开垦对克氏针茅草地生态系统碳通量的影响

doi:10.3773/j.issn.1005-264x.2008.06.011

摘要/Abstract

摘要：

植被-大气间CO₂净交换及其对环境变化的响应是目前全球变化研究的热点问题。该研究通过同化箱式法, 在内蒙古农牧交错带对比研究生长季草地生态系统和耕种多年的小麦田生态系统碳通量的变化, 以探讨该地区碳通量的变化规律及影响碳通量主要因子, 并揭示农田开垦对草原碳通量的影响。结果显示: 两个生态系统的群落净气体交换(Net ecosystem exchange, NEE)有明显的季节变化。整个测定期间, 草地生态系统的净气体交换NEE的最高值为-11.26 µmol CO ₂·m^-2·s^-1, 平均群落净气体交换为-5.33 µmol CO ₂·m^-2·s^-1; 小麦田群落NEE最大值为-12.29 µmol CO ₂·m^-2·s^-1, 平均群落净气体交换为-7.66 µmol CO ₂·m^-2·s^-1。分析发现, 叶面积指数LAI是影响该地区生态系统NEE的主要因子, 相对贫瘠的土壤也是限制该地区生态系统碳固定的一个重要因子。因小麦的生长特性, 在生长中后期, 小麦田生态系统NEE随LAI的变化没有草地生态系统的敏感。此外, 较低的土壤含水量限制了小麦田群落呼吸, 使得小麦田群落呼吸对温度的敏感性降低。

关键词: 同化箱式法, 群落净交换, 群落呼吸, 叶面积指数

Abstract:

Aims In light of increasing interest in understanding carbon fluxes of terrestrial ecosystems under changing climate and escalating human influences, our study examined the dependence of carbon fluxes on abiotic and biotic factors and explored the effects of conversion of grassland to cropland on ecosystem C fluxes.

Methods Our study was carried out in Duolun (42^o02′ N, 116^o17′ E; 1 350 m asl), a semiarid agriculture-pasture transition region in southeastern Inner Mongolia, China. We used the chamber method during the growing season.

Important findings There was no difference in net ecosystem exchange of carbon dioxide (NEE) between wheat field and steppe at the beginning of the growing season. NEE of wheat field became higher than that of steppe in late June. No differences were found between the two ecosystems from mid-July to August 1st. NEE of wheat field became significantly lower than that of steppe starting in mid-August. During the growing season, the maximum of NEE in steppe was -11.26 µmol CO ₂·m^-2·s^-1, while that in wheat field was -12.29 µmol CO ₂·m^-2·s^-1. Mean NEE in steppe (-5.33 µmol CO ₂·m^-2·s^-1) was a little lower than that in wheat field (-7.66 µmol CO ₂·m^-2·s^-1). Leaf area index (LAI) was the main factor controlling NEE of the two ecosystems. Poor soil nutrient levels also might limit NEE in these ecosystems. Because of characteristics of wheat, the sensitivity of NEE response to LAIwas lower in wheat field than steppe in the middle and late growing season. Lower soil volume water content (10 cm depth) in wheat field limited total ecosystem respiration (TER) and decreased the sensitivity of TER to temperature.

Key words: chamber method, net ecosystem gas exchange, total ecosystem respiration, leaf area index

张文丽, 陈世苹, 苗海霞, 林光辉. 开垦对克氏针茅草地生态系统碳通量的影响. 植物生态学报, 2008, 32(6): 1301-1311. DOI: 10.3773/j.issn.1005-264x.2008.06.011

ZHANG Wen-Li, CHEN Shi-Ping, MIAO Hai-Xia, LIN Guang-Hui. EFFECTS ON CARBON FLUX OF CONVERSION OF GRASSLAND STEPPE TO CROPLAND IN CHINA. Chinese Journal of Plant Ecology, 2008, 32(6): 1301-1311. DOI: 10.3773/j.issn.1005-264x.2008.06.011

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链接本文: https://www.plant-ecology.com/CN/10.3773/j.issn.1005-264x.2008.06.011

https://www.plant-ecology.com/CN/Y2008/V32/I6/1301

图/表 8

图1 2006年生长季草地和小麦田生态系统主要环境因子的季节变化 DOY为一年中的天数 Ta, PAR分别为测定时大气的平均温度和光有效辐射 VWC, Ts分别为土壤10 cm深的体积含水量和温度, 其中1表示草地生态系统, 2表示小麦田生态系统。数值为当日测定期间(8:30~10:30)的平均值 Air temperature (Ta) photosynthetically-active radiation (PAR); Soil volume water content (VWC) at 10 cm deep; Soil temperature (Ts)at 10cm deep. “1” indicates steppe “2”indicates wheat field. The data shown are means of data from 8:30 to 10:30 in the measured day

Fig. 1 Seasonal changes of the main environments in steppe and wheat field during the growing season in 2006

图2 2006年生长季草地和小麦田生态系统的叶面积指数(LAI)和地上生物量(BA)的季节变化

Fig 2 Seasonal changes of leaf area index (LAI) and aboveground biomass (BA) in steppe and wheat field during the growing season in 2006

表1 草地和小麦田生态系统地上各部分生物量的季节变化(g·m-2)(平均值±标准误差)

Table 1 Seasonal changes of biomass of different parts of aboveground in steppe and wheat field (g·m-2)(Mean±SE)

天DOY	地上生物量 Aboveground biomass (g)	绿叶 Green leaf (g)		枯叶 Withered leaf (g)		茎 Sterm (g)		生殖穗 Spike (g)
天DOY	地上生物量 Aboveground biomass (g)	草地 Steppe	小麦田 Wheat	草地 Steppe	小麦田 Wheat	草地 Steppe	小麦田 Wheat	草地 Steppe	小麦田 Wheat
192	189.1±13.6	86.3±3.4				102.8±11.3
193	319.8±26.4		65.3±7.0		12.7±1.0		193.3±13.8		45.0±6.1
200	460±32.5		58.4±8.4		22.2±2.6		315.9±30.8		84.2±2.6
206	197.4±17.2	91.2±5.7				98.6±12.8
207	806.5±16.8		78.2±8.0		45.8±4.2		521.9±32.0		160.5±13.6
214	643.5±36.4		38.0±1.8		48.6±2.3		401.3±15.8		155.6±20.2
221	213.7±25.4	82.0±4.0		18.3±3.3		112.8±27.4		21.0±6.0
221	870.7±47.7		21.2±0.9		82.9±4.0		464.0±19.0		302.7±24.5
228	837.7±45.4		4.1±0.4		88.0±2.6		364.6±26.0		381.1±22.6
234	197.2±11.9	68.2±4.2		20.2±4.1		98.3±14.3		10.4±2.4
235	753.7±33.5		1.4±0.9		61.1±5.1		299.3±12.0		391.9±22.4
253	174.5±20.0	47.4±7.6		34.0±2.7		76.3±16.7		16.7±3.8
266	140.4±6.9	36.9±3.2		34.7±3.2		67.1±4.4		1.57±0.3

图3 2006年生长季草地(Steppe)和小麦田生态系统(Wheat)的群落气体净交换速率(NEE)(a)和群落呼吸速率(TER)(b)的季节变化负号表示碳吸收, 正号表示碳释放

Fig 3 Seasonal changes of net ecosystem exchange (NEE) (a) and total ecosystem respiration (TER) (b) of steppe and wheat field during the growing season in 2006 Negative indicates carbon uptake, positive indicates carbon release *: p <0.05 **: p <0.01

图4 2006年6月18日(DOY169)草地和小麦田生态系统的群落净气体交换速率(NEE)(a)、群落初级同化速率(PA)(b)和群落呼吸速率(TER)(c)的日变化负号表示碳吸收

Fig. 4 Diel variations of net ecosystem exchange (NEE) (a), primary assimilation (PA) (b) and total ecosystem respiration (TER) (c) on 18 June, 2006 in steppe and wheat field Negative means carbon uptake

图5 生长季草地和小麦田生态系统的群落净气体交换(NEE)与叶面积指数(LAI)的线性关系负号表示碳吸收

Fig. 5 Linear relationships between net ecosystem exchange (NEE) with leaf area index (LAI) in steppe and wheat field during the growing season Negative means carbon uptake

图6 生长季草地和小麦田生态系统的群落呼吸(TER)分别与土壤温度(Ts, 10 cm深)的线性关系

Fig. 6 Linear relationships between total ecosystem respiration (TER) and soil temperature at 10 cm depth (Ts) in the steppe and wheat field during the growing season

图7 生长季草地和小麦田生态系统的群落呼吸(TER)分别与土壤体积含水量(VWC, 10 cm深)的线性关系。

Fig. 7 Linear relationships between total ecosystem respiration (TER) and soil volume water content at 10 cm depth (VWC) in the steppe and wheat field during the growing season

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