利用遥感技术监测锡林郭勒天然草原利用强度方法初探

利用多时相的遥感数据,对2005年锡林郭勒天然草原生长期放牧利用强度进行了信息提取、监测和制图.结果表明:在牧草生长季节,天然草原各旬度的利用强度与植被指数旬度变动系数成反比,并与降雨和植被长势时空分布格局相一致;放牧初期旬度变动系数下降4%左右,利用强度较轻,处于轻度过牧状态;6月中旬以后,旬度变动系数下降12%～20%之间,利用强度加重,处于中度超载过牧状态;8月下旬后植物生长停止,旬度变动系数下降27%左右,利用强度最重,处于重度超载过牧状态.遥感监测结果经过地面同步采集数据验证,监测精度达到79.6%.     

锡林郭勒草原地上净第一性生产力遥感反演方法初探

探索了利用遥感方法进行牧草消耗量估测，进而进行大面积天然草原地上净第一性生产力估测的方法和技术流程。并以锡林郭勒草原为例，提出了利用MODIS-NDVI反演最高生物量期的牧草采食消耗昔，再利用地面获取的旬度采食系数，推算整个生长季的牧草采食消耗量的思路。在获得草原放牧消耗量基础上，反演了草原净第一性生产力。由于野外测量草原净第一性生产力和消耗量数据的难度较大，所以该方法中的定量分析缺乏对研究区草原净第一性生产力分布特征和消耗量的直接验证，有关反演的方法和可靠性仍有待于进一步验证。     

青海省海西州天然草地资源现状及动态

根据2005-2009年对青海省海西蒙古族藏族自治州天然草地资源的监测结果发现,目前该州天然草地可划分为高寒草原、温性草原、温性荒漠草原、高寒草甸、低地草甸和高寒草甸草原6类;海西州可利用草地面积不断减少,与2007年相比,2008年和2009年全州可利用草地面积分别减少226.07和169.31万hm2;各类型草地鲜草总产量大幅度降低;草地连年超载过牧,且逐年加重,2005、2007和2009年全州草地分别超载13.97、26.56和33.94万羊单位;草地生态破坏,出现不同程度的沙化、退化现象。分析海西州天然草地资源现状,建议对现有天然草地实施封育保护,加强人工草地建植,调整畜群结构,严格控制放牧强度。     

不同放牧强度对羊草草原近地面反射波谱特征的影响研究

测试并分析了在生长季节不同放牧强度（无牧、中轻度和重度放牧）对羊草草原植被反射波谱特征的影响。羊草草原不同放牧强度群落的种类组成、结构和生物量特征上的明显不同，导致植被反射波谱特征表现出显著差异。不同放牧强度群落的近地面反射特征在6月底的差异最为显著，在5月底的差异最不明显。使用主分量分析（PCA）和模式识别方法，利用多时相的植被反射特征组合数据，对3个不同放牧强度的群落进行了鉴别，后者对退化草地鉴别精度较高。对不同放牧等级群落分类效果最佳的3个反射率组合包括蓝光、红光和近红外光反射率。6月底的鉴别效果最好，最大错误概率小于4％；5月底的鉴别效果最差，最大错误概率高20％左右。     

辽宁省草原资源调查与研究

草原作为重要的自然资源不仅成为保护生态的绿色屏障，而且对畜牧业特别是草食畜牧业的发展有着举足轻重的作用。辽宁属北方重要草原区，长期受盲目开垦和超载过牧影响，70％的天然草原出现不同程度的“三化”，生产力水平不断下降。由于管理不利，监测不到位，导致原本不够完整的有关草原资源资料也严重缺损，信息陈旧失准。为了加强草原的保护建设，     

马尔康市草原生态保护与畜牧经济可持续发展初探

由于缺乏对草原的科学认识,人们不顾草原的载畜能力而一味地追求牲畜数量,导致草原生态系统入不敷出.传统原始放牧习惯,使草地利用强度不均衡,采挖药材和毁草开荒、超载过牧严重,草原植被得不到休养生息,导致草地退化、鼠虫害危害面积逐年扩大,可利用面积不断减少,草地生产力明显下降,草原开始逆向演替,生态系统日趋恶化,严重制约着马...     

要闻

农业部：我国草原综合植被盖度51％ 农业部日前发布《2011年全国草原监测报告》指出，2011年我国草原综合植被盖度为51％，草原植被总体长势偏好，天然草原鲜草总产量达100248．26万吨，较上年增加2．68％，但草原超载过牧依然严重，草原退化、沙化、盐渍化仍在不断发展，全国草原生态环境治理步入攻坚阶段。     

实现草畜平衡的措施

长期以来由于经济的发展、人口增长和资源的不合理利用、草原超载过牧、沙化退化严重．导致草畜矛盾突出。从总体上看新疆草原面积在不断减少．究其原因：一方面，近20年来农业综合开发使天然草场尤其是冬春草场大面积减少：另一方面．因超载过牧草原沙化面积不断扩大。草原面积的减少造成冬春草料不足．夏季草场严重超载．使牧区草场处于超饱和状态。草原畜牧业正处于一个草原退化（减少）-人口增加-牲畜扩增-牲畜品种弱化-畜牧业产出低-牧民增收困难的恶性循环。加之农区牲畜到放牧场更加重了天然草原的压力。     

放牧对星毛委陵菜(Potentilla acaulis) 种群生殖对策的影响

在种群水平上系统研究了不同放牧强度对内蒙古冷蒿小禾草退化草原星毛委陵菜（Potentilla acaulis)种群克隆生长，有性生殖的影响，结果表明：星毛委陵菜匍匐茎长度在轻牧处理最大，而重牧条件下显著缩短；分株密度随放牧强度增加而增加。种群营养枝密度在不放牧与放牧处理之间差异显著，尤其是不放牧与重牧之间，而相邻放牧强度之间差异不显著。星毛萎陵菜生殖植密度在放牧处理间差异不显著，但不放牧与重牧差异显著，与轻放，中牧差异不显著。种群生殖分化率不放牧显著高于中牧和重牧，但与轻牧间差异不显著。随放牧强度的增加，生殖植上花序数目增加，但差异不显著。     

阿坝州草原超载过牧现状与思考

阿坝州草原是川西北草原的重要组成部分,在气候、地理、人文等多重压力下,草原长期处于超载过牧状态,尤以阿坝县、若尔盖县、红原县、松潘县、壤塘县牧区五县最为突出。阿坝州采取一系列因地制宜的措施,着力解决牲畜超载过牧、草原退化等问题,确保草原生态环境和草原畜牧业健康可持续发展。     

不同放牧密度对草原植被特征的影响分析

呼伦贝尔天然草原在不同放牧半径条件下的草原植被演替特征，包括植被组成、群落主要植物的优势度、植被演替度、植被高度、盖度以及生产力与放牧强度的变化关系等。结果分析表明：呼伦贝尔草原放牧密度的差异将导致植被组成中的减少种、增加种与侵入种比例呈有规律改变，特别是随放牧密度的增大，侵入种比例急剧开始升高；同时草原植被中优势种比例下降，而且植被演替度减小，植被生产力下降。应用植被生态学的定量分析方法，对不同     

Long-Term Vegetation Productivity and Trend Under Two Stocking Levels on Chihuahuan Desert Rangeland

Vegetation changes were evaluated over an 11-year period (1995–2005) on 2 light- and 2 conservative-stocked Chihuahuan Desert pastures in south central New Mexico. Grazing treatments were applied to the pastures over a 5-year period from 1997 through 2001. Pastures were not grazed in the 1995–1996 and 2002–2005 periods due to drought. During the 1997–2001 grazing period, grazing use of primary forage species averaged 29% and 40% on light- and conservative-stocked rangelands, respectively. Grazing intensity was consistently higher on conservative-stocked than light-stocked pastures. During our study heavy grazing occurred only in 1 year on pastures with conservative stocking. There were no differences in species or species categories (grasses, forbs, shrubs) of autumn standing crop and basal cover between light-and conservative-stocked pastures. Standing crop of total vegetation and perennial grasses showed large fluctuations among the years due to variable rainfall. Under both treatments, total herbaceous standing crop was unchanged, but perennial grass standing crop declined by over 50% when the last 3 years of study were compared with the first 3 years of study. Broom snakeweed (Gutierrezia sarothrae Pursh), a poisonous half shrub, increased in standing crop and cover during the study. Basal cover of total perennial grasses declined less under light than conservative stocking during the study period. However, climatic conditions exerted the overriding influence on vegetation standing crop and basal cover. Our study indicates that light stocking in the Chihuahuan Desert does not increase perennial grass production compared to conservative grazing but it could have a small benefit in maintaining perennial grass cover during drought. We believe our findings have broad application in the Chihauhuan Desert, but caution they might not apply well to other arid rangeland types.     

Are Droppings,Distance From Pastoralist Camps,and Pika Burrows Good Proxies for Local Grazing Pressure?

Grazing is regarded as one of the most important factors influencing rangeland ecosystems. Many previous studies have used indirect measures (proxies) of grazing intensity, such as the distance from congregation areas and the number of herbivore excreta, to estimate effects of grazing on vegetation parameters in rangeland ecosystems. However, little is known about how such proxies reflect the true grazing intensity, and if their suitability is consistent across landscape conditions. We measured grazing intensity based on the amount of plant ramets being grazed in 75 plots positioned across a rangeland landscape in central Tibet. Several grazing intensity proxies (distance from pastoral camp sites, number of yak dung patches (old and fresh), sheep and goat dropping piles, and pika (Ochotona curzoniae) burrows (active and abandoned)) were also measured in each plot. Regression models were used to examine the suitability of these proxies in predicting our measure of real grazing intensity. None of the examined proxies satisfactorily predicted real grazing intensity in our study system. The distance from camp sites was the best proxy for grazing intensity (P<0.001), but it explained only 30% of its variation. Fresh yak dung and active pika burrows explained only 10% and 3% of the variation in grazing intensity, respectively. The suitability of using proxies for grazing intensity did not significantly differ along landscape parameters (elevation, aspect directions, and slope angle) (P>0.05), except that the number of animal excreta and pika burrows functioned better as proxies at low, compared to high, elevation (P<0.05). Our results should be of concern since many studies use proxies to estimate effects of grazing on vegetation dynamics and ecosystem properties. We recommend awareness of potential limitations and suitability of proxies, when real grazing intensity is not measured.     

珍珠草原对不同模拟放牧强度的响应

草与畜的关系是放牧生态学研究的重点。以阿拉善荒漠草原典型植物珍珠(Salsola passerina)为研究对象,人工设置不同的处理模拟不同放牧强度对珍珠生长的影响,为荒漠草原的合理利用提供依据。研究结果表明,轻度、中度及重度放牧条件下,珍珠种群密度随处理强度的增加而增加。不同处理下植株的冠幅变化不明显,植株的高度在中度干扰下最大,轻度放牧次之,重度放牧最低。3种处理对珍珠生物量都有很大影响,轻度及中度放牧有利于珍珠的生长,而重度放牧则使生物量下降。计算补偿生长指数发现珍珠秋季的补偿生长旺盛,春季中度放牧有利于珍珠的补偿性生长,夏季补偿性生长表现不明显。因此,适度放牧有利于珍珠草原的恢复与健康发展,珍珠这种荒漠草原特有的植物在秋季具有极好的耐牧性。     

不同放牧强度对滩羊生产性能影响的研究

为寻找适宜宁夏盐池县草地的放牧强度,于2003年5-11月在该县四墩子试点设5个处理(0.45、0.60、1.75、1.05和1.50只/hm2)进行轮牧,轮牧周期为42 d,共放牧154 d。结果表明:1)滩羊采食量随放牧强度的加重而降低。同一放牧强度下,随放牧时间推移,采食量先逐渐增大而后下降。2)在试验期内,不同放牧强度下,滩羊体重随时间推移总体上都呈增加趋势。在10月2日之后体重开始出现分化。与放牧强度重的处理相比,放牧强度轻的处理日增重峰值较高,持续时间较长。3)滩羊个体增重与放牧强度之间存在着强的负相关;单位草地面积(1 hm2)增重与放牧强度之间呈强的正相关,初步可以确定在该类草地上放牧强度应在0.75只/hm2左右。4)随着放牧强度的加重,饲料报酬先增大后减小。在同一放牧强度下,饲料报酬随时间的推移先升高后降低。5)当放牧强度超过0.75只/hm2以后,滩羊出现了空怀、产羔率降低和推迟怀孕的现象。6)综合考虑各研究指标,该类草地放牧强度以不应超过0.75只/hm2为宜。     

防治沙尘暴须坚持草原自然资源可持续利用

开垦草原、过度农垦和撂荒、过度利用水资源、超采地下水,导致干旱区土地沙化、沙尘源面积扩大;草原持续超载过牧,滥采滥挖草原的植物资源,无序开发草原矿产资源,人为破坏草原植被,造成草原沙化;超越水土资源承载力,追求高产出的不当农业经营方式,违反自然规律的生态建设,造就了新的沙尘源,助长了沙尘暴的暴发。通过采用资源可持续利用技术、降低草原和土地利用强度、恢复干旱草原以牧为主的经营方式等措施,可以提高植被覆盖度,减少裸露旱作农田、撂荒地等沙尘源面积,从而减少沙尘暴的暴发次数,减轻其危害程度。     

Comparison of Two Sampling Methods for Quantifying Changes in Vegetation Composition Under Rangeland Development

Rapid vegetation sampling methods based on visual estimation are useful for monitoring changes in rangeland vegetation composition because large spatial and temporal scales are often involved and have limited sampling resources available. Here we compared two sampling methods in their ability to detect changes in vegetation composition following rangeland development: 1) species percent cover estimates within subplots (the percent cover [PC] method) and 2) rankings of relative biomass of the 10 most abundant species across the whole plot and the ratio of two of them (the visual ranking [VR] method). Both methods were applied on 30 experimental plots at year 26 of a long-term factorial trial of five soil fertility levels and three sheep grazing intensities. Multivariate statistical methods showed significant effects of experimental treatments (fertilizer level and sheep grazing intensity) and of vegetation sampling method (VR vs. PC) on vegetation composition. Importantly, we detected no significant interactions involving sampling method, indicating that the effect of sampling method was consistent across experimental treatments. Effects of fertilizer on vegetation composition were an order of magnitude greater than the effect of sampling method, whereas the latter was twice as important as the effect of grazing. Results were robust to differential weights given to relative abundances vs. compositional changes. Differences between methods were primarily driven by the PC method giving lower abundance estimates of one species, lupin (a hybrid of Lupinus polyphyllus Lindl.), relative to the VR method. Our results support the use of the VR method as a rapid yet powerful method for monitoring changes in vegetation composition under rangeland development.     

Grazing Intensity on Vegetation Dynamics of a Typical Steppe in Northeast Inner Mongolia

Vegetation features radiating from residential areas in response to livestock grazing were quantified for an arid steppe rangeland in the Keshiketeng Banner, Chifeng Prefecture, in northeastern Inner Mongolia in 2004 and 2006. The aim of this study was to estimate grazing impacts on the vegetation dynamics of these historical grazed ecosystems. Grazing intensities were classified as reference area (RA), light (LG), moderate (MG), and heavy (HG) according to the vegetation utilization across the study area. Rangelands were studied along a grazing gradient, where characteristics of plant communities, heights of dominant species, aboveground vertical structures, and belowground biomass were investigated. Along this grazing gradient, vegetation changed from the original dominant plant species Leymus chinensis (Trin.) Tzvel. to a semi-subshrub species Artemisia frigida Willd. when moving from the reference area (RA) to the region around the settlement. Canopy coverage, aboveground productivity, and the number of perennial species declined as one moved toward the residential area. Heights of five dominant species, except for Stipa grandis P. Smirn., declined with increased grazing intensity. Aboveground vertical structure in the RA treatment showed more resilience than the other treatments. There was no difference in root biomass in the top 1 m of soil (P > 0.05) between the RA treatment and the area immediately around settlement (HG treatment). Generally, we found that the intensity of grazing disturbance did not exceed the tolerance of the rangeland ecosystem within LG treatment. However, vegetative conditions in HG treatment became worse with increased grazing pressure. Rangelands in this arid steppe are under tremendous threat due to excessive forage utilization, which cannot be considered a sustainable practice.     

放牧强度对高寒草甸群落碳氮磷化学计量特征的影响

植被生态化学计量特征是高寒草甸生态系统稳定性的基础,但其对放牧管理的响应仍不清楚。为此,以2011年在青海海北高寒矮嵩草(Kobresia humilis)草甸建立的不同放牧强度试验地为研究对象,于2014年植物生长季的5月-9月,通过测定禁牧(对照,CK)、轻度放牧(light grazing,LG)、中度放牧(moderate grazing,MG)和重度放牧(heavy grazing,HG)样地的地上植被生产力和植被群落结构及群落叶片碳(carbon,C)、氮(nitrogen,N)、磷(phosphorus,P)含量,研究放牧强度对高寒草甸群落生态化学计量的影响。结果表明,MG能显著提高地上生物量和优良牧草禾草类植物的生物量比例,C含量的变异均在MG处理下最大,此结果支持了中度干扰理论;重牧能显著提高群落叶片的N含量(P0.05);放牧管理对叶片P含量的影响无明显规律;禁牧有利于系统N和P的周转。本研究结果显示,适度的放牧强度有利于高寒草甸生产力的提高,而禁牧可能通过改变群落优势种增强系统的N、P循环强度。     

Detecting the Influence of Best Management Practices on Vegetation Near Ephemeral Streams With Landsat Data

Various best management practices (BMPs) have been implemented on rangelands with the goals of controlling nonpoint source pollution, reducing the impact of livestock in ecologically important riparian areas, and improving grazing distribution. Providing off-stream water sources to livestock in pastures, cross-fencing, and rotational grazing are common rangeland BMPs that have demonstrated success in drawing livestock grazing pressure away from streams. We evaluated the effects of rangeland BMP implementation with six commercial-scale pastures in the northern mixed-grass prairie. Four pastures received a BMP suite consisting of off-stream water, cross-fencing, and deferred-rotation grazing, and two pastures did not receive BMPs. We hypothesized that the BMPs increased the quantity of riparian vegetation cover relative to the conditions in these pastures during the pre-BMP period and to the two pastures that did not receive BMPs. We used a series of 30-m Landsat normalized difference vegetation index (NDVI) images to track the spatial and temporal changes (1984–2010, n = 24) in vegetation cover, to which NDVI has been well correlated. Validation indicated that the remotely sensed signal from in-channel vegetation was representative of ground conditions. The BMP suite was associated with a 15% increase in the in-channel NDVI (0–30 m from stream centerline) and 18% increase in the riparian NDVI (30–180 m from stream center line). Conversely, the in-channel and riparian NDVI of non-BMP pastures declined 30% and 18% over the study period. The majority of change occurred within 2 yr of BMP implementation. The patterns of in-channel NDVI among pastures suggested that BMP implementation likely altered grazing distribution by decreasing the preferential use of riparian and in-channel areas. We demonstrated that satellite imagery time series are useful in retrospectively evaluating the efficacy of conservation practices, providing critical information to guide adaptive management and decision makers.