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1.
1980s-2010s内蒙古草地表层土壤有机碳储量及其变化 总被引：1，自引：1，他引：0
以我国内蒙古草原为研究区域,结合1982-1988年第二次土壤普查资料以及2011-2012年实地考察数据,构建了基于遥感数据和土壤数据的区域表层土壤有机碳储量估算方法,对研究区1980s和2010s表层土壤有机碳储量、空间分布特征及其变化进行研究,结果表明：(1) 1980s、2010s内蒙古草地表层土壤 (0~20 cm) 有机碳储量分别为2.05 Pg C、2.17 Pg C,土壤有机碳密度约为3.48 kg C·m-2、3.69 kg C·m-2,其空间分布上呈现从草甸草原、典型草原、荒漠草原逐渐降低的特征;(2) 1982-2012年间,内蒙古草地表层土壤有机碳储量略有增加,但增加幅度较小,其中草甸草原和典型草原表层土壤有机碳储量增加,荒漠草原则表现为减少。研究结果将为研究区因地制宜地采取固碳措施,实现草地可持续管理提供科学参考。 相似文献
2.
Accurate quantification of aboveground biomass of grasslands in alpine regions plays an important role in accurate quantification of global carbon cycling. The monthly normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), mean air temperature (Ta), ≥5℃ accumulated air temperature (AccT), total precipitation (TP), and the ratio of TP to AccT (TP/AccT) were used to model aboveground biomass (AGB) in grasslands on the Tibetan Plateau. Three stepwise multiple regression methods, including stepwise multiple regression of AGB with NDVI and EVI, stepwise multiple regression of AGB with Ta, AccT, TP and TP/AccT, and stepwise multiple regression of AGB with NDVI, EVI, Ta, AccT, TP and TP/AccT were compared. The mean absolute error (MAE) and root mean squared error (RMSE) values between estimated AGB by the NDVI and measured AGB were 31.05 g m-2 and 44.12 g m-2, and 95.43 g m-2 and 131.58 g m-2 in the meadow and steppe, respectively. The MAE and RMSE values between estimated AGB by the AccT and measured AGB were 33.61g m-2 and 48.04 g m-2 in the steppe, respectively. The MAE and RMSE values between estimated AGB by the vegetation index and climatic data and measured AGB were 28.09 g m-2 and 42.71 g m-2, and 35.86 g m-2 and 47.94 g m-2, in the meadow and steppe, respectively. The study finds that a combination of vegetation index and climatic data can improve the accuracy of estimates of AGB that are arrived at using the vegetation index or climatic data. The accuracy of estimates varied depending on the type of grassland. 相似文献
3.
研究了科尔沁沙地疏林草地、针茅草原和草甸植被盖度、地上和地下生物量、物种多样性对围封和放牧的响应。结果表明：（1）围封与放牧草地的优势植物不同,围封草地植物群落优势植物为多年生禾本科植物,放牧草地中一年生植物和小半灌木优势明显。（2）围封和放牧草地的植物盖度、凋落物量、地上生物量和物种丰富度存在明显差异（P<0.05）;围封显著提高了植被盖度和地上生物量,由疏林草地、针茅草原到草甸,植物盖度和地上生物量逐渐增加,而3种草地植被凋落物量大小顺序为针茅草原> 疏林草地> 草甸;放牧条件下植物盖度、凋落物量和物种丰富度差异不显著（P>0.05）。（3）3种草地之间的地下生物量无显著差异（P>0.05）,但围封与放牧之间、不同土壤层次之间地下生物量存在明显差异（P<0.05）;围封显著提高草地的地下生物量（P<0.05）;草地地下生物量随着土壤深度表现出下降趋势（P<0.05）。长期放牧增加了草地一年生植物和小半灌木植物的优势,消除了不同草地之间植被盖度和物种丰富度的差异;而围封能提高草地多年生禾本科植物的优势、增加其物种丰富度,对于草地质量和植物多样性的恢复和保育具有积极作用。 相似文献
4.
To understand the effects of grazing activities and climate change on sandy grassland ecosystems in northern China, a livestock field grazing and enclosure experiment was conducted from 1992 to 2006 in Horqin Sand Land, Inner Mongolia. The results showed that sustained heavy grazing resulted in serious degradation of the vegetation; moderate grazing can maintain vegetation stabilization; and light grazing can promote rapid restoration of degraded vegetation. The livestock productivity was the highest in the moderate grazing grassland, and sustained heavy grazing resulted in rapid decrease of the livestock productivity. Heavy grazing can cause a retrogressive succession of grassland vegetation, whereas moderate and light grazing may promote progressive succession of plant species. The effects of changing climate on succession processes were not significant in the short term; a warm-humid climate is favorable to restoration of degraded vegetation, whereas a sustained warm-drought climate may result in degradation of grassland vegetation. Heavy livestock grazing should be stopped for the sustainable use of grassland; the proper grazing intensity for sandy grassland is two to three sheep or sheep equivalents per hectare in Inner Mongolia. 相似文献
5.
科尔沁沙质草地植物群落的放牧退化及其自然恢复过程 总被引：6，自引：5，他引：1
为了了解不同放牧强度对我国北方沙质草地的影响及其封禁停牧后草地植被的自然恢复过程,我们于1992—2006年在科尔沁沙地开展了草地放牧和封育试验,分析研究了人类放牧活动对草地植被的影响,比较了不同程度退化草地恢复速度及其所受气候变化影响。研究结果表明:①在科尔沁沙地,随着放牧强度的增加,草地植被受放牧影响的程度会加重,但只有持续重牧才会导致植被的严重退化,而且持续重牧对植被盖度、高度和草地生产力的危害程度要大于对物种丰富度和多样性的危害程度;中度放牧可以导致植被盖度、高度、生物量的轻度下降,但对物种丰富度、多样性没有不良影响;对于退化草地而言,持续轻牧可促进植被的有效恢复;②封禁停牧以后,草地原受干扰程度不同,其恢复的相对速度也不同,表现为原草地退化越严重,其恢复速度相对越快,而且是植被高度、盖度、生物量的恢复速度要大于物种丰富度、多样性和频度的恢复速度;③草地植被的恢复演替明显受到气候变化的影响,暖湿气候有利于植被的恢复,暖干气候对于植被的恢复不利。 相似文献
6.
Detecting the storage and change on topsoil organic carbon in grasslands of Inner Mongolia from 1980s to 2010s 总被引：2，自引：2，他引：0
Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon（SOC） storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil（0–20 cm） organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that：（1） the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.（2） SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn＇t show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection. 相似文献
7.
Comparison of ecosystem services provided by grasslands with different utilization patterns in China’s Inner Mongolia Autonomous Region 总被引：1，自引：0，他引：1
Bingzhen Du Lin Zhen Yunfeng Hu Huimin Yan Rudolf De Groot Rik Leemans 《地理学报(英文版)》2018,28(10):1399-1414
Although several previous studies in Inner Mongolia examined the effects of ecological conservation on the delivery of ecosystem services, they were often limited in scope (few ecosystem services were assessed) and often suffered from confounding by spatial variation. In this study, we examined the impact of conservation measures (changes in grassland utilization patterns) on the provision of selected ecosystem services in three types of grasslands (meadow steppe in Hulun Buir, typical steppe in Xilin Gol, and semi-desert steppe in Ordos) in Inner Mongolia. We examined five utilization patterns: no use (natural grasslands), light use, moderate use, intensive use, and recovery sites (degraded sites protected from further use). Through household surveys and vegetation and soil surveys, we measured the differences in ecosystem services among the different grassland utilization patterns. We also identified spatial factors that confounded the quantification of ecosystem services in different types of grasslands. We found that light use generally provided high levels of ecosystem services in meadow steppe and typical steppe, with the main differences in the supporting ecosystem services. Surprisingly, we found no consistently positive impacts of strict conservation activities across the sites, since the results varied spatially and with respect to differences in the land-use patterns. Our study suggests that appropriate grassland utilization patterns can enhance the supply of ecosystem services and reduce negative effects on both household livelihoods and the environment. 相似文献
8.
Although several previous studies in Inner Mongolia examined the effects of ecological conservation on the delivery of ecosystem services, they were often limited in scope(few ecosystem services were assessed) and often suffered from confounding by spatial variation. In this study, we examined the impact of conservation measures(changes in grassland utilization patterns) on the provision of selected ecosystem services in three types of grasslands(meadow steppe in Hulun Buir, typical steppe in Xilin Gol, and semi-desert steppe in Ordos) in Inner Mongolia. We examined five utilization patterns: no use(natural grasslands), light use, moderate use, intensive use, and recovery sites(degraded sites protected from further use). Through household surveys and vegetation and soil surveys, we measured the differences in ecosystem services among the different grassland utilization patterns. We also identified spatial factors that confounded the quantification of ecosystem services in different types of grasslands. We found that light use generally provided high levels of ecosystem services in meadow steppe and typical steppe, with the main differences in the supporting ecosystem services. Surprisingly, we found no consistently positive impacts of strict conservation activities across the sites, since the results varied spatially and with respect to differences in the land-use patterns. Our study suggests that appropriate grassland utilization patterns can enhance the supply of ecosystem services and reduce negative effects on both household livelihoods and the environment. 相似文献
9.
利用2005-2011年内蒙古西部草原756个地面调查样方与2001-2011年MODIS NDVI数据集,建立统计模型,估算了内蒙古西部草原地上生物量,并探索了地上生物量与气候因子的关系.结论如下:①内蒙古西部草原地上生物量2001-2011年均值为5.27 Tg(1 Tg=1012g).2001-2011年间,内蒙古西部草原地上生物量呈波动状态且略有下降趋势.②内蒙古西部草原地上生物量的空间差异显著,总体自东南向西北逐步降低.③内蒙古西部草原地上生物量年际波动的主要驱动因子是1-7月的降水量,而与同期气温无显著关系;降水量同样是决定地上生物量空间分布的重要因素,而气温的影响较弱.本研究的估值仍存在一定的不确定性,主要来源于样方的采集标准差异、样方生物量的折算偏差、灌木生物量的低估与遥感数据集误差. 相似文献
10.
放牧强度影响草原植被的固碳能力。本文以呼伦贝尔克鲁伦河流域的半干旱典型草原作为研究区域,开展不同放牧压力下异质性植被-土壤系统中碳截存的特征研究。研究发现:不同放牧梯度下,土壤有机质、地上生物量、地下生物量和土壤微生物生物量碳彼此之间呈一定的相关性。随着放牧强度的加剧及土层深度的加深,土壤碳截存量呈减少趋势。其中,土壤有机质的变化趋势与土壤碳截存量趋势相同;而土壤无机碳含量呈现逐渐增大的特征。过度放牧破坏了土壤的理化性质及土壤质量,加速了土壤有机质的损失。草原群落的根冠比也随着放牧强度的增大而增加。以土壤微生物生物量碳作为土壤固碳能力的指标,不同放牧强度下的草原群落土壤固碳能力为轻牧区>中牧区>重牧区。 相似文献
11.
Spatial pattern of grassland aboveground biomass and its environmental controls in the Eurasian steppe 总被引：1，自引：0，他引：1
Vegetation biomass is an important component of terrestrial ecosystem carbon stocks. Grasslands are one of the most widespread biomes worldwideplaying an important role in global carbon cycling. Thereforestudying spatial patterns of biomass and their correlations to environment in grasslands is fundamental to quantifying terrestrial carbon budgets. The Eurasian steppean important part of global grasslandsis the largest and relatively well preserved grassland in the world. In this studywe analyzed the spatial pattern of aboveground biomass(AGB)and correlations of AGB to its environment in the Eurasian steppe by meta-analysis. AGB data used in this study were derived from the harvesting method and were obtained from three data sources(literatureglobal NPP database at the Oak Ridge National Laboratory Distributed Active Archive Center(ORNL)some data provided by other researchers). Our results demonstrated that:(1) as for the Eurasian steppe overallthe spatial variation in AGB exhibited significant horizontal and vertical zonality. In detailAGB showed an inverted parabola curve with the latitude and with the elevationwhile a parabola curve with the longitude. In additionthe spatial pattern of AGB had marked horizontal zonality in the Black Sea-Kazakhstan steppe subregion and the Mongolian Plateau steppe subregionwhile horizontal and vertical zonality in the Tibetan Plateau alpine steppe subregion.(2) Of the examined environmental variablesthe spatial variation of AGB was related to mean annual precipitation(MAP)mean annual temperature(MAT)mean annual solar radiation(MAR)soil Gravel contentsoil p H and soil organic content(SOC) at the depth of 0–30 cm. NeverthelessMAP dominated spatial patterns of AGB in the Eurasian steppe and its three subregions.(3) A Gaussian function was found between AGB and MAP in the Eurasian steppe overallwhich was primarily determined by unique patterns of grasslands and environment in the Tibetan Plateau. AGB was significantly positively related to MAP in the Black Sea-Kazakhstan steppe subregion(elevation 3000 m)the Mongolian Plateau steppe subregion(elevation 3000 m) and the surface(elevation ≥ 4800 m) of the Tibetan Plateau. Neverthelessthe spatial variation in AGB exhibited a Gaussian function curve with the increasing MAP in the east and southeast margins(elevation 4800 m) of the Tibetan Plateau. This study provided more knowledge of spatial patterns of AGB and their environmental controls in grasslands than previous studies only conducted in local regions like the Inner Mongolian temperate grasslandthe Tibetan Plateau alpine grasslandetc. 相似文献
12.
羊啃食动力学模拟与内蒙古西部气候变化适应 总被引：1，自引：0，他引：1
将定性分析、民主参与式评估和定量数值模拟方法结合起来,对阿拉善气候变化适应问题进行了简要评估并重点分析了土地退化、放牧和草原管理策略之间的关系。阿拉善主要的适应政策是禁牧和生态移民。禁牧后荒漠草原植被得到恢复,但移民增加了绿洲压力,过度开垦又造成周边土地沙化;过度抽取地下水致使水位下降并伴随咸水入侵和地表盐碱化。禁牧的另一个副作用是造成草原鼠害加重及火灾风险增加,生物多样性也呈现先升后降趋势。一些灌木因缺乏啃食出现退化迹象等,说明一定程度的啃食有利于维持草原生态平衡。因此,动物是草原生态系统不可或缺的成员之一。我们用一个包含动物啃食等的森林生态动力模式模拟了啃食动力学,结果表明,有限的放牧有利于草场更新并能充分利用草原资源;过度放牧导致草场退化并伴随羊群死亡。因此,需要将圈养和限制性放牧结合起来,制定可持续性适应政策。 相似文献
13.
以内蒙古苏尼特右旗短花针茅荒漠草原为研究对象,通过划区轮牧与自由放牧的比较试验,从植物构件方面研究了3种主要植物种短花针茅、无芒隐子草和碱韭营养枝、生殖枝、分蘖节及其根生物量和能量分配对不同放牧制度的响应。结果表明,禁牧和划区轮牧有利于植物的地上部分生长和有性繁殖,自由放牧区短花针茅和无芒隐子草将把更多的资源和能量用于营养生长,有性生殖严重受阻,以抵御不利的生长环境;划区轮牧提高了碱韭分蘖节的生物量、短花针茅和碱韭构件能量现存量及总能量现存量。短花针茅、无芒隐子草和碱韭根的生物量、能量现存量、生物量分配比例以及根冠比能量现存量、根的能量分配比例划区轮牧区与自由放牧区均高于禁牧对照区;短花针茅、无芒隐子草和碱韭不同构件及植株整体热值划区轮牧区也高于自由放牧区。营养枝与生殖枝的生物量和能量分配没有显著的颉颃关系,但营养枝与分蘖节生物量和能量分配比例间呈显著的颉颃关系。 相似文献
14.
2001-2010 年内蒙古植被覆盖度时空变化特征 总被引：65，自引：4，他引：61
基于MODIS-NDVI 遥感数据反演了内蒙古地区2001-2010 年植被覆盖度的空间格局和变化规律, 并结合该地区同期降雨量和温度数据, 分别从不同空间和时间尺度上分析了森林生态区、草原生态区和荒漠生态区植被的年际变化和月际变化对气候变化的响应。结果表明:(1) 内蒙古植被覆盖度在空间上呈现东高西低的分布特征, 自西向东的变化速率为0.2/10°N, 10 年间森林、草原和荒漠生态区的年均植被覆盖度分别为0.57、0.4 和0.16;(2) 2001-2010年, 内蒙古植被覆盖度总体上呈上升趋势, 研究区内植被覆盖度极显著增加和显著增加的面积分别占总面积的11.25%和29.13%, 二者之和大于植被覆盖度极显著减少和显著减少的面积比例之和, 后者分别为7.65%和26.61%;(3) 在年际水平上, 内蒙古植被生长总体上与降雨量的关系更加密切, 而在月际水平上, 降雨量和温度对植被生长的影响作用相当, 说明年内植被生长更依赖于水热组合的共同作用, 而与单一气候因子的相关性降低;(4) 森林生态区植被覆盖度在年/月际水平上均与温度的相关性较强, 荒漠生态区植被覆盖度在年/月际水平上均与降雨量相关性较强, 而草原生态区植被覆盖度在年际水平上主要受降雨影响, 在月际水平上与二者相关性相当;(5) 草原区月植被覆盖度对降雨量的响应存在时滞效应。 相似文献
15.
基于植被盖度和高度的不同退化程度高寒草地地上生物量估算 总被引：1，自引：0，他引：1
由于气候变化和不合理的人类活动,20世纪80年代以来青藏高原高寒草地发生严重退化。地上生物量是评价草地退化的直观指标。通常采用植被盖度和高度来估算草地地上生物量,但草地退化后,植被盖度和高度与地上生物量之间的关系是否会发生变化目前还不清楚,这影响着退化草地生物量估算的精度。通过多元回归分析研究了青藏高原中部和东北部高寒草甸、高寒草原在不同退化程度下植被盖度和高度与地上生物量的关系。结果表明：（1）高寒草甸与高寒草原地上生物量整体上及不同退化阶段都没有显著差异（P>0.05）。（2）随着退化程度的加剧植被盖度和高度对地上生物量的影响也发生改变,体现在未退化阶段地上生物量主要受植被高度影响,退化后主要受植被盖度影响。（3）无论是高寒草甸还是高寒草原分退化程度的回归模型估算结果都较不分退化程度模型估算的生物量更接近实测值。我们建议在退化高寒草地研究中采用盖度和高度估算生物量时,根据退化阶段采用不同的估算模型。 相似文献
16.
内蒙古植被覆盖度的时空动态变化及其与气候因子的关系(英文) 总被引：5，自引：2，他引：3
The vegetation coverage dynamics and its relationship with climate factors on different spatial and temporal scales in Inner Mongolia during 2001-2010 were analyzed based on MODIS-NDVI data and climate data.The results indicated that vegetation coverage in Inner Mongolia showed obvious longitudinal zonality,increasing from west to east across the region with a change rate of 0.2/10°N.During 2001-2010,the mean vegetation coverage was 0.57,0.4 and 0.16 in forest,grassland and desert biome,respectively,exhibiting evident spatial heterogeneities.Totally,vegetation coverage had a slight increasing trend during the study period.Across Inner Mongolia,the area of which the vegetation coverage showed extremely significant and significant increase accounted for 11.25% and 29.13% of the area of whole region,respectively,while the area of which the vegetation coverage showed extremely significant and significant decrease accounted for 7.65% and 26.61%,respectively.On inter-annual time scale,precipitation was the dominant driving force of vegetation coverage for the whole region.On inter-monthly scale,the change of vegetation coverage was consistent with both the change of temperature and precipitation,implying that the vegetation growth within a year is more sensitive to the combined effects of water and heat rather than either single climate factor.The vegetation coverage in forest biome was mainly driven by temperature on both inter-annual and inter-monthly scales,while that in desert biome was mainly influenced by precipitation on both the two temporal scales.In grassland biome,the yearly vegetation coverage had a better correlation with precipitation,while the monthly vegetation coverage was influenced by both temperature and precipitation.In grassland biome,the impacts of precipitation on monthly vegetation coverage showed time-delay effects. 相似文献
17.
在内蒙古呼伦贝尔草原克鲁伦河流域选取轻度、中度和重度3个放牧区研究植物地上和地下生物量、根冠比及土壤有机质、氮、磷等养分含量对放牧强度的响应。结果表明:重度放牧区的地上生物量(89.73 g·m-2)显著低于轻度(565. 61 g·m-2)和中度放牧区(488. 92 g·m-2),地下生物量(1 029. 90 g·m-2)则显著高于轻度(604.92 g·m-2)和中度放牧区(418.38 g·m-2)。重度放牧区的根冠比为11.54,显著高于轻度(1.11)和中度放牧区(0.89)。土壤有机质及各养分含量随着放牧强度的增加先显著降低而后显著增大,中度放牧区的养分含量最低。 相似文献
18.
江河源区的草地资源特征与草地生态变化 总被引：83，自引：12，他引：83
通过对江河源区草地生态类型与分布、草地资源特征及其利用现状的研究和生产力的评价，并根据70年代以来3期遥感资料和区域调查结果，分析了江河源区草地生态变化态势，结果表明：现状江河源区草地以高寒草原化草甸为主要草地类型，其分布面积占江河源区总草地面积的53.78%。组成草地牧草的主要植物种类的粗蛋白含量超过10%，粗脂肪含量在2%以上，能值储量在9.34KJ.g^-1以上；自70年代以来，由于区域畜牧业的迅速发展，江河源区冷季草场严重过牧，超载牲畜量达理论载畜量的1-5倍，大部分地区夏季草场亦超载，导致江河源区草地生态严重退化，年退化速度达6.64%-34.35%。合理利用草地资源，保护该区域脆弱生态环境已迫在眉睫。 相似文献
19.
A precise understanding of the aboveground biomass of desert steppe and its spatio-temporal variation is important to understand how arid ecosystems respond to climate change and to ensure that scarce grassland resources are used rationally. On the basis of 756 ground survey quadrats sampled in western Inner Mongolia steppe in 2005–2011 and remote sensing data from the Moderate Resolution Imaging Spectroradiometer (MODIS)—the normalized difference vegetation index (NDVI) dataset for the period of 2001–2011—we developed a statistical model to estimate the aboveground biomass of the desert steppe and further explored the relationships between aboveground biomass and climate factors. The conclusions are as follows: (1) the aboveground biomass of the steppe in the research area was 5.27 Tg (1 Tg=1012 g) on average over 11 years; between 2001 and 2011, the aboveground biomass of the western Inner Mongolia steppe exhibited fluctuations, with no significant trend over time; (2) the aboveground biomass of the steppe in the research area exhibits distinct spatial variation and generally decreases gradually from southeast to northwest; and (3) the important factor causing interannual variations in aboveground biomass is precipitation during the period from January to July, but we did not find a significant relationship between the aboveground biomass and the corresponding temperature changes. The precipitation in this period is also an important factor influencing the spatial distribution of aboveground biomass (R2=0.39, P<0.001), while the temperature might be a minor factor (R2=0.12, P<0.01). The uncertainties in our estimate are primarily due to uncertainty in converting the fresh grass yield estimates to dry weight, underestimates of the biomass of shrubs, and error in remote sensing dataset. 相似文献
20.
放牧强度对科尔沁沙地沙质草地植被的影响 总被引：5，自引：3，他引：2
为了研究科尔沁沙地沙质草地在不同放牧强度下植被特征的变化规律,比较了围封、中度放牧、重度放牧3种条件下的植被盖度、群落组成、物种多样性、地上/地下生物量和凋落物量等植被特征的变化特征。结果表明:(1)围封、中度放牧和重度放牧沙质草地的优势植物均为一年生植物,但围封和中度放牧中多年生禾本科植物优势度高于重度放牧,重度放牧沙质草地一年生植物所占优势度最大;(2)放牧强度对沙质草地植被盖度、地上生物量及凋落物量有显著影响。随着放牧强度的增加,植被盖度、地上生物量和凋落物量均降低;(3)围封、中度放牧和重度放牧沙质草地物种丰富度及多样性差异均不显著;(4)放牧强度和土壤深度及其交互作用均能影响地下生物量。随着放牧强度的增加,总的地下根系生物量减小。而重度放牧草地中, 3个土壤深度间地下根系生物量差异不显著。放牧改变了沙质草地植物群落的组成、极大降低了植被盖度和生产力;尤其是重度放牧急剧增加了一年生植物的优势、且对浅层根分布的减少影响最大。 相似文献