Climate–growth relationships of Schrenk spruce (Picea schrenkiana) along an altitudinal gradient in the western Tianshan mountains, northwest China

Lü

Intl Journal of Climatology

et al. 2019

In this study, 85 tree cores from 45 Schrenk spruces (Picea schrenkiana) were used to establish a regional tree‐ring chronology. A 256‐year pJune–May precipitation (where p denotes a month from the previous year) for northern Kyrgyzstan in central Asia was reconstructed using this newly developed chronology. The tree‐ring‐based precipitation reconstruction tracks the observed data well (r = .622, p < .0001, n = 105). Spatial correlation proved that the reconstructed precipitation series contains climatic signals representative of a larger area, including eastern Kyrgyzstan and parts of Kazakhstan. A comparison between the newly reconstructed precipitation series and four tree‐ring‐based precipitation reconstructions for the surrounding areas reveals similar variations, particularly in the high‐frequency domain. Furthermore, this reconstructed precipitation series matches nine flood (1785, 1786, 1792, 1952, 1953, 1970, 1971, 1973, and 2000) and four drought (1917, 1919, 1927, and 1944) events noted in the historical documents and captures a dry decade that occurred in the 1910s in central Asia.

Section: Discussionmentioning

confidence: 98%

A 256‐year‐long precipitation reconstruction for northern Kyrgyzstan based on tree‐ring width

Lü

Intl Journal of Climatology

et al. 2019

“…In S2700 and S2900, tree growth was positively correlated (p < 0.05) with SPEI and precipitation, and more than 25% of BAI variation was explained by SPEI ( Figure 6c,e and Figure S3). This suggests water deficit inhibits tree growth and might weaken the benefit of climate warming especially in lower elevations, as also found in the Mediterranean regions, Central European, and southern Tibetan Plantae [14,16,33]. Higher MS values at low altitudes (Table 2) also suggest the water limit, as the mean sensitivity of tree rings are usually higher in arid sites than in wet sites [26].…”

Section: Discussionmentioning

confidence: 74%

Divergent Growth Responses to Warming between Stand-Grown and Open-Grown Trees in a Dryland Montane Forest in Northwestern China

Shi

et al. 2019

Forests

Dryland montane forests conserve water for people living in the fluvial plains. The fate of these forests under climate warming is strongly affected by local environmental factors. The question remains of how internal factors contribute to climate change impacts on forest growth in these regions. Here, we investigated tree ring records for similar-aged stand-grown trees and their neighboring open-grown trees at elevation in a dryland montane forest (Picea crassifolia Kom.) in northwestern China. The growth rate of open-grown trees is much higher than their neighboring stand-grown trees across the entire elevation gradient, and the lower the altitude, the greater the difference. Open-grown trees at different elevations showed similar growth patterns, as tree growth at all sites was accelerated over time. In contrast, growth patterns of stand-grown trees were divergent at different altitudes, as growth at high elevations (3100-3300 m a.s.l.) was accelerated, whereas growth at low elevations (2700-2900 m a.s.l.) became stable after the year 1990. Analysis of growth-climate relationships indicated that warming promoted open-grown tree growth across the entire altitude gradient, and also stand-grown tree growth at high elevations, but negatively affected the growth of stand-grown trees at low elevations. Water scarcity can be exacerbated by competition within forests, inhibiting the warming-induced benefits on tree growth. Moving window correlation analysis suggested the negative effect of warming on tree growth at low elevations was diminished after the late 1990s, as the drought stress was alleviated. Our research shows the divergent growth responses to warming of stand-grown and open-grown trees along elevation. It reveals effects of internal factors in determining tree growth response to warming and holds the potential to aid forest management and ecosystem models in responding to climate change.

“…Blooming was observed in the forests of the Xinjiang Tien Shan between in mid-May and July depending on the weather (Pan et al, 2013). Its lower altitudinal belt limit is responsive to moisture availability and its upper limit to temperature (Huo et al, 2017). It grows preferably on north-facing shady mountain slopes (Wu et al, 2015).…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Humid and cold periods in the last 5600 years in Arid Central Asia revealed by palynology of Picea schrenkiana from Issyk-Kul

Leroy

Giralt

2020

The Holocene

Central Asia, with its high mountains, despite its location between Europe and eastern Asia remains a data poor area. However, mountain glaciers are strongly affected by global change and have a wide-ranging impact. A new pollen record over the last 5600 years shows the extension of a dry Artemisia steppe around Lake Issyk-Kul, with a slightly wetter period from 4.5 to 2.7 ka BP (less Ephedra). Picea schrenkiana forest growing on north-facing slopes of the northern Tien Shan Range, are exposed to Westerlies-related precipitation. The pollen record of Picea is therefore a very good marker of wetter and cold conditions. A comparison to a nearby synchronous pollen record at a higher altitude indicates that the whole forest belt moved down, and that it was not a downwards extension of the lower forest limit only. Four cold and humid phases were evidenced over the last 5.6 ka: 5.5 ka, 4.2 ka and following centuries, 3.2 ka and following centuries (before the end of the Bronze Age) and finally the Little Ice Age, with the latter two being more strongly expressed. These climatic changes, in agreement with other Arid Central Asia investigations, corroborate the driving role of the Westerlies far inland. Human activities were more intense in the Mid and Late Bronze Age (4.5–3.2 ka) and in the last 800 years, confirmed by archaeological and historical information. Issyk-Kul and surrounding rich pastureland were most likely an important step in the ancient Silk Road.