Thawing permafrost can mitigate warming-induced drought stress in boreal forest trees

Dual Carbon and Oxygen Isotopes in Siberian Tree Rings as Indicator of Millennia Sunshine Duration Changes

“…The recent air temperature and vapor pressure deficit (VPD) increase along with a decrease of precipitation in the Siberian subarctic is leading to warming-induced drought stress in the boreal trees . It has been shown that changes in tree growth are predominantly controlled by the air temperature and moisture content of the active soil and upper permafrost layers, which is the main water source for trees during dry summers (Churakova (Sidorova) et al, 2016Kirdyanov et al, 2023;Li et al, 2023). Temperature increases, and a reduction of precipitation can result in permafrost degradation (Sugimoto et al, 2002;Saurer et al, 2016;Churakova (Sidorova) et al, 2019;Churakova (Sidorova), 2022;Kirdyanov et al, 2023;Li et al, 2023).…”

“…It has been shown that changes in tree growth are predominantly controlled by the air temperature and moisture content of the active soil and upper permafrost layers, which is the main water source for trees during dry summers (Churakova (Sidorova) et al, 2016Kirdyanov et al, 2023;Li et al, 2023). Temperature increases, and a reduction of precipitation can result in permafrost degradation (Sugimoto et al, 2002;Saurer et al, 2016;Churakova (Sidorova) et al, 2019;Churakova (Sidorova), 2022;Kirdyanov et al, 2023;Li et al, 2023). Our long-term filtered stable carbon and oxygen isotopic compositions over the past 1505 years show significant running correlations and coherences between each other except of 1049-1089 CE (Fig.…”

“…). Therefore, these subarctic trees growing on frozen soils (permafrost) are highly sensitive to temperature changes at the local and global scales (Sidorova et al, 2008;Saurer et al, 2016;Kirdyanov et al, 2023;Churakova (Sidorova) et al, 2016, Churakova (Sidorova), 2022Sugimoto et al, 2002;Li et al, 2023). Larch trees growing in continuous permafrost soil at the high-northern latitudes (68-70 • N, 139-149 • E) are unique paleoclimatic archives.…”

“…Although not yet often applied in this context, stable oxygen isotopes (δ 18 O) might further strengthen sunshine reconstructions. So far δ 18 O in tree rings was mainly used as indicator for air temperature and moisture changes (Sidorova et al, 2008;Churakova (Sidorova) et al, 2016, 2023, 2022; Konecky et al, 2023;Kirdyanov et al, 2023), but also atmospheric circulation (Saurer et al, 2012;Gagen et al, 2016;Churakova (Sidorova) et al, 2021). Saurer et al (2016) demonstrated that oxygen isotopes in precipitation and, therefore, source water for trees are influenced by large-scale hydrological processes.…”