不同放牧强度对荒漠草原植被和滩羊生产性能影响研究

通过放牧强度对荒漠草原植被和滩羊生产性能影响的研究得出:(1)随着放牧强度的增大,草地牧草生活力减弱;(2)放牧强度与植被总盖度之间存在负相关关系,随着放牧强度的增大草地植被总盖度减小;(3)放牧强度与草地牧草现存量之间存在负相关关系,随着放牧强度的增大,草地牧草现存量减少;(4)放牧强度越大,禾本科、豆科和杂类草牧草所占总产草量的比例越小;(5)滩羊个体增重与放牧强度之间存在着强的负相关,回归方程为:Ga=18.48-7.01G(r=-0.97**);单位革地面积(1 hm2)增重与放牧强度之间呈强的相关,回归方程为:Gh=0.31 17.60G-6.60G2(r=0.87*);(6)综合考虑各研究指标,本类草地放牧强度应以不超过0.75只/hm2为宜.     

宁夏滩羊放牧系统草地利用率及草畜平衡性研究

2003年5-10月在宁夏盐池荒漠草地进行了滩羊放牧强度试验,测定了宁夏滩羊采食量、采食率和草地产草量,以期确定草地适宜利用率,为解决宁夏草地全面禁牧后的重新利用提供依据。结果表明,在整个放牧季,草地现存量波动明显,放牧强度对试验区荒漠草地现存量峰值的出现时间及出现次数有明显影响;滩羊日采食量与放牧强度呈负相关,其回归方程为:y=2.04-0.54x (R²=－0.85,n=55)。滩羊采食量呈现先增加后减少趋势,具有周期波动特性;滩羊采食率在整个放牧季呈单峰变化趋势;试验草地的适宜利用率为10%～15%。实践中,不能仅依靠草地现存量去确定草地载畜量,这往往会被草地现存量“过剩”的假象所迷惑,造成草地超载、退化。     

滩羊不同放牧强度对盐池草地植被组成的影响

5种不同放牧强度,历时150 d的滩羊放牧试验结果如下:1)放牧强度与草地禾本科牧草现存量之间存在极显著负相关关系和极显著回归关系,禾本科牧草现存量随放牧强度变化趋势是先增后减。当放牧强度为0.45只/(hm2.d)时,禾本科牧草的现存量最大。2)随着放牧强度增大,禾本科牧草所占总产草量的比例减小。当放牧强度为0.45只/(hm2.d)时,禾本科牧草所占比例最大。3)随着放牧强度的增大,豆科牧草所占比例呈先减后增再减的变化趋势,即呈“V”字型。4)当放牧强度逐渐增大时,杂类草变化趋势呈“N”型变化。5)随着放牧强度的增大,禾本科牧草比例相对降低,而豆科牧草比例相对增加。草地植被组成改变。以宁夏盐池草地现状,放牧强度不能大于0.45只/(hm2.d)。     

放牧强度对高寒混播草地群落结构的影响

垂穗披碱草/星星草混播草地三个放牧季的放牧试验结果表明:(1)植物群落盖度与放牧强度呈显著的负相关;(2)垂穗披碱草地上现存量的比例随放牧强度的增加而呈下降趋势,星星草和杂类草的比例呈上升趋势;(3)随放牧强度的增加,建群植物垂穗披碱草和星星草的株高呈下降趋势;(4)对照区与其它各放牧区植物群落的相似性系数随放牧强度的增加而减小,说明各放牧处理组植物群落朝着远离对照群落的方向演替。     

滩羊放牧强度对草地植被组成影响的研究

在试验区围成面积相等的5个放牧区和1个对照封育区(每区6.67hm2),每个放牧区隔成面积相等的3个小区(每小区2.22hm2)。5个放牧区放牧羊只数依次为3只、4只、5只、7只、10只。试验为期150d。试验结果如下:①放牧强度与草地禾本科牧草现存量之间存在极显著负相关关系和极显著回归关系,禾本科牧草现存量随放牧强度变化趋势是先增后减。当放牧强度为0.45只/hm2时,禾本科牧草的现存量最大。②随着放牧强度增大,禾本科牧草所占总产草量的比例减小。当放牧强度为0.45只/hm2时,禾本科牧草所占比例最大。③随着放牧强度的增大,豆科牧草所占比例呈现先减后增再减的变化趋势,即呈“V”字型。④当放牧强度逐渐增大时,杂类草变化趋势呈现“N”型变化。⑤随着放牧强度的增大,禾本科牧草比例相对降低,而豆科牧草比例相对增加,草地植被组成改变。以宁夏盐池草地现状,放牧强度不能大于0.45只/hm2。     

不同放牧强度对牧草地下贮藏物质的影响

探讨了荒漠草原建群种短花针茅地下器官中还原糖在整个生长季内的变化规律，提示了贮藏营养物质与植物生长发育之间的内在关系，重点讨论了放牧强度对还原糖在地下不同器官中的分配和累积的影响，从而得出了该类型草地适宜放牧强度下的还原糖变化模式     

牦牛放牧模式对西藏高山嵩草草甸群落特征的影响

利用样方法对西藏高山嵩草（Kobresia pygmaea）草甸群落进行实地调查,分析了2010-2012年不同强度的牦牛放牧试验对植物群落动态和地上生物量的影响,以期为高寒牧区退化草地的恢复及草地高效利用提供理论指导。结果表明：适度放牧能提高物种多样性、丰富度、均一度和地上生物量,降低植物群落盖度;重度放牧降低植物群落的多样性和生物量;重度延迟放牧能缓减重度放牧对草地的不良影响;相关分析结果表明,植物群落盖度与均匀度、丰富度、植物密度、多样性和地上生物量成正相关。高山嵩草草甸的功能群随着放牧强度的增加而显著变化,其优势功能群多年生根茎型牧草高山嵩草和苔草（Carex moorcroftii）、多年生丛生型牧草紫花针茅（Stipa purpurea）的盖度和地上生物量随着放牧强度增加而下降。     

垂穗披碱草/星星草混播草地优化牦牛放牧强度的研究

以植被和牦牛生产力变化为目标研究草地不退化的最大放牧强度,在垂穗披碱草/星星草高寒混播草地3年的牦牛放牧试验结果表明,1)优良牧草比例和牦牛个体增重的平均年度变化随放牧强度的增加而减小,牦牛个体增重和优良牧草比例的平均年度变化之间存在着正相关,因此确立了不同放牧强度下优良牧草比例的年度变化是评价高寒混播群落放牧价值的直接度量指标.2)虽然群落相似性系数和草地质量指数可以评价草场的相对变化,但相似性系数的变化与牦牛个体生产力没有显著关系,因而不能反映草场放牧价值的变化,而计算草地质量指数时,不同植物类群盖度的测定和适口性的判别受人为因素的干扰较大,因此它也不是一个很客观的指标.3)当放牧强度为9.97头/hm2时,优良牧草比例和牦牛个体增重的年度变化能维持基本不变,因此,可以认为该放牧强度是高寒人工草地生长季放牧不退化的最大放牧强度.     

科尔沁沙质草地禾本科植物主要功能类型对连续放牧的反应

为了正确评价连续放牧对禾本科牧草的影响,在科尔沁典型沙质草地,设置不同放牧强度的4块样区,连续放牧4年后对各样区植被中禾本科植物的盖度和高度进行了样方调查,分析了3个禾本科植物功能类型.结果表明:1)禾本科植物的平均盖度对重牧比较敏感,而在中牧区、低牧区和对照区差异较小;2)3个功能类型植物的高度随放牧强度的增加,呈有规律的降低.而且多年生牧草的高度对放牧强度最敏感,一年生优质牧草次之,一年生劣性牧草最不敏感;3)多年生牧草在各样区的相对盖度随放牧强度的增加,逐渐减少,在重牧区仅为0.69%;一年生优质牧草在各样区的相对盖度表现为中牧区＞低牧区＞重牧区＞封育对照区,说明放牧干扰有提高此相对盖度的影响;一年生劣性牧草在各样区的相对盖度随放牧强度的增加,逐渐增大.     

放牧与舍饲对滩羊生产性能的影响

滩羊是产于中国西北干旱半荒漠地区的一个独特的绵羊 品种,主要分布在东经105°～108°,北纬35°45′～39°40′的区 域内,以宁夏中、北部为中心产区。传统的生产方式为放牧,当 地特殊的自然和生产条件形成了滩羊特殊的品种特点。近年 来,随着西部大开发战略决策的实施,滩羊中心产区全面实行 了退牧还草和禁牧措施。从而改变了滩羊的传统生产方 式———由放牧转为舍饲,由采食荒漠及干旱草原牧草为主转向 以人工牧草和作物秸秆为主。为了了解舍饲对滩羊生产性能 的影响及程度,为今后科学组织生产提供依据,特以宁夏滩羊 保种基地盐池滩羊…     

放牧生态系统中的组织物质循环及其在牧场管理中的应用

综述了组织物质循环的理论及其在牧场管理中的应用。放牧过程中牧地草丛内的物流和能流循环是维持放牧生态系统平衡的重要基础,进行牧地草丛中植物组织循环,特别是其生长和萎蔫死亡的动态分析,为草地的有效利用提供了理论依据。文中对于牧地草丛内及刈牧过程中的组织物质循环,连续放牧及间断放牧条件下的组织物质循环进行了重点分析论述。建议在中国各类型草地上应用组织物质循环理论开展放牧管理研究,以推动草地管理理论和实践的发展。     

放牧绵羊牧食行为与生产性能的研究

该试验在内蒙古锡林郭勒草原沙质草地放牧条件下,分别对4月龄和6月龄杂种羊、引种羊和蒙古羊的牧食行为、生产性能以及羊肉品质进行了比较研究,并探讨了年龄对绵羊生产性能与肉品质的影响。     

科尔沁草地不同放牧制度牧食行为研究

2006年7~10月在科尔沁草地研究了不同放牧制度下科尔沁牛的牧食行为。结果表明:科尔沁牛的采食选择性很强,不仅表现在牧草的种类上,还表现在牧草的生长季节上,主要选择那些易消化的植物种类或部位,在两种放牧制度的食谱中狗尾草所占的比例均高于45%。植物种群采食后的平均留茬高度在不同放牧制度和不同月份具有不同的表现,轮牧条件下表现为10月份7月份8月份9月份;自由放牧条件下表现为10月份9月份8月份7月份。不同放牧制度下的采食速率、采食习性、排泄行为不同,轮牧条件下采食时间和采食路线短,采食速率和采食量高,反刍?卧息和站立时间均较长,排粪和排尿次数少。     

放牧绵羊牧食行为及采食量研究

在锡林郭勒草原对三种放牧绵羊(蒙古羊、引种羊、杂种羊)进行不同月份的牧食行为观察及采食量测定,结果表明:放牧绵羊9月份的采食时间比例均高于8月份;沙质草地放牧绵羊的采食和游走时间比例低于高平原草地;蒙古羊、引种羊和杂种羊沙质草地的平均采食量分别为1.15kg/d、1.60kg/d和1.35kg/d,高平原草地为1.56kg/d、1.82kg/d和1.71kg/d,分别相差0.41kg/d、0.22kg/d和0.36kg/d。     

Rotational Grazing Systems and Livestock Grazing Behavior in Shrub-Dominated Semi-Arid and Arid Rangelands

Rotational grazing systems (RGS) are often implemented to alleviate undesirable selective grazing by livestock. At both fine and coarse scales, livestock selectively graze individual plants, patches, communities, and landscapes. Smaller pastures, increased stocking density, and rotation allow managers to constrain livestock movement and determine season and frequency of grazing, potentially limiting selectivity and preventing repeated grazing of preferred plants. However, in arid and semi-arid rangelands, forage growth is limited primarily by precipitation rather than defoliation frequency. When soil moisture is adequate, forage is abundant and defoliation levels are typically low, and repeated, intensive defoliation of preferred plants is less likely than in more mesic areas where more consistent precipitation and soil moisture storage allows animals to establish and maintain spatial hierarchies of grazing patterns. Many southwestern rangelands contain diverse vegetation, which provides quality forage during different times of the year. These spatial and temporal patterns of forage distribution may not be amenable to manipulation with RGS. Tracking data show that livestock often alternate among locations within pasture boundaries and can opportunistically exploit areas with higher quality forage when they are available. Higher stock densities combined with higher stocking rates can increase livestock use of less preferred areas, but overall distribution patterns of intensive-rotational and extensive grazing systems are often comparable at similar stocking rates and distances from water. Management that ensures that grazing of riparian areas does not occur during the critical late summer period may be more beneficial than RGS that periodically defers livestock use throughout the grazing season. In arid and semi-arid shrublands, timely adjustments to animal numbers and practices that improve grazing distribution at regional and landscape scales are more likely to be effective in maintaining or improving rangeland health than fencing and RGS.     

Grazing and Grazing Exclusion Along a Resource Gradient in Magellanic Meadows of Tierra del Fuego

Although Magellanic meadows have been subject to ungulate herbivory for a long time; they have suffered severe grazing by domestic sheep since the end of the 19th century. We hypothesized that, if protected from grazing, the present dominant dwarf forms would be replaced by taller competitive forms, mainly grasses. We then monitored floristic composition along a gradient of soils over periods of 5 to 16  on seven meadow sites under grazing and, in five, also on exclosures. Initial and final floristic samples were classified with TWINSPAN and ordinated with Detrended Correspondence Analysis (DCA). We also tracked cover changes in life-forms (grasses, dwarf sedges/rushes, rhizomatous helophytes, and cushion shrubs). At the end of the study, we assessed floristic similarity between paired grazed and exclosed treatments, and compared their life-form cover, diversity, biomass, and soil compaction with Student's t and Mann-Whitney's tests. Temporal displacements of composition in ordination space showed the effect of a long drought (DCA axis 1) and of grazing removal (DCA axis 2). Grazing exclusion had a much greater impact in wet meadows–where grasses became the dominant life-form–than in dry meadows. The effect of drought was shown in 1) the expansion of the cushion shrub Azorella trifurcata (Gaertn.) Pers. in both grazed and nongrazed treatments of the drier wetlands; 2) the decrease in Caltha sagittata Cav. in riparian meadows, and its encroachment under grazing in the wettest spring meadow; and 3) the large increase in Poa pratensis L. in exclosed wet meadows. Despite this strong response to environmental conditions, overall results supported the idea that these wetlands are equilibrium systems. Although the drier meadows have crossed an irreversible threshold, the Caltha-encroached wet meadows returned to a grass state in about 4  when protected from grazing. Their resilience suggests that they could be partly restored with rest-rotation grazing.     

草地家畜放牧系统饲料预算与放牧技术

贵州省地处云贵高原,属亚热带气候,雨量充沛,气候温和,雨热同期,适合大多数优良牧草生长,草山草坡资源丰富,传统畜牧业在山区经济中占有很重要的位置,有着发展集约化草地畜牧业得天独厚的自然条件.     

Feed Intake and Performance of Sheep Grazing Semiarid Grassland in Response to Different Grazing Systems

Effects of grazing management systems (GS) on biomass production and nutritional quality of rangeland vegetation in semiarid regions are extensively studied; however, limited information is available regarding their effects on diet digestibility and feed intake of grazing livestock. We therefore analyzed digestibility of ingested organic matter (dOM), organic matter intake (OMI), and live weight gain (LWG) of sheep in a grazing experiment established in the Inner Mongolian steppe of China, where two GS were tested for six different grazing intensities (GI) from very light to heavy grazing. For the continuous grazing system, sheep grazed the same plots each year, and for the alternating system, grazing and hay making were alternated annually between two adjacent plots. In July, August, and September 2009 and 2010, feed intake and live weight of sheep were determined. The GS did not affect dOM (P = 0.101), OMI (P = 0.381), and LWG of sheep (P = 0.701). Across both GS LWG decreased from 98 g · d^-1 for GI1 to 62 g · d^-1 for GI6 (P &spilt; 0.001; R² = 0.42). There were no interactions between GS and GI for all measured parameters (P ≥ 0.061), indicating that alternating grazing did not compensate for negative effects of heavy grazing even after 4 yr of grassland use. In summary, our study showed that irrespective of GI, alternating grassland use does not improve dOM, OMI, and hence, LWG of sheep. However, it might enhance revenues and ecological sustainability in the long term when compared to the common practice of continuous grazing at very high stocking rates.     

Comparison of Season-Long Grazing Applied Annually and a 2-Year Rotation of Intensive Early Stocking Plus Late-Season Grazing and Season-Long Grazing

This research measured steer gains, aboveground biomass remaining at the end of the growing season, and economic returns of tallgrass prairie grazed under season-long stocking (SLS-C) and a grazing system that included a 2-yr rotation of SLS-rotated (SLS-R) and intensive early stocking (IES; 2× normal stocking rate) + late-season grazing at the normal stocking rate (IES + LSG-R). We hypothesized that even though the stocking rate on the IES + LSG-R pasture was above the recommended rate, the greater regrowth availability in the late season would result in steers gaining as well as or better than those stocked SLS at the normal rate. By rotating the IES + LSG treatment with SLS over 2 yr, we anticipated that the aboveground biomass productive capacity of the IES + LSG pasture would be restored in one growing season. Further, we hypothesized that the increased stocking rate with IES + LSG would increase net profit. Comparing traditional season-long stocking to the system, which was a combination of SLS and IES + LSG rotated sequentially over a 2-yr period, the system increased steer gains by 7 kg · hd^?1 and by 30 kg · ha^?1, had a consistent reduction of 429 kg · ha^?1 biomass productivity, and increased net profit by $55.19 per steer and $34.28 per hectare.     

不同放牧压和放牧时期对山羊牧食行为的影响

在南方人工草地上,对云岭黑山羊在不同放牧压和放牧时期的牧食行为进行研究。结果表明:放牧压指数较小时,能减少采食时间和采食时行进步数,明显增加每步吃草口数、采食速度、口食量、日采食量、反刍时间,对其他牧食行为影响不大;9月份采食口数、行进步数最少,口食量、日采食量最大,6月份每步吃草口数明显小于其他月份。7,8,9月份采食速度相差不大,小于10月份采食速度;10月份反刍时间、每个食团咀嚼时间最长,反刍咀嚼速度、逆呕时间间隔在不同月份差别不大。