极端干旱对草甸草原优势植物非结构性碳水化合物的影响

doi:10.17521/cjpe.2019.0331

摘要/Abstract

摘要：

植物光合作用产生的非结构性碳水化合物(NSCs)水平可以反映植物和生态系统对环境变化的响应程度。近年来, 草原极端干旱事件的发生频率和持续时间增加趋势明显, 对生态系统结构和功能产生深远影响。该研究以内蒙古呼伦贝尔草甸草原为研究对象, 通过连续4年减少66%生长季降水量的控制实验来模拟极端干旱事件, 分析草原6种优势物种和植物功能群NSCs各组分对极端干旱的响应规律与机制。结果显示, 由于植物生物学、光合特性以及生理生态等特性的差异, 不同物种对干旱胁迫的响应具有明显差异。这表明草地植物NSCs组分及其利用策略对干旱胁迫的响应具有物种特异性, 从而导致其生物量的不同响应。将6种植物分为禾草和非禾草两类, 发现干旱显著增加了禾草的淀粉含量, 但对其可溶性糖含量无显著影响; 相反, 干旱显著增加了非禾草功能群的可溶性糖含量, 对其淀粉含量无显著影响, 表明不同功能群采取了不同的干旱应对策略。禾草选择将光合作用固定的能量进行储存以应对干旱胁迫, 其生物量对干旱响应不敏感; 而非禾草选择将能量以可溶性糖的形式直接供植物生长利用以及抵御干旱胁迫, 其生物量对干旱响应较为敏感。这一发现可为预测在全球气候变化背景下草甸草原生态系统结构与功能对极端干旱的响应提供科学参考。

关键词: 极端干旱, 非结构性碳水化合物, 草原植物, 功能群, 生物量, 响应比

Abstract:

Aims Plant nonstructural carbohydrates (NSCs) produced by photosynthesis can reflect the responses of plants and/or ecosystem to environmental changes. Climate models recently predicted an increase in the frequency and duration of extreme drought (ED) events that could profoundly impact ecosystem structure and functions. Yet, less is understood about the response patterns of different plant species and functional groups to extreme drought.
Methods Here we studied the effects of extreme drought on the NSCs of dominant species belonging to different functional groups in grasslands. To achieve ED, we experimentally reduced precipitation amounts by 66% during four consecutive growing seasons in a meadow steppe in Hulunbeier, North China. The NSCs of six plants grouped into two functional groups (i.e., grass and non-grass) were examined.
Important findings We found different species responded differently to drought, due to their differences in plant biological characteristics, photosynthetic characteristics and physiological ecology. This result implied that different species used different NSC-use strategies to cope with drought stress, resulting in different responses of their biomass to extreme drought. Extreme drought significantly increased the starch concentrations, and had no effect on the soluble sugar concentrations of the grass functional group. Contrarily, ED significantly increased the soluble sugar concentrations, and had no significant effects on the starch concentrations of the non-grass functional group. These results indicate that grasses moderately use and store photosynthate to cope with drought stress, hence their biomass was less sensitive. The biomass of the non-grasses was more sensitive perhaps because they maximally utilize soluble sugar for plant growth, defense and reproduction. Our results showed that different species or functional groups exhibit different NSC-use strategies to cope with drought stress. This study could provide scientific data for predicting future ecosystem responses to extreme drought.

Key words: extreme drought, nonstructural carbohydrates, grassland plants, functional groups, biomass, response ratio

宋琳, 雒文涛, 马望, 何鹏, 梁潇洒, 王正文. 极端干旱对草甸草原优势植物非结构性碳水化合物的影响. 植物生态学报, 2020, 44(6): 669-676. DOI: 10.17521/cjpe.2019.0331

SONG Lin, LUO Wen-Tao, MA Wang, HE Peng, LIANG Xiao-Sa, WANG Zheng-Wen. Extreme drought effects on nonstructural carbohydrates of dominant plant species in a meadow grassland. Chinese Journal of Plant Ecology, 2020, 44(6): 669-676. DOI: 10.17521/cjpe.2019.0331

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2019.0331

https://www.plant-ecology.com/CN/Y2020/V44/I6/669

图/表 4

图1 干旱处理对草甸草原降水量发生概率及土壤含水量的影响(平均值±标准误差)。

Fig. 1 Effects of drought treatment on precipitation probability and soil moisture content in a meadow grassland (mean ± SE).

表1 干旱处理、物种/功能群及其交互作用对草甸草原优势植物生物量和植物非结构性碳水化合物(NSCs)各组分含量及其比值影响的混合效应模型结果

Table 1 Results of mixed-effect model analysis of drought treatment, species/functional group and their interactions on the nonstructural carbohydrates (NSCs), soluble sugars (SS) and starch (ST) concent and biomass of different species in a meadow grassland

	生物量 Biomass		可溶性糖 SS		淀粉 ST		可溶性糖/淀粉 SS/ST		NSCs
	F	p	F	p	F	p	F	p	F	p
物种 Species
干旱 Drought (D)	2.195	0.146	33.645	<0.001	0.216	0.645	12.937	0.001	27.713	<0.001
物种 Species (S)	28.212	<0.001	36.017	<0.001	8.115	<0.001	47.012	<0.001	20.478	<0.001
干旱×物种 D × S	0.558	0.732	25.508	<0.001	3.321	0.012	13.872	<0.001	19.880	<0.001
功能群 Functional group
干旱 Drought (D)	0.960	0.332	5.528	0.023	0.130	0.720	2.144	0.149	6.627	0.013
功能群 Functional (F)	26.055	<0.001	1.510	0.225	0.459	0.501	0.412	0.524	2.185	0.145
干旱×功能群 D × F	0.154	0.696	0.014	0.905	6.236	0.016	0.326	0.571	0.280	0.599

图2 草甸草原物种和功能群植物生物量对干旱处理的响应。 Grass, 禾草功能群; Non-grass, 非禾草功能群。其中响应比为干旱与对照小区中非结构性碳水化合物(NSCs)的比值, 水平误差条表示95%的置信区间, 皆由R语言中的“metaphor”包计算得出。圆代表物种, 方块代表功能群; 实心表示响应显著(p < 0.05), 空心表示响应不显著。

Fig. 2 Response ratio of the biomass of six herbaceous species and different plant functional groups to drought in a meadow grassland. T.l., Thermopsis lanceolata; A.f., Artemisia frigida; C.d., Carex duriuscula; Cy.d., Cymbaria dahurica; L.c., Leymus chinensis; S.b., Stipa baicalensis; Grass, grass functional group; Non-grass, non-grass functional group. The response ratio is biomass (drought)/biomass (control), the horizontal error bars represent the 95% confidence interval, which are calculated by “metaphor” in R. Solid circles indicate the significant responses of herbaceous plant species level nonstructural carbohydrates (NSCs) to drought (p < 0.05), while the hollow circles represent no significant response. Solid squares represent significant response of NSCs in different functional groups to drought, while hollow squares represent no significant response.

图3 草甸草原不同物种和功能群植物叶片可溶性糖含量(A)、淀粉含量(B)、可溶性糖/淀粉(C)及非结构性碳水化合物(NSCs) 含量(D)对干旱的响应。水平误差条表示95%的置信区间。圆代表物种, 方块代表功能群; 实心表示响应显著(p < 0.05), 空心表示响应不显著。

Fig. 3 Response ratio of soluble sugar content (A), starch concentrations content (B), soluble sugar/starch ratios (C) and nonstructural carbohydrates (NSCs) content (D) in leaves of six herbaceous species and two plant functional groups to drought treatments. T.l., Thermopsis lanceolata; A.f., Artemisia frigida; C.d., Carex duriuscula; Cy.d., Cymbaria dahurica; L.c., Leymus chinensis; S.b., Stipa baicalensis; Grass, grass functional group; Non-grass, non-grass functional group. The horizontal error bars represent the 95% confidence interval. Solid circles indicate the significant responses of herbaceous plant species level NSCs to drought (p < 0.05), while the hollow circles represent no significant response. Solid squares represent significant response of NSCs in different functional groups to drought, while hollow squares represent no significant response.

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