Carbon Cycles of Forest Ecosystems in a Typical Climate Transition Zone under Future Climate Change: A Case Study of Shaanxi Province, China

Siqi Liang,Yunming Chen,Shouzhang Peng

doi:10.3390/f10121150

Abstract

As global climate change has a large effect on the carbon cycle of forests, it is very important to understand how forests in climate transition regions respond to climate change. Specifically, the LPJ-GUESS (Lund-Potsdam-Jena General Ecosystem Simulator) model was used to simulate net ecosystem productivity (NEP) and soil heterotrophic respiration (Rh) dynamics of two forest ecosystems of different origins between 1951 and 2100, to quantitatively analyze the carbon source and sink functions and potential changes in soil carbon dynamics in arid and humid regions under future climate change, simulate the dynamics of forest net primary productivity (NPP) under different climatic factors, and analyze the sensitivity of forests in arid and humid regions to temperature, precipitation, and carbon dioxide (CO2) concentration. We found that: (1) in both the historical and future periods, the average NEP of both studied forests in the humid region was larger than that in the arid region, the carbon sink function of the humid region being predicted to become stronger and the arid zone possibly becoming a carbon source; (2) between 1951 and 2100, the forest soil Rh in the arid region was lower than that in the humid region and under future climate change, forest in the humid region may have higher soil carbon loss; (3) increasing temperature had a negative effect and CO2 concentration had a positive effect on the forests in the study area, and forests in arid areas are more sensitive to precipitation change. We believe our research could be applied to help policy makers in planning sustainable forest management under future climate change.

Highlights

Since the industrial revolution, atmospheric CO2 concentration has increased from 280 ppmv before the industrial revolution to 400 ppmv at present, and the global average surface temperature has increased by 0.85 ◦ C [1]
Under the three representative concentration path (RCP) scenarios, the average net ecosystem productivity (NEP) of R. pseudoacacia and Q. wutaishanica forests in arid regions were predicted to range between 5.8–78.3 g C m−2 yr−1 and 30.2–63.1 g C m−2 yr−1, respectively, and the average NEPs in humid regions were predicted as 78.5–124.9 g C m−2 yr−1 and 83.9–131.2 g C m−2 yr−1, respectively
Our results show that forest NEP increases with the increase of emission intensity in future climate change, which may be attributed to higher CO2 concentration in high emission intensity, because forest net primary productivity (NPP) is most sensitive to increases in CO2 concentration, which only provides more organic carbon for the forest’s underground carbon pool but does not directly promote soil Rh

Summary

Introduction

Atmospheric CO2 concentration has increased from 280 ppmv before the industrial revolution to 400 ppmv at present, and the global average surface temperature has increased by 0.85 ◦ C [1]. Previous studies on the impact of climate change on the carbon cycle of forest ecosystems have mainly focused on single climatic zones [3,4,5], while forest ecosystems located in different climatic zones are likely to respond differently to climate change. Forests 2019, 10, 1150 of 0.6 ◦ C 10 yr−1 [6], which is far higher than the global average of 0.27 ◦ C 10 yr−1 [7], and together with average temperature, seasonal precipitation has changed significantly [8]. These climate changes are evident in northern China [9].

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Discussion

Conclusion