放牧强度对青海海北高寒矮嵩草草甸碳交换的影响
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摘要
以禁牧、轻度放牧、中度放牧和重度放牧4种不同放牧强度的高寒矮嵩草草甸为研究对象,分别于2014年和2015年植物生长季5～9月,使用LI-6400便携式光合仪和同化箱测定生态系统净CO_2交换(NEE)和生态系统呼吸(ER),并利用土壤温湿度自动记录仪测定土壤10cm处的温度和体积含水率,以研究放牧强度对青海海北高寒矮嵩草草甸碳交换的影响。结果表明:生长季5～9月,试验地10cm土壤温度的变化范围在7.21～13.23℃,随放牧强度增大而增大;体积含水率在19.68%～32.33%间波动,随放牧强度增大而减小。高寒草甸NEE在生长季表现出明显的"V"型变化,5月NEE最大,为1.43μmolCO_2/m~2·s,此时草地仍处于碳排放状态,7月最小(碳吸收速率最大),为-14.32μmolCO_2/m~2·s,吸收强度表现出随放牧强度增大而增大的趋势;ER呈倒"V"型变化规律,7月最大,为12.15μmolCO_2/m~2·s,放牧强度仅对7月的ER产生影响,其余月份4个样地差异均不显著。相关分析表明,NEE与土壤温度和绿体生物量极显著负相关,相关系数分别为-0.910和-0.559,与土壤湿度显著正相关,相关系数为0.559;ER与土壤温度和绿体生物量显著正相关,相关系数分别为0.824和0.453,与土壤有机碳含量极显著负相关,相关系数为-0.605,与土壤湿度、枯体生物量和全氮含量相关不显著。
In order to study the influence of grazing density on carbon exchange of alpine Kobresia meadow, net ecosystem CO_2 exchange(NEE) and ecosystem respiration(ER) was measured by LI-6400 and carbon assimilation chamber under four different grazing density(Forbidden grazing, light grazing, moderate grazing and heavy grazing) during the plant growing season of 2014 and 2015. The temperature and volumetric moisture content at 10 cm of soil were measured by an automatic soil temperature and humidity recorder. The results showed that 10 cm soil temperature changes in the range of 7.21～13.23℃, and with the grazing intensity increases; the volume moisture content fluctuated from 19.68% to 32.33% and with the grazing intensity decreased. NEE of alpine meadow showed obvious "V" type change during the growing season. The maximum value of NEE was 1.43μmol CO_2/m~2·s in May, and the grassland was still in the state of carbon emission. The minimum valve(The maximum carbon absorption rate) was-14.32μmol CO_2/m~2·s in July, and the absorption intensity increased with the increase of grazing intensity. ER showed an inverted "V" pattern, with the maximum value at 12.15μmol CO_2/m~2·s in July. Grazing intensity only affects the ER in July and the differences of ER between the four plots were not significant in the other months. The correlation analysis showed that NEE had significant negative correlation with soil temperature and fresh biomass, with correlation coefficients of-0.910 and-0.559, respectively, and had significant positive correlation with soil water content, with correlation coefficient of 0.559. ER had significant positive correlation with soil temperature and fresh biomass, with correlation coefficients of 0.824 and 0.453, respectively, and had significant negative correlation with soil organic carbon content, with correlation coefficient of-0.605. It had no significant correlations with soil water content, litter biomass and soil nitrogen content.
In order to study the influence of grazing density on carbon exchange of alpine Kobresia meadow, net ecosystem CO_2 exchange(NEE) and ecosystem respiration(ER) was measured by LI-6400 and carbon assimilation chamber under four different grazing density(Forbidden grazing, light grazing, moderate grazing and heavy grazing) during the plant growing season of 2014 and 2015. The temperature and volumetric moisture content at 10 cm of soil were measured by an automatic soil temperature and humidity recorder. The results showed that 10 cm soil temperature changes in the range of 7.21～13.23℃, and with the grazing intensity increases; the volume moisture content fluctuated from 19.68% to 32.33% and with the grazing intensity decreased. NEE of alpine meadow showed obvious "V" type change during the growing season. The maximum value of NEE was 1.43μmol CO_2/m~2·s in May, and the grassland was still in the state of carbon emission. The minimum valve(The maximum carbon absorption rate) was-14.32μmol CO_2/m~2·s in July, and the absorption intensity increased with the increase of grazing intensity. ER showed an inverted "V" pattern, with the maximum value at 12.15μmol CO_2/m~2·s in July. Grazing intensity only affects the ER in July and the differences of ER between the four plots were not significant in the other months. The correlation analysis showed that NEE had significant negative correlation with soil temperature and fresh biomass, with correlation coefficients of-0.910 and-0.559, respectively, and had significant positive correlation with soil water content, with correlation coefficient of 0.559. ER had significant positive correlation with soil temperature and fresh biomass, with correlation coefficients of 0.824 and 0.453, respectively, and had significant negative correlation with soil organic carbon content, with correlation coefficient of-0.605. It had no significant correlations with soil water content, litter biomass and soil nitrogen content.
引文
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[3] Houghton R A. Revised estimates of the annual net flux of carbon to the atmosphere from changes in land use and land management 1850-2000[J]. Tellus Series B-Chemical and Physical Meteorology, 2003, 55(2): 378-390.
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[6] 董全民,赵新全,马玉寿,等. 牦牛放牧率与小嵩草高寒草甸暖季草地地上、地下生物量相关分析[J]. 草业科学, 2005, 22(5): 65-71.Dong Quanmin, Zhao Xinquan,Ma Yushou, et al. Regressive analysis between stocking rate for yak and aboveground and underground biomass of warm-season pasture in Kobrecia parva alpine meadow[J]. Pratacultural Science, 2005, 22(5): 66-71.
[7] Cheng J, Wu G L, Zhao L P, et al. Cumulative effects of 20-year exclusion of livestock grazing on above- and belowground biomass of typical steppe communities in arid areas of the Loess Plateau, China[J]. Plant Soil & Environment, 2011, 57(1): 40-44.
[8] Sch?nbach P, Wan H, Gierus M, et al. Grassland responses to grazing: effects of grazing intensity and management system in an Inner Mongolian steppe ecosystem[J]. Plant & Soil, 2011, 340(1-2): 103-115.
[9] 傅华,陈亚明,王彦荣,等. 阿拉善主要草地类型土壤有机碳特征及其影响因素[J]. 生态学报, 2004, 24(3): 469-476.Fu Hua, Chen Yaming, Wang Yanrong, et al. Organic carbon content in major grassland types in Alex, Inner Mongolia[J]. Acta Ecologica Sinica, 2004, 24(3): 469-476.
[10] 张法伟,王军邦,李以康,等. 高寒嵩草草甸不同退化梯度下生态系统光合和呼吸响应特征[J]. 中国草地学报, 2016, 38(1): 34-40.Zhang Fawei, Wang Junbang, Li Yikang, et al. Response of ecosystem photosynthesis and respiration to degradation gradients in an alpine Kobersia meadow[J]. Chinese Journal of Grassland, 2016, 38(1): 34-40.
[11] 沈晓坤,刘明惠,张燕堃,等. 黄土高原围封与自然放牧草地碳交换特征[J]. 西北植物学报, 2014, 34(9): 1869-1877.Shen Xiaokun, Liu Minghui, Zhang Yankun, et al. Carbon exchange characteristics of fenced and natural grazed grassland in Loess Plateau[J]. Acta Botanic Boreali-Occidentalia Sinica, 2014, 34(9): 1869-1877.
[12] Li X, Zhang C, Hua F, et al. Grazing exclusion alters soil microbial respiration, root respiration and the soil carbon balance in grasslands of the Loess Plateau, northern China[J]. Soil Science & Plant Nutrition, 2013, 59(6): 877-887.
[13] Lecain D R, Morgan J A, Schuman G E, et al. Carbon exchange rates in grazed and ungrazed pastures of Wyoming[J]. Journal of Range Management, 2000, 53(2): 199-206.
[14] Liebig M A, Gross J R, Kronberg S L, et al. Soil response to long-term grazing in the northern Great Plains of North America[J]. Agriculture Ecosystems & Environment, 2006, 115(1): 270-276.
[15] 黄祥忠,郝彦宾,王艳芬,等. 极端干旱条件下锡林河流域羊草草原净生态系统碳交换特征[J]. 植物生态学报, 2006, 30(6): 894-900.Huang Xiangzhong, Hao Yanbin, Wang Yanfen, et al. Impact of extreme drought on net ecosystem exchange from Leymus chinensis steppe in Xilin river basin, China[J]. Journal of Plant Ecology, 2006, 30(6): 894-900.
[16] Raich J W, Schlesinger W H. The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate[J]. Tellus B: Chemical and Physical Meteorology, 1992, 44(2): 81-99.
[17] 高丽,董婷婷,王育青,等. 不同降雨量年份鄂尔多斯高原油蒿灌丛生态系统碳交换特征[J]. 应用生态学报, 2014, 25(8): 2167-2175.Gao Li, Dong Tingting, Wang Yuqing, et al. Ecosystem carbon exchange in Artemisia ordosica shrubland of Ordos plateau in two different precipitation years[J]. Chinese Journal of Applied Ecology, 2014, 25(8): 2167-2175.
[2] Maia S M F, Ogle S M, Cerri C E P, et al. Effect of grassland management on soil carbon sequestration in Rond?nia and Mato Grosso states, Brazil[J]. Geoderma, 2009, 149(1): 84-91.
[3] Houghton R A. Revised estimates of the annual net flux of carbon to the atmosphere from changes in land use and land management 1850-2000[J]. Tellus Series B-Chemical and Physical Meteorology, 2003, 55(2): 378-390.
[4] 陈晓鹏,尚占环. 中国草地生态系统碳循环研究进展[J]. 中国草地学报,2011, 33(4): 99-110.Chen Xiaopeng, Shang Zhanhuan. Progress of carbon cycle research in China grassland ecosystem[J]. Chinese Journal of Grassland,2011, 33(4): 99-110.
[5] Lin X, Zhang Z, Wang S, et al. Response of ecosystem respiration to warming and grazing during the growing seasons in the alpine meadow on the Tibetan plateau[J]. Agricultural & Forest Meteorology, 2011, 151(7): 802.
[6] 董全民,赵新全,马玉寿,等. 牦牛放牧率与小嵩草高寒草甸暖季草地地上、地下生物量相关分析[J]. 草业科学, 2005, 22(5): 65-71.Dong Quanmin, Zhao Xinquan,Ma Yushou, et al. Regressive analysis between stocking rate for yak and aboveground and underground biomass of warm-season pasture in Kobrecia parva alpine meadow[J]. Pratacultural Science, 2005, 22(5): 66-71.
[7] Cheng J, Wu G L, Zhao L P, et al. Cumulative effects of 20-year exclusion of livestock grazing on above- and belowground biomass of typical steppe communities in arid areas of the Loess Plateau, China[J]. Plant Soil & Environment, 2011, 57(1): 40-44.
[8] Sch?nbach P, Wan H, Gierus M, et al. Grassland responses to grazing: effects of grazing intensity and management system in an Inner Mongolian steppe ecosystem[J]. Plant & Soil, 2011, 340(1-2): 103-115.
[9] 傅华,陈亚明,王彦荣,等. 阿拉善主要草地类型土壤有机碳特征及其影响因素[J]. 生态学报, 2004, 24(3): 469-476.Fu Hua, Chen Yaming, Wang Yanrong, et al. Organic carbon content in major grassland types in Alex, Inner Mongolia[J]. Acta Ecologica Sinica, 2004, 24(3): 469-476.
[10] 张法伟,王军邦,李以康,等. 高寒嵩草草甸不同退化梯度下生态系统光合和呼吸响应特征[J]. 中国草地学报, 2016, 38(1): 34-40.Zhang Fawei, Wang Junbang, Li Yikang, et al. Response of ecosystem photosynthesis and respiration to degradation gradients in an alpine Kobersia meadow[J]. Chinese Journal of Grassland, 2016, 38(1): 34-40.
[11] 沈晓坤,刘明惠,张燕堃,等. 黄土高原围封与自然放牧草地碳交换特征[J]. 西北植物学报, 2014, 34(9): 1869-1877.Shen Xiaokun, Liu Minghui, Zhang Yankun, et al. Carbon exchange characteristics of fenced and natural grazed grassland in Loess Plateau[J]. Acta Botanic Boreali-Occidentalia Sinica, 2014, 34(9): 1869-1877.
[12] Li X, Zhang C, Hua F, et al. Grazing exclusion alters soil microbial respiration, root respiration and the soil carbon balance in grasslands of the Loess Plateau, northern China[J]. Soil Science & Plant Nutrition, 2013, 59(6): 877-887.
[13] Lecain D R, Morgan J A, Schuman G E, et al. Carbon exchange rates in grazed and ungrazed pastures of Wyoming[J]. Journal of Range Management, 2000, 53(2): 199-206.
[14] Liebig M A, Gross J R, Kronberg S L, et al. Soil response to long-term grazing in the northern Great Plains of North America[J]. Agriculture Ecosystems & Environment, 2006, 115(1): 270-276.
[15] 黄祥忠,郝彦宾,王艳芬,等. 极端干旱条件下锡林河流域羊草草原净生态系统碳交换特征[J]. 植物生态学报, 2006, 30(6): 894-900.Huang Xiangzhong, Hao Yanbin, Wang Yanfen, et al. Impact of extreme drought on net ecosystem exchange from Leymus chinensis steppe in Xilin river basin, China[J]. Journal of Plant Ecology, 2006, 30(6): 894-900.
[16] Raich J W, Schlesinger W H. The global carbon dioxide flux in soil respiration and its relationship to vegetation and climate[J]. Tellus B: Chemical and Physical Meteorology, 1992, 44(2): 81-99.
[17] 高丽,董婷婷,王育青,等. 不同降雨量年份鄂尔多斯高原油蒿灌丛生态系统碳交换特征[J]. 应用生态学报, 2014, 25(8): 2167-2175.Gao Li, Dong Tingting, Wang Yuqing, et al. Ecosystem carbon exchange in Artemisia ordosica shrubland of Ordos plateau in two different precipitation years[J]. Chinese Journal of Applied Ecology, 2014, 25(8): 2167-2175.
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