Radial Growth and Physiological Response of Coniferous Trees to Arctic Amplification

Abstract

We describe the physiological responses of boreal conifers to climate change for the past 112 years using ring‐width and carbon isotope ratio (δ13C) chronologies at six forest sites in northern Eurasia and Canada. Responses differed among regions, depending on their climatic and/or geographic characteristics. Tree radial growth decreased over the past 52 years in central eastern Siberia with the higher rate of summer temperature increase than other regions, as indicated by the negative correlation between radial growth and summer temperature, but increased in northern Europe and Canada. Changes in tree‐ring δ13C indicated that recent climatic conditions have induced stronger drought stress for trees from central eastern Siberia than for those from other regions. The observed tree growth trends were compared to those simulated using a dynamic global vegetation model. Although the modeled annual net primary production (NPP) for trees generally exhibited similar decadal variation to radial growth, simulations did not show a recent decrease in tree growth, even in central eastern Siberia. This was probably due to an overestimation of the sensitivity of modeled tree NPP to precipitation. Our results suggest that the tree NPP forecasted under the expected future increases in temperature and average precipitation might be overestimated, especially in severely dry regions such as central eastern Siberia.

Time lag and negative responses of forest greenness and tree growth to warming over circumboreal forests

“…The negative response to the summer temperature (PS model), as well as the positive response to precipitation probably indicate temperature‐induced drought stress caused by a reduction in the stomatal conductance of plants under the limited availability of soil moisture. This finding corresponds well with previous local/regional tree‐ring studies in continental dry climate regions (e.g., Andreu‐Hayles et al., ; Barber et al., ; Dulamsuren, Hauck, Khishigjargal, Leuschner, & Leuschner, ; Nikolaev et al., ; Silva et al., ; Tei, Sugimoto, Liang, et al., ; Tei et al., ). Although it is difficult to explain the mechanism of the negative response of the NDVI3g to temperature in the AW model, the temperature, as well as precipitation in the previous autumn and winter could have affected vegetation activities.…”

“…Dendroecological analysis is useful for studying the past response of a forest ecosystem to a changing environment (e.g., Nikolaev, Fedorov, & Desyatkin, ; Sidorova et al., ; Tei, Sugimoto, Liang, et al., ; Tei, Sugimoto, Yonenobu, et al., ). Tree‐ring width indices (RWI) are regarded widely as useful long‐term indicators of past forest productivity because of the frequently observed close relationship of the RWI with the forest‐level gross primary production (GPP) and/or net ecosystem exchange (NEE) (e.g., Xu et al., ).…”

“…However, several recent studies have demonstrated the reduced sensitivity of tree growth to rising temperatures, at least since the 1960s (e.g., Wilson et al., ). This could be ascribed to temperature‐induced drought because of the limited availability of soil moisture, which could limit tree growth (e.g., Barber, Juday, & Finney, ; Linares & Camarero, ; Silva, Anand, Oliveira, & Pillar, ; Tei, Sugimoto, Liang, et al., ; Tei, Sugimoto, Yonenobu, Ohta, & Maximov, ) and increase tree mortality (van Mantgem et al., ).…”

“…Satellite image analyses indicated that spring temperatures could influence the vegetation productivity in North America (Wang et al., ). Furthermore, studies on tree rings have indicated characteristic correlations between radial growth and the previous autumn and the current spring climate in Eurasian and Canadian forests (e.g., Kirdyanov, Hughes, Vaganov, Schweingruber, & Silkin, ; Sidorova et al., ; Tei, Sugimoto, Liang, et al., ; Vaganov, Hughes, Kirdyanov, Schweingruber, & Silkin, ). There have been improvements recently in the knowledge on the importance of climatic drivers other than the summer season for vegetation activity.…”

Effects of extreme drought and wet events for tree mortality: Insights from tree‐ring width and carbon isotope ratio in a Siberian larch forest

“…Previous studies in this forest site indicated that the dominant larch trees in this region are subjected to drought stress (Kagawa et al, 2003;Lopez et al, 2007;Nikolaev et al, 2009;Tei et al, 2014;Tei & Sugimoto, 2018;Tei, Sugimoto, Liang, et al, 2017; (Figure 4 and Table 2). Actually, three of the four individuals used for the tree-ring width and Δ 13 C chronologies had lower variability after 2002-2003 as reflected in Figure 4, whereas the remaining one showed less variability in Δ 13 C after 1998 and in ring width for the following year than the living trees ( Figure S5).…”