Radial Growth Response of Picea crassifolia to Climatic Conditions in a Dryland Forest Ecosystem in Northwest China

Hanxue Liang,Ali Muhammad,Jian Kang,Xuebin Li,Shaowei Jiang,Lin Chen,Liangjun Zhu,Huoxing Zhu,Jian-Guo Huang

doi:10.3390/f12101382

Abstract

As an important barrier against desert invasion in Northwest China, Helan Mountains (HL), Luoshan Mountains (LS) and their natural forests have an extremely important ecological status. It is of great significance to study the relationship between forest growth and climate in this region under the background of global change. At present, relevant research mostly focuses on the Chinese pine (Pinus tabulaeformis Carr.), and little is known about how Qinghai spruce (Picea crassifolia Kom.) responds to climate change. To investigate the potential relationships between radial growth of P. crassifolia and climatic conditions in Ningxia, China, we collected tree-ring samples from P. crassifolia growing in the HL and LS and then established the standard tree-ring width chronologies for the two sites. Correlation analysis together with multivariate linear regression and relative contribution analyses were used, and results showed that radial growth in the HL was determined by the precipitation in the previous September, by the standardized evapotranspiration index (SPEI) in the current March and June, and by the maximum air temperature in the current September. The maximum air temperature in the current September contributed the most (0.348) to the radial growth in the HL. In the LS, radial growth was determined by the precipitation in the previous September and in the current March and by the minimum air temperature in the current July. The factor that made the most contribution was the precipitation in the current March (0.489). Our results suggested that in the wetting and warming future, growth of P. crassifolia in the HL will increase while that in the LS needs further investigation. Our results also provide a basis for predicting how P. crassifolia in northwest China will grow under the background of future climate change and provide a reference for formulating relevant management measures to achieve ecological protection and sustainable development policies.

Highlights

Being vital massive carbon pools in the terrestrial ecosystems, forests are facing severe challenges posed by global warming
The high expressed population signal (EPS) and signal-to-noise ratio (SNR) values in the regional chronology for the Helan Mountains (HL) during the period 1950–2018 indicated that the chronology contains a high common signal, which may indicate the growth pattern of spruce in the HL
The parameter values for the regional chronology for the Luoshan Mountains (LS) are relatively lower than those for the HL, but they can describe the growth of Forests 2021, 12, x FOR PEER REVIEWspruce in the LS (Table 1)

Summary

Introduction

Being vital massive carbon pools in the terrestrial ecosystems, forests are facing severe challenges posed by global warming. Its forest covers mostly consist of coniferous species and are mainly distributed in mountainous areas The climate in this region has been getting warmer and wetter since the 1980s [15]. Jiang et al [12] studied the radial growth of larch (Larix sibirica Ledeb.) growing in the southern slope of the Altai Mountain They found that the low-elevation forest was affected by precipitation, whereas the high-elevation forest was affected by air temperature. Gao et al [19] found that the tree rings of S. przewalskii in the Qilian Mountains were limited by cold winter and drought in early spring They found that growth of Qinghai spruce (Picea crassifolia Kom.) growing in the lower elevation of the Qianlian Mountains was mainly correlated with moisture conditions in the previous late summer (July–August) and with air temperature in the current March, whereas in the upper tree line, it was limited by air temperature in the previous August and by precipitation in December [20].

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Results

Discussion

Conclusion