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水热条件对锡林河流域典型草原退化群落土壤呼吸的影响
引用本文:陈全胜,李凌浩,韩兴国,阎志丹,王艳芬,袁志友.水热条件对锡林河流域典型草原退化群落土壤呼吸的影响[J].植物生态学报,2003,27(2):202-209.
作者姓名:陈全胜  李凌浩  韩兴国  阎志丹  王艳芬  袁志友
作者单位:中国科学院植物研究所植被数量生态学重点研究实验室,北京,100093
基金项目:国家重点基础研究发展规划项目 (G2 0 0 0 0 186 0 3G19990 4 34 0 7),中国科学院知识创新工程重大项目(KSCX1_0 8_0 3)
摘    要: 采用碱液吸收法对锡林河流域温带典型草原一退化群落的土壤呼吸进行了测定,并分析了温度和水分对土壤呼吸的影响,结果表明:1)土壤呼吸总体趋势是夏季高,其它季节低,但季节动态呈现不规律的波动曲线;2)气温、地表温度以及5 cm、10 cm、15 cm和25 cm的土壤温度均与土壤呼吸速率呈显著的指数关系,温度对土壤呼吸的影响在低温时比高温时更显著;3)0~10 cm和10~20 cm土层的土壤含水量均与土壤呼吸速率呈显著的线性关系,消除气温的影响后则呈更为显著的乘幂关系;4)根据变量在p=0.05水平上的多元回归分析结果得到关于土壤呼吸与气温和10~20 cm土壤含水量的关系模型:y=5 911.648×e0.04216Ta×M20. 90758 (R2=0.8584,p<0.0001) ,这一模型比单变量模型能更好地解释土壤呼吸的变化情况;5)实验期间土壤呼吸的平均速率为661.35 mgC·m-2·d-1,以气温、地表温度以及5 cm、10 cm、15 cm和25 cm的土壤温度为依据得到的Q10值依次为1.63、1.47、1.52、1.70、1.90、1.97。

关 键 词:土壤呼吸  退化草原  温度  土壤水分  Q10
修稿时间:2002年2月3日

INFLUENCE OF TEMPERATURE AND SOIL MOISTURE ON SOIL RESPIRATION OF A DEGRADED STEPPE COMMUNITY IN THE XILIN RIVER BASIN OF INNER MONGOLIA
CHEN Quan-Sheng,LI Ling-Hao,HAN Xing-Guo,YAN Zhi-Dan,WANG Yan-Fen and YUAN Zhi-You.INFLUENCE OF TEMPERATURE AND SOIL MOISTURE ON SOIL RESPIRATION OF A DEGRADED STEPPE COMMUNITY IN THE XILIN RIVER BASIN OF INNER MONGOLIA[J].Acta Phytoecologica Sinica,2003,27(2):202-209.
Authors:CHEN Quan-Sheng  LI Ling-Hao  HAN Xing-Guo  YAN Zhi-Dan  WANG Yan-Fen and YUAN Zhi-You
Abstract:Soil respiration is not only an indicator of belowground metabolic activity of roots and soil microbes, but also a necessary component of carbon cycle. Measurement of the CO2 efflux from soil and the determination of the relationship between soil respiration and environmental factors such as temperature and water regime are of great importance in understanding the carbon cycling processes in terrestrial and aquatic ecosystems. To evaluate the role that the degraded steppe ecosystems in the temperate China play in global carbon cycle and to determine the factors that regulate soil respiration in these ecosystems, we conducted field experiment to examine the soil respiration rate by using the alkali absorption technique in a degraded steppe community in the Xilin River Basin, Inner Mongolia. We also evaluated the influence of temperature and soil moisture on soil respiration rate. The research site is located in the Baiyinxile Livestock Farm (43°55′ N, 116°19′ E, with an altitude of about 1 200 m). This region has a typical temperate and semi_arid climate. The topography is basically flat with mild relief and the soil is classified as chestnut. The original vegetation was Leymus chinensis steppe, and, due to over_grazing in the past decades, the vegetation has degraded to some extent depending on habitat types and grazing intensity. More than 30 species of plants can be found in the region, among which Achillea frigida,Cleistogenes squarrosa and Carex korshinskyi are the most dominant, followed by L. chinensis, Stipa grandis, Agropyron cristatum, Heteropappus altaicus and Kochia prostrata in terms of their importance value. In addition,Caragana microphylla is sparsely scattered. The maximum coverage is about 40%.The seasonal pattern of CO2 efflux was irregular, though the rate of CO2 evolution was greater in summer than in other seasons. Significant relationships were found between CO2 evolution rate, ambient air temperature and soil temperature (the surface, 5 cm depth, 10 cm depth, 15 cm depth and 20 cm depth, respectively), which could be best described by exponential equations (R2=0.407-0.571 4, p=0.001 8-0.014 1). The influence of temperature was more conspicuous at lower temperature than at higher temperature conditions. This was consistent with the results reported by other researchers. Soil respiration rate was linearly correlated with soil gravimetric water content at 0-10 cm (R2=0.422 5, p=0.011 9) and 10 20 cm (R2=0.500 9, p=0.004 6), but more significant power functions could be obtained after removing the confounded effect by temperature (0-10 cm: R2=0.551 8, p=0.003 9; 10-20 cm: R2=0.645 1, p=0.000 8). The relationship between soil respiration rate (y) and the two variables of air temperature (Ta) and soil moisture at 10-20 cm soil depth (M2) could be described by the following multiple regression equation: y=5 911.648×e0.042 16Ta×M20. 907 58 (R2=0.858 4,p<0.000 1). This equation has much more predicative power than that using temperature and water as single independent variables. The mean soil respiration rate during the study period was 661.35 mg C·m-2·d-1, and the calculated Q10 values based on air temperature and soil temperature at surface, 5 cm, 10 cm, 15 cm and 20 cm depth were 1.63, 1.47, 1.52, 1.70, 1.90 and 1.97, respectively. Both Q10 and soil respiration rate were lower at our study site than at the original L. chinensis community studied by Li et al. (2000) in the adjacent area, possibly due to the difference in water content in the two sites. Our results implied that drought in the growing season tended to have lower Q10 values and lower soil respiration rate. We suggested that the variations in soil respiration and Q10 between degraded and undegraded L. chinensis steppe ecosystems as affected by other environmental factors need to be further studied.
Keywords:Soil respiration  Degraded steppe community  Temperat ure  Soil moisture  Q    10  
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