不同放牧率下绵羊的食性及食物多样性与草地植物多样性间的关系

用显微技术法分别在放牧率为1.33．4．00和6．67只／hm^2下对内蒙古细毛羊的食性进行了研究。结果表明,随着放牧率的增大,草场的植物种类组成及其相对比例发生了明显的变化。由于不同牧草的可利用性不同,其食性选择也发生了明显的变化。在重牧条件下,原先为随意采食的冷蒿和厌食的寸草苔则升级为“喜食”的植物,星毛委陵菜的选择性指数也有较大提高;且星毛委陵菜成为主要的食物资源,占全部食物的80%以上,这说明放牧率的增大和绵羊选择性的采食是草场植物种类组成发生变化的主要原因之一。食物的选择性主要与草地牧草的相对生物量、高度和频度显著相关;当草地植物多样性指数较高时,放牧绵羊的食物选择性较大。不同放牧率条件下,在以冷蒿和小禾草为主的退化草原上．草地植物多样性指数随放牧率的增大而显著降低,但食物多样性指数以放牧率4．00只／hm^2的处理最高。     

地植物多样性间的关系

用显微技术法分别在放牧率为 1 .33,4 .0 0和 6.67只 / hm2下对内蒙古细毛羊的食性进行了研究。结果表明 ,随着放牧率的增大 ,草场的植物种类组成及其相对比例发生了明显的变化。由于不同牧草的可利用性不同 ,其食性选择也发生了明显的变化。在重牧条件下 ,原先为随意采食的冷蒿和厌食的寸草苔则升级为“喜食”的植物 ,星毛委陵菜的选择性指数也有较大提高 ;且星毛委陵菜成为主要的食物资源 ,占全部食物的 80 %以上。这说明放牧率的增大和绵羊选择性的采食是草场植物种类组成发生变化的主要原因之一。食物的选择性主要与草地牧草的相对生物量、高度和频度显著相关 ;当草地植物多样性指数较高时 ,放牧绵羊的食物选择性较大。不同放牧率条件下 ,在以冷蒿和小禾草为主的退化草原上 ,草地植物多样性指数随放牧率的增大而显著降低 ,但食物多样性指数以放牧率 4 .0 0只 / hm2 的处理最高。     

放牧家畜类型对内蒙古典型草原植物多样性和群落结构的影响

放牧家畜是调控草原植物多样性的重要因素, 探究不同家畜类型及其放牧行为下植物多样性的响应, 有助于全面理解草原植物多样性维持机制。该研究以内蒙古大学野外实验基地放牧控制实验为平台, 研究了中等放牧强度下不同家畜类型(牛、山羊、绵羊)及其选择性采食和聚集性放牧行为对植物α、β和γ多样性以及群落结构的影响。结果表明: (1)中等强度放牧牛、山羊和绵羊均在一定程度上提高了植物α、β和γ多样性。其中, 牛对植物多样性的提升作用最大且具有显著性。(2) 3种家畜放牧均显著改变了植物群落结构。绵羊的选择性采食导致下层优势物种糙隐子草(Cleistogenes squarrosa)的相对多度显著降低, 使其与牛或山羊放牧导致的群落结构变化趋势相反。(3) 3种家畜具有不同的牧草选择和放牧聚集行为。牛和山羊放牧使上层优势种羊草(Leymus chinensis)和大针茅(Stipa grandis)以及下层优势种糙隐子草地上生物量均显著降低, 而绵羊放牧仅使糙隐子草地上生物量显著降低。此外, 牛的采食空间聚集性显著低于山羊和绵羊。(4)植物多样性随上层或下层优势种地上生物量增加而显著降低或呈下降趋势, 表明放牧家畜能够通过抑制优势种生物量来提高植物多样性。(5)植物多样性随家畜采食空间聚集程度增加而显著降低或表现出下降趋势, 说明较低的放牧聚集性有利于植物多样性的维持。该研究表明, 内蒙古典型草原植物多样性保护和持续管理体系需要同时考虑放牧强度和家畜类型的影响。     

放牧对黄河低阶地盐化草场土壤水盐空间异质性的影响

选定黄河低阶地地形大致相近的放牧草场与封育草场,按实地情况分别设置长770m（放牧）、370m（放牧）和240m（封育）3条样线,采用校正后的便携式WET Sensor以10m为间隔进行土壤水盐的分层（0～10cm,10～20cm）测定,并对其进行地统计学分析.结果表明：黄河低阶地盐化草场表层土壤水盐的变异系数和相关性高于下层,土壤水分的变异系数低于土壤盐分且层间的相关性较高;放牧使土壤水盐之间的相关程度增大,变异降低,且使土壤水分存在一定的冗余.所研究草场的土壤水盐表现为中等或强烈空间自相关,封育盐化草场水盐空间相关尺度的差异较小,而放牧草场则相反.持续放牧已经成为一种稳定影响盐化草场水盐空间分布的结构性因素,使盐化草场的水盐空间异质性减弱.盐生植物在草场内随机分布且不受放牧干扰,是封育盐化草场随机作用较强的最可能原因;而放牧草场内牲畜的啃食和践踏对盐生植物和土壤结构改变所形成的反馈作用大大降低了这些植物对水分特别是盐分的再分配,进而导致放牧草场水盐的含量趋于增大且分布格局趋于简单.     

羊草(Leymus chinensis)草地雨天放牧与非雨天放牧的绵羊采食特征

通过受控实验,比较了雨天和非雨天放牧在采食方式、采食损失量、践踏折损率以及土壤含水量和容重的差异.得出雨天放牧条件下,羊草各种采食方式的比例降低,去顶量依旧随放牧压升高而增加,但与非雨天放牧不同的是不再占主要比例.羊草采食损失量与非雨天差异不大,对于适口性更高的植物,如芦苇和全叶马兰,雨天放牧时损失更高.绵羊在冷湿环境中活动明显减少,羊草的践踏折损率各放牧压下差异不大,但芦苇的折损率依旧表现为随放牧压增强而增加.放牧后土壤15cm的含水量都低于对照小区,表明绵羊践踏加速了土壤水分的蒸发.放牧后土壤容重与放牧前和非牧区差异显著,并且容重随放牧压增强而增加.     

呼伦贝尔草原黄羊冬季食性的研究

本文采用粪便显微组织学分析技术,分析了呼伦贝尔草原黄羊与放牧绵羊冬季采食植物的种类组成和比例,探讨了黄羊与放牧家羊冬季对食物资源利用的关系。研究表明,黄羊与放牧家羊冬季采食的植物均以禾本科、豆科等草本植物为主,二者在冬季对食物资源利用的重叠性较大,相似性系数ＰＳ＝０．７８９。     

内蒙古草原布氏田鼠与绵羊的营养生态位研究

放牧活动对小型啮齿动物种群数量的影响是草原生态系统研究中的热点问题,确定绵羊和小型啮齿动物的营养生态位关系对于草原生态系统的管理具有重要的作用。运用粪便显微分析法分析了内蒙古草原动物生态研究站大型野外围栏内布氏田鼠和绵羊在6-9月份的食谱组成,确定两种草食动物食性选择和营养生态位的变化,从食物利用途径揭示放牧活动对布氏田鼠种群数量的影响方式及二者之间的竞争与共存关系。研究结果表明：围栏中共有23种植物,其中糙隐子草、克氏针茅、羊草和刺藜是围栏中的优势植物;布氏田鼠共取食10种植物,绵羊共取食8种植物,禾本植物为两种动物的主要采食植物。布氏田鼠和绵羊的喜食植物种类都存在季节性变化;除7月外,两种动物的食物多样性与围栏植物多样性有显著的正相关关系,表明动物的食性选择受植物资源变化的影响。布氏田鼠和绵羊具有很高的营养生态位重叠度,除8月（0.691）外,6、7、9月份的营养生态位重叠度均高于0.9,表明二者之间存在激烈的食物竞争;放牧活动极显著地降低了禾本科植物的地上生物量,导致布氏田鼠的食物数量减少;放牧处理下布氏田鼠的喜食植物的物种数和营养生态位宽度（除9月）增加,导致布氏田鼠的食物质量下降。以上研究结果说明,较高的营养生态位重叠度引起动物间激烈的食物竞争;放牧会影响围栏中植物资源的变化,进而影响布氏田鼠的食性选择,放牧活动可能通过降低布氏田鼠的食物数量和质量对其种群数量产生负面效应;这也说明适度的放牧活动在增加人类对草场利用的同时,又可降低小型啮齿动物的数量及危害。     

草地放牧系统中土壤-植被系统各因子对放牧响应的研究进展

基于草业系统界面理论,综述了草地放牧系统中草地土壤-植被因子对放牧的响应以及放牧条件下植物的补偿性生长,认为在大气候一致的区域,放牧强度对植物群落的影响大于其他环境因子,从而成为影响植物群落特征的主导因子;科学的放牧制度和合理的放牧强度可以改善土壤结构,增强土壤对外界环境变化的抵抗力,否则会导致土壤质量下降,加速土壤侵蚀与退化;放牧家畜采食对植物生产力的影响和植物的补偿性生长是一般的生态学过程,但超补偿性生长与植物被采食前后的状况和环境条件密切相关,也与草地的放牧史有较强关系。因此,建议在研究草地放牧系统时,应以草场本身的条件和动态特征加以评价,用动态规划和系统优化模型,对草地的持续利用和畜牧业的可持续发展进行动态模拟,建立草地放牧管理专家系统。     

内蒙古天然草原不同放牧压力下亚洲小车蝗的食性及营养生态位（英文）

植物表皮蜡质中的饱和链烷作为内源指示剂广泛用于评价放牧家畜的食性和食量, 但用于天然草原蝗虫食性的评价研究较少。为了探讨天然草原蝗虫的食性及其生态位变化, 本研究以内蒙古天然草原为研究对象, 于2003年7-8月沿降水梯度选择3种典型植物群落（小针茅Stipa klemenzii、 羊草Leymus chinensis和大针茅Stipa grandis群落）, 在每个植物群落不同放牧压力下小区随机做20个植被样方, 样方内植物齐地面刈割, 测定其地上生物量和物种多样性, 取主要植物种测定其链烷模式, 同时采集放牧小区优势蝗虫种亚洲小车蝗Oedaleus asiaticus的粪便, 测定其链烷模式, 运用链烷技术评价蝗虫的食性及其营养生态位。结果表明： 不同植物群落中优势牧草种类及其比例不同, 其链烷模式存在种间差异, 链烷技术可以评价亚洲小车蝗的食性。亚洲小车蝗的食性在不同植物群落及不同放牧压力下存在显著的差异, 在羊草和大针茅群落中, 亚洲小车蝗是禾草采食者, 主要采食羊草和糙隐子草Cleistogenes squarrosa, 且与绵羊的营养生态位重叠指数较低, 分别为0.0619和0.0172; 在小针茅群落中亚洲小车蝗是杂类草采食者, 主要采食无芒隐子草Cleistogenes songorica、 猪毛菜Salsola collina和小针茅, 且与绵羊的营养生态位重叠指数较高, 达到0.1815。因此, 放牧不仅改变了群落的植物种类组成, 而且直接影响了亚洲小车蝗的食物组成, 二者对食物资源利用存在一定程度的竞争。     

不同放牧率对内蒙古冷蒿草原植物多样性的影响

以８年（１９８９－１９９７年定位的放牧试验数据为基础,较全面分析了不同放牧率对冷蒿（Ａrtemisia frigida）草原植物多样性和草场异质性的影响,并从内蒙古细毛羊选择性采食和植物适应策略的角度探讨其影响机制。研究发现,在进行冷蒿小禾草草原的物种丰富度调查是,１００m的样线法是可行的;在探讨放牧对群落多样性的影响时,Ｓimpson多样性指数和均匀度指数对放牧率大小的变化更敏感。经过连续８年的放牧,不同放牧率对物种丰富度的影响不大。但植物多样性和均匀度随放牧率的增大而下降,群落优势度却随放牧率增大而增大,;内蒙古细毛羊的选择性采食和较高放牧率和互作是导致植物多样性和均匀度下降及群落优势度上升的主要原因。冷蒿、糙隐子草（Cleistogenes squarrosa)、星毛委陵菜（Potentilla acaulis)、冰草（Ａgropyron cristatum)和寸草苔（Carex duriusula)在不同放牧率下的种群消长决定了冷蒿草原的放牧演退规律和植物多样性大小;尽管内蒙古细毛羊较喜食糙隐子草,但其种群在所有放牧率下均是多度最大的３个种群之一。     

Influence of livestock grazing on meadow pipit foraging behaviour in upland grassland

Changes in grazing management are believed to be responsible for declines in populations of birds breeding in grassland over the last decades. The relationships between grazing management regimes, vegetation structure and composition and the availability of invertebrate food resources to passerine birds remain poorly understood. In this study, we investigated the foraging site selection of meadow pipits (Anthus pratensis L.) breeding in high intensity sheep-grazed plots or low intensity mixed (i.e. sheep and cattle)-grazed plots. We sampled above-ground invertebrates, measured vegetation height and density and conducted a vegetation survey in areas where meadow pipits were observed to forage and areas that were randomly selected. Birds foraged in areas with a lower vegetation height and density and in areas containing a lower proportion of the dominant, tussock-forming grass species Molinia caerulea. They did not forage in areas with a total higher invertebrate biomass but at areas with preferred vegetation characteristics invertebrate biomass tended to be higher in foraging sites than random sites. The foraging distance of meadow pipits was higher in the intensively grazed plots. Our findings support the hypothesis that resource-independent factors such as food accessibility and forager mobility may determine patch selection and are of more importance as selection criteria than food abundance per se. Food accessibility seems to become an even more important selection criterion under high grazing intensity, where prey abundance and size decrease. In our upland grazing system, a low intensity, mixed grazing regime seems to provide a more suitable combination of sward height, plant diversity, structural heterogeneity and food supply for meadow pipit foraging activity compared to a more intensive grazing regime dominated by sheep.     

放牧和刈割条件下草山草坡群落空间异质性分析

采用变异矩分析和分形方法,研究了草山草坡群落在放牧和刈割条件下的空间异质性及空间自相关性,结果表明,群落空间格局有尺度依赖性,刈割条件下空物异质性及空间相关性弱,多样性梯度即β多样性小,放牧消除地形引起的样地差异,因而使空间异质性简单化。     

The impact of grazing management on Orthoptera abundance varies over the season in Mediterranean steppe-like grassland

As semi-natural grassland has a high level of biological diversity, understanding the effects of grazing and its variation over time is important in order to identify sustainable grazing practices. We measured temporal variation in Orthoptera abundance and spatial vegetation structure during seasonal grazing in an extensive sheep-farming system. We studied five grazed pasture areas (pre-grazing and post-grazing) and two adjacent ungrazed grasslands. We recorded the total abundance of Orthoptera and described the vegetation structure of 175 replicate plots (25 per pasture/grassland) during six field sampling sessions. We demonstrated that the impact of grazing on Orthoptera abundance is species-specific and greatly varies over the grazing season. The decrease of phytovolume is significant after 4–7 weeks of sheep grazing. Total Orthoptera abundance was higher in pre-grazed plots than in ungrazed plots, and higher in ungrazed plots than in post-grazed plots. These differences were particularly high during the peak of adult abundance. No difference in species richness was observed between grazing intensities. Total Orthoptera abundance positively correlated to phytovolume only when grazing pressure was high. However, the relationship between abundance and phytovolume differed between species. Extensive grazing by sheep tends to homogenize spatial vegetation structure and to temporarily reduce total Orthoptera abundance at pasture scale. However, rotational grazing allows spatial and temporal heterogeneity in vegetation structure to be maintained at farm scale, heterogeneity that is beneficial for Orthoptera. In contrast, absence of grazing has a negative impact on Orthoptera abundance as it favours the accumulation of litter, which is detrimental for a high proportion of xerothermophilic Orthoptera associated with bare ground and short vegetation.     

科尔沁沙质草地植物群落高度空间异质性对不同放牧方式的响应

放牧是影响草地植被空间异质性的重要生物驱动因素。大型草食动物会通过采食、践踏和排泄粪便等方式影响草地植被空间异质性。同时, 植物群落高度是重要的草地结构参数, 但目前关于不同放牧方式对草地植物群落高度空间异质性的研究较少。该研究基于传统及地统计学方法, 设置未放牧(NG)、牛单牧(CG)、羊单牧(SG)、牛羊混牧(MG) 4种处理, 探究科尔沁沙质草地植物群落高度空间异质性对不同放牧方式的响应。结果表明: 研究样地内植物群落平均高度为SG (38.86 cm) > NG (21.01 cm) > MG (17.29 cm) > CG (13.36 cm)。各处理下变异系数的结果均为中等变异, 且变异范围在37.82%-66.97%之间, 依次为NG > MG > CG > SG。通过对半方差函数参数进行最适模型拟合, NG、MG、CG、SG 4种处理分别对应球状模型、指数模型、线性模型、线性模型, 且结构比大小为MG (82.7%) > NG (80.3%) > SG (40.2%) > CG (39.1%)。此外, 采用Kriging插值法和分形维数对研究样地内植物群落高度空间格局分析表明, NG样地中植被高度呈现斑块化空间分布特征, MG维持了植被群落高度斑块化的空间格局, CG、SG则均质化植被群落高度空间格局。各放牧处理中分形维数(D₀)均较接近2, 即各放牧样地内植被高度格局简单, 空间结构较好。综上所述, 牛羊混牧能够维持草地植物群落高度的空间异质性, 而牛单牧和羊单牧则降低了其空间异质性, 由此建议科尔沁沙质草地可采取牛羊混合放牧的管理制度来维持草地植被空间异质性, 进而可能间接促进草地动物多样性。     

高寒草甸物种多样性对藏系牧羊放牧行为的影响

为探究草原植物物种多样性对家畜放牧行为的影响及其机制,在青藏高原高寒草甸开展藏系牧羊轮牧试验,调查植被物种多样性,观察藏系牧羊采食速率、觅食速率和采食时间,并计算藏系牧羊日采食量。结果表明：两年间,植物物种丰富度与藏系牧羊采食速率呈显著正相关关系（P<0.05）;觅食速率、采食时间和日采食量对放牧率响应敏感（P<0.05）,呈夏秋增冬春减的趋势。植物Shannon-Wiener指数与藏系牧羊的采食时间显著负相关（P<0.05）;在暖季或8羊/hm²放牧率下植物Shannon-Wiener指数与藏系牧羊日采食量呈显著正相关（P<0.05）。Pilelou均匀度指数与藏系牧羊采食速率和采食时间显著负相关（P<0.05）;在暖季或8羊/hm²放牧率下Pilelou均匀度指数与藏系牧羊日采食量呈显著负相关（P<0.05）。植物物种丰富度对藏系牧羊放牧行为贡献较大,且放牧藏系牧羊的采食速率和采食时间比觅食速率和日采食量对植物物种丰富度响应更敏感,以用植物物种丰富度为自变量可以更好预测藏系牧羊放牧行为。放牧管理通过影响植被物种多样性从而进一步影响了藏系牧羊放牧行为。放牧行为不仅是评价草地营养价值和家畜生产力的关键指标,也是草地健康管理的基础。因此,明确草原植物物种多样性-藏系牧羊放牧行为的互作机制有助于更好的提高藏系牧羊地生产力,维护草原生态健康。     

阿尔泰山两河源牧区草地群落生物量及物种多样性

群落生物量和物种多样性是表征草地生态系统数量特征的重要指标。该研究以新疆阿尔泰山南麓两河源放牧区草地为研究对象,利用样方法对两河源不同放牧区的草地植被进行调查,分析研究区生物量和物种多样性变化,探讨二者与环境因子之间的关联性,为草地群落物种保护以及草地可持续利用提供理论依据。结果表明：(1) 两河源不同牧区间群落盖度、高度、植株密度、地上生物量和单位盖度生物量存在差异。(2) 两河源牧区草地群落地上生物量与群落盖度、植株密度呈显著正相关关系(P<0.05),且地上生物量主要受草地群落盖度的影响;不同牧区的物种多样性指数有一定差异,但物种分布相对均匀。(3)两河源牧区草地群落生物量及物种多样性主要受气温和降水的影响。     

放牧和水淹干扰对松嫩平原碱化草地空间格局影响的分形分析

对东北松嫩平原碱化草地植物群落空间格局的分形性质进行了分析,分别用边长面积指数和Ｋｏｒｃａｋ相对斑块化指数估计了斑块边界复杂性和斑块面积大小频率分布格局。结果表明：随放牧强度增加,占优势的羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ（Ｔｒｉｎ．）Ｔｚｒｅｌ）斑块的斑块化加剧,而斑块的边界在中度放牧时最不规则;在水淹地,占优势的羊草斑块和次优势的碱茅（Ｐｕｃｉｎｅｌｉａｓｐｐ．）斑块、獐茅（Ａｅｌｕｒｏｐｕｓｌｉｔｏｒａｌｉｓ（Ｇｏｕａｎ）Ｐａｒｌ．ｖａｒ．ｓｉｎｅｎｓｉｓＤｅｂｅａｕｘ）斑块的斑块边界复杂性和斑块化程度比未水淹地都低,说明水淹降低了群落复合体内的异质性;在水淹地,优势斑块的边长面积指数和Ｋｏｒｃａｋ指数均低于次优势种,但在重度放牧地结果正好相反,可能是由于两种样地处于不同的演替阶段;而且,斑块边界复杂性符合同一尺度规律,在现有的面积范围内没有尺度转换,斑块面积大小的频率分布格局则存在尺度转换点。     

Using Grazing to Manage Herbaceous Structure for a Heterogeneity-Dependent Bird

Grazing management recommendations often sacrifice the intrinsic heterogeneity of grasslands by prescribing uniform grazing distributions through smaller pastures, increased stocking densities, and reduced grazing periods. The lack of patch-burn grazing in semi-arid landscapes of the western Great Plains in North America requires alternative grazing management strategies to create and maintain heterogeneity of habitat structure (e.g., animal unit distribution, pasture configuration), but knowledge of their effects on grassland fauna is limited. The lesser prairie-chicken (Tympanuchus pallidicinctus), an imperiled, grassland-obligate, native to the southern Great Plains, is an excellent candidate for investigating effects of heterogeneity-based grazing management strategies because it requires diverse microhabitats among life-history stages in a semi-arid landscape. We evaluated influences of heterogeneity-based grazing management strategies on vegetation structure, habitat selection, and nest and adult survival of lesser prairie-chickens in western Kansas, USA. We captured and monitored 116 female lesser prairie-chickens marked with very high frequency (VHF) or global positioning system (GPS) transmitters and collected landscape-scale vegetation and grazing data during 2013–2015. Vegetation structure heterogeneity increased at stocking densities ≤0.26 animal units/ha, where use by nonbreeding female lesser prairie-chickens also increased. Probability of use for nonbreeding lesser prairie-chickens peaked at values of cattle forage use values near 37% and steadily decreased with use ≥40%. Probability of use was positively affected by increasing pasture area. A quadratic relationship existed between growing season deferment and probability of use. We found that 70% of nests were located in grazing units in which grazing pressure was <0.8 animal unit months/ha. Daily nest survival was negatively correlated with grazing pressure. We found no relationship between adult survival and grazing management strategies. Conservation in grasslands expressing flora community composition appropriate for lesser prairie-chickens can maintain appropriate habitat structure heterogeneity through the use of low to moderate stocking densities (<0.26 animal units/ha), greater pasture areas, and site-appropriate deferment periods. Alternative grazing management strategies (e.g., rest-rotation, season-long rest) may be appropriate in grasslands requiring greater heterogeneity or during intensive drought. Grazing management favoring habitat heterogeneity instead of uniform grazing distributions will likely be more conducive for preserving lesser prairie-chicken populations and grassland biodiversity. © 2021 The Wildlife Society.     

A comparison of two rotational stocking strategies on the foraging behaviour and herbage intake by grazing sheep

An understanding of the processes involved in grazing behaviour is a prerequisite for the design of efficient grassland management systems. The purpose of managing the grazing process is to identify sward structures that can maximize animal forage daily intake and optimize grazing time. Our aim was to evaluate the effect of different grazing management strategies on foraging behaviour and herbage intake by sheep grazing Italian ryegrass under rotational stocking. The experiment was carried out in 2015 in southern Brazil. The experimental design was a randomized complete block with two grazing management strategies and four replicates. The grazing management treatments were a traditional rotational stocking (RT), with pre- and post-grazing sward heights of 25 and 5 cm, respectively, and a ‘Rotatinuous’ stocking (RN) with pre- and post-grazing sward heights of 18 and 11 cm, respectively. Male sheep with an average live weight of 32 ± 2.3 kg were used. As intended, the pre- and post-grazing sward heights were according to the treatments. The pre-grazing leaf/stem ratio of the Italian ryegrass pasture did not differ between treatments (P > 0.05) (~2.87), but the post-grazing leaf/stem ratio was greater (P < 0.001) in the RN than in the RT treatment (1.59 and 0.76, respectively). The percentage of the non-grazed area was greater (P < 0.01) in post-grazing for RN compared with RT treatment, with an average of 29.7% and 3.49%, respectively. Herbage nutritive value was greater for the RN than for the RT treatment, with greater CP and lower ADF and NDF contents. The total time spent grazing, ruminating and resting did not differ between treatments (P > 0.05), with averages of 439, 167 and 85 min, respectively. The bite rate, feeding stations per min and steps per min by sheep were greater (P < 0.05) in the RN than in the RT treatment. The grazing time per hour and the bite rate were greater (P < 0.05) in the afternoon than in the morning in both treatments. The daily herbage intake by sheep grazing Italian ryegrass was greater (P < 0.05) in the RN than in the RT treatment (843.7 and 707.8 g organic matter/sheep, respectively). Our study supports the idea that even though the grazing time was not affected by the grazing management strategies when the animal behaviour responses drive management targets, such as in ‘Rotatinuous’ stocking, the sheep herbage intake is maximized, and the grazing time is optimized.     

载畜率对荒漠草原冷蒿植物种群密度及其空间分布的影响

载畜率是衡量草原生产能力的指标之一,研究荒漠草原冷蒿(Artemisia frigida)植物种群在不同载畜率下的耐牧程度和空间分布特征,对退化草原的恢复具有重要的指导意义。以短花针茅荒漠草原优势种冷蒿为研究对象,在4个不同载畜率放牧试验设计(对照区CK(0只/hm~2)、轻度放牧区LG(0.93只/hm~2)、中度放牧区MG(1.82只/hm~2)和重度放牧区HG(2.71只/hm~2))小区中选择代表性样地(面积为40m×40m),采用机械取样法进行取样,记录冷蒿植物种群的密度,使用SAS 9.4软件对其进行描述性统计和方差分析,并用地统计学软件GS+9.0进行空间异质性统计分析。结果表明：荒漠草原优势种冷蒿密度、出现频率和单位均值上的变异值随载畜率增大都明显下降,其植物种群空间分布的决定性因素随载畜率增大由结构性因素转变为随机性因素。LG和HG处理区的空间自相关距离较大,但这两者表现结果的影响因素存在差异。在CK和HG区,冷蒿空间分布斑块化较为明显,LG区的冷蒿空间分布的特征表现为带状分布,MG区冷蒿空间分布形成了一处大的条带和零星的几块斑块。基于上述研究结果可以得出,随着载畜率...