The drought-resistant shrubs Caragana korshinskii, Caragana stenophylla, Caragana roborovskyi, and Caragana tibetica , are distributed mainly in the arid and semi-arid areas of the Inner Mongolia Plateau, China. They are important plants for fodder resource, and are known as "lifesaving plants" to livestock. In addition, they play an important role in fixing sand dunes and conserving water resources. So far, however, very little attention has been paid to the factors determining the sand-fixing capability of Caragana shrubs. In this study, we explored the relationships between the morphology of shrubs and nabkhas and sand-fixing capability for the four dominant Caragana species in the desert region of the Inner Mongolia Plateau. The results showed that C. korshinskii nabkhas were spherical and coronary, C. stenophylla nabkhas were conical, and the nabkhas of C. roborovskyi and C. tibetica were platform and hemispherical, respectively. Within each of the four Caragana species, shrub aboveground biomass significantly correlated with both nabkhas' horizontal scale and slope angle ( P P >0.05). Nabkhas' vertical scale significantly correlated with plant height ( P Caragana shrub's extension. And the development of shrubs and nabkhas was faster in horizontal scale than in vertical scale. The sand-fixing capability of nabkhas also increased as Caragana shrub extended. Among the four Caragana species, the morphological characteristics of shrub and nabkha were significantly different. C. korshinskii had the highest shrub height, the largest nabkhas vertical scale and the highest shrub aboveground biomass. C. roborovskyi had the largest nabkha horizontal scale, the smallest vertical scale, and the smallest slope angle. C. stenophylla and C. tibetica had relatively smaller nabkhas, but larger nabkha slope angles than the two Caragana species above. For C. korshinskii and C. stenophylla, the ratio between horizontal and vertical expansion remained relatively constant. But for C. roborovskyi and C. tibetica , the shrub height remained similar regardless of the size of shrub bottom. As the shrub extended, the nabkhas' bottom area of the four Caragana species all increased but with significantly different rates. The bottom area of C. roborovskyi and C. tibetica nabkhas tended to expand faster than that of C. korshinskii and C. stenophylla. Within the four Caragana species, the vertical expansion of C. roborovskyi was the slowest, resulting in the lowest plant height. While, C. korshinkii , C. stenophylla , and C. tibetica shrub nabkhas remained in relative balance in horizontal and vertical development. The order of nabkha volume and sand-fixing efficiency of four dominant Caragana species were all as following: C. roborovskyi > C. korshinskii > C. stenophylla > C. tibetica . Based on the results of this study, we can draw two main conclusions: (1) Within each of the four Caragana species, the nabkha volume, morphology and sand-fixing capacity were probably determined by shrubs' aboveground biomass. (2) Among the four Caragana species, the difference of nabkha morphology, development characteristics, and shrubs' sand-fixing capability were probably caused by the interspecific differences in morphology and development strategies.

测定了内蒙古高原荒漠区4种锦鸡儿属优势植物(柠条锦鸡儿、狭叶锦鸡儿、荒漠锦鸡儿和垫状锦鸡儿)不同大小灌丛的灌丛形态参数、沙包形态参数和沙包体积,目的是掌握这些锦鸡儿属植物灌丛的沙包形态特征、沙包发育特征和固沙能力随着灌丛发育的变化,比较4种锦鸡儿属植物灌丛沙包的形态、发育特征和固沙能力的差异。研究发现:柠条锦鸡儿沙包形态呈球冠状,狭叶锦鸡儿沙包呈圆锥状,荒漠锦鸡儿沙包呈圆台状,垫状锦鸡儿沙包呈半球状。同种锦鸡儿属灌丛沙包的底面直径与地上枝条鲜重呈极显著正相关关系( P ＜0.01),沙包高度与地上枝条鲜重无显著相关性( P ＞0.05),沙包高度与植物株高呈显著正相关关系( P ＜0.05),沙包坡角与地上枝条鲜重呈显著负相关关系( P ＜0.05),沙包半径与沙包高度呈显著正相关关系( P ＜0.05)。灌丛水平扩展快于垂向生长,灌丛沙包的水平发育也快于垂向发育。随着灌丛地上生物量的增加,4种锦鸡儿属植物不仅沙包体积增大,而且固沙效率也显著增加( P ＜0.01)。不同锦鸡儿属植物灌丛和沙包形态参数存在显著差异。柠条锦鸡儿和狭叶锦鸡儿的灌丛水平和垂直方向成比例扩展,而荒漠锦鸡儿和垫状锦鸡儿无论灌丛面积多大,高度基本不变。随着灌丛地上枝条鲜重的增加,4种锦鸡儿灌丛沙包底面积都在增大,其中荒漠锦鸡儿增长最快,垫状锦鸡儿次之,柠条锦鸡儿排位第三,狭叶锦鸡儿增长最慢。随着灌丛沙包水平方向的扩展,荒漠锦鸡儿沙包垂向扩展最慢,最终导致其沙包垂向尺度最小;柠条锦鸡儿、垫状锦鸡儿和狭叶锦鸡儿沙包两个方向发育较为均衡。4种锦鸡儿属植物的固定沙包体积和固沙效率都表现为:荒漠锦鸡儿＞柠条锦鸡儿＞狭叶锦鸡儿＞垫状锦鸡儿。这些研究结果表明,灌丛地上生物量的不同决定了种内沙包的体积、形态和植物固沙能力的差异;灌丛形态和发育特征的不同决定了种间沙包形态、沙包发育和植物固沙能力的差异。

本研究连续3年对小叶锦鸡儿的生长规律及物候期进行观察,并采集1～8 a不同年龄枝条及3 a不同物候期枝条(带叶、花、果)测定并比较其营养成分(粗蛋白、粗脂肪、粗纤维、粗灰分、无氮浸出物、钙、磷等)的含量;采用层次分析法(AHP),计算各枝龄、物候期与参考向量的灰色关联度,确定最佳饲用采收期,以期评价小叶锦鸡儿(Caragana microphylla)不同年龄枝条和年生长周期的不同物候期营养成分变化规律,确定其饲用最佳采收期,为科学经营和合理利用资源提供理论依据.结果表明,1)按枝条不同生长年龄营养价值等权关联度排序为3 a＞2 a＞4 a＞5 a＞1 a＞6 a＞7 a＞8 a;加权关联度排序为3 a＞1 a＞5 a＞2 a＞4 a＞6 a＞7 a＞8 a.2)按不同物候期等权关联度排序为结果中期＞果熟期＞果后生长期＞花期＞展叶期＞萌芽期＞落叶期＞休眠期;加权关联度排序为结果中期＞果后生长期＞果熟期＞花期＞展叶期＞落叶期＞萌芽期＞休眠期.3 a枝条结果中期作为加工饲料的最佳采收期,也是最佳平茬更新时期.

在文献综述的基础上，说明了锡林河流域草原中小叶锦鸡儿分布增加的趋势，认为在过度放牧引起草原退化、甚至荒漠化(沙化)发生的情况下，小叶锦鸡儿分布的增加首先与其生物—生态学特性和生活史特征有密切关系，同时也与放牧引起的系统物理环境的改变有关，最终可能形成以小叶锦鸡儿为优势种的灌丛化牧场或沙丘灌丛地。

针对我国内蒙古半干旱草原普遍发生的灌丛化现象,运用反映干旱和半干旱放牧系统一般动态的状态与过渡模式,建立了半干旱草原灌丛沙漠化研究的基本构架.将灌丛化作为草原沙漠化的核心过程,提出内蒙古半干旱草原灌丛化机制的假说,以及利用时空替代方法开展草原灌丛沙漠化研究的设想及其意义.

A three year grazing trial was conducted in a two seasonal grazing (warm-season and cold-season) pasture in alpine meadow to study the variations of the plant community characteristics in the warm-season pasture and winter pasture. In the two seasonal grazing pasture, the aboveground biomass of plant communities decreased with grazing intensity increasing, and the aboveground biomass of graminoid had similar performance with plant community. The influence of grazing treatments in warm-season pasture was higher than that in winter pasture. The dominant plant species under no grazing, heavy grazing in cold-season pasture were Stipa purpurea and Kobresia humilis , whereas the dominant species under the other grazing treatments were S. purpurea and Thermopsis lanceolata . The diversity index and evenness index of the plant community in warm-season pasture firstly decreased and then increase with grazing intensity increasing, however, these two indices of the plant community in cold-season pasture increased with grazing intensity increasing. For warm-season pasture and cold-season pasture, the diversity index was the highest under heavy grazing intensity.

基于青海湖北岸高寒草原连续3年放牧控制试验,研究了暖季和冷季放牧草地植物群落特征的变化。结果表明,暖季和冷季放牧草地群落地上生物量均随放牧强度的增加呈现下降趋势,禾本科地上生物量的变化趋势基本与群落地上生物量的一致;中度放牧对暖季放牧草地植被的影响程度高于冷季放牧草地;围栏封育区和冷季重度放牧草地的优势种均为紫花针茅( Stipa purpurea )和矮嵩草( Kobresia humilis ),暖季放牧各放牧小区和冷季放牧草地轻度和中度放牧处理优势种均为紫花针茅和披针叶黄华( Thermopsis lanceolata );随放牧强度的增加,暖季放牧草地群落物种多样性指数和均匀度指数表现出先降低后增加的趋势,冷季放牧草地群落物种多样性指数和均匀度指数表现出增加的趋势,但是多样性指数在暖、冷季放牧草地均以重度放牧区最高。

摘　要： 载畜率对草地生态系统的稳定有着重要的作用,研究其对植被的影响可为草畜平衡管理提供科学依据。基于四期Landsat卫星数据,利用像元二分模型,对不同载畜率水平的短花针茅荒漠草原植被覆盖进行了近13年的动态监测。研究结果表明,植被覆盖呈现对照区〉轻度放牧区〉中度放牧区〉重度放牧区。多年围封后,对照区植被覆盖由以中低覆盖为主转变为以高覆盖为主,高覆盖植被显著高于试验前;轻度放牧区植被由以中低覆盖为主转变为中覆盖植被为主,中覆盖植被显著高于与试验前。中度和重度放牧区植被多年仍以中低覆盖植被为主,但次要植被覆盖却由低覆盖转变为中覆盖,植被总覆盖度高于试验前,呈增长趋势。试验结论认为围封和轻放牧措施明显增加植被覆盖度,有助于短花针茅荒漠草原可持续发展,而中度和重度放牧显著减少植被覆盖度,但是由于冬春季休牧管理及降水量的共同作用促使中度和重牧处理区植被总盖度高于试验前。

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。

为确定川西北地区高寒草甸的最佳放牧强度,根据牦牛的采食量和草地地上生物量,设置了轻度(0.71头·hm-2)、中度(1.19头·hm-2)、重度(1.60头·hm-2) 3个放牧强度处理,进行连续3年的放牧,测定其对草地植物物种丰富度、地上生物量的影响.结果表明,随着放牧强度的增加,植物物种丰富度呈下降趋势;放牧第3年,中度放牧草地年度地上生物量最高,显著高于其它两处理(P<0.05),轻度放牧次之,重度放牧最低;和放牧第1年相比,轻度放牧和中度放牧草地地上生物量中杂类草生物量比例显著减少(P<0.05),禾草生物量比例显著增加(P<0.05),而重度放牧草地杂类草生物量比例未变,禾草生物量比例显著下降(P<0.05),但3个放牧处理中莎草占地上生物量的比例均显著增加(P<0.05).因此,川西北地区高寒草甸的最佳放牧强度为1.19头·hm-2,这利于草地高产和优良牧草禾草及莎草的生长.

Aims Grazing is one of the major measures for grassland management in Nei Mongol steppe. The growth and reproductive strategies of grassland plants are developed under their long-term co-evolution with ungulates in grassland ecosystems. This study was conducted to understand how Thalictrum petaloideum would change its growth and reproductive strategies with increasing stocking rate. Methods By using a grazing experiment in a typical steppe ecosystem initiated by the Nei Mongol Grassland Ecosystem Research Station in 2006, we examined the responses of T. petaloideum to stocking rates at population, individual and organ levels during the 2012 and 2013 growing seasons. Important findings With increasing stocking rate, the number of reproductive individuals decreased and the reproductive process ceased in T. petaloideum at the population level. The threshold for ceasing the reproductive process was at a stocking rate of 7.5 sheep per hm 2 . The plant height, plant biomass and the numbers of reproductive branches, flowers and seeds all decreased with increasing stocking rate at an individual level. Two shifts were detected for the reproductive allometric relationships with increases in stocking rate. With the increase of stocking rates, T. petaloideum reduced the number of flowers per reproductive branch decreased but the individual seed weight increased with increasing stocking rate at the organ level. A trade-off between the number of seed and the weight of seed was found, which might be an important mechanism in T. petaloideum responding to grazing disturbance.

放牧是内蒙古草原最主要的利用方式, 而草原植物在不同放牧压力下的生长和繁殖策略是它们与有蹄类动物长期协同进化的结果。为了了解瓣蕊唐松草( Thalictrum petaloideum )的生长和繁殖策略如何响应载畜率的变化, 作者依托中国科学院内蒙古草原站的大型放牧实验平台, 从种群、个体和器官三个组织水平上研究了该物种对放牧强度的响应。结果表明: 1)在种群水平上, 随着载畜率的增加, 瓣蕊唐松草减少了生殖株丛数或不进行有性生殖生长。该实验条件下, 载畜率每hm 2 7.5只羊(夏季)是瓣蕊唐松草不再进行生殖生长的阈值; 2)在个体水平上, 随着载畜率的增加, 瓣蕊唐松草降低了株高和个体生物量, 减少了生殖枝、花朵和种子等生殖器官的数量。随着载畜率的增加, 瓣蕊唐松草生殖分配的调节从依赖于植株个体大小向不依赖于植株个体大小转变。3)在器官水平上, 随着载畜率的增加, 瓣蕊唐松草减少了生殖枝的花朵负荷, 提高了单粒质量。籽粒数量和籽粒质量之间的权衡是瓣蕊唐松草应对放牧干扰的重要机制。

Population density and branching pattern of T.repens was studied on ungrazed and grazed swards with different soil conditions.The percentage of the stem severed plants of T.repens was 76.5%～80.4%.Compared with the sward ungrazed,the swards moderately grazed keeped a higher densities of plant,leaf and stem,and lower number of leaf and the length of stem.The number of modules per plant increased while the branching intensity of T.repens decreased on the sward under better soil conditions.There w...

对白三叶长期禁牧草地及土壤斑块质量不同的春季休牧草地的研究结果显示 ,4月份 ,在中等放牧强度草地上 ,约有 76.5%～ 80 .4 %的白三叶植株为茎部出现断折的残株 ,放牧草地植株密度明显高于对照草地。放牧草地较好的土壤营养条件使白三叶单株构件数量明显上升 ,但使分枝强度略有下降。白三叶各构件密度之间存在显著正相关。不同样地上白三叶的分枝均以 2、3级分枝为主。放牧草地的分枝角度大小顺序为 :1级分枝角 >2级分枝角 >3级分枝角 ;对照草地为 :2级分枝角 >3级分枝角 >1级分枝角。放牧及对照草地白三叶平均分枝角分别为 73 .0°、4 6.5°。

气候变化背景下,植物群落特征与功能性状对不同类型和强度人类干扰的响应与适应是植被生态学研究的热点命题之一。本文以拉萨干暖河谷达孜县新仓村沟域山麓冲积扇上的亚高山草甸草原为研究对象,采用样方调查法,探究全年禁牧、暖季禁牧、全年放牧情况下,不同干扰强度对群落特征(群落结构、物种多样性)和功能性状的影响。结果表明,群落高度、地上生物量和立枯物随干扰强度增强而降低,群落盖度差异不显著。排除干扰强度因素,物种多样性与以株高、可食性为代表的功能性状无相关性。全部物种和可食性物种的物种多样性随干扰强度变化差异不显著,即物种丰富度S、多样性指数H、均匀度指数E差异均不显著。以株高、可食性为代表的功能性状随干扰强度增强而降低,表明不同干扰强度对功能性状的影响较物种多样性更显著。未来应更广泛地探讨物种多样性、功能性状和生态系统功能的内在联系,以及3者在不同干扰强度下的响应时间和模式。

摘　要： 坡位对植物种子散布、繁殖和土壤水、热与营养再分配等生态、水文方面各有差异,不适坡位使其生态功能被破坏,造成水土流失、生物多样性降低等失衡生态结构。分析坡位对植物种群的空间分布格局的影响,有助于认识其潜在的生态学过程、种群的生物学特性及其与环境因子之间的相互关系,为合理规划不同坡位植被类型提供依据,对于荒漠化地区意义重大。采用空间格局分析方法,将浑善达克沙地坡位对小叶锦鸡儿空间分布的影响进行了分析。结果表明:(1)在坡上及平地部位,小叶锦鸡儿种群在小尺度上呈现高度聚集分布,随着尺度增大,聚集强度逐渐减弱,最终表现为随机分布,而在坡中及坡下部位,小叶锦鸡儿种群在小尺度上表现为均匀或随机分布;(2)根据冠幅、株高将小叶锦鸡儿分为大苗、幼苗,从坡上、坡中、坡下到平地,小叶锦鸡儿大苗灌丛沙堆与小叶锦鸡儿幼苗灌丛沙堆均表现为负相关关系,随着尺度增大,这种关系逐渐减弱,最后表现为无关联。

The studies of specific evolution of genus Caragana demonstrate that pinnately compound leaf group is preliminary, and pseudo-palmately compound leaf group belongs to the relative evolved. Pinnately compound leaf group gradually evolved into pseudo-palmately compound leaf group with the increase in the degree of drought. This point of view is based on studies of the geographical distribution and the morphological characteristics of plants, but lacks physiological and biochemical proof. The characteristics o...

对锦鸡儿属羽状叶类群的代表植物——小叶锦鸡儿和假掌状叶类群的代表植物——狭叶锦鸡儿的地理分布、生长发育、形态结构、渗透调节和水分代谢进行了比较研究。小叶锦鸡儿在内蒙古高原分布于东起呼伦贝尔 (1 2 4 .0 0°E)西至达茂旗(1 1 0 .4 3°E)的半湿润至半干旱地区 ,生长发育最适地区是锡林浩特 ;狭叶锦鸡儿在内蒙古高原分布于东起锡林浩特 (1 1 6 .0 7°E)西至阿拉善 (98°E)的半干旱至极干旱地区 ,生长发育最适地区是阿拉善。这种分布格局和生长发育适应性说明 ,狭叶锦鸡儿比小叶锦鸡儿更适宜干旱环境。小叶锦鸡儿叶片平展、被绿色柔毛 ,有时上面近无毛 ,狭叶锦鸡儿叶片呈瓦状、被粉白色柔毛 ;狭叶锦鸡儿叶片厚度 /面积比值和长 /宽比值大于小叶锦鸡儿 ,叶片生物量小于小叶锦鸡儿。这些特性使狭叶锦鸡儿比小叶锦鸡儿保水能力强。由于狭叶锦鸡儿的渗透调节物质浓度大于小叶锦鸡儿 ,导致细胞渗透势低于小叶锦鸡儿 ;狭叶锦鸡儿叶含水量低于小叶锦鸡儿 ,束缚水 /自由水比值大于小叶锦鸡儿 ;狭叶锦鸡儿叶水势低于小叶锦鸡儿。这些特性表明狭叶锦鸡儿比小叶锦鸡儿渗透调节能力强。狭叶锦鸡儿的蒸腾速率和日蒸腾积累值均小于小叶锦鸡儿，水分利用效率高于小叶锦鸡儿。由于叶形态变异、良好的渗透调节功能、低蒸腾速率，使生活在半干旱至极干旱地区的狭叶锦鸡儿植株水分状况甚至好于生活在半湿润至半干旱地区的小叶锦鸡儿。研究结果表明：（1）小叶锦鸡儿和狭叶锦鸡儿与它们分布区的环境气候条件相适应，表现在形态变异、完善的渗透调节功能、低蒸腾和高水分利用效率；（2）羽状叶类群的代表植物——小叶锦鸡儿适应在半湿润半干旱地区生活，假掌状叶类群的代表植物——狭叶锦鸡儿适应在半干旱至极干旱地区生活。狭叶锦鸡儿比小叶锦鸡儿有更好的干旱适应性。这一研究结果可以作为羽状叶是原始类群，假掌状叶是较进化类群观点的证据。

Caragana microphylla is the most dominant and constructive shrub species. We evaluated the level of genetic variation within and among populations sampled from two different altitude gradients using intersimple sequence repeat polymorphism (ISSR) molecular markers. The results showed that eight ISSR primers generated 142 bands, of which 126 (88.73%) were polymorphic. Based on Nei’s Gst value calculated by POPGENE, the gene diversity (h) and Shannon’s information index (I) was 0.292 9 and 0.441 7, respectively indicating considerable genetic variations at the species level. At the altitude gradients, the genetic diversity index in populations from low altitude region was higher than from high altitude region, shows that the gene exchange between populations was blocked by the increase of altitude.

以小叶锦鸡儿（Caragana microphylla）为研究对象，利用ISSR分子标记技术，对不同海拔梯度下小叶锦鸡儿6个居群遗传多样性进行分析。研究发现,8条ISSR扩增引物得到142条清晰的DNA条带，其中多态性条带为126条，多态位点百分率为88.73%。用POPGENE软件计算不同海拔梯度下各居群间和居群内的遗传参数，结果表明， Nei’s基因多样性为0.292 9，香农信息指数为0.441 7，表明在物种水平上小叶锦鸡儿居群具有较高的遗传多样性；低海拔区域居群的所有遗传多样性高于高海拔区域居群，表明海拔高度增加阻碍了居群间的基因交流，导致小叶锦鸡儿居群遗传多样性水平降低。

该实验在内蒙古乌兰察布盟短花针茅荒漠草原上比较了不同载畜率对 植物群落与家畜的影响,旨在为草地合理入牧利用提供理论依据.研究结果:(1)轻度、中度放牧压力下,植物群落总盖度、总密度增加,但重度放牧压力下这些 指示降低.(2)短花针茅草原绵羊放牧系统植物补偿性生长与载畜率密切相关.(3)绵羊个体体重随载畜率的增加表现出先增加后降低的趋势,载畜率低于 1.027sheep/hmyear时绵羊日增重较大,大于此载畜率则增重速度变慢.(4)绵羊食谱主要由几种适口性好的牧草组成, 同一季节绵羊食谱各处理无显著差异,但随着放牧时间的延续,食谱中的植物种类数...

摘　要： 柠条（Caragana korshinskii）在地上组织破坏后进行补偿性生长，这是重复利用柠条资源的基础，但对柠条不同刈割方式下营养生长补偿的模式有待探讨。该文通过5 种刈割方式：去除主枝长的30％（30％RSL）、去除主枝长的60％（60％RSL）、去除分枝数的25％（25％RSN）、去除分枝数的50％ （50％RSN）和去除分枝数的100％（100％RSN）来研究柠条的营养生长补偿。结果表明：刈割处理的柠条生物量当年发生了超补偿，当年生枝数／ 枝、当年生枝长、当年生枝生物量／枝、当年生枝生物量／株比对照高。对照、30％RSL和60％RSL处理未长出基梢。100％RSN处理的基梢数／刈割 枝、基梢长、单个基梢平均生物量显著高于25％RSN和50％RSN处理，基梢生物量／株随刈割去除生物量的增加而增加。100％RSN处理未结果，其它 处理果实产量表现出超补偿或精确补偿。对照处理营养生长和生殖生长均低，其它处理当年生枝生物量与果实产量成显著负相关。从整个生长季节来看，营养生长主 要集中在果实成熟之前。我们认为，100％RSN处理是柠条地上组织破坏后尽快恢复的合理方式，其当年生生物量远高于其它处理。顶端优势的破坏促使休眠芽 的萌发，根冠比的改变使地上组织获得较多养分和水分，根系储存的碳水化合物的供应是促使刈割柠条营养生长超补偿的的可能机制，而减少生殖生长对资源的消 耗，是100％RSN处理地上生物量尽快恢复的另一重要因素。

草原放牧系统是陆地生态系统中消费效率最高的系统。目前针对不同年度、不同载畜率条件下草原放牧系统稳定性的长期、重复性对比研究报道不多。本研究通过对短花针茅荒漠草原草、土、畜变化的连续监测，揭示载畜率对草原放牧生态系统的影响，探讨不同载畜率下草原放牧生态系统的变异性，找出该类草地适宜的载畜率。 试验在内蒙古短花针茅荒漠草原上进行，采用完全随机区组试验设计，设4个不同的处理（载畜率）：对照（CK）、轻度载畜率（LG）、中度载畜率（MG）和重度载畜率（HG），其载畜率分别为0、0.91、1.82和2.71羊单位/h㎡/半年。各3次重复，连续5年每年于6月初-11...

对三峡地区灌丛草地灌木植被在山羊放牧条件下的数量特征进行了定量研究。结果表明 ,不同放牧强度处理区内灌木种间平均重要值的大小均存在着显著差异 (P 0 .0 5) ,各区内平均重要值最大者均为白栎 ,对照、轻牧和重牧区内其平均重要值分别为 57.1%、51.3%和 39.7%。放牧 (轻牧和重牧 ,5月、7月和 9月 )期间白栎的重要值为上升趋势 (除 9月重牧之外 ) ,美丽胡枝子的重要值为下降趋势 (除 5月轻牧之外 ) ,水锦树的重要值为上升趋势 (除 9月轻牧之外 )。轻牧能使白栎、麻栎、盐肤木、柳杉、美丽胡枝子、马桑和小果蔷薇的重要值增加 ,这说明轻牧在一定程度上能促进它们的再生 ,增加植冠盖度 ,从而提高它们在灌木群落中的优势地位。而对于某些粗蛋白质含量较高的灌木种 ,如宜昌木兰和黄檀等 ,放牧会影响其再生 ,故应严格控制其放牧强度才不致使其从灌木群落中衰减甚至消失。

草地是我国最大的陆地生态系统,土壤呼吸是草地碳循环研究的重要内容,是土壤碳库输出的主要方式,影响大气中CO2浓度变化。放牧是草地主要利用方式之一,通过动物采食和践踏,改变植被冠层结构,对土壤理化性质、土壤有机质和土壤微生物产生影响,进而改变土壤呼吸速率。为探究不同载畜率对短花针茅(Stipa breviflora)荒漠草原土壤呼吸速率的影响,2011—2012年用Li-8100开路式碳通量测定系统,对生长季内(6—10月)4个不同载畜率处理下的土壤呼吸进行测定,测定周期为2周1次。辅助测定地下10 cm的土壤温度及土壤湿度,并分析土壤呼吸与土壤温、湿度的关系。结果表明:1)2011年不同载畜率对土壤呼吸速率无显著影响,表现为对照中度放牧轻度放牧重度放牧的变化趋势。2012年与对照(1.6μmol·m-2·s-1)相比,重度放牧(1.07μmol·m-2·s-1)显著降低土壤呼吸速率。总体而言,2011年土壤呼吸速率低于2012年,但差异不显著。2011年土壤温度(20.73℃)显著高于2012年(14.38℃),不同处理间无显著差异,重度放牧区偏高。2012年土壤湿度(7.24%)显著高于2011年(4.11%),对2年数据整体分析发现,轻度放牧区土壤湿度显著低于对照和中度放牧。2011年土壤湿度变化趋势为中度放牧对照重度放牧轻度放牧。2012年,轻度放牧土壤湿度最小,各处理间差异不显著。2)2011年,土壤呼吸与土壤温度月动态无明显规律,与土壤湿度呈现相反的变化趋势。2012年土壤呼吸的月动态与土壤温、湿度变化趋势相似。3)2011年,土壤呼吸速率随温度升高出现波动,与土壤湿度呈负相关。2012年,土壤呼吸速率随土壤温、湿度升高而增大。在干旱年份,降水减少会掩盖放牧对土壤呼吸的影响;在降雨较多的年份,重度放牧显著降低土壤呼吸速率。

以内蒙古短花针茅(Stipa breviflora)草原为研究对象,设置4个载畜率水平的随机区组实验,根据生活型和不同光合途径划分植物功能群,探讨载畜率对群落地上地下生物量和不同功能群生物量的影响。结果表明:群落地上生物量随载畜率的增大而显著降低(P0.05),且二者呈负相关关系,回归方程Y=281.54-53.47X;地下生物量呈"T"字型分布,约80%生物量集中分布在0~20 cm土层中,载畜率对地下生物量及分布无显著影响(P0.05);群落根冠比在7~12之间,随载畜率的增大而显著增大(P0.05)。载畜率对C4植物地上生物量无显著影响(P0.05),但其相对生物量随载畜率的增大而增大,C3植物地上生物量与相对生物量均随载畜率的增大而降低(P0.05)。多年生丛生禾草地上生物量相对稳定,受载畜率的影响差异不显著(P0.05);其相对生物量在群落中最高,且均随载畜率的增大而增大(P0.05);灌木、半灌木和小半灌木的地上生物量随载畜率的增大而减小(P0.05),但其相对生物量除重度放牧显著最低(P0.05)外,其他处理之间无显著差异(P0.05);多年生杂类草、多年生根茎禾草和一、二年生植物地上生物量与相对生物量均随载畜率的增大而显著降低(P0.05),多年生根茎禾草在轻度放牧下就几乎消失,而一、二年生植物在重度放牧下消失。

摘　要： 通过野外调查与室内分析相结合的方法研究不同放牧强度对群落特征、多样性及冠层截留的影响。结果表明：随着放牧强度的增加,群落高度、盖度、地上生物量及凋落物均呈显著性降低趋势,而群落密度呈相反趋势,地下生物量受放牧影响不大,呈倒金字塔型;受放牧影响各样地优势种发生改变,重度放牧区出现乳白黄耆等退化指示种;Simpson指数、Shannon-Wiener指数、Pielou指数均在中度放牧样地最大,Margalef指数则随放牧强度的增大呈减小趋势;群落冠层最大截留量随放牧强度的增加呈降低趋势,最大截留率呈先增后降趋势,在轻牧区最大。