The Radial Growth of Schrenk Spruce (Picea schrenkiana Fisch. et Mey.) Records the Hydroclimatic Changes in the Chu River Basin over the Past 175 Years

Ruibo Zhang,Tongwen Zhang,Bakytbek Ermenbaev,Li Qin,Mamtimin Ali,Rysbek Satylkanov

doi:10.3390/f10030223

Abstract

The Chu River is one of the most important rivers in arid Central Asia. Its discharge is affected by climate change. Here, we establish a tree-ring chronology for the upper Chu River Basin and analyze the relationships between radial growth, climate, and discharge. The results show that the radial growth of Schrenk spruce (Picea schrenkiana Fisch. et Mey.) is controlled by moisture. We also reconstruct a 175-year standardized precipitation-evapotranspiration index (SPEI) for the Chu River Basin. A comparison of the reconstructed and observed indices reveal that 39.5% of the variance occurred during the calibration period of 1952–2014. The SPEI reconstruction and discharge variability of the Chu River show consistent long-term change. They also show that the Chu River Basin became increasingly dry between the 1840s and the 1960s, with a significant drought during the 1970s. A long and rapid wetting period occurred between the 1970s and the 2000s, and was followed by increasing drought since 2004. The change in the SPEI in the Chu River Basin is consistent with records of long-term precipitation, SPEI and Palmer Drought Severity Indices (PDSI) in other proximate regions of the western Tianshan Mountains. The hydroclimatic change of the Chu River Basin may be associated with westerly wind. This study is helpful for disaster prevention and water resource management in arid central Asia.

Highlights

It is widely recognized that global warming has occurred since the mid-19th century [1]
Schrenk spruce in the Tianshan ofistree-ring widths their radial growth of Schrenk spruce in the Studies of tree-ring widths and their relation to climate for conifers in arid and semiarid sites iteratively demonstrate that ring-width relation for conifers aridtheand semiarid sitesthe iteratively growthtoisclimate influenced not onlyin by climate during growingdemonstrate season, but that alsoring-width by climatic
The results showed that the reconstruction successfully represents the changes in climate over the whole of Central Asia during the past Kazakhstan

Summary

Introduction

It is widely recognized that global warming has occurred since the mid-19th century [1]. Corresponding hydroclimatic changes demonstrate significant regional variations [2]. Asia (ACA) covers 5 × 106 km , and includes Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan, and Xinjiang in northwest China. Drought is a major climate disaster in ACA and the Forests 2019, 10, 223; doi:10.3390/f10030223 www.mdpi.com/journal/forests. Forests 2019, 10, 223 cause of considerable agricultural, economic and environmental damage. The Tianshan Mountains, which extend across the region, are known as the “water towers” of Central Asia, and are the largest and most important mountain system in ACA. The region is especially sensitive to climate change [3,4]

Methods

Findings

Discussion

Conclusion