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为更好地了解青藏高原高寒草甸区暖季放牧条件下人工草地牧草的生长特点,为制定合理放牧制度提供依据,于2001~2003年开展了暖季放牧牦牛对多年生人工草地影响的试验。结果表明:放牧2年后轮牧人工草地播种牧草比例为95.27%,连续放牧人工草地为86.15%,无放牧人工草地为58.01%。轮牧人工草地牧草月风干重最高值3 198.8 kg/hm2,连续放牧人工草地为3 023.2 kg/hm2。放牧可以提高人工草地牧草生长率,轮牧人工草地的牧草生长率高于连续放牧人工草地。放牧还影响着第2年播种牧草的生长,轮牧能促进种子出苗数,播种牧草的鲜重,风干重和种子产量分别达到了5 088.88 kg/hm2,3 053.33 kg/hm2和480 kg/hm2,均高于连续放牧人工草地和无放牧草地,轮牧人工草地杂草鲜草产量最低,为193.33 kg/hm2。适宜的放牧是保持人工草地可持续利用的手段之一。 相似文献
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选取内蒙古自治区克什克腾旗达来诺日镇典型草原区封育恢复中天然放牧草场,于2008年6～10月进行毛肉兼用细毛羊的暖季放牧试验.采用2×5完全随机试验设计,设定不同放牧方式(不放牧,连续放牧,四区、五区、六区轮牧)及2种放牧强度,研究围封过程中放牧绵羊对封育草场牧草营养物质含量的影响.结果表明,不放牧区牧草初水分、粗蛋白质、粗脂肪和粗灰分含量显著高于轮牧和连续放牧区,酸性洗涤纤维和中性洗涤纤维含量显著低于放牧区;随着放牧季节的延续,不放牧区牧草营养价值下降速度最慢,轮牧区次之,连续放牧处理下降最明显;四区、五区和六区轮牧处理间牧草营养物质含量变化差异不显著.放牧方式与放牧强度对草场营养物质含量动态变化表现出不同程度的瓦作效应.因此,在放牧强度适中时,划区轮牧能够体现其优越性,随着牧草生长季的延续,较好地保存牧草的营养价值. 相似文献
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奶牛放牧对北方农牧交错带人工草地植被的影响 总被引：2，自引：2，他引：0
研究了不同处理奶牛放牧对混播人工草地植被的影响。结果表明,牧草现存量随着放牧强度的增加而降低,轻牧比中牧高7.28%,且轮牧高于连续放牧1.99%,轮牧对紫花苜蓿和无芒雀麦的再生有利。随放牧强度增加,紫花苜蓿和无芒雀麦重要值下降,蓝茎冰草和新麦草增加。放牧对牧草的茎叶比有显著影响,放牧后4种牧草的茎叶比均有下降,连续放牧高于轮牧。根系主要集中在土壤表层0~10 cm,约占0~30 cm总量的70%,且其生物量也以轮牧制较高,随放牧强度的增加而下降。 相似文献
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本试验在内蒙古呼伦贝尔市草甸草原,针对划区轮牧和自由放牧对植物群落及主要植物种群的影响进行做了比较研究．分析结果表明：（1）羊草的高度、盖度和密度在划区轮牧区较在自由放牧区高,说明划区轮牧有利于多年生根茎禾草的繁殖,对一年生植物的生长起到了一定的抑制作用。（2）Margalef指数、Shannon-wiener指数、Simpson指数和Pielou指数划区轮牧区均高于自由放牧区,说明划区轮牧较自由放牧更有利于提高物种的多样性和丰富度。（3）植物群落总的地上现存量划区轮牧较自由放牧高,说明划区轮牧较自由放牧能够保持群落具有更高的地上现存量。 相似文献
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2000～2002年通过对内蒙古短花针茅荒漠草原在不同放牧制度下植物净初级生长量和家畜采食率的研究,探讨了划区轮牧制度和自由放牧制度草地植物的补偿性生长.结果表明实验期间,不同放牧制度的草群净初级生长量与对照区的差异不显著(P>0.05),表现为等补偿性生长;主要植物种群的净初级生长量在不同放牧处理区存在着差异,从而表现出不同的补偿性生长趋势;草群和主要植物种群的采食率自由放牧区高于划区轮牧区.试验还表明,生长季节降雨量状况也是影响植物补偿性生长的关键因子,植物的净初级生长量随降雨量的增加而增加. 相似文献
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选取内蒙古自治区典型草原区封育恢复中天然放牧草场,进行毛肉兼用细毛羊的暖季放牧试验.采用2×5完全随机试验设计,设定不同放牧方式（不放牧,连续放牧,四区、五区、六区轮牧）及2种放牧强度（1.0,1.4 hm2/un.sh）,运用酶分析方法分析比较了围封过程中放牧绵羊对封育草场牧草细胞壁成分月动态变化及营养价值的影响.结果表明,整个暖季放牧期内,不同放牧区牧草营养物质含量主要受到放牧方式的显著影响（P＜0.05）.具体表现为,不放牧处理牧草细胞壁有机物（OCW）含量始终显著低于各放牧处理,不同放牧处理间没有明显差异;划区轮牧处理牧草始终保持着较高的消化性部分且显著高于连续放牧处理;不放牧处理牧草始终保持着较高的Oa和较低的Ob,而连续放牧处理与其相反,各轮牧处理间没有显著差异;轮牧处理总可消化养分（TDN）和代谢能（ME）含量较高,尤其在牧草生长旺盛期（八月份）,六区轮牧放牧场牧草可利用营养物质含量最高,营养价值最高. 相似文献
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以生长在高寒山区的多年生和一年生牧草为材料,研究了牧草生长过程中叶中可溶性蛋白质、脯氨酸、碳水化合物等低温保护物质含量的变化,分析了它们与植物叶片含水量和低温生长过程的关系.结果表明,在生长季中,多年生牧草叶片含水量相对较低,四种牧草平均叶片含水量在56.4%～71.8%,而一年牧草叶片含水量较高,为87.0%.总体看,抗冷力强的多年生牧草中低温保护物质明显高于抗冷力弱的一年生牧草.其中,随着生长季气温增高,多年生牧草叶中脯氨酸含量下降,下降幅度平均为64.5%,在晚秋气温下降时又回升.生长季中牧草叶中可溶性蛋白质含量增加,尤其是苜蓿和无芒雀麦.几种多年生禾草叶片碳水化合物含量一直较高,可溶性糖在生长季呈上升趋势.这表明低温保护物质不仅在多年生牧草越冬中起着重要作用,而且与牧草低温生长相关.同时,牧草叶片含水量在维持低温光合作用、控制生长速率、平衡机体能量代谢及低温保护物质积累与转运上起重要调节作用. 相似文献
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Root proliferation is important in determining root foraging capability of rangeland grasses to unpredictable soil-nutrient pulses. However, root proliferation responses are often confounded by the inherent relative growth rate (RGR) of the particular species being compared. Additionally, inherent biomass allocation to roots (R:S ratio) can be associated with root RGR, hence likely influencing root foraging responses. The influence of relative growth rate and biomass allocation patterns on the speed and efficiency of root foraging responses at the critical seeding stage was examined in two important perennial rangeland grasses that occur widely in the Great Basin Region of the United States (Whitmar bluebunch wheatgrass [Pseudoroegneria spicata {Pursh} Löve] and Hycrest crested wheatgrass [Agropyron desertorum {Fisch. ex Link} Schult. × A. cristatum L. Gaert.]) as well as in the widespread exotic invasive annual grass, cheatgrass (Bromus tectorum L.). Greenhouse-grown seedlings were exposed to four nutrient regimes: uniform–low, uniform–high, soil-nutrient pulse, soil-nutrient depletion, and to either no clipping or clipping (80% removal of standing shoot biomass). Hycrest was the only species that exhibited root proliferation responses to the short-lived nutrient pulse, and this response occurred through root elongation rather than initiation of lateral root branches. Overall, defoliation inhibited proliferation-based root responses to a larger extent than topological-based root responses. Defoliated plants of Hycrest interrupted root development (topological index did not change) following shoot defoliation compared to undefoliated plants. In contrast, root topological developmental patterns were the same for defoliated and undefoliated plants of Whitmar, whereas cheatgrass exhibited an intermediate response between Whitmar and Hycrest. Our results suggest that inherent biomass allocation to roots contributes to enhanced capabilities of proliferation-based root responses. 相似文献
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D. L. Barnes 《African Journal of Range and Forage Science》2013,30(1):138-145
Although an adequate knowledge of growth patterns and defoliation effects in perennial grasses is a prerequisite for the rational use of veld and pastures for animal production, our knowledge of this subject is far from adequate. The results of various physiological and clipping studies on tropical and subtropical grasses are appraised and their weaknesses in providing information applicable in practical management are indicated. It is suggested that there is a need for increased emphasis on studies of growth patterns and defoliation effects giving priority to (a) defining and evaluating the extrinsic and intrinsic factors affecting differential response to similar defoliation treatments in different circumstances, (b) applying defoliation treatments with a practical bias, and (c) determining actual defoliation patterns under grazing. 相似文献
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Craig D Morris 《African Journal of Range and Forage Science》2016,33(4):235-245
An ability to tolerate recurrent defoliation likely plays a role in the compositional shift from decreaser to increaser species with overgrazing of mesic grassland, but the grazing tolerance of local species has not been extensively studied. The growth response of two decreasers, three Increaser II grasses, and an Increaser III species to frequent, severe defoliation under three levels of competition from neighbours and two levels of soil nutrients was examined in a pot trial. The effects of competition and especially nutrients markedly modified the defoliation tolerance of different species, and grazing response groups varied in the manner in which their defoliation responses were mediated by these interactions. Contrary to expectation, defoliation constrained potential productivity most in nutrient-rich, competition-free environments, probably because it exacerbates a carbon limitation on growth. However, nutrient enrichment did enable Increaser II grasses, but not other species, to better tolerate intense defoliation, explaining why they can persist on intensively grazed fertile patches and in heavily stocked grassland, such as in communal areas, where nutrients are more available. It is concluded that grazing tolerance is not a fixed property of species or grazing response groups but depends on biotic and abiotic environmental factors. 相似文献
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Targeted grazing is a promising strategy for addressing management issues in annual grasslands. We evaluated targeted cattle grazing strategies for tarweed (Hemizonia fitchii A. Gray) and vinegarweed (Trichostema lanceolatum Benth.). These native annual forbs provide biodiversity to annual grass-dominated landscapes, in addition to being important pollinator plants that discourage yellow starthistle (Centaurea solstitialis L.) invasion. However, these forbs can form dense stands that interfere with grazing. Therefore, we sought grazing strategies that promote sparse stands to maintain livestock production while supporting other ecosystem services. Treatments were 1) early grazing when dominant annual grasses were vegetative, 2) late grazing when grasses were senescing, 3) repeated grazing, and 4) a nongrazed control. These treatments were applied in 2011, 2012, and 2013. In 2012, neither tarweed nor vinegarweed were observed regardless of treatment, likely due to low water availability during their major growth period. In 2011 and 2013, grazing grasses repeatedly throughout the growing season increased tarweed to 3 ? 5 plants m? 2, compared with < 1 plants m? 2 in the control, and in 2011 repeated grazing also increased vinegarweed. Therefore, although environmental factors can prevent tarweed and vinegarweed from forming stands some years, defoliating grasses repeatedly from vegetative through senesced stages is the most reliable way to encourage these forbs in annual grasslands. However, a single period of defoliation can also encourage tarweed: In 2011 and 2013, we found a single period of grazing as annual grasses senesced and tarweed began rapid growth increased tarweed, possibly by increasing light availability. Finally, we found grazing once early in the growing season provided low tarweed and vinegarweed densities, likely because the long postgrazing period allowed annual grasses to recover and competitively suppress these forbs. Therefore, early grazing may reduce/prevent overly dense tarweed and vinegarweed stands. 相似文献
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Andrew J. Ash Jeff P. Corfield John G. McIvor Taoufik S. Ksiksi 《Strength and Conditioning Journal》2011,64(3):223-239
Grazing management is important for sustaining the productivity and health of rangelands. However, the effects of grazing management on herbage growth and species composition in the tropical savannas of northern Australia are not well known. In this eight-year study the influences of utilization rate and resting pastures from grazing on vegetation dynamics were measured at three sites in northeast Queensland, Australia. The sites had high, medium, and low soil fertility, and there were two land condition classes (States I and II) at each site. Severe drought occurred during the first four years, but above-average rainfall was received in the second half of the study. High utilization rates reduced biomass, perennial grass basal area, and ground cover. The reduction in biomass was due to both higher consumption and decreased primary production. State I condition plots at the high and medium soil fertility sites were initially dominated by decreaser perennial grasses, but these declined at all utilization levels, particularly the high rate. They were largely replaced by exotic perennial grasses. At the low fertility site there were no exotic grasses, and the decreaser grasses increased in all treatments, with the increases greatest in plots with low utilization or medium utilization plus resting. In the State II condition plots at the high and medium fertility sites, low or moderate utilization, led to an increase in both decreaser and exotic perennial grasses; with high utilization the decreaser perennial grasses declined and were replaced largely by exotic perennial grasses. This study clearly demonstrated that either conservative stocking with year-round grazing or a grazing system that includes some wet-season resting will help maintain land in a desirable state or help facilitate the transition from a less desirable ecological state to one more desirable for pastoral production and rangeland condition. 相似文献
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在江河源区2龄混播禾草草地(垂穗披碱草 星星草)上牦牛放牧试验结果表明: 随着放牧率的增加,在生长期内不同功能群地上净初级生产量和总地上初级生产量均出现了单峰曲线变化,即“S”型变化趋势; 总的地上净初级生产量和垂穗披碱草地上净初级生产量对放牧率的变化很敏感, 且随着放牧率的增加, 峰值出现日期提前; 其它禾草和星星草的峰值对放牧率的变化不很敏感;莎草类和杂草类对放牧率的变化比较敏感。随放牧率的增加, 地上现存量和总地上初级生产量的峰值下降, 且达到峰值的时间提前。在整个放牧期(植物生长期),重度放牧的RYT值均小于1,表明重度放牧使垂穗披碱草和星星草一直处于拮抗状态,其它各处理组在生长中后期也处于拮抗状态; 不同放牧率(包括对照)下垂穗披碱草的竞争力强于星星草, 垂穗披碱草因其高度和发达而较深的根系成为竞争的优胜者。 相似文献
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Katie R. Benzel Tracy K. Mosley Jeffrey C. Mosley 《Strength and Conditioning Journal》2009,62(6):550-556
Spotted knapweed (Centaurea stoebe L.), a perennial invasive forb that reproduces largely by seed, often forms new flowers after prescribed sheep grazing or mowing is applied during the bolting or flowering stage. It is unknown if these new flowers produce viable seeds by the end of the growing season. The purpose of this 2-yr study was to determine the appropriate timing (or timings) or combination (or combinations) of timings of defoliation on spotted knapweed to reduce its viable seed production. Spotted knapweed plants on foothill rangeland in west-central Montana were hand-clipped at seven different timings and frequencies of defoliation: June (bolting stage); July (late-bud–early flowering stage); August (full-flowering stage); June + July; June + August; July + August; or June + July + August. Unclipped plants were controls. Plants clipped in the bolting stage were defoliated at 35–40% relative utilization. Plants clipped at all other timings had 100% of their buds and flowers removed, plus 3 cm of each bud or flower stem. Plant response was evaluated from mid-August through September, whenever the seed heads of each treatment’s plants reached maturity but while their seed-head bracts remained tightly closed. Clipping at any timing or combination of timings reduced the number of buds and flower heads per plant (P < 0.01), number of seeds per plant (P < 0.01), percentage of viability of seeds (P < 0.01), and number of viable seeds per plant (P < 0.01) compared with no clipping. Clipping during the bolting stage reduced the number of viable seeds by nearly 90% compared with no clipping. Clipping during the late-bud–early-flower or full-flower stage reduced the number of viable seeds by nearly 100% compared with no clipping. Spotted knapweed defoliation via prescribed sheep grazing or mowing in summer should suppress viable seed production of spotted knapweed. 相似文献
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Abstract Defoliation by goats (leaves plus shoots) during the growing phenophases resulted in a considerable stimulation of leaf and shoot growth relative to non‐defoliated plants. The response differed considerably depending on the intensity and phenophase of defoliation. Plants were most susceptible to defoliation and young shoot removal during the spring flush when carbohydrate levels were at their lowest. During the rest of the growing season carbohydrate levels were high. At these times moderate to heavy (50 % to 75 % leaf removal) defoliations resulted in the greatest leaf and shoot growth. In contrast, the initial and continuing impact of avian and insect consumption of leaves only reduced leaf and shoot production. The stimulatory effect of defoliation in one season carried through the dormant season to the following growing season. Defoliations during the dormant season did not have any positive or negative impact on plants relative to non‐defoliated plants. Leaf and shoot material removed when the plants were growing, was replaced within weeks of defoliation. 相似文献
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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. 相似文献