凋落物去除和添加处理对典型草原生态系统碳通量的影响

doi:10.17521/cjpe.2016.0083

摘要/Abstract

摘要：

为揭示凋落物去除和添加处理对草原生态系统碳通量的影响, 2013和2014年连续两年在成熟群落围封样地进行凋落物去除实验、在退化群落放牧样地进行凋落物添加实验, 并运用静态箱法探讨碳通量变化规律并分析其主要影响因子。结果表明: 两种群落的净生态系统CO₂交换(NEE)有明显的季节性变化。对成熟群落而言, 去除50%凋落物显著增加了NEE, 去除100%凋落物显著降低了NEE, 而对生态系统总初级生产力(GEP)和生态系统呼吸(ER)均无显著影响; 对退化群落而言, 凋落物添加显著增加了GEP和NEE, 而对ER无显著影响。两种群落的GEP与10 cm土壤温度显著正相关, 但NEE和GEP的变化规律与土壤温度相反, 与10 cm土壤湿度相同。由此可见, 凋落物去除和添加处理对生态系统碳通量的影响主要是改变土壤湿度和地上生物量,而不是改变土壤温度。该研究为合理利用凋落物改善草地生态系统管理和促进草地恢复提供了理论依据。

关键词: 凋落物, 生态系统总初级生产力, 生态系统呼吸, 生态系统净CO₂交换

Abstract:

Aims Our objectives were to investigate: 1) How does litter affect the ecosystem carbon fluxes in mature and degraded community ecosystems? and 2) What are the effects of litter on the ecosystem carbon fluxes of the two ecosystems?

Methods The study was carried out at Baiyinxile Ranch experiment site, which is located in the semiarid agriculture-pasture transition region in southeastern Nei Mongol, China. The treatments were litter removal (50% and 100%) in mature community and litter addition (50% and 100%) in degraded community. We measured net ecosystem CO₂ exchange (NEE) by the chamber method during the growing season of 2013 and 2014.

Important findings Our results showed that there were significant seasonal changes of NEE in both mature and degraded community. After the consecutive treatments for two years, in mature community, the 50% litter removal significantly increased NEE and the 100% litter removal significantly reduced the NEE, while litter removal had no significant effect on the ecosystem gross primary productivity (GEP) and ecosystem respiration (ER). In the degraded community, litter addition significantly increased NEE and GEP and had no effect on ER. Meanwhile, neither litter removal nor litter addition had significant effect on the total ecosystem respiration (ER). In both communities, the correlation between GEP and soil temperature at 10 cm was significantly positive (p < 0.05). However, the changes of GEP and NEE under litter treatments was contrary to the changes of soil temperature, and consistent with the changes of soil moisture content at 10 cm depth. We concluded that the mechanism underlying the effects of litter removal and addition on the carbon flux of ecosystem was mainly attributed to soil moisture and above ground biomass.

Key words: litter, gross ecosystem productivity, ecosystem respiration, net ecosystem CO₂exchange

张素彦, 蒋红志, 王扬, 张艳杰, 鲁顺保, 白永飞. 凋落物去除和添加处理对典型草原生态系统碳通量的影响. 植物生态学报, 2018, 42(3): 349-360. DOI: 10.17521/cjpe.2016.0083

ZHANG Su-Yan, JIANG Hong-Zhi, WANG Yang, ZHANG Yan-Jie, LU Shun-Bao, BAI Yong-Fei. Effects of litter removal and addition on ecosystem carbon fluxes in a typical steppe. Chinese Journal of Plant Ecology, 2018, 42(3): 349-360. DOI: 10.17521/cjpe.2016.0083

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2016.0083

https://www.plant-ecology.com/CN/Y2018/V42/I3/349

图/表 8

图1 2014-2015年日平均温度(曲线形)与日降水量(柱形) 动态。

Fig. 1 Dynamics of daily mean temperature (curve) and daily precipitation (bars) in 2014 and 2015.

表1 2013-2014年成熟群落不同处理下凋落物去除量(g·m-2)

Table 1 The amounts (g·m-2) of litter removal under different treatments in the mature community in 2013 and 2014

处理 Treatment	2013	2014
对照 Control	0	0
剪碎凋落物, 不移除0, litter cut but not removed	0	0
凋落物去除50% 50% litter removal	333	61
凋落物去除100% 100% litter removal	667	122

表2 2013-2014年退化群落不同处理下每平方米凋落物的添加量(g·m-2)

Table 2 The amounts (g·m-2) of litter addition under different treatments in the degraded community in 2013 and 2014

处理 Treatment	2013	2014
对照 Control	0	0
凋落物添加50% 50% litter addition	333	61
凋落物添加100% 100% litter addition	667	122

图2 2014-2015年成熟群落凋落物去除和退化群落凋落物添加对土壤温度和土壤水分的影响(平均值±标准误差)。不同小写字母a、b、c表示同一群落不同处理间差异显著(p < 0.05)。ns表示处理之间差异不显著(p > 0.05)。Control, 对照; -50%, 凋落物去除50%; -100%, 凋落物去除100%; +50%, 凋落物添加50%; +100%, 凋落物添加100%。

Fig. 2 Effects of litter removal in the mature community and litter addition in the degraded community on soil temperature and soil moisture in 2014 and 2015 (mean ± SE). Different small letters a, b and c indicate significant differences among treatments in the same community (p < 0.05). ns indicates no significant differences among treatments (p > 0.05). -50%, litter removal of 50%; -100%, litter removal of 100%; +50%, 50% litter addition; +100%, 100% litter addition.

图3 成熟群落凋落物去除和退化群落凋落物添加对地上生物量的影响(平均值±标准误差)。不同小写字母a、b表示同一群落不同处理间差异显著(p < 0.05)。ns表示处理之间差异不显著(p > 0.05)。Control, 对照; -50%, 凋落物去除50%; -100%, 凋落物去除100%; +50%, 凋落物添加50%; +100%, 凋落物添加100%。

Fig. 3 Effects of litter removal in the mature community and litter addition in the degraded community on aboveground biomass (mean ± SE). Different small letters a and b indicate significant differences among treatments in the same community (p < 0.05). ns indicates no significant differences among treatments (p > 0.05). -50%, litter removal of 50%; -100%, litter removal of 100%; +50%, 50% litter addition; +100%, 100% litter addition.

表3 凋落物去除和添加对生态系统总初级生产力(GEP)、生态系统呼吸(ER)和净生态系统CO2交换(NEE)影响的重复测量方差分析

Table 3 Effects of litter removal and addition on gross ecosystem productivity (GEP), ecosystem respiration (ER) and net ecosystem CO2 exchange (NEE) based on repeated measures ANOVA

指标 Index	因素 Factor	自由度 Degree of freedom	p值 p value
指标 Index	因素 Factor	自由度 Degree of freedom	成熟群落 Mature community	退化群落 Degraded community
GEP	时间 Time	5	0.000^****	0.000^****
	处理 Treatment	2	0.132	0.037^*
	时间×处理 Time × treatment	10	0.000^****	0.000^****
ER	时间 time	5	0.000^****	0.000^****
	处理 Treatment	2	0.605	0.709
	时间×处理 Time × treatment	10	0.047^*	0.189
NEE	时间 Time	5	0.000^****	0.000^****
	处理 Treatment	2	0.008^**	0.018^*
	时间×处理 Time × treatment	10	0.000^****	0.013^*

图4 两种群落凋落物去除和添加处理下生态系统总初级生产力(GEP)、生态系统呼吸(ER)和CO2净交换(NEE)的季节动态。不同小写字母a、b、c表示相同测定时间下不同处理间差异显著(p < 0.05)。ns表示处理之间差异不显著(p > 0.05)。 Control, 对照; -50%, 凋落物去除50%; -100%, 凋落物去除100%; +50%, 凋落物添加50%; +100%, 凋落物添加100%。

Fig. 4 Seasonal dynamics of net ecosystem CO2 exchange (NEE), ecosystem respiration (ER) and gross ecosystem productivity (GEP) under litter removal and addition treatments in the two communities. Different small letters a, b, and c indicate significant differences among treatments (p < 0.05). ns indicates no significant difference among treatments (p > 0.05). -50%, litter removal of 50%; -100%, litter removal of 100%; +50%, 50% litter addition; +100%, 100% litter addition.

图5 凋落物去除和添加两种群落生态系统总初级生产力(GEP)、生态系统呼吸(ER)和净生态系统CO2交换(NEE)与土壤温度的相关性分析。Control, 对照; -50%, 凋落物去除50%; -100%, 凋落物去除100%。+50%, 凋落物添加50%; +100%, 凋落物添加100%。

Fig. 5 Correlation analysis of the two communitiess of net ecosystem CO2 exchange (NEE), ecosystem respiration (ER) and gross ecosystem productivity (GEP) and soil temperature under litter removal and addition treatments. -50%, litter removal of 50%; -100%, litter removal of 100%; +50%, 50% litter addition; +100%, 100% litter addition.

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