不同幅度的实验增温对藏北高寒草甸净生态系统碳交换的影响

doi:10.17521/cjpe.2016.0186

摘要/Abstract

摘要：

全球气候变暖将对陆地生态系统(尤其是高寒草甸生态系统)碳循环产生深远影响。该研究依托中国科学院地理科学与资源研究所藏北高原草地生态系统研究站(那曲站), 设置不同增温幅度实验, 模拟未来2 ℃增温和4 ℃增温的情景, 探究不同增温幅度对青藏高原高寒草甸净生态系统碳交换(NEE)的影响。研究结果显示: 1)在2015年生长季(6-9月), 不增温和2 ℃增温处理下NEE小于0, 总体表现为碳汇, 而4 ℃增温处理下NEE大于0, 总体表现为碳源; 2)在生长季的6月、8月及整个生长季, 与不增温相比, 4 ℃增温处理显著提高了NEE, 而2 ℃增温处理没有显著改变NEE; 7月, 2 ℃和4 ℃增温处理均显著提高了NEE; 3)在半干旱的高寒草甸生态系统, 土壤水分是决定NEE的关键因素, 增温通过降低土壤水分而导致高寒草甸生态系统碳汇能力下降。该研究可为青藏高原高寒草甸生态系统应对未来气候变化提供基础数据和理论依据。

关键词: 气候变暖, 高寒草甸, 净生态系统碳交换, 碳收支, 藏北高原

Abstract: AimsGlobal warming could have profound effects on ecosystem carbon (C) fluxes in alpine ecosystems. The aim of our study is to examine the effects of gradient warming on net ecosystem carbon exchange (NEE).MethodsIn the Northern Tibetan Grassland Ecosystem Research Station (Nagqu station), Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, we conducted various levels of temperature increasing experiments (i.e., 2 °C and 4 °C increments). The warming was achieved using open-top chambers (OTCs). In total, there were three levels of temperature treatments (control, 2 °C and 4 °C increment), and four replicates for each treatment. The ecosystem NEE was monitored every five days during the growing season in 2015.Important findings Our findings highlight the importance of soil moisture in mediating the responses of NEE to climatic warming in alpine meadow ecosystem. The 4 °C warming significantly stimulated NEE,except for July measurements. The 2 °C warming had no effects on NEE during the growing season. Compared to the 2 °C warming, the 4 °C warming significantly stimulated NEE. The results showed that our targeted ecosystem acts as a carbon sink under 2 °C warming, whereas will act as a net carbon source under 4 °C warming in the future. This study provides basic data and theoretical basis for evaluating the alpine ecosystem’s responses to climate change.

Key words: global warming, alpine meadow, net ecosystem carbon exchange, carbon budget, Northern Xizang plateau

朱军涛, 陈宁, 张扬建, 刘瑶杰. 不同幅度的实验增温对藏北高寒草甸净生态系统碳交换的影响. 植物生态学报, 2016, 40(12): 1219-1229. DOI: 10.17521/cjpe.2016.0186

Jun-Tao ZHU, Ning CHEN, Yang-Jian ZHANG, Yao-Jie LIU. Effects of experimental warming on net ecosystem CO₂ exchange in Northern Xizang alpine meadow. Chinese Journal of Plant Ecology, 2016, 40(12): 1219-1229. DOI: 10.17521/cjpe.2016.0186

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2016.0186

https://www.plant-ecology.com/CN/Y2016/V40/I12/1219

图/表 6

图1 植物生长季日降水量(柱状图)(P)与不同增温幅度的土壤湿度(折线图)。CK, 不增温; W1、W2分别代表模拟未来增温2 ℃和4 ℃的实验处理。

Fig. 1 Daily precipitation (bars) (P) and soil moisture (lines) under different warming treatments during the plant growing season. CK, no warming; W1, W2 represent the simulation of future temperature increase of 2 °C and 4 °C experimental treatment.

图2 植物生长季不同增温幅度处理下的土壤温度(A)和土壤湿度(B) (平均值±标准误差)。CK, 不增温; W1、W2分别代表模拟未来增温2 ℃和4 ℃的实验处理。不同小写字母表示在0.05水平上差异显著。

Fig. 2 Soil temperature (A), soil moisture (B) during the growing season under different warming treatments (mean ± SE). CK, no warming; W1, W2 represent the simulation of future temperature increase 2 °C and 4 °C. The different lowercase letters at the top of the figures represent significant differences at the 0.05 level.

表1 增温(W)、测量时间(T)及其交互作用(T × W)对净生态系统碳交换(NEE)的影响的重复测量方差分析结果

Table 1 Results (F values) of repeated-measurement ANOVA on the effects of warming (W), measuring date (T), and their interactions (T × W) on net ecosystem CO2 exchange (NEE)

	生长季 Growing season		6月 June		7月 July		8月 August
	df	F	df	F	df	F	df	F
T	2.25	23.38^***	2	45.78^***	2.18	8.93^***	5	19.22^***
W	2.00	8.72^**	2	6.58^**	2.00	6.58^**	2	4.77^*
T × W	4.51	2.27	4	0.47	2.00	13.57^***	10	0.74

图3 植物生长季不同增温实验处理下的净生态系统碳交换(NEE, A)、生态系统呼吸(ER, B)和生态系统总初级生产力(GPP, C)的季节动态(平均值±标准误差)。CK, 不增温; W1、W2分别代表模拟未来增温2 ℃和4 ℃的实验处理。

Fig. 3 Seasonal dynamics of net ecosystem CO2 exchange (NEE, A) , ecosystem respiration (ER, B) and gross primary productivity (GPP, C) during the growing season under different warming treatments (mean ± SE). CK, no warming; W1, W2 represent the simulation of future temperature increase 2 °C and 4 °C.

图4 植物生长季不同月份实验增温对净生态系统碳交换(NEE)的影响。A, 6月。B, 7月。C, 8月。D, 2015年生长季。CK, 不增温; W1、W2分别代表模拟未来增温2 ℃和4 ℃的实验处理。各图中上方的不同字母代表在0.05水平上差异显著。

Fig. 4 Different warming treatments effect on net ecosystem CO2 exchange (NEE) in different months during the growing season. A, June. B, July. C, August. D, Growing season in 2015. CK, no warming; W1, W2 represent the simulation of future temperature increase 2 °C and 4 °C. The different letters at the top of the figures represent significant differences at the 0.05 level.

图5 土壤湿度、土壤温度与净生态系统碳交换(NEE)的回归分析。

Fig. 5 Regression analysis for the relationships between net ecosystem CO2 exchange (NEE) and soil moisture, soil temperature．

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