ‘Divergence Problem’ in the Alatau Mountains, Central Asia: A Study of the Responses of Schrenk Spruce Tree-Ring Width to Climate under the Recent Warming and Wetting Trend

Abstract

The divergence problem, which manifests as an unstable response relationship between tree-ring growth and climatic factors under the background of global warming, poses a challenge to both the traditional theory of dendroclimatology and the reliability of climatic reconstructions based on tree-ring data. Although Schrenk spruce, as the dominant tree species in the Tianshan Mountains, is frequently applied in the dendrochronological studies, the understanding of the divergence problem of this tree species is still limited. This study conducted correlation analysis between climatic factors and tree-ring width chronologies from 51 living and healthy specimens of Schrenk spruce at sites of high and low elevation in the Alatau Mountains to determine the stability of the response. The results revealed that the tree-ring width of the spruce specimens was correlated positively with precipitation and correlated negatively with temperature. Although the variations of the two tree-ring chronologies were similar, the radial growth of the spruce at the low elevation was found more sensitive to climatic factors. Furthermore, the sensitivity of tree growth to climate demonstrated an obvious increase after an abrupt change of climate under the background of the recent warming and wetting trend. Increased drought stress, calculated based on climatic data, was regarded as the main reason for this phenomenon. The results supply the gap of the stability of climatic response of tree growth in Central Asia to some extent.

Increasing precipitation variability and climate-growth responses of five tree species in North Carolina, USA

“…However, it is common to find that the strength of climate-growth relationships varies at multiple time scales (Carrer 2011, Schwab et al 2018 and correlations between climate and radial growth can oscillate, sometimes altering statistical significance. Among the most discussed alterations of climate-growth relationships is the divergence problem where correlations between radial growth and temperature decreased beginning in the mid-20th century in the Northern Hemisphere latitudes (Briffa et al 1998, D'Arrigo et al 2008, Zhang et al 2019. This change in climate-growth relations can significantly impair dendroclimatic reconstructions (Cerrato et al 2020, Peltier and Ogle 2020, Büntgen et al 2022.…”

Nonlinear Weather–Growth Relationships Suggest Disproportional Growth Changes of Norway Spruce in the Eastern Baltic Region

“…The stationarity (stability) of weather-growth relationships is crucial for the reliability of reconstructions of past environments, as well as projections of future growth [12,26,27,72,73], while the nonstationarities of linear relationships are one of the main causes for the divergence problem [23,72,74]. The observed nonlinear regional weather-growth responses (Figure 3) indicate that the nonstationarities (both temporal and spatial) of local linear weather-growth relationships (Figure 2 and Figures S4-S9) were largely caused by the shifts in the regional climatic gradient [12,13] and are hence expected [14].…”

Analysis of Tree-Ring Chronologies in Coniferous Forests of Southeastern Kazakhstan

“…The samples were pre-processed using standard dendrochronological procedures at the China Meteorological Administration's Key Laboratory of Tree-ring Physical and Chemical Research. The width of the rings was measured with an accuracy of 0.001 mm using the Lintab system (Germany) after visual cross-dating (Zhang et al, 2019). Rows of ring widths were visually compared with graphs and the dating was checked using the COFECHA program (Grissino-Mayer, 2001).…”