松嫩平原主要草原群落放牧干扰梯度对植物多样性的影响

松嫩草原五个主要群落类型放牧干扰梯度对植物样性影响的研究结果表明,在放牧过程通过牧畜的啃食、践踏作用干扰草原环境,使群落物种组成发生变化,优势地位发生更替,导致植物多样性变化。随着放牧干扰强度的增大,群落丰富度随之下降。多样性指标在中牧或重牧阶段出现峰值,主要缘于群落均匀度的增加。β多样性研究结果表明,羊草群落和羊草－杂类草群落植物多样性的耐牧性较差,而贝加尔针茅－羊草群落、贝加尔针茅－杂类草群落     

定边荒漠草原蝗虫群落多样性研究

为查明定边县荒漠草原蝗虫区系及物种多样性,采用α和β多样性方法进行研究。结果表明,该区域蝗虫区系由7科、17属、19种组成,单种属和寡种属多是各蝗虫群落组成的共同特点;各蝗虫群落种的丰富度、均匀度及多样性指数变化趋势相同,自大至小排序为:农田蝗虫群落>平沙地荒漠草原蝗虫群落>半流动半固定沙丘荒漠草原蝗虫群落,3个蝗虫群落的生境差异性比较大。     

盐池县典型草原蝗虫发生与植被群落的关系

草原蝗虫生态分布特征及其与环境因子的关系研究, 是揭示蝗虫地理发生规律的理论基础。以宁夏盐池县典型草原区为例, 采用野外调查和定量分析方法, 研究了不同草地蝗虫组成及其与植被群落的关系。结果表明, 麻黄山典型草原区蝗虫种类有24种, 主要种类为短星翅蝗(Epacromius coerulipes)、亚洲小车蝗(Oedaleus asiaticus)、赤翅皱膝蝗(Angaracris rhodopa)、白纹雏蝗(Chorthippus albonemus)、裴氏短鼻蝗(Filchnerella beicki)等。蝗虫总个体数、群落丰富度、群落多样性与植被群落多样性、生物量、盖度呈正相关, 与植被群落均匀度、草层高度呈负相关。蝗虫总个体数、群落丰富度、群落多样性与禾本科优势度、菊科优势度呈负相关, 与豆科优势度和其他科优势度呈正相关。从优势种与植被群落相关性来看, 白纹雏蝗、亚洲小车蝗、赤翅皱膝蝗对禾本科牧草选择性最强, 裴氏短鼻蝗、短星翅蝗对菊科牧草选择性最强。     

牧鸡防治草原蝗虫效果试验

在蝗虫危害严重的草地上放牧90日龄鸡群，试验结果表明，在60d的防治期，牧鸡防治面积757hm^2，平均灭效96．5％，投入产出比1：3．2，为今后应用该生物技术防治草原蝗虫提供了依据。     

限时放牧对草原利用影响的研究

在内蒙古鄂尔多斯市鄂托克前旗绒山羊增绒示范区进行限时放牧对草原利用的影响研究表明,限时放牧区与自由放牧区相比,植被平均高度增加5cm左右,盖度提高12%左右,密度增加40株/m2,地上生物量增加20%～40%。     

放牧强度对羊草草原的影响

研究放牧强度对羊草草原植物群落组成、数量特征、生物量及土壤特性等的影响.结果表明,随着放牧强度的增加,羊草草原的植被盖度和生物量随之降低,优势羊草群落将逐渐被盐生植物所替代,群落结构趋于简化,物种向旱生化和盐生化演替.同时土壤容重、含水量、有机质和氮、磷、钾、钙、镁等营养元素含量亦随着放牧强度的增加而逐渐降低.春季过度放牧对土壤表层的水分、有机质和钙、镁等元素造成的损失最为严重.因此,制定科学的草原管理措施,特别是春季限制放牧等措施对于维持草原的可持续发展具有重要意义.     

放牧强度对羊草草原的影响

研究放牧强度对羊草草原植物群落组成、数量特征、生物量及土壤特性等的影响.结果表明,随着放牧强度的增加,羊草草原的植被盖度和生物量随之降低,优势羊草群落将逐渐被盐生植物所替代,群落结构趋于简化,物种向旱生化和盐生化演替.同时土壤容重、含水量、有机质和氮、磷、钾、钙、镁等营养元素含量亦随着放牧强度的增加而逐渐降低.春季过度放牧对土壤表层的水分、有机质和钙、镁等元素造成的损失最为严重.因此,制定科学的草原管理措施,特别是春季限制放牧等措施对于维持草原的可持续发展具有重要意义.     

放牧对草原植物的影响

较全面的研究了内蒙古典型草原在不同放牧条件下的植物种类组成,生活型谱和种群特性及其生产力的变化,发现适度放牧下草原生产力具有补偿或超补偿性生产的现象,且草原植物多样性最高。     

适度放牧对林间草原植物形态特征及生物多样性的影响

本研究通过对伊犁巩留县东部保护区适度放牧和无放牧的山地草本植物群落样方的调查,对植株生长周期、株高、生长型、是否有刺、茎性质、叶大小6个形态特征植物的数量进行统计,并计算4个多样性指数：Simpson指数,Shannon Wiener指数,Brillouin指数和Fager指数,从而得到适度放牧对该山区草地生态系统生物多样性的影响。结果表明,(1) 适度放牧样地内,各种形态性状植物的数量都较无牧样地有所提高,其中中等型、直立、无刺、草本以及木本植物数量显著增多（P=0.048,P=0.017,P=0.019,P=0.016,P=0.045）,其余性状植物的数量增加不显著。 (2)适度放牧条件下低海拔植被的丰富度,多度较无牧样地均有所提高,Simpson指数和 Shannon wiener指数均有显著的提高（P=0.028,P=0.003）。综上所述,本研究结果能为西天山国家级自然保护区的建设管理提供一定理论参考。     

宁夏干草原不同放牧方式对植被特征影响的研究

采用不同放牧方式,在宁夏干草原系统地开展了草地植物特性与生态学特性方面的研究,结果表明:实行六区的划区轮牧方式是科学利用该类草地的最佳方式。轮牧比对照草地生产力提高73.84%。     

宁对夏干草原不同放牧方式植被特征影响的研究

采用不同放牧方式，在宁夏干草原系统地开展了草地植物特性与生态学特性方面的研究，结果表明：实行六区的划区轮牧方式是科学利用该类草地的最佳方式，轮牧比对照草地生产力提高73．84％。     

科尔沁丘陵草甸草原蝗虫群落特征与植被的关系

近年来, 科尔沁丘陵草甸草原发生周期性、大面积、高密度的蝗虫灾害, 威胁着该区畜牧业的发展。本研究对该草原类型4类植被样地[样地Ⅰ:贝加尔针茅(Stipa baicalensis)+羽茅(Achnatherum sibiricum)群落;样地Ⅱ:中华糙隐子草(Cleistogenes chinensis)+兴安胡枝子(Lespedeza daurica)群落;样地Ⅲ:蓖齿蒿(Artemisia pectinatal)群落;样地Ⅳ:糙隐子草(C. squarrosa)群落]的植物群落、蝗虫群落及二者之间的关系进行了分析。结果表明, 不同样地间的植物群落丰富度、多样性和均匀度指数差异显著(P＜0.05);蝗虫群落丰富度、多样性和均匀度指数差异不显著(P0.05);4类样地中蝗虫群落与植物群落相关参数之间的相关性表现各异:样地Ⅱ蝗虫群落多样性与植物群落多样性呈负相关但不显著(P0.05), 样地Ⅰ和Ⅲ蝗虫群落多样性与植物群落多样性呈正相关但不显著(P0.05), 样地Ⅳ蝗虫群落多样性与植物群落多样性呈显著正相关(P0.05)。植物群落所构成的栖境条件以及蝗虫自身生物学特点影响或决定蝗虫的分布与发生;蝗虫对栖境选择的多样性反映了蝗虫具有较强适应能力及蝗虫与植被的协同作用。     

Impact of grazing intensity on herbage intake, composition, and digestibility and on live weight gain of sheep on the Inner Mongolian steppe

High grazing pressure during the last decades caused severe ecological problems in the steppe of Inner Mongolia, China. The objective of the present study was to determine the effects of grazing intensity of sheep on herbage mass (HM) and intake, chemical composition and digestibility of herbage, and on live weight gain (LWG). A grazing experiment with six different grazing intensities (1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 sheep/ha) was conducted in the growing season of 2005 in the Xilin River Basin. HM decreased from 1.5 t DM/ha at the lowest grazing intensity to 0.6 t DM/ha at the highest grazing intensity. NDF content of the herbage was high (> 700 g/kg DM) and relatively constant, whereas acid detergent lignin (ADL) content increased with grazing intensity and with proceeding grazing season. Digestibility of organic matter ingested (DOM) tended to decrease with grazing intensity as well as intake of organic matter (OMI) and of digestible organic matter (DOMI) per sheep (P = 0.090 and P = 0.065, respectively), whereas LWG per sheep decreased with increasing grazing intensity (P = 0.018). DOM and OMI were negatively related to ADL content. However, herbage intake and LWG per ha increased with grazing intensity (P < 0.001) and reached their maximum at 9 and 7.5 sheep per ha, respectively. This observation confirms the current farmers' practise of high grazing pressure ignoring long term grassland productivity and ecological problems. Therefore, the studies are continued to provide further information on long term effects. This study could show pronounced effects of grazing intensity on animal and grassland productivity and the suitability of the methods applied to measure intake and digestibility of herbage in a large scale grazing experiment with sheep.     

The influence of urine and dung deposition on patch grazing patterns of cattle and sheep in the Southern Tall Grassveld

Abstract

The effect of urine and dung deposition on the patch grazing patterns of cattle and sheep in the Southern Tall Grassveld was investigated using an experiment with four treatments, viz. artificial urine, fresh cattle dung, fresh sheep dung, and a control. Cattle and sheep preferentially grazed the sward surrounding and within urine deposits for six months after deposition. Cattle rejected herbage from both cattle and sheep dung patches for six months after deposition. Sheep initially rejected the herbage from cattle dung patches, but their grazing patterns were no longer affected at six months after deposition. Sheep grazing tended not to be influenced by sheep dung. Urine deposition may consequently be an important factor in patch initiation and patch development.     

放牧对草甸草原植物群落结构及多样性的影响

在贝加尔针茅—羊草草甸草原的同一草地地境上,按放牧退化程度,将其划分为轻度退化区、中度退化区及重度退化区,并测定每一样地内植物群落特征及多样性指标。结果表明,随着放牧强度的增加,群落地上总生物量与中旱生植物的生物量变化保持一致,均呈降低趋势;中生植物先呈增加趋势,后下降;旱生植物呈增加趋势;群落优势种贝加尔针茅Stipa baicalensis和羊草Leymus chinensis呈降低趋势;物种丰富度指数先增加,而后降低;多样性指数和均匀度指数均呈增加趋势,优势度指数则相反。     

不同轮牧方式对荒漠草原植物群落特征的影响

研究轮牧方式对草地植被特征的影响,可为草地合理放牧提供科学依据。在宁夏荒漠草原,以载畜率0.75只·hm^-2为水平,以围封禁牧草地为对照(CK),对连续放牧(CG)、二区轮牧(TG)、四区轮牧(FG)和六区轮牧(SG)方式下草地物种植被组成、群落盖度、生物量、净初级生产力、物种多样性以及群落稳定性进行研究。结果表明:1)轮牧使荒漠草原优良牧草重要值下降,但可增加植物物种种类;增加轮牧分区有利于优良牧草和多年生草本重要值的保持,但对半灌木的影响较小;2)植被盖度以封育和四区轮牧较高,地上生物量和净初级生产力以四区轮牧和六区轮牧草地较高,地下生物量以封育和六区轮牧处理较高,草地凋落物量以封育较高;3)轮牧可增加物种丰富度、多样性以及优势度,但群落均匀度指数下降;4)各处理下植物群落均不稳定,相比之下,围封禁牧群落稳定性最高,连续放牧最低。综合植被特征和生产中的便利性,研究认为四区轮牧是研究区最适宜的轮牧方式。     

Response of lambs to continuous and rotational grazing at four grazing intensities on Midmar Italian ryegrass

Abstract

Irrigated Midmar Italian ryegrass (Lolium multiflorum Lam.) was grazed either continuously or rotationally at four grazing intensities by three successive sets of weaned lambs for the winter, spring and summer periods, respectively. The “put‐and‐take” system was applied. In the case of continuous grazing, amounts of available dry matter (DM) per hectare were varied, whereas with rotational grazing different grazing intensities were established by allocating different amounts of DM per unit livemass. Amounts of DM on offer were determined in both systems to provide a basis for comparison.

There were no differences in average daily gain (ADG) at equivalent levels of available DM between grazing procedures in winter. In both spring and summer, however, ADG at given levels of available DM was greater (P ≤0,01) with continuous than with rotational grazing. Stocking rate at equivalent levels of available DM was higher (P ≤0,01) for rotational as compared with continuous grazing in winter and summer, but in summer, grazing procedure had no effect on stocking rate. There was an interaction between stocking rate and grazing method in winter (P ≤0,01). At high stocking rates, ADG were higher (P ≤0,01) under rotational than under continuous grazing. In spring and summer the ADG for continuous grazing was higher (P ≤0,01) than that for rotational grazing at equivalent stocking rates. The estimated stocking rates for maximum gains/ha ranged in the different seasons from 45 to 123 lambs/ha.     

Effects of eight grazing systems on carcass mass gains of steers grazing irrigated Cynodon aethiopicus pastures

Abstract

Eight grazing systems were compared on irrigated Cynodon aethiopicus pastures which received 650 kg N, 36 kg P and 200 kg dolomitic limestone/ha, annually. There were either one, two, three, six or 18 paddocks in the systems, the single paddock system being continuously grazed. The others were rotational systems with various periods of grazing and of resting.

Using the comparative slaughter technique carcass mass gains of crossbred Hereford/Afrikaner steers were calculated. Three‐year mean carcass mass gains over stocking rates from 12 to 18 steers/ha ranged from 872 to 997 kg/ha. None of the rotational systems were better than continuous grazing.

Estimates of amounts of herbage available for grazing in each system showed that there was least in the continuous grazed and most in the multi‐paddock systems where there were long periods of rest between successive grazing.