Carbon is one of the most important life elements on the earth It distributes widely in the atmosphere, biosphere, hydrosphere and lithosphere Together with the exchange of the substance and energy, the carbon element is transformed among different earth layers, as constitutes the most important biogeochemical cycle process of the earth Atmosphere, ocean, terrestrial ecosystem and lithosphere are four main carbon pools Among these carbon pools, the terrestrial ecosystem has the biggest uncertainty because of the complexity of underlying surface and the human activities Study on the carbon cycle of the terrestrial ecosystem has become the focus of global change research As one of the important parts of terrestrial ecosystem, grassland ecosystem occupies particular eco geographical place and has special biogeochemical cycling process, which make it important in the study of the terrestrial ecosystem carbon cycle and the sustainable development of eco environment In this paper, the importance of the carbon cycle in grassland ecosystem was discussed Then, the research results of carbon cycle in the grassland ecosystem in China were summarized and analyzed, including the plant, the litter fall, the soil carbon pool and the greenhouse gases flux and so on.

文中首先分析了草地生态系统在碳循环研究中的地位和重要性,进而对我国草地生态系统碳循环的研究现状作了较为详尽的阐述,包括植物、凋落物、土壤三大碳库以及主要含碳温室气体通量等,对其主要研究结论进行了深入的剖析。同时提出了今后我国草地生态系统碳循环的重点研究方向和研究领域。

本研究用综合顺序分类法（ＣＳＣＳ）分析了１９５０－２０００年和２００１－２０５０年期间的草原类型演替及碳汇动态。证明中国草地的碳汇主体依次是冻原和高山草地、温带湿润草地、斯泰普草地和半荒漠草地大类，占中国潜在草地总面积的８５．５２％，年碳汇潜力占中国潜在草地年碳汇潜力的９３．２９％。全球草地的碳汇主体是萨王纳、冻原和高山草地大类，两者的面积和占全球潜在草地总面积的４８．５０％，年碳汇潜力占全球潜在草地年碳汇潜力的７２．２２％。在全球气候暖干化的强（Ａ２ａ）、弱（Ｂ２ａ）情景下，与当前（１９５０－２０００年）情景相比，中国将呈现草地面积减少，林地面积增加的态势；与中国的趋势相反，全球将呈现草地面积增加，林地面积减少的态势。在全球暖干化的Ａ２ａ和Ｂ２ａ模式下，草地年碳汇潜力，中国将分别提升１４．６％和１８．５％，全球将分别提升１７．３％ 和１６．８％。但两者的增长方式不同，全球是以温带湿润草地大类年碳汇潜力大幅增加为特征，而中国是以负增长为特征。我国的暖干化趋势在草地年碳汇潜力上的反映较之全球更强烈。尽管造成全球气候暖干化的自然因素远非人力所能控制，但系统问题只能靠系统综合的办法治理。这是草地工作者当前的使命。

森林生态系统作为陆地生态系统 的重要组成部分,是全球碳循环重要的库与汇,森林生态系统碳储量的变化直接影响到陆地生态系统碳储量和全球碳平衡。通过综述相关文献,介绍森林生态系统碳 储量研究状况及其估算常用方法的优缺点,综合分析自然因素、森林采伐、树种、森林类型及森林更新、氮肥和森林火灾等因素对森林生态系统碳储量的影响,并在 此基础上对如何提高碳储量估算精度进行展望,以期为后来研究者提供参考。

提高森林生态系统碳储量估算的 精度,在全球碳循环和气候变化研究中具有重要意义。从生物量和净初级生产力角度出发,综述了中国森林生态系统碳储量估算的主要方法及手段,阐述了综合遥 感、地面观测数据及生态系统过程模型来研究特定区域特定时段森林生态系统碳循环及碳储量的必要性,探讨了我国森林生态系统碳储量研究的发展趋势和亟待解决 的一些问题。

利用高寒草甸区植被、土壤和气候等资料,借助Century模型研究了青藏高原高寒草甸生态系统土壤有机碳的动态。以2003年7月-2005年7月逐月气象观测资料为输入变量,模拟了自然条件下高寒矮嵩草草甸0～20cm土壤微生物呼吸CO2-C通量季节变化。模拟值与观测值进行的回归分析显示,二者具有较好的一致性(R2=0.89,P＜0.05)。土壤有机碳动态模拟表明:1)自然条件下高寒草甸土壤有机碳在经历了一个快速积累过程后,积累速率逐渐趋于缓和,最终达到并接近稳定状态。稳定状态下0～20cm土壤总有机碳库约7597.50～7694.10gC/m2。其中活性、缓性和惰性土壤有机碳组分占土壤总有机碳储量的2.80%,58.50%和38.70%。2)过去45年(1960-2005)高寒草甸土壤有机碳呈振幅较为稳定的波动变化,但这种变化主要是土壤有机碳各组分波动变化的结果。气候波动对土壤有机碳影响主要与温度变化引起的惰性土壤有机碳库的变化有关,二者呈显著负相关(r=-0.548,P＜0.01)。降水量对土壤有机碳及有机碳各组分的影响不显著。

The Tibetan Plateau, the third pole of the earth, is one of the least human-disturbed regions in the world. Its outstanding topographic feature and ecological characteristics have significant effects on modern atmospheric circulation and climate, so the greenhouse gases emission and absorption are linked to climate changes at local, regional and even global scales. Also, to examine or estimate the actual magnitude of carbon uptake or release from this terrestrial ecosystem has become the central issue in global carbon cycle researches. However, relatively few studies have been reported in the literatures about the carbon contributions of the alpine grassland area on the Tibetan Plateau. In this paper, we use a mechanistically based ecological simulation model to describe and analyze the spatial pattern of terrestrial net primary productivity (NPP), carbon fluxes and net ecosystem productivity (NEP) in this alpine steppe area. The NASA-CASA (Carnegie-Ames-Stanford Biosphere) model is designed to simulate seasonal patterns in net carbon fixation and allocation, litterfall, and soil nutrient mineralization, and soil CO 2 emissions. Our fundamental approach is to use CASA to estimate net primary production (NPP) in the alpine steppe area on the Tibetan Plateau. We combined MODIS data and CASA to estimate NPP, and soil carbon emissions were calculated by the regression formula obtained in the pre-study. Upon these, we estimated the carbon budget for each of the 0.05° latitude×0.05° longitude grid cells in the alpine steppe area. The potential annual net primary productivity (NPP) of this alpine steppe area is estimated to be 20.57×10 12 g · a -1 of carbon. The annual NPP has the distinct spatial distribution, whereas vegetation NPP decreased gradually from southeast to northwest due to the temperature and precipitation gradients. Soil carbon emission (heterotrophic respiration) is estimated to be 8.07×10 12 g · a -1 . Net ecosystem productivity (NEP), an indicator for carbon budget, is the difference between annual net primary productivity (NPP) and annual soil respiration. Determination of net ecosystem productivity showed that the alpine steppe ecosystem acts as a distinct carbon sink (12.50×10 12 g · a -1 of carbon), although this carbon reservoir is quite small.

CASA(Carnegie-Ames-Stanford Biosphere)模型是一个表征陆地生态系统水、碳素和氮素通量随时间变化的生态系统过程模型。本研究采用MODIS遥感数据与CASA模型相结合的方法计算了青藏高原高寒草原生态系统植被净初级生产力(NPP)总量为20.57×10 12 g·a -1 的碳。同时根据五道梁实验点上得到的经验关系估算了青藏高原高寒草原生态系统区域上的土壤碳排放(Heterotrophic respiration)总量为8.07×10 12 g·a -1 ,因此推算得高寒草原区域内净生态系统生产力(NEP)折算成碳为12.50×10 12 g·a -1 。

青藏高原属于气候变化的敏感区和生态脆弱带，对气候变化和人类活动扰动十分敏感，在未来全球碳循环调控中发挥着重要的作用。为增进对青藏高原高寒草地生态系统碳循环的理解，综述了近１０年来气候变化、氮沉降和人类活动干扰下青藏高原温室气体排放、土壤碳库变化以及模型模拟应用等方面的最新研究进展。概括出高寒草地生态系统碳循环研究的草地类型主要包括高寒草原、高寒草甸、灌丛草甸草原、沼泽化草甸以及高寒湿地等。阐述了温室气体产生的机理、青藏高原高寒草地碳循环的源汇关系，指出温度升高、放牧、氮沉降是影响青藏高原温室气体排放、土壤碳库变化最重要的外界扰动，但是温室气体排放、土壤碳库对这３个因子之间协同作用的响应目前还不清楚。现有的高寒草地生态系统碳循环模型，主要以植被类型为基础，大多只考虑了水热因子，很少包含土壤因子和生物因子及其协同作用的影响。在此基础上，指出未来拟加强的研究重点：１）冻融交替过程土壤温室气体排放研究；２）非生长季土壤呼吸作用研究；３）碳循环和植物物候耦合研究；４）高寒草地生态系统碳循环模型的开发。

根据植被种类组成、植被盖度以及枯枝落叶的积累量在内蒙古四子王旗的短花针茅草原样地设4个退化梯度,分别为对照、轻度放牧、中度放牧和重度放牧,研究了不同放牧强度对土壤有机碳和全氮含量的影响.结果表明:2007年土壤有机碳和全氮含量分别介于25.32～27.02g/kg、1.40～1.47g/kg之间,2008年分别介于25.22～27.20g/kg、1.55～1.62g/kg之间,2009年分别介于25.44～27.51g/kg、1.64～1.71g/kg之间;土壤表层(0～20cm)的有机碳和全氮含量随着放牧强度的增大而逐渐降低,重度放牧区显著低于不放牧区、轻度放牧区和中度放牧区;土壤C/N比逐年降低,不同放牧区间差异不显著.

本文从2009年7月12日到11月5日,利用静态箱-气象色谱 法对内蒙古荒漠草地不同放牧强度试验区痕量气体交换进行监测.结果表明:不同放牧强度没有改变放牧草地、裸地原有气体通量交换方向及季节变化形式.荒漠草 地生态系统是CH4弱的汇,是CO2的源.荒漠草地输出C素.同时这一过程受取样温度,土壤相对湿度,土壤状况及植被群落等多种因素影响.

The Hulunber grasslands in Inner Mongolia cover an area of up to 9.97×10 6 km 2 . Within this area, the Hulunber Leymus chinensis meadow steppe is located in the eastern part of the Eurasian continent grassland region. It is a very important example of a temperate grassland ecosystem. Grazing is the most common land use in the Hulunber meadow grasslands, therefore, understanding the changes of soil carbon, soil nitrogen and carbon sequestration under different grazing gradients will provide an important scientific basis for grassland carbon sink management in Inner Mongolia. Six stocking rate treatments (0, 0.23, 0.34, 0.46, 0.69 and 0.92 Au/hm 2 ) repeated three times for each treatment, were established, with soil samples collected in early August 2011. The experimental results showed that the grazing gradient has a distinct effect on the change of soil carbon and nitrogen content and soil carbon and nitrogen storage. Soil carbon and nitrogen storage and carbon sequestration potential in the top 0-30 cm soil layers had a significant linear downward trend as the grazing gradient increased. Compared with non-grazed grassland G0.00 (107.1 t/hm 2 ), the soil carbon sequestration potentials are 108.61-109.67 t/hm 2 , 107.06 t/hm 2 , 95.13-100.14 t/hm 2 in light grazing, moderate grazing and heavy grazing grassland, respectively. For the soil nitrogen, compared with non-grazed grassland G0.00 (9.22 t/hm 2 ), soil nitrogen sequestration potentials were 8.37-8.65 t/hm 2 , 8.20 t/hm 2 , 6.74-7.35 t/hm 2 in light grazing, moderate grazing and heavy grazing grassland, respectively. Light grazing improved the soil carbon storage and carbon sequestration potential. With an extension of the grazing time, the soil carbon and nitrogen content, carbon and nitrogen storage, and carbon and nitrogen sequestration potential in soils of heavily grazed grasslands decreased significantly. There were obvious vertical distributions in the soil carbon and nitrogen content and carbon and nitrogen storage under different grazing gradients. The change of soil carbon and nitrogen was higher in the 0-10 cm soil layer under different grazing gradients while soil carbon and nitrogen content and carbon and nitrogen storage significantly decreased with the increase in soil depths in different grazing gradients. About 42.26% of the soil organic carbon was distributed in the top 0-10 cm soil layer, 30.67% in the 10-20 cm layer, and 27.07% in the 20-30 cm layer. For the 0-10 cm, 10-20 cm and 20-30 cm soil layers, the total soil contents were 44.39%、30.13% and 25.48%, respectively; the soil carbon storage were 39.60%, 31.26% and 29.14%, respectively; the soil nitrogen storage were 41.57%, 30.97% and 27.46%, respectively. The soil carbon and nitrogen content and soil carbon and nitrogen storage for the 0-10 cm soil layer were significantly higher than those for the 10-20 cm and 20-30 cm soil layer. We found that there was an underlying transformation from soil carbon sequestration under light grazing gradient to soil carbon loss under a heavy grazing gradient, and this transformation threshold was found to be 0.46 Au/hm 2 . In short, the Hulunber meadow steppe of Inner Mongolia has a good capacity to sequester carbon in soil, and that can increase the soil carbon sequestration potential through rational control of grazing gradients to achieve carbon sinks. We can increase the soil carbon sequestration potential to achieve carbon sinks through controlling grazing gradients.

放牧是内蒙古呼伦贝尔草甸草原主要的利用方式，弄清放牧情况下草地土壤碳氮变化和固碳效应，将为我国内蒙古地区草地碳汇管理提供重要的科学依据。通过小区控制放牧实验(放牧梯度0.00，0.23，0.34，0.46，0.69，0.92Au/hm 2 )，探讨了不同放牧梯度下土壤碳氮变化及固碳效应，实验结果表明：放牧梯度对土壤碳氮含量、土壤碳氮贮量的变化有明显的影响，0-30 cm土层碳氮贮量随着放牧梯度增加呈显著的线性下降趋势。随着放牧时间的延续，轻度放牧利于提高草地的土壤有机碳密度和碳固持潜力，重度放牧显著降低了土壤碳氮含量、碳氮贮量和碳氮固持潜力。不同放牧梯度下土壤碳氮含量和碳氮贮量具有明显的垂直分布特征，随着土壤深度的增加土壤碳氮含量、碳氮贮量均呈明显的下降趋势。轻度放牧草地表现为碳固持，重度放草地表现为碳流失，对呼伦贝尔羊草草甸草原而言，土壤碳固持/碳流失的转化阈值为0.46Au/hm 2 ，通过合理控制放牧梯度能够达到增加草地土壤固碳潜力，实现碳增汇的目的。

Background and Aims Accurate estimates on the size of terrestrial organic carbon stocks are necessary for understanding their importance in regulating atmospheric CO2 concentrations. In this paper, biomass and SOC contents in alpine grass lands (alpine steppe and alpine meadow) in Bayinbulak were estimated. In addition, the vertical distribution of belowground carbon was discussed. Our objectives were to (a) estimate biomass and SOC contents of two different alpine grasslands, (b) investigate the root distribution of two alpine grasslands, and (c) explore the vertical distribution of SOC of two alpine grasslands. Methods SOC content was estimated by an improved method (integral arith metic m ethod). Based on continuous decrease of SOC density with soil depth, integral arithmetic method could estimate SOC content to a given soil depth. Key Results There were significant differences in the biomass between t he alpine steppe and alpine meadow; aboveground biomass of the alpine steppe was 71.4 g C•m -2 , whereas aboveground biomass of the alpine meadow was 94.9 g C•m -2 ; belowground biomass of the two alpine grasslands was 1 033.5 and 1 285.2 g C•m -2 , respectively. No significant differences were found between integral arithmetic and traditional methods of estimating SOC contents. SOC contents of the alpine meadow was higher than in the alpine steppe; SOC contents in the two alpine grasslands was 25.7 and 38.8 kg•m -2 , respectively. Most of the root biomass of the two alpine grasslands was in the upper 40 cm of the soil profile, while SOC was concentrated in the top 60 cm. The two alpine grasslands had different root distributions; the percentage of root biomass in the top 20 cm averaged 76%-80% for the alpine steppe and alpine meadow. Alpine meadows had a deeper root profile with only 49% of the SOC in the upper 20 cm, whereas the alpine steppe had 55% of the total SOC in the top 20 cm.  Conclusions This study suggests that vegetation determines the vertical distribution of SOC through root: shoot ratio and its vertical root distribution.

对新疆天山中段巴音布鲁克高山草地(高山草原和高山草甸)的生物量和土壤有机碳进行了测定。结果表明积分和分层两种估算方法得到的土壤有机碳含量没有显著差异，但积分算法的优势在于能推算不同深度的土壤有机碳含量，便于与以往的研究进行比较；高山草甸的生物量和土壤有机碳含量均大于高山草原；其地上生物量分别为71.4和94.9 g C•m －2 ，地下生物量分别为1 033.5和1 285.2 g C•m －2 ；1 m深度的土壤有机碳含量分别为25.7和38.8 kg•m －2 ；地上生物量呈现较为明显的垂直分布格局，即随着海拔的增加，地上生物量先呈增加趋势，但当海拔超过一定界限后生物量突然下降；土壤含水率是导致南坡( 阳坡)土壤有机碳含量空间分异的重要因素，但北坡(阴坡)土壤有机碳含量还可能与地形、土壤质地等其它因素有关； 两种高山草地(高山草原和高山草甸)的根系集中分布在40 cm以内，0～20 cm根系分别占其总量的76%和80%；土壤有机碳集中分布在60 cm以内，0～20 cm土壤有机碳分别占其总量的55%和 49%；高山草原根系分布比高山草甸深，但较低的地下/地上比使得其有机碳分布比高山草甸浅。

草地生态系统的碳循环是维系陆 地生态系统的基本机制之一,并与陆地生态系统的维持、发展和稳定性机制等相联系。通过对草地植物碳库、草地凋落物碳库、草地土壤碳库等草地生态系统碳循环 的研究动态进行综述,旨在把握草地生态系统碳循环的特征及规律,从而深入研究碳元素各个贮存库间的定量迁移和转化关系的内部机制。

高寒草原是青藏高原广泛分布的植被类型.本文以贡嘎南山-拉轨岗日山南坡高寒草原生态系统为对象,采用野外调查与室内分析相结合的试验方法,对高寒草原生态系统植被碳密度的分布特征及其影响因素进行了研究.结果表明:贡嘎南山-拉轨岗日山南坡高寒草原生态系统植被碳密度平均为0.8435±0.6048 kg/m~2,变异系数71.69%.在海拔4424～4804 m范围内,随着海拔升高,植被碳密度表现出先增加后减少的分布特征.影响植被碳密度的关键环境因子是:植被高度、0-10 cm地下生物量、10-20 cm地下生物量、0-40 cm土壤含水量、0-20cm土壤容重、20-40 cm土壤容重、土壤有机质、土壤速效钾含量和土壤速效氮含量. Abstract： Alpine grasslands are one of the most widely distributed vegetation types on the Qinghai-Tibet Plateau. In this paper, alpine grassland ecosystem of Gongga South Mountain-Lhagoi Kangri mountain southern slopes as targeted field,alpine grassland ecosystem carbon density distribution of vegetation characteristics and influencing factors were studied with a combinative test methods of field investigation and laboratory analysis. The results showed that the average vegetation carbon density was 0.8435 + 0.6048 kg/m~2 and coefficient variation was 71.69% in Gongga South Mountain-Lhagoi Kangri mountains southern slopes of alpine grassland ecosystems. With the elevation increasing, vegetation carbon density showed increase to decrease in distribution characters in the altitude scope of 4424-4804 m. The key environ-mental factors which effected vegetation carbon density were vegetation height, biomass 0-10 cm below-ground, 10-20 cm below-ground biomass, 0-40 cm soil moisture, 0-20 cm soil bulk density, 20-40 cm soil bulk density, soil organic matter, soil available potassium and soil available nitrogen.

草地是世界上分布最广的植被类 型之一,作为陆地生态系统的重要组成部分,参与了全球碳源/汇及碳循环过程,在全球气候变化中扮演着重要角色,并对其产生重大影响。以黄土高原草地植被为 研究对象,结合国家退耕还林草与封山禁牧工程的实施,对封禁前后的天然草地和退化草地,采用样带多点调查与多年定位测定相结合的方法,分析了黄土高原不同 类型草地植物活体、凋落物和根系碳密度分布格局与地带性规律,系统研究了黄土高原不同草地类型退化草地和封禁草地生物量与碳密度沿海拔及降水梯度的时空变 异特征,阐述了影响草地碳密度分布的主要驱动因子及其作用机理。结果表明:4种草地类型3种处理的草地生物量和碳密度自西北向东南均与降雨量呈指数增长趋 势,并随海拔降低而显著降低,且二者呈显著的线性回归关系;各草地类型地上/地下生物量与碳密度分布规律均为荒漠草原丘陵典型草原梁塬典型草原草甸草原; 封禁11a草地活体植物、凋落物和根系碳密度总量:荒漠草原为7.066 t/hm2,丘陵典型草原为8.080 t/hm2,梁塬典型草原为15.319 t/hm2,草甸草原为20.982 t/hm2,分别是退化草地的14.8、8.33、6.5倍和15.88倍。充分表明,封禁不仅能使草地植被恢复和生物量提高,而且也是草地生产力和碳密 度增加的一条重要途径。由此可见,气候干旱和草地退化是影响草地生物量和碳密度的关键因素,系统研究黄土高原封禁草地生物量增长与碳密度变化过程,将会对 未来全球气候变化分析作出重要贡献。

本文选取草甸草原上的三家牧户作为样地,研究了在不同的放牧强度对草甸草原植物根系碳密度的影响。研究结果表明植物根系碳密度在轻度放牧显著高于中度和重度放牧草地。根系碳密度与根系深度之间呈幂函数关系。

Rest grazing is an important means to maintain the sustainability of grassland ecosystems. To evaluate the potential effects of rest grazing on organic carbon storage in the Leymus chinensis Steppe, organic carbon storage in plant and soil was compared in the steppes with different rest grazing durations（3 years—RG3a, 6 years—RG6a, and 9 years—RG9a） using long-period free choice grazing（RG0） as the control. Compared with long-period free choice grazing, biomass of aboveground, litter and underground parts of plants, and organic carbon storages in plant communities and soils increased with increased rest grazing durations. Total cost of carbon sequestration increased as years of rest grazing increased, with up to 8 710.20 Yuan（RMB）·hm-2, while the unit cost reduced. Considering the growth characteristics of grassland plants, the spring season should be free of grazing. Timely rest grazing could restore and renew grassland vegetation.

为了揭示休牧对羊草草原有机碳储量的影响，以休牧3年（RG3a）、6年（RG6a）和9年（RG9a）的羊草草原为对象，采用重铬酸-浓硫酸外加热法，研究了不同休牧年限草原植物群落和土壤的有机碳储量变化。结果表明，地上植被生物量、凋落物量和根系生物量随着休牧年限的延长而逐渐增加。与长期自由放牧草地相比，植物群落和土壤有机碳储量均随休牧年限的延长而增多。长期自由放牧草地（RG0）、休牧3年、休牧6年和休牧9年植物群落地上部有机碳储量为65.17~98.69 gC·m-2，地表凋落物有机碳储量为3.07~10.84 gC·m-2；植物群落0~100 cm地下根系有机碳储量为397.13~1 480.28 gC·m-2，0~100 cm土壤有机碳储量为28 306.39~38 372.46 gC·m-2。从固碳成本角度，总固碳成本随着休牧年限的延长而增加，最高为8 710.20 元·hm-2，固碳成本分别为0.09、0.11、0.08 元·kg-1C。从现有数据显示，休牧9年的固碳量最高，固碳成本最低。春季休牧可以使草地植被得到有效的恢复与更新，有利于草地的可持续利用；随休牧年限的增加，草地有机碳储量增加，固碳成本基本呈现降低趋势。因此，综合现有指标的测定数据，春季休牧是一个非常好的草地利用措施，在休牧过程中草地是一个碳汇，应该鼓励持续进行。

土壤碳库是陆地生态系统中最大且最活跃的碳库之一,是全球碳循环的核心内容.土壤有机碳的固定和矿化不仅对全球大气CO2浓度起着重要的调节作用[1],而且影响着土壤肥力及作物产量[2-3],指示着植被演替的结果和演化的趋势,倍受学术界广泛关注.

As an important component of the carbon pool of terrestrial ecosystem, soil carbon pool plays a key role in the studies of greenhouse effect and global change. By using a 1:50000 soil database, the organic carbon density in the 0-100 cm layer of 277 soil species in Zhejiang Province was estimated, and the soil organic carbon (SOC) density and storage in the whole Province as well as the spatial distribution of the SOC density and storage in the main soil types of the Province were analyzed. In the whole Province, the SOC density ranged from 5 kg·m -2  to 10 kg·m -2 . Among the main soil types in the Province, humic mountain yellow soil had the highest SOC density (52.80 kg·m -2 ), whereas fluvio-sand ridge soil had the lowest one (1.82 kg·m -2 ). Red soil and paddy soil had the largest SOC storages, with the sum accounting for 63.8% of the total SOC storage in the Province. The total area of the soils in the Province was 100784.19 km 2 , the estimated SOC storage was 875.42×10 6 t, and the estimated SOC density was averagely 8.69 kg·m -2 . The analysis with the superposition digital elevation model showed that the SOC density presented an obvious variation trend with the changes of elevation, slope gradient, and aspect.

土壤有机碳库作为陆地生态系统中重要的碳库之一，对于温室效应和全球变化研究具有重要意义.利用浙江省1∶5万土壤数据库，对浙江省277个土种0～100 cm土层的有机碳密度进行估算，分析了全省土壤有机碳密度和储量,以及各主要土壤类型有机碳密度和分布.结果表明： 浙江省土壤有机碳密度值主要集中在5～10 kg·m -2 ；山香灰土有机碳密度最高，为52.80 kg·m -2 ，清水砂最低，为1.82 kg·m -2 ；红壤和水稻土土类土壤有机碳储量最大，两者之和占浙江省土壤有机碳总储量的63.8%；浙江省土壤总面积为100784.19 km 2 ，土壤有机碳储量为875.42×10 6 t，土壤有机碳平均密度为8.69 kg·m -2 .通过叠加数字高程模型分析,发现土壤有机碳密度随高程、坡度和坡向的变化均呈现明显的变化趋势.  

通过对青海湖流域不同退化程度矮嵩草草甸土壤容重和有机碳含量的 测定,确定了其土壤有机碳密度.结果表明:不同退化程度下矮嵩草草甸土壤有机碳含量和变化特征各有不同.从未退化-重度退化,0-100 cm土壤剖面平均有机碳含量分别为(25.17±4.73) g/kg,(17.51±3.06) g/kg,(20.79±1.30) g/kg和(14.53±1.20) g/kg,即未退化＞中度退化＞轻度退化＞重度退化;0---20 cm土壤平均有机碳含量从(64.47±11.70) g/kg减少为(14.52±1.52) g/kg,减少了77.48％.土壤剖面有机碳密度变化趋势与其有机碳含量变化趋势一致.0-100 cm土壤剖面有机碳密度分别为(18.16±4.12) kg/m3,(14.24±3.52) kg/m3,(18.64±2.82) kg/m3和(13.27±2.28) kg/m3,即中度退化＞未退化＞轻度退化＞重度退化;土壤有机碳集中分布在0-40 cm深度,从未退化到严重退化,该深度有机碳密度分别为(32.06±6.41) kg/m3,(25.10±4.20) kg/m3,(22.68±3.17) kg/m3和(17.10±2.77) kg/m3,比整个剖面有机碳密度高出76.53％,76.25％,21.68％和28.88％.不考虑其他因素,以空间尺度代替时间尺度,这一结果说明 矮嵩草草甸的退化导致土壤逐渐释放有机碳,其作为储存碳的功能在减弱,必须加强对矮嵩草草甸生态系统的保护,以防止其碳库变为碳源.

摘　要： 以内蒙古短花针茅荒漠草原自由放牧样地、划区轮牧样地和围栏禁牧样地为对象,通过分析整个生 长季5～10月地上植物、枯落物、根系和土壤有机碳储量,研究草原生态系统碳储量变化规律,从碳储量角度为草原合理利用提供指导.研究结果表明：（1）自 由放牧样地生态系统有机碳储量显著低于围栏禁牧和划区轮牧样地（P＜0.05）;（2）生长季内自由放牧样地生态系统有机碳储量变化表现为降-升-降趋 势,划区轮牧和围栏禁牧样地表现为升-降趋势;（3）生长季内生态系统有机碳储量总净增量呈负增长趋势,表现为自由放牧＞划区轮牧＞围栏禁牧,分别为 -636.35g/m2、-265.06 g/m2和-46.74g/m2;（4）各部分所占生态系统有机碳储量比例表现为土壤＞根系＞地上植物＞枯落物,地下部分碳储量为草原碳储量主体.综合分 析表明,放牧制度明显改变了短花针茅荒漠草原生态系统有机碳储量的积累过程,有利于有机碳储量积累的放牧制度排序为围栏禁牧＞划区轮牧＞自由放牧.

大气中温室气体增加带来的全球 变暖等负面影响已经威胁到全球生态系统。如何降低二氧化碳浓度以及防止全球变暖等问题的研究已经成为全球关注的热点。全球草地面积 2.40×108km2,占陆地生态系统的33%。其中有半数已处于退化或正在退化的状态。我国草地面积约4.00×106km2,已退化草地占总草地面 积的56.5%。通过对草地退化问题的研究发现,围封是恢复退化草地较为有效的方法之一。而对围封后草地植物和土壤碳储量变化的研究则很少。本研究选择了 在新巴尔虎右旗草甸草原中的5个亚类进行碳储量的研究,在每个草地亚类的放牧地和围封保护样地进行。研究围封后草地的植物地上部分、枯落物、根系、土壤的 碳密度及碳储量的变化情况。 研究结果如下： 1围封后植物地上部分、枯落物、根系的生物量增加；植物地上部分、枯落物、根系、土壤碳密度也增加。 2草地生物量与碳密度之间有显著正相关关系(R2=0.9986、R2=0.9991)。围封条件下根系碳密度与地上碳密度在有显著正相关关系 (R2=0.9005),放牧条件下有不显著相关关系(R2=0.7350)。草地植物碳密度与土壤碳密度相关性不显著(R2=0.7729、 R2=0.5568)。 3根系碳密度和土壤碳密度均随土壤深度的增加而减小,碳密度主要集中在0-20cm土层。围封对根系碳密度和土壤碳密度在0-30cm和50-100cm 会显著增加(P0.05)。 4围封使草地总碳密度增加,不同草地类型增加幅度不同,其中低地草甸草原草地碳密度的增加最显著。

大气中二氧化碳等温室气体的增加导致全球气候的巨大变化，对地球 上的所有生命带来了巨大的影响，二氧化碳及地球生态系统的碳循环研究已成为最为热门的课题。对陆地生态系统的碳循环的研究大部分集中于森林以及农田，而对 于草地这个最大的陆地生态系统在自由放牧情况下放牧强度对草地各个部分的碳贮量的影响研究则相对较少。草地最广泛的利用方式是放牧，且绝大多数以自由放牧 为主。本研究以羊草草甸草原作为研究地点，在天然草原自由放牧方式下家庭牧场在居住点为中心向外延伸所形成的放牧梯度下进行了定量划分，确定了轻度、中度 和重度放牧强度。在此...

放牧是人类利用草地最普遍、最 简便和最经济的方式。本研究选取内蒙古东北部赤峰克旗砧子山境内天然大针茅典型草原上的自由放牧家庭牧场为试验区,于2009年以实验生态学为手段设置试 验,并通过测定草地生态系统地上、地下植物生物量、植物含碳量、土壤容重和土壤含碳量等指标,研究不同放牧强度下草地总碳储量及不同组分碳储量的分布格 局,进而评价典型草原在放牧条件下,草地碳储量的更新潜力及草地可持续发展潜力,为应对气候变化背景下,草地生态系统应对固碳减排的潜在作用提供数据支 持。研究结果如下: 1.各个区中植物地上部分单位面积碳储量有所不同,对照区为60.38g/m~2,轻度放牧区为66.80g/m~2,中度放牧区为44.93g /m~2,重度放牧区为32.72g/m~2。轻度放牧可以使植物地上部分单位面积碳储量增加,而中度和重度放牧都使其减少。放牧主要是通过影响植物地上 部分生物量来改变其碳储量,放牧对植物地上部分的含碳量的影响不显著。 2.各个研究区中植物地下部分单位面积碳储量最高的为对照区652.87g/m~2,各个放牧区均低于对照区,轻度放牧区为546.48g/m~2,中度 放牧区为518.36g/m~2,重度放牧区为413.54g/m~2。放牧使植物地下部分单位面积碳储量减少,随着放牧强度的增加,减少量增大。与地上 部分相同放牧主要通过使地下部分的生物量减少而导致其碳储量减少,植物地下部分的含碳量仍然比较稳定,受放牧影响不显著。同时放牧会导致地下根系分布表层 化现象更严重。 3.放牧对土壤的影响比较复杂,首先放牧会改变表层土壤的容重,而对深层土壤的容重基本没有影响,另外放牧会使表层土壤的含碳量降低。各个研究区中,对照 区的土壤单位面积碳储量明显高于各放牧区,其值为2370.39g/m~2,轻度区为891.68g/m~2,中度区为1212.61g/m~2,重度区 为1723.38g/m~2,与不放牧相比放牧会使土壤单位面碳储量下降。 4.综合植物和土壤碳储量研究结果,得出各个研究区中草地总单位面积碳储量的值,对照区最高为3083.64g/m~2,轻度放牧区为1504.96g /m~2,中度放牧区为1775.90g/m~2,重度放牧区为2196.64g/m~2。放牧会使大针茅典型草原单位面积总碳储量减少,但是各个放牧强 度之间并有显著差异。

摘　要： 通过放牧强度对草原土壤物理性质、化学性质和植物群落以及植物养分的影响的阐述，强调了制定并遵循合理的放牧制度和严格控制载畜量是保护草原土壤与植被，永续利用草原以及发挥草原生态功能，提高草原经济效益的必要措施。

草地生态系统是全球生态系统中 不可或缺的构成成分,对研究全球碳循环过程具有重要作用。青藏高原草地是草地生态系统的核心组成部分,青藏高原独有的气候环境及地理位置,直接影响青藏高 原草地生态系统的碳循环作用,甚至全球生态系统碳循环作用。尽管众多专家对青藏高原草地碳储量进行了不少研究,然而,由于青藏高原海拔高、面积广、工作条 件艰苦和开展研究工作难度大,现有研究多集中于草地地上植被,缺乏对草地土壤、地下根系及枯落物碳储量进行深入研究。因此,系统地研究青藏高原地区草地生 态系统碳储量是我国急需解决的一个重要课题。我国当前草地的主要利用方式是放牧利用,结合草地不同放牧程度研究青藏高原区域草地碳储量具有重要的理论价值 与现实的生态意义。 本研究对位于青藏高原阿坝地区的不同利用方式与程度草地植被与土壤的碳储量特征进行分析,实验包括18个调查样地,即每类草地3个样地,草地根据利用方式 及利用程度不同分为封育天然割草地、人工栽培草地、冬春放牧草地、夏秋轻度放牧草地、夏秋中度放牧草地和夏秋重度放牧草地。每个样地随机选取3个样方运用 样线法采集植被地上生物量及枯落物,在采集过植被的样方内运用土钻法采集土壤,土壤取样分为七个层次；运用根钻法采集植被地下根系,地下根系取样分为四个 层次。实验室内采用重铬酸钾外加热法测定有机碳含量,以探讨不同利用方式草地碳储量特征,试验结果如下： 1.不同利用方式与程度草地之间土壤碳储量有显著差异(P0.05),且夏秋轻度放牧草地(36.2586kg/m2)最高,夏秋重度放牧草地 (29.4767kg/m2)次之,接下来依次是冬春放牧草地(24.3447kg/m2)、封育天然割草地(20.943kg/m2)、夏秋中度放牧草 地(18.1502kg/m2),人工栽培草地(17.825kg/m2)最低。不同利用方式草地中,冬春放牧草地碳储量最高,人工栽培草地最低；不同放 牧程度草地中,夏秋轻度放牧草地碳储量最高,夏秋中度放牧草地最低。各种利用方式与程度草地土壤碳储量在不同土层间差异显著,且随着土壤深度等梯度增加, 土壤碳储量依次递减。 2.不同利用方式与程度草地之间地上植被碳储量有显著差异(P0.05),且封育天然割草地(331.781g/m2)最高,冬春放牧草地 (276.548g/m2)次之,接下来依次为夏秋轻度放牧草地(191.983/m2)、人工栽培草地(143.8905/m2)、夏秋中度放牧草地 (90.7125/m2),夏秋重度放牧草地(55.9165/m2)最低。不同利用方式草地中,封育天然割草地碳储量最高,人工栽培草地最低；不同放牧 程度草地中,夏秋轻度放牧草地碳储量最高,夏秋重度放牧草地最低。 3.不同利用方式与程度草地之间地下根系碳储量有显著差异(P0.05),且夏秋中度放牧草地(23.8735g/m2)最高,夏秋轻度放牧草地 (23.069g/m2)次之,接下来依次是封育天然割草地(21.851g/m2)、夏秋重度放牧草地(19.7731/m2)、冬春放牧草地 (16.332g/m2),人工栽培草地(14.3645g/m2)最低。不同利用方式草地中,封育天然割草地碳储量最高,人工栽培草地最低；不同放牧程 度草地中,夏秋中度放牧草地碳储量最高,夏秋重度放牧草地最低。各种利用方式与程度草地地下根系碳储量在不同土层间差异显著,且随着土壤深度等梯度增加, 地下根系碳储量依次递减。 4.不同利用方式与程度草地之间枯落物碳储量有显著差异(P0.05),且人工栽培草地(5.525g/m2)最高,冬春放牧草地(3.2285g /m2)次之,接下来依次是封育天然割草地(3.0905g/m2)、夏秋中度放牧草地(2.953g/m2)、夏秋轻度放牧草地(2.787g /m2),夏秋重度放牧草地(2.601g/m2)最低。不同利用方式草地中,人工栽培草地碳储量最高,封育天然割草地最低；不同放牧程度草地中,夏秋中 度放牧草地最高,夏秋重度放牧草地最低。 5.不同利用方式与程度草地土壤碳储量远远高于植被碳储量；地上植被碳储量高于地下根系碳储量；表层土壤(0-20cm)碳储量约为土壤总碳储量的百分之 四十左右。 综上所述,不同利用方式与程度草地碳储量之间差异显著,表现为夏秋轻度放牧草地最高,其次是夏秋重度放牧草地,再次是冬春放牧草地,接下来是封育天然割草 地与人工栽培草地,夏秋中度放牧草地最低。不同利用方式草地中,冬春放牧草地碳储量最高,而人工栽培草地最低；不同放牧程度草地中,夏秋轻度放牧草地碳储 量最高,夏秋中度放牧草地最低。试验结果为进一步研究青藏高原区域草地碳储量提供数据参考与理论支持。

Human activity has adversely affected global carbon(C) and nitrogen(N), and contributed to an alteration of climate that will generate discernible feedbacks to all organisms and ecosystems on earth. The purpose of this study was to provide the basis of degrading mechanisms in alpine meadow research and understanding global C reserves and quantifying the pools and changing of soil carbon under grazing intensity. The combined methods of field survey and experiment analysis were applied to detect the influence of biomass and soil carbon characteristics under different grazing intensity: enclosure (EN), light grazing (LG), moderate grazing (MG), heavy grazing(HG) and control (CK)on an alpine meadow. The experiment plots were located in the Yushu Longbao alpine meadow. The results showed that aboveground biomass and underground biomass of grassland were maximum in EN treatment. With the grazing intensity increasing, the aboveground biomass and underground biomass decreased. The soil moisture in EN and LG treatments were significantly higher( P ＜0.05) than the other treatments which influenced by grazing disturbance. In the soil profile, the soil moisture decreased with soil depth increase in all treatments. Trampling of grazed not only influenced soil moisture but also impacted soil bulk density, the soil bulk density increased with the grazing intensity increasing. The soil organic carbon(SOC) and total nitrogen were also influenced by grazing, the total nitrogen decreased in the following order: LG＞EN＞MG＞CK＞HG whereas the SOC decreased in the following order LG＞EN＞MG＞HG＞CK. Optium trampling of grazing increased soil bulk density, however, but the effects on meadow vegetation and soil structure of high grazing intensity were not benefical for sustainable development of grassland ecosystem.

为了揭示高寒草甸生态系统在放牧扰动下的植被和土壤特征变化,通过野外样地调查和室内分析法研究和探讨围栏封育(EN)、轻度放牧(LG)、中度放牧(MG)、重度放牧(HG)、对照区(CK)几种不同放牧强度对草地生物量和土壤碳特征的影响,为高寒草甸的退化研究提供依据。结果表明,封育区地上生物量和地下生物量最高,随着放牧强度的增加,草地地上生物量和地下生物量均呈减少趋势;放牧干扰对高寒草甸土壤湿度也产生影响,其中封育区和轻牧区土壤湿度显著高于其他处理( P ＜0.05);在土壤剖面上,随着土层深度的增加土壤湿度呈明显降低趋势;放牧的践踏作用不仅影响土壤湿度,而且随着放牧强度的增加土壤容重增加;土壤全氮和土壤有机碳也对放牧有一定的响应,土壤全氮表现为LG＞EN＞MG＞CK＞HG,土壤有机碳从高到底为LG＞EN＞MG＞HG＞CK。草地受到放牧干扰时,适度的践踏干扰将提高草地生产力和碳固存,但是高强度的放牧对草地植被和土壤结构的干扰作用不利于草地生态系统的可持续发展。

Grazing is significant factor impacting the ecological processes of grassland ecosystems.This study was conducted to investigate the effects of natural grazing intensity on plant community and soil nutrients in alpine meadow.Using comparative experiments,research was initiated under different grazing intensities to provide a theoretical basis for defining the reasonable stocking rate of alpine meadow.Our results showed that: Both above-ground biomass and species richness of plant community were the highest in fencing than that in light and moderate grazing,and the least in heavy grazing treatment;Shannon-Wiener diversity index was not significantly different among fencing,light and moderate grazing;the above-ground biomass and cover of palatable herbages(grasses and sedges) was reduced with grazing intensity increasing,while the forbs in heavy grazing treatment had higher above-ground biomass than that in fencing,light and moderate grazing;over three growing stages,soil moisture decreased with grazing intensity enhancing in May,but increased in July and September;the soil bulk density in moderate grazing was significantly lower than that in other three grazing treatment( P <0.05);the pH value was the highest(pH 7.31) in heavy grazing and was not significantly different among fencing,light and moderate grazing treatment;soil organic carbon was reduced with increasing grazing intensity in plant growing stages;soil total nitrogen was not significant different among light,moderate and heavy grazing treatment.However,soil ammonium-N and nitrate-N increased along the increasing of grazing intensities over the whole plant growing stages;soil available phosphorus shared the same trend as total phosphorus that they had the highest value under moderate grazing.Our result suggested that the moderate grazing was effective way to protect biodiversity and improve grassland productivity,while fencing is beneficial for recovering of the degraded alpine meadow.

放牧作为最主要的生物干扰因子之一,影响着草地生态系统植被和土壤的生态进程。在自然放牧条件下,通过不同放牧强度的比较试验,对高寒草甸土壤营养成分及地上群落特征进行分析,为制定合理的放牧强度提供理论依据。结果表明:随着放牧强度加大,地上总生物量、物种丰富度在封育样地最高,在重牧样地最低,而封育、轻牧、中牧样地香浓-威纳多样性指数并没有显著的差异;禾草和莎草的地上生物量和总盖度在中牧条件下最高。与轻牧、中牧和封育样地相比,重牧样地的杂草有较高的地上生物量和总盖度;5月份土壤含水量随放牧强度增加而减少,7月份、9月份则相反;封育、轻牧、重牧样地的土壤容重显著低于中牧样地( P P <0.05);土壤的全氮含量在各放牧样地里并没有显著变化,而土壤氨态氮、硝态氮则在植物整个生长季节随着放牧强度的加大而增加;在整个生长季节里全磷含量最大值都出现在中牧样地里,速效磷含量表现出了和全磷一致的结果。因此,适度放牧是保护生物多样性,维持土壤养分以及提高草地生产力的有效途径;当高寒草甸由于退化导致生物量锐减,生物多样性丧失等严重后果时,围栏可以作为有效的恢复手段。

Alpine grassland degradation has an important impact on the carbon cycle of grassland ecosystems.To investigate the soil organic carbon density changes during different process of grassland degradation will have important theoretical value to the evaluation of alpine grassland soil carbon sequestration capacity and maintenance of climate change.The objective was mainly to discuss the variation characteristics of soil organic carbon density under the interference of grassland degradation.Three different degradation degrees,namely light,moderate,and heavy,of alpine grasslands were chosen in Tianzhu area located in the eastern of Qilian Mountain in 2008.Research results show that the soil water content decreased and bulk density and pH value increased along with the increasing of degradation degree.Soil organic matter and total nitrogen showed similar change trend and significant difference existed between moderate and light or heavy degradation degree( P light degradation degree>heavy degradation degree.

于2008年在祁连山东段天祝地区选取轻度、中度和重度3个不同退化程度的高寒草地,以土壤有机碳密度为研究对象,探讨高寒草地在不同退化程度干扰下土壤有机碳密度的变化特征。结果表明:随着高寒草地退化程度的加重,土壤含水量降低,容重和pH值增大;土壤有机质和全氮有相似的变化趋势,中度与轻度或重度退化草地土壤有机质和全氮差异显著( P P 轻度>重度退化草地。