The Seriphidium transiliense desert is an essential grassland type in northern Xinjiang. The grassland has different degradation due to long-term overgrazing which restrained the grassland function in production and ecological aspects. In this paper, grassland characteristics and herbivore-carrying capacity of different degraded Seriphidium transiliense deserts were investigated in order to provide information for grassland rational utilization and animal husbandry sustainable development. Results showed that the dominant species transferred from Seriphidium transiliense to Petrosimonia sibirica with the degraded degree of grassland increasing. The ash and crude fiber contents of Seriphidium transiliense and grassland communities had a similar change tendency in spring, but the crude protein and ash with crude fiber had an opposite change tendency in autumn. The herbivore-carrying capacity of the non-degraded grassland in spring and autumn were 1.20 and 1.78 sheep unit per hm 2 , and the moderate degraded grassland were 0.29 and 1.15 sheep unit per hm 2 . Efficient protective measures should be taken to prevent ecological environment deterioration before the dominant species changed, that is, the herbivore-carrying capacity of non-degraded and medium-degraded grassland should not beyond the theoretical threshold, and grazing activity in the heavy-degradation and over-degradation area should be forbidden.

伊犁绢蒿( Seriphidium transiliense )荒漠是新疆北疆地区重要的草地类型,但长期的超载过牧使该区域草地呈现不同程度的退化,严重地制约草地生产及生态功能的发挥。对伊犁绢蒿荒漠不同退化阶段草地的植物性状和载畜力进行分析,以期为区域草地的合理利用和畜牧业的可持续发展提供参考。结果表明:随着草地退化程度的加剧,伊犁绢蒿在群落中的优势地位逐渐被叉毛蓬( Petrosimonia sibirica )取代;伊犁绢蒿和群落的粗灰分与粗纤维含量在春季变化趋势相似,而伊犁绢蒿和群落的粗蛋白及粗灰分含量与粗纤维含量在秋季变化趋势相反;未退化草地春、秋季载畜力分别为1.20个绵羊单位/hm 2 和1.78个绵羊单位/hm 2 ,中度退化草地春、秋季载畜力分别为0.29个绵羊单位/hm 2 和1.15个绵羊单位/hm 2 。为防止当地生态环境恶化,应在优势种发生更替前对草地进行有效的保护措施,即在对未退化和中度退化的草地利用时应以理论载畜力为最大承载力阈值。

The restoration process of the grassland was studied through observing the grassland under enclosure and grazing conditions. The results showed that enclosure to prevent grazing have the obvious effects on vegetation coverage, biomass and net productivity. And the coverage and biomass increased as the time elongating. Moreover，the species diversity of the grassland increased at the early period of enclosure, but the species diversity and the richness decreased as the enclosure time elongating. Long time enclosure could not help to improve the species diversity of the grassland.

通过对不同时期（1987、1997、2003年）围封禁牧的草地与自由放牧草地的对比试验，研究了封育后锡林郭勒典型草原的恢复过程，结果表明：围封禁牧对草原植被的盖度、地上生物量、净生产力都有显著的影响；随禁牧时间的增加，群落覆盖度及生物量都有明显的增加；随着封育时间的延长，草原生态系统的物种多样性和丰富度都表现出先上升后下降的趋势；长期封育不利于草地物种多样性的提高。

Abstract: The influence of shortterm fencing on soil nutrients was discussed by comparatively analyzing the change of nutrients in the 0－20 cm soil layer inside and outside of fences at the degenerated desert grassland of Xinjiang. The results showed that the soil OlsenP content was depressed inside fences. The topsoil available N contents of fenced moderate degraded and fenced severe degraded grassland were depressed; while that of fenced extreme degraded grassland was increased. After fencing, soil organic matter content of moderate degraded and extreme degraded grassland were increased. It can be seen due to the local harsh natural conditions and levels of grassland degradation were different. The effect of  shortterm fences on restoration of soil nutrients except OlsenP content was depressed consistently. The changes of the soil organic matter, available N and available K were not obvious. For that reason, only through longterm monitoring, the effect of fencing on soil nutrients will be evaluated objectively.

以新疆天山北坡荒漠草地为研究对象，通过对两年围栏内外的0~20 cm土壤养分进行对比分析，探讨短期围栏封育对土壤的影响。结果表明，退化草地围栏后土壤有效磷含量降低；中度、重度退化草地土壤表层碱解氮含量降低，极度退化草地土壤碱解氮含量升高；中度、极度退化草地土壤有机质含量升高。由此可以看出，当地严酷的自然条件和草地退化程度的不同，使得短期围栏封育对土壤养分恢复的效果除有效磷变化一致降低外，有机质、碱解氮、速效钾变化不一致，差异不明显。因此，只有通过长期监测，才能对围栏封育的效果做出客观的评价。

针对典型草原退化草地恢复与合 理利用问题,选取生长季(4-9月)围封收获干草,其他时间轻度放牧利用的天然草地为研究对象,同时选取自由放牧草地为对照,进行不同围封年限草原植物群 落与土壤特征的比较研究。结果表明,1)与自由放牧草地相比,重度退化草地采用生长季围封恢复措施后群落地上现存量、盖度、密度、根系生物量、地表凋落物 现存量及土壤养分含量显著增加,土壤容重、紧实度及0.25 mm的粗颗粒含量显著降低,群落结构优化,土壤环境改善,植被与土壤间形成一个相互作用的良性循环系统,退化草地正向演替。2)草地在围封恢复过程中若连 续多年刈割利用,容易导致生产性能降低,群落盖度与密度下降,草群矮化,土壤养分含量下降,草地发生2次逆行演替。3)季节性围封的管理方式既可保证退化 草地在一定程度上得到恢复,也能达到充分利用草地资源的目的。季节性围封在我国牧区是可行方法之一,但适宜的围封季节及围封后的合理利用问题(如合理的割 草制度等)有待进一步研究。

摘　要： 以新疆伊犁绢蒿属荒漠草地为对象,研究了不同封育年限对草地土壤有机质、土壤全氮、全磷、全钾、碱解氮、速效磷、速效钾的影响.结果表明：随封育时间的延续,土壤有机质、全氮及碱解氮在表层基本呈先降后升趋势,且在封育9年均达到最高值;速效钾与速效磷均呈先降后升再降趋势,且在封育6年达到最大值;全钾与全磷无明显变化趋势.土壤有机质、全氮及速效养分呈现表聚现象,且土壤有机质与全量及速效养分相关性显著.

The influence of grazing intensity including light grazing (0.38 cattle·hm -2 ), moderate grazing (0.64 cattle·hm -2 ) and heavy grazing (0.90 cattle·hm -2 ) on soil total nitrogen, total phosphorus, total potassium and pH in Zhaosu Meadow Steppe was studied from 2010 to 2012 by plot grazing experiment. Result showed that the contents of soil total nitrogen, phosphorus and potassium in 0~10 cm, 10~20 cm, 20~30 cm soil layers were not significantly different among different grazing intensities at the same year during the short grazing period, and the same as soil pH. Compared with before grazing, the soil total nitrogen content and soil pH of 0~30 cm soil layer after grazing decreased 5.8%~29.7%, 0%~5.0%, respectively; and the contents of soil total phosphorus and potassium increased 4.5%~29.2%, 35.0%~100.8%, respectively. The contents of soil total nitrogen, total phosphorus, total potassium increased and soil pH first increased then decreased with increasing grazing intensity. There was no significant correlation between grazing intensities and soil total nitrogen, total phosphorus, total potassium, pH under short grazing period. Whether grazing or not, the contents of soil total nitrogen and total phosphorus decreased, pH increased with the increase of soil depth. In short, different grazing intensities under short grazing period did not have significant influence on soil total nitrogen, total phosphorus, total potassium contents and soil pH value.

2010-2012年采用小区控制放牧试验,在伊犁昭苏草甸草原上研究了轻度放牧(0.38头牛·hm -2 )、中度放牧(0.64头牛·hm -2 )和重度放牧(0.90头牛·hm -2 )对草地全氮、全磷、全钾及pH的影响。结果表明:短期放牧条件下,同一年度不同放牧强度间0~10 cm,10~20 cm和20~30 cm土层全氮、全磷、全钾含量及pH差异不显著;与放牧前比,放牧后0~30 cm土层全氮含量及pH出现一定程度降低,降幅分别为5.8%~29.7%和0%~5.0%,而全磷、全钾含量出现一定程度的增加,增幅分别为4.5%~29.2%和35.0%~100.8%;随着放牧强度的增加,土壤全氮、全磷、全钾含量呈增加趋势,pH呈先增加后降低的趋势;短期放牧强度与土壤全氮、全磷、全钾及pH间均无显著相关性;无论放牧与否,土壤全氮、全磷含量随剖面深度的增加呈现降低趋势,而pH基本呈增加趋势。总之,短期放牧强度对草地土壤全氮、全磷、全钾、pH影响不显著。

Inner Mongolia grasslands are an important ecosystem of the Euro-Asia plateau. However, in recent decades, it has been severely degraded due to overgrazing, and, at the same time, soil carbon storage has changed. Because of the high background variation and diversity of natural soils, it is difficult to detect changes in soil carbon pools, especially over short time periods. Some experiments have attempted to detect changes in different fractions of soil carbon pools. In Inner Mongolia grasslands, experiments have showed there was no evident decrease of soil organic carbon for grazing. In this study, we examined the effects of grazing on soil carbon fractions: soil microbial carbon (MB-C) and soil labile carbon (Lab-C) in the grasslands of the Xilin River Basin of Inner Mongolia. MB-C was determined using the chloroform fumigation method and Lab-C was determined using the potassium permanganate oxidation method. The results indicated that after 22 years of grazing in Leymus chinensis dominated grasslands. Soil microbial biomass decreased by 27.9% and 12.8% in the 0-10 cm and 10-20 cm layers, respectively, and Lab-C decreased by 22.0% and 12.6% in the two soil layers. After 22 years of grazing in a Stipa grandis grassland, MB-C decreased by 38.2% and 12.2% in the 0-5 cm and 5-15 cm soil layers, respectively. The time at which soil microbial biomass reached a peak in S. grandis was delayed (August) as compared to L. chinensis, and MB-C was significantly correlated with aboveground grass biomass (p<0.000 1). Soil microbial carbon and Lab-C were more sensitive than SOC to the impacts of grazing on changes in soil carbon storage. There were no significant decreases in any of the soil carbon fractions in the Artemisia frigida+short bunchgrasses grassland with increases in the stocking rates, but the ratios of MB-C/total C and Lab-C/total C decreased gradually with increases in stocking rates. These results indicate that the ratios of MB-C/total C and Lab-C/total C are more sensitive indicators than MB-C and Lab-C in reflecting soil carbon changes under grazing pressure in the Artemisia frigida+short bunchgrasses grassland.

选择内蒙古锡林河流域三种草原，较系统地研究了放牧对微生物量碳(MB-C)和易分解碳(Lab-C)两种碳素组分的影响。结果表明，自由放牧22年后，羊草（Leymus chinensis）草原土壤0～10 cm和10～20 cm土层土壤微生物量碳分别下降了27.9%和12.8%；土壤易分解碳分别下降了22.0%和12.6%，自由放牧没有改变羊草草原土壤活性碳的季节变化形式。大针茅(Stipa grandis)草原0～5 cm表层和5～15 cm下层土壤微生物量碳分别下降了38.2%和12.2%。大针茅草原季节波动出现高峰的时间较羊草草原推后，基本在8月下旬，并且与地上生物量存在明显的正相关关系（p 中牧>重牧，这说明，在表征放牧对冷蒿-小禾草草原土壤的影响指示上，MB-C/Org-C和Lab-C/Org-C要比MB-C和Lab-C敏感。

The influence of grazing on soil organic carbon content, soil readily oxidizable carbon and its distribution ratio, soil particulate component ratio, soil light fraction component ratio in Zhaosu meadow steppe were studied in grazing experiment plot with short period. The result showed that there was no significant effects of short-period grazing on soil organic carbon content although which decreased compared with CK at 0-10 cm soil layer ( P >0.05). The readily oxidizable carbon distribution ratio and particulate component ratio of 0-10 cm soil layer increased after grazing. There was no significant effects of different grazing intensity on soil organic carbon, readily oxidizable carbon and light fraction component ratio ( P >0.05). However, there were great fluctuations on the readily oxidizable carbon distribution ratio and particulate component ratio. Soil readily oxidizable carbon, readily oxidizable carbon distribution ratio, soil particulate component ratio of 10-20 cm soil layer, especially readily oxidizable carbon distribution ratio, could be used as sensitive indicators of soil organic carbon dynamics in the study region.

采用小区控制放牧试验,在昭苏草甸草原上研究了短期放牧对土壤有机碳含量、土壤易氧化碳含量及其分配比例、土壤颗粒组分比例、土壤轻组组分比例的影响。结果表明,与对照相比,短期放牧地可以降低0-10 cm土层土壤有机碳含量,但差异不显著( P >0.05),增加0-10 cm的土壤易氧化碳分配比例、颗粒组分比例。放牧强度对土壤易氧化碳分配比例、颗粒组分比例的影响波动性较大,而对土壤有机碳、易氧化碳与轻组组分比例的影响不显著( P >0.05);初步认为10-20 cm土层易氧化碳、易氧化碳分配比例与颗粒组分比例,尤其是易氧化碳分配比例,可作为昭苏草甸草原土壤有机碳动态的敏感性指标。

The distribution characteristics of soil organic carbon (SOC) and its physical fractions under the different land uses in Jinyun Mountain were studied in this paper. Subtropical evergreen broad-leaved forest (forest for short), sloping farmland, orchard and abandoned land were selected and soils at the depths of 0-60 cm were sampled in the spring of 2011 to determine the contents of soil organic carbon fractions. Five soil organic carbon fractions, i.e., coarse particulate organic carbon (cPOC), fine particulate organic carbon (fPOC), intra-microaggregate particulate organic carbon (iPOC), silt and clay within microaggregates (s+c_m), silt and clay (s+c) were separated by physical fractionation technique. The results showed that the contents of SOC, cPOC, fPOC, iPOC, s+c_m and s+c in the whole soil depth from 0 to 60 cm were significantly higher in the forest (9.02, 3.14, 1.61, 0.33, 0.42, 3.53 g/kg) than those in the orchard (3.27, 0.93, 0.27, 0.10, 0.24, 1.73 g/kg) and in the sloping farmland (2.58, 0.51, 0.10, 0.12, 0.08, 1.77 g/kg), which indicated the reclamation of forest would result in the loss of SOC and its fractions. 14.90, 5.17, 2.36, 0.42, 0.59, 6.36 g/kg of SOC and its corresponding fractions in the abandoned land were remarkably higher than those in the sloping farmland, which indicated the abandon from farmland would lead to the effective recovery and sequestration of SOC and its fractions. Among the SOC physical fractions, the ratios of iPOC to SOC were the lowest and accounted for only 3% in each land use type. The cPOC and fPOC fractions were considered as unprotected carbon pool with higher liability. The ratios of cPOC and fPOC to SOC were highest in the soils of the forest and abandoned land, reached to more than 50%. The <53 μm fraction contains organic carbon which is stabilized both as a consequence of its complex chemical composition and by adsorption to silt and clay particles. The ratios of <53 μm fraction containing organic carbon to SOC were highest in the soils of the orchard and sloping farmland, 65.9 and 71.6%, respectively. The results showed that the liability of soil organic carbon in the soils of forest and abandoned land were higher than those in the orchard and sloping land, that is to say, there is stronger soil fertility in the soils of forest and abandoned land. Furthermore, we suggest that fPOC is a promising fraction for assessing the impact of land use change on SOC in Jinyun Mountain.

探讨了我国西南地区缙云山亚热带常绿阔叶林(以下简称林地)、果园、坡耕地以及撂荒地4种土地利用方式对土壤有机碳(SOC)组分含量及其分配比例的影响。采用物理分组技术,将SOC分为粗颗粒有机碳(cPOC)、细颗粒有机碳(fPOC)、微团聚体内颗粒有机碳(iPOC)、微团聚体内粉+黏颗粒(s+c_m)有机碳及粉+黏颗粒(s+c)有机碳。研究结果表明:在0-60 cm的土壤深度范围内,SOC、cPOC、fPOC、iPOC、s+c_m组分以及s+c组分有机碳平均含量均为林地(9.02、3.14、1.61、0.33、0.42、3.53 g/kg)显著高于果园(3.27、0.93、0.27、0.10、0.24、1.73 g/kg)和坡耕地(2.58、0.51、0.10、0.12、0.08、1.77 g/kg),说明林地开垦会导致SOC及各组分的流失;而撂荒地上述SOC及其各组分含量分别为14.90、5.17、2.36、0.42、0.59和6.36 g/kg,均显著高于坡耕地,表明耕地撂荒后SOC及其组分能得到有效的恢复和截存。在SOC的各物理组分中,iPOC的有机碳分配比例最低,4种土地利用方式下均为3%左右;cPOC和fPOC作为活性较强的非保护有机碳库,在林地和撂荒地中所占SOC分配比例最高,达到50%以上;而果园和坡耕地中<53 um的粉+黏颗粒有机碳组成的化学保护有机碳库分配比例最大,分别为65.9%和71.6%,表明林地和撂荒地土壤有机碳的活性远远大于坡耕地及果园,支持更高的土壤肥力。在SOC及其组分中,fPOC可作为评估土地利用变化对土壤有机碳库影响的良好指标。

研究耕作年限对棉田土壤颗粒及矿物结合态有机碳的影响.以相应荒 地为对照,选取南北疆兰州湾、31团和普惠农场3个典型绿洲不同耕作年限土壤为研究对象,应用物理分组方法研究颗粒及矿物结合态有机碳的变化规律.结果表 明:耕作有利于棉田土壤总有机碳的积累,耕作(0～5年)总有机碳增加迅速,年均增加在0.65 g/kg以上；颗粒有机物、有机碳和颗粒有机碳的分配比例在耕作0～10年间增加,较荒地分别增加50.12％,263.64％,79.79％,10年后 下降.矿物结合态有机碳含量则随耕作年限的延长递增,矿物结合态有机物含量变化趋势与颗粒有机物相反.土壤有机碳在耕作1～10年增加,有利于土壤质量的 提高,是荒漠区土壤碳汇,是合理的耕作年限.

测定分析了长期放牧与围封对科 尔沁沙漠化草地土壤轻组及全土碳氮储量的影响。结果表明:(1)围封与长期放牧草地0-100 cm土壤轻组有机质占土壤质量的比例分别为0.148%和0.053%,围封比放牧增加181%;土壤轻组含量与全土有机碳和氮含量存在极为显著的线性正 相关关系;(2)围封草地0-100 cm土壤轻组碳和氮储量分别为271.38,20.36 g/m2,比长期放牧分别增加130%和164%;围封草地全土碳和氮储量分别为1 155.86,125.99 g/m2,比长期放牧分别增加58%和24%;(3)轻组有机碳和氮占全土有机碳和氮储量的比例,围封分别为23.48%和16.16%,放牧分别为 16.05%和7.59%;(4)围封恢复对轻组有机质的影响主要发生在表层土壤,围封0-10 cm层土壤轻组含量比长期放牧增加537%,10-20 cm层增加216%,但20 cm深度以下两个样地间无统计学上的显著差异。

封育是当前恢复和改良内蒙古草地的重要措施,也是实现草地固碳效应最有效的途径之一。本文利用内蒙古封育32年和自由放牧的羊草草地,分析了其土壤有机碳组分、土壤团聚体和土壤腐殖质组分碳含量的变化,并运用 13 C核磁共振波普法对土壤腐殖质的有机碳组分进行波普分析,探讨了长期封育对羊草草地土壤有机碳组分和土壤有机质结构的影响,期望能为科学地评估长期封育状况下草地固碳效应及其稳定性提供理论依据。实验结果表明:长期封育显著提高了草地土壤有机碳含量;在土壤有机碳组分中,除土壤微生物碳(MBC)含量降低外,其碳组分含量都相应增加。其中,易氧化有机碳(EOC)含量增加最为明显,长期封育草地是自由放牧草地土壤的4.53倍;长期封育显著提高了草地土壤0.25~2 mm团聚体所占比例及其有机碳含量;长期封育提高了草地土壤腐殖质中的胡敏酸碳(HAC)、胡敏素碳(HUC)含量和胡敏酸/腐殖质碳,降低了富里酸碳(FAC)的含量,封育草地土壤的HAC/FAC是自由放牧草地土壤的5.66倍。此外,长期封育草地土壤的脂族碳含量显著增加,芳香度相应增加,疏水碳/亲水碳增大。总之,长期封育不仅提高了草地土壤有机碳贮量,还能改善草地土壤结构、增强土壤有机碳的稳定性。

摘　要： 通过地面调查研究不同封育管理措施对甘肃景泰绿洲边缘沙质草地土壤轻组及全土碳氮储量的影响。结果表明,在天然封育和人工抚育措施实施后,研究区沙质草地0-40cm层土壤轻组及全土碳氮含量、单位面积有机碳和全氮储量都明显增加（P〈0.05）。（1）和流动沙地相比,封育19年（人工抚育19年）、封育19年（人工抚育5年）、封育10年（自然恢复）沙质草地0-40cm层土壤轻组干物质量分别增加170.8%,150.0%,129.2%,0-40cm层土壤有机碳和全氮平均含量分别增加372.7%和266.7%,190.9%和183.3%,136.4%和91.7%,土壤轻组干物质量与全土有机碳和氮含量呈高度正相关（r=0.95＊＊）。（2）和流动沙地相比,封育19年（人工抚育19年）、封育19年（人工抚育5年）、封育10年（自然恢复）沙质草地0-40cm层土壤轻组碳和氮储量分别比流动沙地增加422.7%和280.7%,345.7%和232.1%,244.4%和152.1%;全土碳和氮储量分别比流动沙地增加了261g/m2和20g/m2,143g/m2和15g/m2,101g/m2和7g/m2。（3）土壤轻组碳（氮）占全土碳（氮）储量的比例以封育沙质草地高于流动沙地;各封育沙质草地和流动沙地中轻组碳占全土碳的比例都高于轻组氮占全土氮的比例。（4）天然封育＋人工抚育措施对沙质草地的影响和改善程度高于纯天然封育措施,它是促进我国北方退化沙质草地恢复的适宜方法。

In order to explore the change patterns of organic carbon fractions and physical stability of sandy sierozem in desert steppe at the early stage of fencing, 0-40 cm soil samples were collected from a 5-year fenced desert steppe (inside the fence) and a free grazing steppe (outside the fence) in Yanchi County of Ningxia, Northwest China, with the soil organic carbon, labile organic carbon, and particulate organic carbon contents and soil particle composition analyzed. No significant differences were observed in the soil organic carbon content and soil particle composition inside and outside the fence. The average soil organic carbon inside and outside the fences was 3.25 g·kg -1 , the percentages of sand, silt, and clay were averagely 72%, 16%, and 12%, respectively, and the soil physical stability index was 1.30%-1.31%. The soil active organic carbon showed a significant change in 10-20 cm layer. The soil labile organic carbon content was 0.80 g·kg -1  inside the fence, which was significantly higher than that outside the fence (0.62 g·kg -1 ). The percentage of soil particulate organic carbon was 50.9% inside the fence, which was also significantly higher than that outside the fence (31.7%). The soil texture inside the fence changed from sandy to loam, and the soil labile organic carbon content increased gradually; while the soil texture outside the fence was sandy, and its vertical change was relatively smooth. The organic carbon of sandy sierozem in the desert steppe under the conditions of short-term fencing was still in a balance between consumption and accumulation, the soil texture was relatively stable, and the soil physical stability changed little. It was suggested that the soil active organic carbon content and its relative percentage in 10-20 cm layer could be used as the indicators of early soil quality change of desert steppe.

以宁夏盐池县荒漠草原5年围栏封育草地(围栏内)和自由放牧草地(围栏外)为对象,分析0～40 cm土层土壤有机碳、易氧化有机碳和颗粒有机碳含量以及土壤粒径组成,研究围栏封育早期沙化灰钙土有机碳组分及物理稳定性的变化规律.结果表明： 围栏内外土壤有机碳含量和颗粒组成差异不显著;围栏内外0～40 cm土层土壤有机碳含量平均为3.25 g·kg -1 ,沙粒、粉粒、黏粒的相对比重平均为72%、16%、12%,土壤物理稳定性指数为1.30%～1.31%.土壤活性有机碳的显著变化集中在10～20 cm土层,围栏内易氧化有机碳含量达0.80 g·kg -1 ,显著高于围栏外的0.62 g·kg -1 ,围栏内颗粒有机碳的分配比例为50.9%,显著高于围栏外的31.7%.随土层深度的增加,围栏内0～40 cm土壤质地由沙性土向沙壤土转变,各层间土质差异显著,易氧化有机碳含量逐渐升高;而围栏外土壤质地的垂直变化相对平缓,基本为沙性土质.退化荒漠草原短期围栏封育条件下,沙化灰钙土土壤有机碳尚处于一个消耗与积累的平衡阶段,土壤质地状况相对稳定,土壤物理稳定性变化较小.10～20 cm土层土壤活性有机碳含量及其相对分配比例可作为围栏封育早期土壤质量变化的指示指标.

封育是退化草地生态系统最为简 便有效的恢复措施之一。本研究以禁牧封育的宁夏荒漠草原为研究对象,采用空间梯度代替时间梯度的方法研究未封育、封育3年、5年、7年与10年的草地土壤 团聚体稳定性和有机碳及其组分含量在土壤剖面及团聚体中的分布及变化,研究取得以下主要结论： 依据大于0.25mm团聚体所占比重R0.25、平均重量直径MWD、几何平均直径GMD的变化,封育初期,植被恢复演替促进了0-20cm土层土壤团聚 作用,有利于大团聚体的形成。团聚体组成以封育3年的草地最好,封育5年的草地团聚体结构最差,之后随封育年限的延长土壤结构逐渐稳定。封育对水稳性团聚 体MWD与GMD的影响主要表现在0-5cm层,封育3年的草地土壤水稳性团聚体较好,封育5年以后,随着封育年限的继续延长,草地土壤水稳性团聚体趋于 稳定。土壤团聚体稳定性随土层深度的增加逐渐增强。 封育对荒漠草原5-10cm、10-20cm、20-40cm土层有机碳总量影响显著,随封育年限的增加,土壤有机碳储量呈先下降后上升趋势。各土层有机 碳含量均以封育7年、10年的草地较高,封育3年、5年的草地较低。土壤颗粒有机碳、水溶性有机碳和易氧化有机碳以封育7年的草地较高。 不同土层土壤各粒级团聚体有机碳含量对封育的响应不同。0-5cm与5-10cm土层以封育3年的草地各粒级团聚体有机碳含量较高,封育5年的草地各粒级 团聚体有机碳含量较低；10-20cm及20-40em土层,各粒级团聚体有机碳含量则以封育7年、10年的草地较高。不同粒径团聚体以1-0.5mm与 0.5-0.25mm粒级团聚体对总有机碳的贡献较大。 10-20cm与20-40cm土层土壤含水量随封育年限的延长表现为先下降后上升趋势。封育对5-10cm及20-40cm土层土壤容重有显著影响,但 不同土层对封育的响应不同。土壤全氮对封育的响应主要体现在10cmm以下土层,以封育3年的草地最低,封育7年、10年的草地较高。 土壤有机碳总量与MWD、GMD、土壤孔隙度及全氮含量呈显著正相关,与土壤容重呈极显著负相关。土壤颗粒有机碳与干筛团聚体R0.25、MWD、GMD 及土壤含水量呈显著负相关,与土壤容重呈显著正相关。可溶性有机碳与土壤容重呈显著负相关。

沙质草地是中国北方干旱半干旱 地区重要的土地资源，其严重的退化/沙漠化已成为中国北方主要的生态环境问题。围栏封育是当前退化草地主要的植被恢复和重建措施之一。开展围封对退化沙质 草地土壤-植被系统影响的研究，不仅是准确评估该地区荒漠化现状及逆转程度的基础工作，也对该地区采取经济而有效的围封方式具有广泛的应用价值和指导意 义。 本研究用空间代替时间的研究方法，通过对甘肃景泰绿洲边缘沙质草地在不同封育措施下生物多样性、构件生物量等植被特征与土壤水分、土壤养分及碳氮储量等土 壤理化因子的变化研究，以掌握该地区沙质草地植被与土壤恢复对封育措施的响应机理，为我国西部生态环境建设和生态恢复提供科学依据。研究结果表明： 1、封育措施对沙质草地植物群落物种组成与多样性特征有显著影响。流动沙地上植物种仅有9种，经过19年的封育后，沙质草地植物种增加到18种。天然围 封+人工抚育措施实施后，沙质草地群落的优势种主要为柠条和花棒等人工建植的灌木种，虽然物种丰富度较纯天然围封和短期人工抚育沙质草地为低，但人工建植 灌木表现出良好的生长状态且处于优势地位。不同封育措施下群落物种多样性特征总的趋势为：封育19年（人工抚育19年）封育19年（人工抚育5年）封育 10年（自然恢复）流动沙地。 2、沙地植被的平均高度、平均密度、平均冠幅和平均盖度在不同封育管理措施下具有显著差异（P0.05）。其各指标的大小均表现为：封育19年（人工抚育 19年）封育19年（人工抚育5年）封育10年（自然恢复）流动沙地。不同坡位比较结果显示，封育沙地植被平均高度、平均密度、平均冠幅和平均盖度受坡位 影响较流动沙地显著（P0.05）。 3、沙地群落总生物量随封育年限的增加而增大。在不同封育措施下，群落总生物量的排序为：封育19年（人工抚育19年）（94.41g/m~2）封育19 年（人工抚育5年）（60.08g/m~2）封育10年（自然恢复）（58.22g/m~2）流动沙地（33.75g/m~2）。但长期的封育（19年天 然围封+19年人工抚育措施）并不能改变1年生草本和多年生草本植物的花、茎、叶和根构件对整个植株的贡献率；而灌木植物的花、茎、叶和根构件对植株的构 成则有所变化。总体上，封育沙地的根冠比小于流动沙地，大部分植物构件对地上生物量的比率顺序为茎叶花根，植物构件对个体生物量的比率顺序为叶茎花根。 4、封育可使沙质草地土壤物理性质发生显著改善。砂粒、粉粒、粘粒含量、土壤容重、总孔隙度、最大含水量和紧实度在不同封育管理沙质草地之间具有显著差异 （P0.05）。和流动沙地相比，沙质草地随着封育年限的增加，土壤中砂粒含量明显减少，粘粒含量明显增加，土壤容重趋于降低，土壤总孔隙度和最大含水量 都显著增加。3个封育沙质草地10cm深度处土壤含水量均低于流动沙地，不同封育类型下土壤储水量的大小依次为：流动沙地封育19年（人工抚育5年）封育 10年（自然恢复）封育19年（人工抚育19年）。不同坡位比较结果显示，封育沙地土壤物理性质受坡位影响比流动沙地显著（P0.05）。 5、封育也使沙质草地土壤有机碳（SOC）和氮磷钾养分大量回归，促进了沙地向高质量土壤性状的良好演变。和流动沙地相比，封育19年（人工抚育19年） 沙质草地0~20cm土层SOC、全N、全P和全K分别增加380.0%，238.9%，75.0%和59.6%。封育沙地土壤理化性质受坡位影响具有显 著差异，而流动沙地各特征值受坡位影响不显著（P0.05）；封育沙质草地SOC、氮磷钾全量和速效养分含量沿上坡到下坡呈增加趋势，而流动沙地中没有表 现出相同的趋势。 6、在天然封育和人工抚育措施实施后，沙质草地0~40cm层土壤轻组及全土碳氮含量、单位面积有机碳和全氮储量都明显增加（P0.05）。沙质草地土壤 轻组碳（氮）占全土碳（氮）储量的比例，封育沙质草地高于流动沙地。与流动沙地比较，天然封育和人工抚育措施都能够有效地降低土壤有机无机复合度 （HFOC/SOC）。总体上，0~20cm土层，HFOC/SOC基本表现为封育沙地大于流动沙地，HFOC/SOC变化规律与LFOC/SOC相反。 7、植被特征与土壤理化因子的相关分析表明，Margalef丰富度指数、Shannon-Wiener指数、Pielou均匀度指数和Simpson优 势度指数与SOC、土壤轻组有机碳（LFOC）、速效氮和土壤含水量呈正相关，与速效磷、土壤容重和砂粒含量呈负相关；不同封育管理沙质草地地上、地下生 物量和凋落物量均与SOC、全N、LFOC、轻组氮（LFN）、重组有机碳（HFOC）含量呈极显著正相关关系（P0.01），而与土壤储水量和砂粒含量 呈极显著负相关关系（P0.01）；封育沙质草地SOC和全N含量的升高与土壤粘粉粒含量的增加呈极显著正相关（P0.01），而与砂粒含量的减少呈极显 著负相关（P0.01）；SOC与全N、全K之间呈极显著正相关（P0.01）；且SOC、全N、全K与植被平均高度、平均冠幅、总生物量等特征呈极显著 （P0.01）和显著（P0.05）正相关；容重、砂粒含量与植被平均高度、平均冠幅、总生物量等特征间呈极显著负相关。 8、天然封育+人工抚育措施对沙质草地的影响和改善程度高于纯天然封育措施。对退化沙质草地采取围栏封育并配合人工造林、补植措施，可促使绿洲外围沙质草 地植被与土壤间逐渐形成一个相互作用的良性循环系统，对促进退化草地正向演替和沙漠化的逆转具有积极而显著的作用。

农耕和畜牧是人类利用草地的主 要方式。然而,大面积开垦耕种和过度放牧破坏了整个草地生态系统的平衡。高寒草甸是青藏高原上分布的主要草地类型,低气温、强辐射、生长季短等严酷的自然 环境使得高寒草甸生态系统非常脆弱。在青藏高原东部地区,长期开垦耕种和过度放牧导致高寒草甸土壤退化,毒草蔓延,而封育禁牧措施在退化草地的恢复和重建 过程中被广泛采用。本论文通过三个野外调查实验,研究了开垦耕种、黄帚橐吾蔓延和封育禁牧对青藏高原高寒草甸土壤碳氮过程的影响。 1.以青藏高原东缘不同耕种年限的土壤为对象,研究了开垦耕种对其有机碳和全氮动态的影响。结果表明：(1)土壤有机碳、全氮总量都随着耕种年限的增加而 下降。相对于对照草地,耕种12年的土壤有机碳、全氮含量分别下降了10.8%和11.3%；而在耕种50年的土壤中,分别下降了24.3%和 26.3%。(2)土壤有机质各组分均随耕种年限的增加而下降,但下降速度各不相同,游离态轻组和包裹态颗粒组有机质在耕种前期下降速度较快,而矿物结合 态有机质的下降速度较为恒定。相对于对照草地,耕种12年的土壤游离态轻组和包裹态颗粒组有机碳分别下降了40.8%和14%,而在耕种50年的土壤中, 游离态轻组和包裹态颗粒有机碳分别下降了61.2%和37.2%;矿物结合态有机碳在耕种50年的土壤中下降了11.4%。(3)耕作活动使土壤团聚体结 构遭到破坏。在对照草地土壤中1mm的团聚体占43%,而在耕种了12年和50年的土壤中1mm的团聚体分别只占16%、7%。(4)土壤有机碳、全氮下 降和1mm的土壤团聚体的破坏显著相关,说明耕作导致的土壤团聚体结构的破坏使得包裹在其内部的有机质暴露,加快了有机质的分解速率,最终导致土壤有机 碳、全氮含量下降。 2.黄帚橐吾是近几十年来青藏高原高寒草甸广泛蔓延的一种毒草,甚至在一些过度放牧的地区成为了优势种。我们对比了黄帚橐吾根区土壤和本底草地土壤的生 物、化学属性差异。我们发现：(1)黄帚橐吾根区表层(0-8cm)土壤中的根生物量、碳水化合物、微生物量都显著高于本底草地土壤的。(2)黄帚橐吾促 进了表层(0-8cm)土壤中有机碳和氮的矿化。(3)黄帚橐吾根区表层(0-8cm)土壤中的脱氢酶、β-葡萄糖苷酶、脲酶、磷酸酶活性显著高于本底草 地土壤的。综上所述,黄帚橐吾改变了土壤生物、化学属性,使其更有利于黄帚橐吾生长,加速了黄帚橐吾在高寒草甸上的扩散。 3.以过度放牧的高寒草甸为对象,对比了封育禁牧6年、8年后,封育草地土壤与常年放牧草地土壤性质的差异。结果表明：封育禁牧8年没有对土壤总有机碳, 全氮含量产生显著影响。即使较为活跃的轻组有机碳、氮和碳水化合物碳也未发生显著变化。封育禁牧草甸植被地上生物量(现存量)显著高于放牧草甸,然而,封 育禁牧草甸植被地下生物量却显著低于放牧草甸。封育禁牧8年后土壤微生物量碳、氮,以及土壤β-葡萄糖苷酶、脲酶活性均未发生显著变化。高寒草甸土壤过程 是一个比较复杂的过程,封育禁牧并不一定导致高寒草甸土壤碳、氮含量的变化。

The combined methods of soil investigation sampling and lab analysis were explored on desert grassland in the North slope of Bogurda mountain. The variations of soil microbial biomass carbon and nutrient were analyzed under the free grazing and fence to investigate the influence of long-term fencing on soil quality. The results showed that, compared with free grazing, the content of soil organic carbon, available nitrogen, available potassium, and Olsen-P of fence for seven years significantly increased in the 0-10 cm layer, and the content of total nitrogen significantly increased in the 10-20 cm layer. The soil microbial biomass carbon content of fence for seven years significantly exceeded that of free grazing at the same soil layer( P <0.05). Soil microbial biomass carbon was more sensitive to fence which could be used as a sensitive indicator to measure changes of soil organic carbon.

采用新疆博格达山北坡荒漠草地土壤调查取样与室内分析相结合的方法,分析自由放牧和围栏封育下草地土壤微生物量碳和土壤养分的变化,探讨了长期围栏封育对土壤的影响。结果表明,与自由放牧草地相比,围封7年可显著增加0-10 cm土壤有机碳、碱解氮、速效钾和有效磷含量,以及10-20 cm土壤全氮含量( P <0.05)。围封7年相同土层微生物碳含量均显著大于自由放牧,表明土壤微生物量碳对围栏封育较为敏感,可作为衡量土壤有机碳变化的敏感指标。

测定了科尔沁沙地不同沙化程度农田 0～ 15cm耕层土壤粒级分布、有机碳 (SOC)和全氮 (N)含量 ,并应用土壤粒级物理分组方法对农田土壤各粒级组分 (2～ 0 .1、0 .1～ 0 .0 5、<0 .0 5mm)中SOC和氮的含量、富集系数、分配比例进行了研究 ,以揭示沙漠化过程中碳、氮衰减的机理。结果表明 ,沙地农田土壤物理稳定性指数大都低于5 % ,是土壤易发生风蚀沙化的内因。沙漠化过程中SOC和氮衰减的机理 ,一方面是与粘粉粒和部分极细沙结合的稳定态的有机碳和氮直接被吹蚀 ,粘粉粒吹蚀 1% ,SOC和全氮含量分别下降 0 .16 9g·kg-1和 0 .0 2 15g·kg-1;另一方面是与沙粒结合的颗粒有机碳 (ParticulateOrganicCarbon ,POC)形成量减少 ,沙漠化程度每增加 1级 ,POC、全氮含量分别下降 0 .4 3g·kg-1和 0 .0 5 9g·kg-1。

Nitrogen content of soil particulate fractions and its re lationship to the vegetation and the elevation in Qilian Mountains were investi gated. T he results showed that the ratio of soil particulate fractions, soil particulate organic matter\|nitrogen(PON) ratio, nitrogen content of soil particulate fractions, soil PON content did not signif icantly change with the altitude. Th e ratio of soil particulate fraction in 0～15 cm soil depth at 3 000 m,3 200 m and 3 500 m of shady slope, or 3 800 m of sunny slope, or that in 15～35 cm so il depth at 3 200 m,3 500 m of shady slope,or 2 800 m of semishady slope wa s the highest among the all elevations slope aspects and soil depths. PON ratio in 0～15 cm soil depth at 3 000 m and 3 200 m of shady slope,or 3 300 m and 3 800 m of sunny slope, or that in 15～35 cm soi l de pth at 3 300 m of sunny slope, or 3 000 m of shady slope was also the highest. The nitrogen content of PON in 0～15 cm at 3 600 m of shady slope was the low est, while the nitrogen content of PON in 0～15 cm at 3 800 m of sunny slope,or 2 800 m of half shady slope, or t hat in 15～35 cm at 3 400 m of shady slope, or 3 300 m of sunny slope was th e highest. The nitrogen content of soil particulate fraction in 0～15 cm soil dep th at 3 400 m of shady slope, or 3 300 m and 3 800 m of sunny slope,or that in 15～35 cm under 3 400 m of shady slope and 3 300 m of sunny slope was th e hi ghest. There were also significant effects of vegetation on the ratio of soil pa rticulate fraction, the ratio of soil PON, soil PON and nitrogen co ntent of soil particulate fraction. The ratio of soil particulate fraction in 0～15 cm soil depth forest or in shrub meadows was the highest, and the diffe rence for this ratio between in forest and shrub meadows or between in dese rt steppe and arid steppe were not significant, and that in 15～35 cm soil depth in forest, shrub meadows or arid steppe was the highest. While there were no significant difference for the ratio of soil particulate fraction among in f orest, shrub meadows and steppe. The ratio of PON in different soil depth in f orest and alpine meadows were the highest, and there were no significant diff er ence for the ratio among under shrub meadows, steppe and arid steppe in 0～15 cm soil depth, and the ratio in steppe or arid steppe in 15～35 cm soil depth w ere the lowest (p te fraction in different soil depth in shrub meadows was the highest, and tha t in desert steppe or arid steppe was the lowest. The nitrogen content of soi l PON in different soil depth under forest or shrub meadows was the highest, whi le that in desert steppe or arid steppe was the lowest, and there were no sig nificant difference for the nitrogen content among forest, alpine meadows and sh rub meadows. The ratio of soil particulate fraction, nitrogen content of soil pa rticulate fraction, soil PON content and soil PON ratio all increased with incre asing total soil nitrogen content (p t increased with increasing nitrogen content of soil particulate fraction ( p ontent (p il nitrogen content increased with increasing elevation, generally, and unprotec ted soil nitrogen ratio in forest and meadows was the highest among the all dif ferent types of vegetations. 

研究祁连山北坡土壤颗粒组分中氮含量及其与海拔和植被的关系。结 果表明：土壤颗粒组分比例、土壤颗粒氮比例、土壤颗粒氮含量和土壤颗粒组分氮含量都随 海拔升高 而差异不显著； 就土壤颗粒组分比例而言，0～15 cm土层在阳坡3 800 m处、阴坡3 000、3 200和3 500 m处较高，15～35 cm土层在阴坡3 200和3 500 m、半阴坡2 800 m处较高 （p 阳坡3 300和3 800 m处最高，15～35 cm土层在阴坡3 000 m和阳坡3 300 m处最高； 就土壤 颗粒氮含量而言，0～15 cm土层在阴坡3 600 m处最低，阳坡3 800 m和半阴坡2 800 m处较 高，15～35 cm土层在阴坡3 400 m、阳坡3 300 m处较高；就土壤颗粒组分氮含量而 言，0～1 5 cm土层在阴坡3 400 m、阳坡3 300和3 800 m处较高，15～35 cm土层在阴坡3 400 m 、阳坡3 300 m处较高（p 、 土壤颗粒组分氮含量和土壤颗粒氮含量的影响显著；就土壤颗粒组分比例而言，0～15 cm土 层在森林和 灌丛草甸中较高，高寒草甸中较低，森林与灌丛草甸及干草原与荒漠草原中差异不显著，15 ～35 cm土层在森林、灌丛草甸和干草原中较高，高寒草甸中最低，森林、灌丛草甸与干草 原中差异不显著； 就土壤颗粒氮比例而言，0～15 cm土层在森林和高寒草甸中较高， 灌丛 草甸、荒漠草原与干草原中差异也不显著，15～35 cm土层在森林和高寒草甸中较高，荒漠 草原和干草原中最低； 就土壤颗粒组分氮含量而言，各土层均在灌丛草甸中较高，干草 原和 荒漠草原中较低； 就土壤颗粒氮含量而言，各土层均在森林和灌丛草甸中最高，干草原 和荒 漠草原中最低，森林、高寒草甸与灌丛草甸中差异不显著； 土壤颗粒组分比例、土壤颗粒 组分氮含量、土壤颗粒氮比例和土壤颗粒氮含量随土壤全氮含量增加而增加(p ，土壤颗粒氮含量随颗粒组分氮含量极显著增加(p 随土壤颗粒氮含量增加显著增加(p 非保护性氮含量总体上随海拔升高而增加，森林和高寒草甸土壤中非保护性氮比例最高。

Carbon sequestration in the grassland ecosystems has important effects on the global carbon stocks. Grazing as one of the most widely land usage methods affects carbon sequestration in the grassland.However, unreasonable and over-grazing can lead to grassland degradation which has negative effects on carbon stocks in the grassland. Livestock enclosure and grazing affect carbon sequestration in the grassland by altering the vegetation productions and soil carbon stocks. This review indicated that livestock exclosure and grazing had positive or negative effects on the vegetation production which were affected by some other factors and their interaction, such as aboveground litter, vegetation structure, climate conditions, and so on. The effects of grazing on vegetation production were also related to the grazing intensity. Livestock exclosure and grazing had positive or negative effects on soil carbon stocks by affecting many processes in the soil carbon cycling. In summary, the effects of livestock exclosure and grazing on carbon sequestration in grassland were complicated. In order to make the scientific decision on grassland managements,the estimations of carbon stocks and researches on the related mechanisms are necessary in the further study.

草地生态系统固碳能力对全球碳贮量的大小有重要影响。放牧作为草地最广泛的利用方式之一影响着草地的碳贮量,过度和不合理的放牧方式造成草地退化,引起草地碳的损失。围栏禁牧与放牧对草地生态系统固碳能力的影响主要包括对植被生产力和土壤碳贮量的影响,本文对有关的报道进行了综述。结果显示,由于受植被凋落物、群落结构和气候等多因素的影响,围栏禁牧对草地植被生产力有正面或负面的效应;放牧对植被生产力的影响也没有一致的结果,此外,放牧对植被生产力的影响还与放牧的强度有关。围栏禁牧与放牧可以通过多种途径对草地土壤碳贮量产生正面或负面的影响。总之,围栏禁牧与放牧对草地生态系统固碳能力的影响是复杂多样的,需要对草地碳贮量进行估算,并对相关的机制进行研究,这样才能在草地管理方面做出合理的决策。

对呼伦贝尔典型草原四种植被类型0～100 cm土层土壤养分含量与植被特征进行了研究,从植被特征的空间梯度模拟草原退化过程的时间梯度.研究结果表明:土壤养分含量(碱解氮、有效磷、速效钾、有机质)与植被水平相互关联,植被类型的土壤养分特征与植被特征存在明显的正相关关系,总体趋势为植被水平高其土壤养分含量也较高.植被种群结构、盖度、高度和生物量差异显著.但只有当植被水平差异达到一定程度,土壤养分含量对其响应才能达到显著水平.不同养分对植被水平差异的响应灵敏度不同.在四种植被类型土壤养分含量比较中,不同养分差异性规律不同,碱解氮和有机质含量具有显著的相关性.

It is considered that active soil organic matter had influence on soil nutrient, plant growth, environment, atmosphere and human kind. Various technical terms and index were used for active soil organic matter in modern soil study. But their analysis methods were not systemic. These technical terms and index related to active soil organic matter, for example, dissolved organic carbon and water soluble carbon, available carbon, mineralized carbon, easy oxidation carbon, microbial biomass carbon, light fraction carbon and so on.

土壤有机物质的活性成分是对土壤养分、植物生长乃至环境、大气和人类有影响的有效物质.在现代土壤研究中,出现了与之相关的繁多术语和应用指标,但是它们的内涵尚为混乱,其分析方法也缺乏系统的归纳.本文对土壤溶性有机碳(DOC)和水溶性有机碳(WSOC)、土壤有效碳(AC)、土壤潜在可矿化碳(PMC)、土壤易氧化碳(ROC)、土壤微生物量碳(SMBC)、土壤轻组有机碳(LF-C)几种较为普遍应用的土壤活性有机质(碳)从概念指标、分析意义到分析方法做了较系统的描述与理顺,以期对土壤有机质应用上的研究起到积极作用.

The grassland is one of important agriculture natural resources. However, the grassland degraded seriously in China because of overgrazing. At the beginning of 21st century, enclosure was praised highly as a primary mean for grassland ecological restoration in west China. Effects of enclosure on the vegetation, soil and grassland ecosystem restoration were reviewed in this paper. It was concluded that the moderate grazing is necessary to restore degraded grassland and long-term enclosure is not as good as expected. According to the degree of grassland degradation in different regions, the enclosure should be flexibly combined with reasonable rotation grazing intensity and time to restore degraded grassland and get animal products simultaneously. It was suggested that the grassland ecological system will be sustainable and in good balance when grassland and animals are in win-win.

草地是我国重要的农业自然资源之一,但目前草地退化的现象十分严重,超载过牧是主要原因之一。本文就针对草地退化提出的围封禁牧措施对草地植被、土壤及草地生态系统恢复过程中的作用进行综述,发现适度放牧对草地恢复是必需的,但采取长期围封禁牧恢复与重建草地的做法不可取,围栏封育并非恢复退化草地的万全之计。建议在我国要因地制宜,根据草地的退化程度,采取合理的划区轮牧强度和放牧时间,与退化草地生态恢复的围封措施结合,以达到既能恢复退化草地,又可收获畜产品的双赢目的,实现草地生态系统持续平衡发展的目标。

对三江平原天然沼泽湿地及湿地垦殖后的农田、弃耕还湿地、人工林地等不同土地利用方式下表层土壤(0～10cm)的活性碳、氮组分:微生物量碳(MBC)、微生物量氮(MBN)、溶解有机碳(DOC)、溶解有机氮(DON)进行了研究.结果表明,天然小叶章沼泽湿地垦殖为农田后,表层土壤各活性碳、氮组分显著降低:MBC减少了63.8%～80.5%; MBN减少了56.3%～67.1%; DOC减少了43.1%～44.3%; DON减少了25.2%～56.1%.农田弃耕还湿和人工造林后表层土壤的活性碳、氮组分有明显恢复的趋势,各组分恢复到天然小叶章湿地土壤水平的36.1%～59.9%(MBC);46.7%～65.9%(MBN);67.0%～69.3%(DOC);81.2%～88.3%(DON),土地利用方式是影响土壤MBC、MBN、DOC、DON变化的重要因素;各土地利用方式表层土壤的DOC、DON、MBC、MBN呈显著的正相关关系,土地利用方式对表层土壤DOC的影响大于对DON的影响;各土地利用方式下土壤微生物可利用碳、氮的来源不同是影响DOC、DON与MBC、MBN相关性差别明显的主要原因.

Research progresses of soil microbial biomass during recent years were reviewed in this paper, including microbial biomass C, microbial N, microbial P. The necessity of soil microbial biomass C, microbial N and microbial P in the nutrient cycling was emphasized and the effects of planting, rotation, grazing, and fertilizer application on soil microbial biomass were discussed. Finally, this study proposed the key points of soil microbial biomass research in the future.

综述了近年来国内外土壤微生物生物量包括微生物生物量碳、微生物生物量氮和微生物生物量磷及其与碳、氮、磷循环方面的研究进展，着重论述了土壤微生物生物量碳、氮、磷在土壤养分转化循环中的重要性，并就种植、轮作、放牧、施肥等措施对土壤微生物生物量的影响进行了探讨。同时，就今后土壤微生物生物量的研究侧重点进行了展望。

This study determined soil carbon, nitrogen contents and C/N of 3 typical vegetation communities in Urad desert steppe. The results showed that: 1) the vegetation coverage of Stipa klemenzii community was significant higher than Achnatherum splendens and Reaumuria soongorica communities ( P A.splendens and R.soongorica respectively; 3) Soil organic carbon content of S.klemenzii community was significant higher than the other two communities, especially in 0-30 cm soil layer, and the total soil nitrogen content of R.soongorica community was the highest among 3 vegetation communities in 0-10 cm layer. There were some differences of soil C/N in different types of vegetation, but the change was not consistent with soil depth.

以乌拉特荒漠草原3种典型植被群落及其不同深度土层为研究对象, 比较不同群落及其土壤碳、氮含量差异。结果显示, 1)小针茅( Stipa klemenzii)群落的植被盖度显著高于芨芨草(Achnatherum splendens)和红砂(Reaumuria soongorica )群落( P <0.05), 但其地上生物量却显著低于其他两个群落;2)3种植被群落间的C含量差异不显著;N含量则表现为芨芨草<小针茅<红砂群落, 且差异均达到显著水平;C/N表现出红砂<小针茅<芨芨草群落, 差异均达显著水平;3)小针茅群落的土壤有机碳含量在0-30 cm层显著高于其余两群落, 红砂群落土壤表层(0-10 cm)全氮含量则显著高于另外两群落。不同植被类型各土层的C/N存在一定差异, 但变化没有随着土层深度的增加呈现出规律性。

碳和氮是土壤质量中最为重要的指标,它不仅反映土壤肥力水平,也印证着区域生态演变规律和生态建设的基本成果。黄土高原是我国主要生态脆弱区之一,多种不 利因素制约着该区土壤有机碳氮积累,因此了解这一地区土壤碳氮空间分布特征及其相关关系,对进一步了解该地区土壤碳氮循环有重要理论意义。本文以黄土高原 中部从北向南依次采集的干润砂质新成土(神木)、黄土正常新成土(

为探讨黄土高原大规模的生态修 复对土壤碳收支的影响,本研究以乔、灌、草和农田等不同植被类型,植被恢复的不同阶段,纯林和混交林等不同林分结构为对象,在野外调查和室内试验分析基础 上,通过测定其典型剖面土壤及其团聚体有机碳的组分、数量变化及相互关系,研究其有机碳组分的变化趋势,探索生态恢复对土壤有机碳固定的影响,为黄土高原 土地利用和生态环境建设规划提供依据