短期增温对紫花针茅草原土壤微生物群落的影响

doi:10.17521/cjpe.2017.0297

摘要/Abstract

摘要：

土壤微生物是生态系统碳循环的重要参与者和调控者。全球变暖可能对土壤微生物群落产生影响, 加速陆地生态系统向大气中释放碳, 进而引起陆地碳循环对气候变暖的正反馈。然而, 目前学术界对土壤微生物群落如何响应气候变暖等问题认识不足, 尤其是缺乏低温干旱条件下土壤微生物对增温响应的实验证据。为此, 该文依托青藏高原紫花针茅(Stipa purpurea)草原建立的增温实验平台, 基于磷脂脂肪酸(PLFA)方法测定了2015和2016年生长季表层(0-10 cm)土壤微生物各类群的生物量, 在此基础上揭示气候变暖对紫花针茅草原土壤微生物群落结构的影响。结果显示, 短期增温处理导致2015和2016年生长季(5-10月)的表层土壤温度均显著提高1.6 ℃, 同时也导致土壤含水量显著下降了3.4%和2.4% (体积分数), 但并没有显著改变土壤化学性质及归一化植被指数。增温处理下, 两年生长季旺期(8月)的微生物生物量碳(MBC)含量分别为749.0和844.3 mg·kg ^-1, 微生物生物量氮(MBN)含量为43.1和102.1 mg·kg ^-1, 微生物生物量碳氮比分别为17.9和8.4, 但实验期间MBC、MBN和微生物生物量碳氮比与对照没有差异。PLFA分析的结果显示细菌在微生物群落中占主导, 而丛枝菌根真菌含量最少, 增温处理并没有改变不同类群的微生物生物量以及群落结构。进一步的分析显示, 土壤温度和含水量是调控土壤微生物群落变异的主要因子, 并且增温导致的微生物生物量碳的变化量分别与土壤温度和含水量的变化量呈显著正相关关系。以上结果表明, 由于受水分的限制, 短期增温对紫花针茅草原土壤微生物群落没有显著影响。

关键词: 气候变暖, 磷脂脂肪酸, 微生物群落, 青藏高原, 高寒草原

Abstract:

Aims Soil microbe plays key role in mediating terrestrial carbon cycles. It has been suggested that climate warming may affect the microbial community, which may accelerate carbon release and induce a positive feedback to soil climate warming. However, there is still controversy on how microbial community responds to experimental warming, especially in cold and drought environment.

Methods We conducted an open top chambers (OTCs) experiment to explore the effects of warming on soil microbial community in an alpine steppe on Qinghai-Xizang Plateau. During the maximum of the growing seasons (August) of 2015 and 2016, we monitored the biomass and structure of soil microbial community in warming and control plots using phospholipid fatty acids (PLFA) as biomarkers.

Important findings Short-term warming treatment significantly increased the soil temperature by 1.6 and 1.6 oC and decreased soil moisture by 3.4% and 2.4% (volume fraction) respectively, but did not alter either soil properties or normalized difference vegetation index (NDVI) during the growing season (from May to October) in 2015 and 2016. During the maximum of growing seasons (August) of 2015 and 2016, the magnitude of microbial biomass carbon (MBC) were 749.0 and 844.3 mg·kg^-1, microbial biomass nitrogen (MBN) were 43.1 and 102.1 mg·kg^-1, and the microbial biomass C:N ranged between 17.9 and 8.4. Moreover, all three showed no significant differences between warming and control treatments. The abundance of bacteria was the most in microbial community, while arbuscular mycorrhizal fungi was the least, and warming treatment did not alter the abundance of different microbial group and the microbial community structure. Nonetheless, our result revealed that warming-induced changes in MBC had significant positive correlation with changes in soil temperature and soil moisture. These patterns indicate that, microbial community in this alpine steppe may not respond substantially to future climate warming due to the limitation of soil drought. Therefore, estimation of microbial community response to climate change calls for consideration on the combined effect of warming and drought.

Key words: climate warming, phospholipid fatty acids (PLFA), microbial community, Qinghai-Xizang Plateau, alpine steppe

王军, 王冠钦, 李飞, 彭云峰, 杨贵彪, 郁建春, 周国英, 杨元合. 短期增温对紫花针茅草原土壤微生物群落的影响. 植物生态学报, 2018, 42(1): 116-125. DOI: 10.17521/cjpe.2017.0297

WANG Jun, WANG Guan-Qin, LI Fei, PENG Yun-Feng, YANG Gui-Biao, YU Jian-Chun, ZHOU Guo-Ying, YANG Yuan-He. Effects of short-term experimental warming on soil microbes in a typical alpine steppe. Chinese Journal of Plant Ecology, 2018, 42(1): 116-125. DOI: 10.17521/cjpe.2017.0297

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2017.0297

https://www.plant-ecology.com/CN/Y2018/V42/I1/116

图/表 7

表1 短期增温对土壤理化性质及地上植被的影响

Table 1 Short-term warming effects on soil physicochemical properties and standing vegetation

土壤因子 Soil factors	2015年		2016年
土壤因子 Soil factors	对照 Control	增温 Warming	对照 Control	增温 Warming
土壤温度 Soil temperature (℃)	12.80 ± 0.30	14.40 ± 0.20^**	13.90 ± 0.20	15.40 ± 0.30^**
土壤含水量(体积分数) Soil moisture (volume fraction)	13.20 ± 1.80	9.80 ± 1.10^**	15.60 ± 1.80	13.30 ± 1.20^*
有机碳含量 Soil organic carbon content (%)	3.20 ± 0.20	3.20 ± 0.20	3.30 ± 0.10	3.32 ± 0.10
总碳含量 Total carbon content (%)	4.50 ± 0.20	4.40 ± 0.20	4.20 ± 0.10	4.50 ± 0.10
全氮含量 Total nitrogen content (%)	0.38 ± 0.02	0.38 ± 0.02	0.38 ± 0.01	0.38 ± 0.01
碳氮比	8.50 ± 0.20	8.60 ± 0.20	8.70 ± 0.20	8.80 ± 0.20
归一化植被指数 Normalized difference vegetation index	0.27 ± 0.01	0.26 ± 0.01	0.18 ± 0.02	0.19 ± 0.02

图1 2015(A)和2016年(B)生长季(8月)对照与增温处理下的土壤微生物生物量碳(MBC)、氮(MBN)、微生物生物量碳氮比(C:N)及MBC与MBN之间的关系(平均值±标准误差)。灰色柱条和圆圈为增温处理; 白色柱条和圆圈为对照处理。

Fig. 1 Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial biomass C:N under control and warming treatment during the growing season (August) in 2015 (A) and 2016 (B), as well as the relationships between MBC and MBN (mean ± SD). The gray bars and cycles represent warming treatments. The white bars and cycles represent control treatments.

图2 短期增温对不同土壤微生物类群的影响(平均值±标准误差)。A, 2015年。B, 2016年。Actinomycetes, 放线菌; AMF, 丛枝菌根真菌; Bacteria, 细菌; Fungi, 真菌; G+, 革兰氏阳性菌; G-, 革兰氏阴性菌; F/B, 真菌与细菌比值; G+/G-, 革兰氏阳性菌与阴性菌比值; S/M, 饱和脂肪酸与不饱和脂肪酸比值。

Fig. 2 Effects of short-term experimental warming on different soil microbial groups (mean ± SD). A, In 2015. B, In 2016. AMF, arbuscular mycorrhizal fungi; G+, gram-positive bacteria; G-, gram-negative bacteria; F/B, ratio of fungi and bacteria; G+/G-, ratio of gram-positive bacteria and gram-negative bacteria; S/M, ratio of saturated PLFAs and monosaturated PLFAs.

表2 基于双因素方差分析得到的短期增温(W)、取样时间(T)及其交互作用(W × T)对微生物群落的影响(F值)

Table 2 Results (F values) of two-way ANOVA on the effects of short-term warming (W), sampling date (T), and their interactions (W × T) on microbial community

微生物群落 Microbial community	T	W	W × T
细菌 Bacteria	159.90^**	0.11	4.30^*
革兰氏阳性菌 Gram-positive bacteria	173.66^**	0.93	2.56
革兰氏阴性菌 Gram-negative bacteria	67.70^**	0.00	2.50
丛枝菌根真菌 Arbuscular mycorrhizal fungi	7.20^*	8.49^*	0.03
真菌 Fungi	2.12	0.18	2.13
放线菌 Actinomycetes	24.28^**	5.37^*	0.02
真菌细菌比 Fungi/Bacteria	123.85^**	0.15	0.01
G⁺/G^- Gram-positive bacteria/Gram-negative bacteria	0.27	0.45	0.28
饱和与不饱和脂肪酸比 Saturated PLFAs / Monosaturated PLFAs	7.13^*	2.24	0.86
磷脂脂肪酸总量 Total phospholipid fatty acids	157.39^**	1.67	1.08

图3 短期增温对土壤微生物群落结构的影响(平均值±标准误差)。A, 2015年。B, 2016年。

Fig. 3 Effects of short-term experimental warming on soil microbial community structure (mean ± SE). A, In 2015. B, In 2016.

图4 基于冗余分析得到的2015和2016年微生物群落与环境因子之间的关系。Actinomycetes, 放线菌; AMF, 丛枝菌根真菌; Bacteria, 细菌; Fungi, 真菌; G+, 革兰氏阳性菌; G-, 革兰氏阴性菌; F/B, 真菌与细菌比值; G+/G-, 革兰氏阳性菌与阴性菌比值; SM, 土壤含水量; ST, 土壤温度; TN, 全氮含量。

Fig. 4 Redundancy analysis of soil microbial community to soil environmental parameters. AMF, arbuscular mycorrhizal fungi; G+, gram-positive bacteria; G-, gram-negative bacteria; F/B, ratio of fungi and bacteria; G+/G-, ratio of gram-positive bacteria and gram-negative bacteria; SM, soil moisture; ST, soil temperature; TN, total nitrogen content.

图5 土壤微生物生物量碳变化量(增温-对照)与土壤温度的变化量(增温-对照, A)、土壤水分的变化量(增温-对照, B)之间的关系及短期增温对土壤温度和土壤含水量的影响。

Fig. 5 Relationships among warming-induced changes (warming-control) in microbial biomass carbon, soil temperature (A) and soil moisture (B), and the effects of short-term warming on soil temperature and moisture.

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