Moisture increase in response to high-altitude warming evidenced by tree-rings on the southeastern Tibetan Plateau

Abstract

Rapid warming has been observed in the high-altitude areas around the globe, but the implications on moisture change are not fully understood. Here we use tree-rings to reveal common moisture change on the southeastern Tibetan Plateau (TP) during the past five centuries, and show that regional moisture change in late spring to early summer (April-June) is closely related to large-scale temperature anomaly over the TP, with increased moisture coincident with periods of high temperature. The most recent pluvial during the 1990s-2000s is likely the wettest for the past five centuries, which coincides with the warmest period on the TP during the past millennium. Dynamic analysis reveals that vertical air convection is enhanced in response to anomalous TP surface warming, leading to an increase in lower-tropospheric humidity and effective precipitation over the southeastern TP. The coherent warm-wet relationship identified in both tree-rings and dynamic analysis implies a generally wetter condition on the southeastern TP under future warming.

Moisture-Limited Tree Growth for a Subtropical Himalayan Conifer Forest in Western Nepal

“…The rising temperature could further amplify drought stress by increasing evapotranspiration rates or by raising vapor pressure deficit [24]. This is supported by previous studies from the Himalayas and surrounding areas [5,6,9,10,15,34,43]. In contrast, a significant positive correlation between tree growth and temperature was observed in the central Himalayas [4,7,13].…”

“…Previous studies in the central Himalayas have shown that pre-monsoon precipitation is the major growth-limiting factor for Himalayan birch (Betula utilis) [5,6], Himalayan fir (Abies spectabilis) [8], alpine dwarf shrubs (Cassiope fastigiata) [31], Himalayan spruce (Picea smithiana), Himalayan blue pine (Pinus wallichiana) [9,10], and Chir pine (Pinus roxburghii) [22]. Similar growth responses in different conifer trees species were also reported from surrounding areas such as in the western Himalayas [11,12,32,33], subtropical broadleaf tree Toon (Toona ciliata) in the eastern Himalayas [17], and in the southeastern Tibetan Plateau [34,35]. However, our study shows that precipitation from November of the previous year to April of the growth year limits the radial growth of Chir pine, suggesting a stronger drought stress for tree growth in the subtropical forest belt in the central Himalayas.…”

Response of <i>Pinus sylvestris</i> var. <i>mongolica</i> to water change and drought history reconstruction in the past 260 years, northeast China

“…Past, 14, 1213-1228, 2018 Scots pine usually has a typical climate (drought) response pattern with positive tree growth response to increasing precipitation and a negative response to increasing temperature (Bao et al, 2015;Davi et al, 2006;Liu et al, 2009). This typical drought response pattern is usually found in other drought or wetness tree-ring reconstructions (Li et al, 2016;Liu et al, 2017). In this study, the correlation between treering index and monthly precipitation and temperature revealed that the radial growth of Scots pine was mainly limited by water, which is consistent with the physiological characteristics of tree species living in semi-arid regions.…”

“…Similar results were also found by Dai (2013), which presented a different dry-wet pattern under global warming using observations and models. In the Tibetan Plateau, Li et al (2016) found moisture increases related to rapid warming (warmwet). Although the reason for this divergence should be further studied, it might be related to the different response to the phase shift (negative to positive) of the PDO in 1976and 1977(Ma, 2007Wang et al, 2014).…”

“…Drought as one of the major natural disasters is being more frequently influenced by climate change in the world (Cook et al, 2010;Dai, 2011Dai, , 2013Davi et al, 2006;Li et al, 2016). Severe droughts can threaten agriculture and human social activities, and also have a devastating impact on human lives and the survival of native and domestic plants and animals (Cook et al, 2010;Dong et al, 2013;Shen, 2008;Sun, 2007).…”