Plant communities of Leymus chinensis , L.chinensis - Artimisia frigida , Stipa grandis , S.krylovii ,and A.intramongolica were transported into experimental station from the field keeping their previous states.The soils were carefully moved with aboveground plants with a depth of 30cm.Soil respiration rate were measured by dynamic chamber/IRGA methods during the main growth period of communities(from later May to later August).The results showed that the soil respiration were significant difference with diurnal and seasonal dynamics.The aboveground biomass and soil respiration were closely correlated of Artimisia community.The rate of soil CO 2 release from A.intramongolica community was consistently lower than other communities,and L.chinensis was higher.only for A.intramongoica was aboveground biomass highly positively correlated with seasonal soil respiration.Temperatures of air and soil had effects on diurnal and seasonal CO 2 release rate.Temperature of 50cm soil layers explained most of the variance of soil respiration.Soil water content had little influence on soil respiration of A.intramongolica communities while it controlled the soil bioactivities of other communities.

从野外选取有代表性的羊草、羊草-冷蒿、大针茅、克氏针茅和沙蒿群落,原状移栽到试验场。采用动态气室/IRGA法在植物主要生长期,连续测定各群落的土壤呼吸。结果表明,土壤呼吸速率具有明显的昼夜变化和季节动态。沙蒿群落土壤呼吸速率和土壤CO 2 排放总量低于其它群落,羊草群落CO 2 日排放量和CO 2 总排放量较高。沙蒿群落地上部生物量与土壤呼吸呈高度正相关。气温和土壤温度对CO 2 排放速度日变化及季节变化都有一定的影响,其中地温能解释土壤呼吸变异的绝大部分。水分对沙蒿群落的影响不大,但对羊草等群落的土壤生物活性有控制作用。

Soil respiration is not only an indicator of belowground metabolic activityof roots and soil microbes, but also a necessary component of carbon cycle. Measurementof the CO2 efflux from soil and the determination of the relationship between soilrespiration and environmental factors such as temperature and water regime are of greatimportance in understanding the carbon cycling processes in terrestrial and aquaticecosystems. To evaluate the role that the degraded steppe ecosystems in the temperateChina play in global carbon cycle and to determine the factors that regulate soilrespiration in these ecosystems, we conducted field experiment to examine the soilrespiration rate by using the alkali absorption technique in a degraded steppe communityin the Xilin River Basin, Inner Mongolia. We also evaluated the influence of temperatureand soil moisture on soil respiration rate. The research site is located in the BaiyinxileLivestock Farm (43°55′ N, 116°19′ E, with an altitude of about 1 200 m). This regionhas a typical temperate and semi_arid climate. The topography is basically flat withmild relief and the soil is classified as chestnut. The original vegetation was Leymuschinensis steppe, and, due to over_grazing in the past decades, the vegetation hasdegraded to some extent depending on habitat types and grazing intensity. More than 30species of plants can be found in the region, among which Achillea frigida，Cleistogenessquarrosa and Carex korshinskyi are the most dominant, followed by L. chinensis, Stipagrandis, Agropyron cristatum, Heteropappus altaicus and Kochia prostrata in terms oftheir importance value. In addition,Caragana microphylla is sparsely scattered. Themaximum coverage is about 40%.The seasonal pattern of CO2 efflux was irregular, thoughthe rate of CO2 evolution was greater in summer than in other seasons. Significantrelationships were found between CO2 evolution rate, ambient air temperature and soiltemperature (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=0.407-0.5714, p=0.001 8-0.014 1). The influence of temperature was more conspicuous at lowertemperature than at higher temperature conditions. This was consistent with the resultsreported by other researchers. Soil respiration rate was linearly correlated with soilgravimetric 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 theconfounded 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 variablesof air temperature (Ta) and soil moisture at 10-20 cm soil depth (M2) could be describedby the following multiple regression equation: y=5 911.648×e0.042 16Ta×M20. 907 58 (R2=0.8584,p<0.000 1). This equation has much more predicative power than that using temperatureand water as single independent variables. The mean soil respiration rate during thestudy period was 661.35 mg C·m-2·d-1, and the calculated Q10 values based on air temperatureand 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 lowerat 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 valuesand lower soil respiration rate. We suggested that the variations in soil respirationand Q10 between degraded and undegraded L. chinensis steppe ecosystems as affected byother environmental factors need to be further studied.

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。

应用静态气室法测定了碱茅群落的土壤呼吸和枯枝落叶分解释放 CO2 贡献量的季节动态 ,结果表明 :1土壤呼吸的季节动态呈现单峰曲线 ,7月中旬达最大值 11.4 g C/ (m2 · d) ;2土壤呼吸的季节变化与地上绿色体生物量季节动态同步 ;3土壤呼吸的季节动态同枯枝落叶分解速率的季节动态同步 ;4土壤呼吸量与 0～ 10 cm的土壤层中的含水量显著正相关 ;5地表枯枝落叶层分解直接排放 CO2 量的季节动态呈现单峰曲线 ,7月中旬达最大值2 .93g C/ (m2·d) ,有减缓土壤向大气排放 CO2 的作用 ;6枯枝落叶分解释放 CO2 量同现存地表枯枝落叶量显著正相关。

采用静态室/碱吸收法研究了内蒙古大针茅典型草原土壤呼吸的时空动态.大针茅群落地上部和地下部生物量的 时空变异不同步,用地上部生物量不能很好地预测群落的根系量.群落土壤呼吸具有明显的时空动态,控制群落土壤呼吸空间变异与时间变异的因子是不同的.土壤 呼吸的季节变化与地上部生物量及土壤水分状况关系密切.根据大针茅群落分别计算了大针茅群落1995、1997和1998年的年CO2排放总量,分别为 180、45.8和225gC·m-2·a-1,年际变异很大.过度放牧大大降低了群落的生物量,也降低了土壤CO2排放量.讨论了建立以降水量为驱动因 子的草地群落土壤呼吸动态模型的可能性.

With enclosed chamber Method,this paper studied the soil respiration in grazing and fenced typical Leymus chinensis steppes,Inner Mongolia,and its relationships with environmental factors.The results showed that the daily pattern of soil respiration could be expressed as a one-humped curve,and the highest values appeared at 13:00～15:00 in the fenced and grazing plots.The diurnal dynamics of soil respiration mainly depended on the surface temperature at the fenced plots and the soil temperature at 5 cm depth at the grazing plots.In June and July,the average soil respiration rate was 2.7 times greater at the fenced plots than that at the grazing plots,while the difference was not distinct in August and September,which was similar with the change of the belowground biomass.The reason was probably that the plant was influenced differently in different phenological phases by grazing and the change of environmental factors.It showed that human activity may not result in the increase of soil respiration rate.The seasonal dynamics of soil respiration was closely correlated with soil water content at the 0～10 cm depth at the fenced and grazing sites,and the maximum R 2 was 0.853 and 0.741,respectively.The difference was that the correlation of soil respiration seasonal dynamics with soil water content was larger at the fenced plots than at the grazing plots.The correlations of soil respiration diurnal and seasonal dynamics with temperature and soil water content at lower profiles were larger than those at deeper profiles at the fenced and grazing sites.

采用静态箱式法,比较分析了内蒙古典型羊草草原放牧与围栏生态系统土壤呼吸作用及其与环境因子的关系.结果表明,围栏和放牧样地的土壤呼吸作用日动态均呈单峰型曲线,高峰值一般出现在13:00～1:00,围栏样地土壤呼吸作用日动态与地表温度相关性最好,而放牧样地与地下5cm温度相关性最好.在整个观测期内,6、7月份是植物生长的旺盛期,围栏样地土壤呼吸作用明显大于放牧样地约2.7倍;到植物生长后期的8、9月份,二者差异不大,与地下生物量的变化相似,可能与牲畜的采食对不同物候期的植物影响不同及周围环境因子的改变有关,说明人类活动的干扰不一定增加土壤呼吸作用.围栏样地和放牧样地土壤呼吸作用季节动态都与0～10 cm的土壤含水量相关性最好,相关系数分别是0.853和0.741,而围栏样地土壤含水量与土壤呼吸作用季节动态的相关性大于放牧样地;围栏和放牧样地不同层次土温、土壤含水量与土壤呼吸作用日、季动态的关系均表现出浅层的相关性普遍大于深层.

摘　要： 羊草草原经过17年的割草，群落的地上和地下生物量及主要种群的重要均均受到了不同程度的影响，而羊草和落草种群的变化尤其明显，而不同频率割草的实验系列中，种群生物量和羊草种群的重要值随割草的频率的增加而降低，在不同时期割草的实验系列中，群落地下生物量随着割草时期的后移呈上升趋势，地上生物量和羊草种群重要值则是8月刈割受到影响较大，落草种群重要值的变化趋势与羊草基本相反。

摘　要： 羊草草地是优良的割草场，通常一年内刈割一次。通过四年的实验证明，羊草草地不施加措施一年内刈割两次对产量和环境均造成不良影响，如施肥和灌溉一年内两次刈割可提高羊草的产量和质量。

对甘南典型高寒草甸退化草地2年的实验研究表明,1) 施肥后草地生产力、草地质量明显提高;2)在每个施肥水平上,刈割处理都对草地质量、生产力没有显著影响;3)施肥刈割的交互作用不显著;4) 施肥、刈割对群落结构有明显影响,施肥使群落结构简化.对照处理有10个物种地上生物量超过最大单种生物量的1/2,而且2年中都是如此;最高施肥水平中1个物种占了绝对优势.沿施肥梯度物种最大重要值从0.107,0.183,0.585一直增加到0.775.在短期内施肥可以使退化草地恢复生产力,退化草地在恢复的同时可以利用.

摘　要：

土壤呼吸是生态系统物质循环和能量流动的重要过程 ,具有多方面的生态意义。在综合比较了土壤呼吸的各种测定方法 ,概括了草地土壤呼吸的速率和年排放量 ,并就影响草地土壤呼吸的一些重要因素进行了阐述 ,文章最后讨论了草地土壤呼吸今后的研究方向。

Soil respiration can be divided into two components: autotrophic(root)respiration and heterotrophic(microbes and soil fauna)respiration. The separation of soil respiration will contribute to the understanding of soil carbon cycle and carbon balance under the condition of global change. Three primary methods have been reviewed to distinguish auto-versus heterotrophic soil respiration including:①components method; ②root exclusion method and ③ isotope method. The isotope method is the best with the least disturbance to soil and roots. Taking into account of all the factors, the root exclusion method will be the most practical in the future.

土壤呼吸分为自养型呼吸(根呼吸)和异养型呼吸(微生物和动物呼吸),区分各组分呼吸可了解在全球变化条件下土壤碳循环和碳平衡的动态.本文综述了3种主要区分自养呼吸和异养呼吸的方法:①组分法;②根去除法;③同位素法.其中同位素法对根和土壤的影响最小,是最可靠的一种方法;综合各方面考虑,根去除法是最切实可行的方法.

Soil respiration is a key process in the carbon cycle for grassland ecosystems. The commonly-used methods for measuring soil respiration were introduced in this paper. The CO 2 flux in soil respiration for major grassland communities in the world and its relation to vegetation and climate were summarized and expounded. The impacts of land-use changes on soil respiration were discussed. Finally, the turnover and residence time of soil organic matter in the soils of different grasslands were compared.

通过土壤呼吸作用向大气释放ＣＯ２是陆地生态系统碳循环的一个最主要的环节，也是人类活动影响下陆地生态系统对大气中ＣＯ２浓度产生影响，从而导致全球气候变化的关键生态学过程，因而成为全球碳循环研究中倍受关注的核心问题［３３，３７，３８］。１土壤呼吸的测定方...

土壤呼吸作用是全球碳循环中一个主要的流通途径 ,导致土壤碳以CO2 形式流向大气圈。全球土壤中碳贮存量的增加有助于缓和人为CO2 的进一步释放 ,而土壤CO2 的流失则显著地加剧大气CO2 的升高和增强温室效应。文章简单评述了土壤呼吸作用、大气CO2 升高、全球温度升高三者之间的关系 ,并提出 :改进的管理实践能减少农业土壤中CO2 净流失 ,增加有机碳贮存。减缓土壤呼吸作用的一项简单措施是减少土壤耕作。土壤扰动最小的耕作实践称为免耕作。实践证明 ,当实施免耕作时 ,土壤有机质的流失明显降低。

The Biomass and root vertical distribution of Atriplex canescens (Pursh) Nutt.under different cutting frequencies were studied in the field.The results show that cutting frequency had significant effects on the aboveground and underground biomass allocation and root vertical distribution of A.canescens ( P -1 under two cutting times and the contents of crude protein,crude fat,ash,and N-free extract were always increased,but the crude fibre decreased gradually.Secondly,as the cutting frequencies increased,the taproot diameter,root system volume,root system biomass,and rude root percentage were decreased significantly( P 0 ) of root vertical distribution under all cutting treatments were smaller than that of the control and decreased gradually along with the increasing of cutting frequency.

为科学指导四翅滨藜( Atriplex canescens (Pursh)Nutt.)在我国西北沙区的生产和利用,研究不同刈割处理下四翅滨藜生物量变化及其根系垂直分布。结果表明:刈割频度对四翅滨藜的地上、地下部分生物量积累均有极显著影响( P P 0 ),并随刈割频度增大其值逐渐减小。

根据 5年平均 ,以留茬高度为 0cm时刈割强度 (利用率 )为 10 0 % ,4cm时为 81.87% ,8cm时为 73.71% ,12cm时为 5 8.89%。群落和羊草的地上生物量 ,有随刈割强度减弱而下降较慢的趋势。依上述留茬高度的顺序 ,群落的地上生物量较相应对照平均每年下降 4.5 3%、3.5 5 %、2 .49%和 1.5 6% ;羊草平均下降 6.82 %、5 .96%、5 .85 %和 2 .67% ;刈割强度与下降速度之间的关系 ,分别达到极显著和显著的水平。羊草单株重、高度和在群落生物量中占的比例 ,亦有类似的趋势。可见 ,减轻刈割强度是改良天然割草地的有效措施之一