放牧强度对宁夏荒漠草原植物群落结构及草地生产力的影响

以宁夏盐池县的荒漠草原区为试验地,以现场试验为手段,研究放牧强度(1.50只/hm2、0.75只/hm2、0.50只/hm2、0只/hm2)对荒漠草原植物群落结构及草地生产力的影响。结果表明:随着放牧强度的增加,植物群落优质牧草的重要值明显下降,毒草及家畜厌食植物的重要值明显上升;植物群落总盖度呈下降趋势,植物群落多样性呈现先增加后降低的趋势;草地生产力呈下降趋势,当放牧强度达到1.50只/hm2时,家畜的采食量超过了50%,草产量比封育地下降了54.9%。最后,根据草场资源可持续发展利用原则提出了宁夏荒漠草原合理的放牧强度以0.75只/hm2为宜。     

苏尼特右旗荒漠草原不同放牧强度土壤可蚀性K值研究

土壤侵蚀与土壤物理特性、抗蚀性密切相关,研究放牧强度对荒漠草原地表土壤颗粒组成及其可蚀性的影响,可为阐明放牧强度与土壤可蚀性间的响应机制提供科学依据,并可为科学利用草地提供参考.文中以苏尼特右旗荒漠草原5种强度放牧小区为研究对象,运用野外调查取样与室内试验相结合的方法,测定不同放牧强度小区的土壤颗粒粒径体积分数及有机碳...     

草原区沙地放牧草地合理利用途径

本文通过对草原区沙地放牧草地在畜牧业生产实践中出现大面积退化和沙化现象的分析 ,探讨了沙地放牧草地合理利用的途径 ,认为对于沙地放牧草地的保护 ,重点应放在草地的合理利用方面。通过以草定畜 ,合理调整载畜量 ;建立合理的利用制度 ;发展季节畜牧业 ;调整畜群结构 ,增加良种畜比例 ;以及改良天然草地 ,建立人工、半人工草地等措施 ,达到草原区沙地草地的可持续利用。     

牧民草地生态保护认知与行为的实证分析——基于西藏75个自然村的实证分析

依据拉萨、那曲及林芝地区牧民入户调查资料,对西藏牧民草地退化的认知及其放牧行为进行深入分析,揭示牧民草地资源保护诉求与草地资源利用倾向。分析结果表明:牧民对草地资源退化已经形成共识;牧民具有草地保护认知,但草地退化原因大多归因于政府保护不力,较少考虑养殖规模的影响;面对日益恶化的草地资源,牧民仍有扩大养殖规模趋势。     

祁连山不同海拔梯度和放牧强度土壤呼吸变化特征

分析青海云杉林、灌丛林、放牧草地三者的呼吸速率差异性以及放牧强度对土壤呼吸速率的影响,结果表明:①云杉林、灌丛林和放牧草地在16:00之前的呼吸速率大小顺序为:灌从林>云杉林>草地;16:00之后顺序为:云杉林>灌丛林>草地.②土壤呼吸速率和日均温有Y=10.342e-0.0002x,R2=0.0002的线性关系.这一线性关系可以解释很多土壤呼吸的变化情况.③放牧直接影响土壤含水量,放牧强度与土壤含水量呈负相关,土壤含水量与土壤呼吸速率呈正相关.土壤含水量为:重度放牧区>过度放牧区>极度放牧区;土壤呼吸速率为:重度放牧区>过度放牧区>极度放牧区.④温度是影响土壤呼吸的主要因子,与土壤呼吸速率呈正相关,呼吸速率日均最大值出现在6～7月,为8.66umoL/(m2·s);最小值出现在5月,为0.37umol/(m2·s).     

围栏与不同放牧强度对东祁连山高寒草甸植被和土壤的影响

在东祁连山高寒草地,对围栏7年和不同放牧强度的草地进行了物种数、地上生物量、地下生物量、土壤理化性质等研究。结果表明,围栏7年的高寒草地鲜草产量为425.8 g·m-2,显著高于夏季中牧159.3 g·m-2和夏季重牧91.0 g·m-2,但与冬季轻牧、夏季轻牧差异不显著。围栏条件下的物种数为26.3种·16 m-2,显著低于其他放牧条件下的物种数,但显著高于夏季重牧条件下的物种数23.0种·16 m-2;轻度或重度放牧都会使物种数减少,夏季中牧下的物种数最高(33.5种·16 m-2)。在0~10 cm的表层土壤中,围栏7年的草地根系生物量显著高于其他放牧强度。随着放牧强度的增加,根系生物量在0~10 cm土壤中呈下降趋势,在30~40 cm土壤中则表现为升高趋势。围栏7年的土壤容重低于其他放牧强度下的土壤容重,但差异不显著;夏季重牧的土壤容重显著高于围栏7年和其他放牧强度的土壤容重。随着放牧强度的增加,0~10 cm土壤碱解氮增加,围栏7年草地最低。围栏封育可有效改善和恢复草地植被,但不能长时间禁牧不进行放牧利用。合理的放牧能够维护高寒草甸草地生态系统功能、促进物种丰富度和土壤营养的均衡。     

放牧模式对高山草地蝗虫群落生物多样性的影响及其作用机制

为明确不同放牧模式对高山草地蝗虫群落生物多样性的影响及其作用机制,本研究调查牛放牧、羊放牧、牛羊混合放牧和休牧4种模式下高山草地植物群落特征、蝗虫群落组成和数量,分析蝗虫群落生物多样性特征,利用冗余分析方法分析植物群落与蝗虫群落的相关性,采用结构方程模型分析放牧模式对蝗虫群落的影响路径。结果显示,与休牧相比,牛放牧、羊放牧、牛羊混合放牧模式显著影响高山草地植物群落高度、植物群落覆盖度和禾本科牧草高度,但对植物群落生物多样性影响不显著。4种放牧模式下共捕获蝗虫13种,不同放牧模式下,高山草地的生物指示种不同。与休牧模式相比,牛放牧、羊放牧、牛羊混合放牧模式显著影响高山草地Shannon-Wiener指数、Simpson优势度指数和Pielou均匀度指数;在牛放牧、羊放牧和牛羊混合放牧模式下,高山草地蝗虫群落Shannon-Wiener指数分别为0.36、0.35和0.29,高山草地蝗虫群落Simpson优势度指数分别为0.45、0.45和0.35,高山草地蝗虫群落Pielou均匀度指数分别为0.33、0.33和0.24。高山草地植物群落高度、覆盖度和禾本科牧草高度与红翅皱膝蝗Angaracris rhodopa、鼓翅皱膝蝗A.barabensis、青海痂蝗Bryodema miramae等呈负相关,与狭翅雏蝗Chorthippus dubius呈正相关。结构方程模型分析表明不同高山草地放牧模式主要通过改变植物群落高度间接影响蝗虫群落生物多样性。     

放牧干扰对典型草原植被光谱及蝗虫密度的影响

为研究内蒙古典型草原不同放牧强度植被反射光谱与植被参数和蝗虫密度的关系,使用地物波谱仪于2015年和2016年对5个放牧梯度,共20hm~2样地进行调查研究。结果表明,不同放牧强度植被地上总生物量与归一化植被指数(NDVI)关系为y=0.034 8+0.002 9x(R~2=0.645 5,P=0.000 2),蝗虫密度与NDVI线性关系为y=0.067+0.013x(R~2=0.415,P=0.006)。对其进行冗余分析(RDA)发现,植被地上总生物量、植物高度、糙隐子草生物量是蝗虫数量和NDVI变化的主要影响因子,其中植被地上总生物量是显著性影响因子(P=0.001)。在不同放牧强度下蝗虫密度与草地NDVI显著相关(P0.05),随NDVI增大而增多。本文研究结果为进一步开展放牧区蝗灾遥感监测和科学合理地利用草地资源奠定了基础。     

呼伦贝尔草原植物功能群对围封及放牧的响应特征

植物功能群可以表征草地群落结构的复杂性和稳定性.文中以呼伦贝尔草原为研究对象,采用样线法开展植物群落样方调查,对比分析不同放牧强度下(轻度放牧-LG、重度放牧-HG、长期围封不放牧-EN)草地植物功能群(多年生根茎禾草-PRG、多年生丛生禾草-PBG、多年生杂草-FO、灌木及半灌木-SHS、一、二年生草本-AB、莎草-...     

新疆草地生态安全问题、现状与对策分析

简要介绍新疆草地生态问题的由来及现状，运用新的生态安全理论分析新疆草地生态安全时空特征，指出新疆草地生态安全问题是长期人地矛盾不断尖锐与发展演变而来。人口膨胀引起的资源环境破坏、超载过牧造成对资源的掠夺经营等，使草地稳定自协调机制破坏，草地自然生态系统由稳定走向严重危机，并引发新的牧业危机。分析指出，实现人地关系的和谐，需综合考虑生态、经济、社会历史等方面的因素。其中，绿洲区牧民定居点的综合发展水平是维护草地生态安全、实现牧业可持续发展的关键。实现生态安全与可持续发展的主要对策有：依法监理草地放牧状况、合理利用、改良与保护天然草地、高效经营人工草料基地、提高畜牧业经营水平等。依托的关键技术有：草地资源监测技术、退化草地治理及草地利用实用技术等。     

Mute swan grazing on winter crops: Evaluation of three grazing deterrents on oilseed rape

The population of mute swans Cygnus olor (Gmelin) in the UK has increased since 1986 to >25 000 birds, leading to increased complaints of damage to winter crops, and the need for cost-effective management measures. Using a randomized block design in a split-field experiment, the effectiveness of three licensed grazing deterrents was evaluated for mute swans feeding on oil-seed rape: (1) a ziram-based chemical repellent (AAprotect TM at 10 kg ha -1 ), (2) white flags (25 flags ha -1 ), and (3) hazard warning tape (1000 m ha -1 ) with twine (400 m ha -1 ). Deterrents and control (no treatment) were assigned to one of four plots (approximately 1 ha) in each of four fields. From 4 December 1998 to 26 March 1999, grazing intensity was estimated by counting mute swan droppings on plots at approximately 2-week intervals. Over the entire study (10 - 15 weeks depending on field), total numbers of droppings did not differ significantly between treatments. Over the initial 8 weeks, however, droppings were significantly lower on tape/twine. Tape/twine may therefore potentially be cost-effective in reducing mute swan grazing, and further work is recommended to refine the technique.     

Impacts of livestock grazing on a savanna grassland in Kenya

The dynamics of most rangelands in Kenya remain to be poorly understood.This paper provides baseline information on the response of a semiarid rangeland under different livestock grazing regimes on land inhabited by the Massai people in the east side of Amboseli National Park in Kenya.The data were collected from grasslands designated into four types:(1) grassland from previous Massai settlements that had been abandoned for over twenty years;(2) grassland excluded from livestock grazing for eight years;(3) a dry season grazing area;and (4) a continuous grazing area where grazing occurred throughout all seasons.Collected data included grass species composition,grass height,inter-tuft distance,standing grass biomass and soil characteristics.The results indicated that continuous grazing area in semiarid rangelands exhibited loss of vegetation with negative,long-term effects on grass functional qualities and forage production,whereas grassland that used traditional Maasai grazing methods showed efficiency and desirable effects on the rangelands.The results also showed that abandoned homestead sites,though degraded,were important nutrient reservoirs.     

The effect of grazing on seed production in Echium plantagineum

This study measured the effect of livestock grazing on the seed production and the seed-bank of the annual weed, Echium plantagineum L., by comparing six sites across south-eastern Australia. Maximum taproot diameter predicted seed production of ungrazed plants irrespectiveof site. Seed losses to flowering plants grazed in spring were calculated using the taproot diameter relationship. Moderate continual grazing pressure throughout the seeding period (December-January) reduced seed production by at least 87%, although grazing was most destructive per unit of time in the first half of this period (peak seed production of the infestation). E. plantagineum has a strong c apacity to compensate for stock grazing should the stock be removed too early. Seedbanks generally increased following significant seed rain, although this trend was not always consistent. In manipulated quadrats, where seed production was reduced by atleast 90% for 4 years, germination of E. plantagineum was lower relative to controls from the second year and the seedbank was 10 times lower when measured in the fourth year. The implications of these results are discussed in relation to existing control strategies for this weed.     

放牧强度对小针茅草原枯落物分解的影响

文中依托内蒙古苏尼特右旗中国农业科学院荒漠草原试验示范基地的放牧控制试验平台,研究了不同放牧强度下小针茅草原枯落物的残留率、分解速率和质量损失率的动态变化,并探讨了分解速率与水热因子的关系。研究结果表明:1)经过一个生长季的分解,放牧不同程度地加速了枯落物的分解。中度放牧小区群落枯落物的分解速率最高,为1.225×10~(-3)g·d~(-1),比对照区高35.28%。2)随着分解时间的延长,不同放牧强度下小针茅群落枯落物的质量累积损失率呈增加的趋势。3)枯落物分解的质量损失量在不同的季节其增加的快慢有差异,在分解的5~7月,枯落物月质量损失量迅速增加,8月份以后枯落物月质量损失量开始降低。不同放牧强度下枯落物质量损失量大小依次为:MG>EG>HG>LG>CK。说明适度放牧有利于枯落物的分解。4)7月份枯落物的分解速率最快,其次为8月份,7、8月份水热条件较好,有利于土壤微生物的生长和繁殖,对枯落物的分解具有促进作用。     

利用强度对荒漠草原土壤氮循环系统的影响

随着气候的变化和人类的干扰,草原退化日趋严重。文中研究了内蒙古荒漠草原不同利用强度下土壤中4类氮素转化菌,以及土壤的固氮作用、氨化作用和硝化作用强度。结果表明,轻牧区土壤中4类氮素转化菌的数量显著增加（P〉0.05）,也显著加强了土壤中的固氮作用、氨化作用和硝化作用。有利于促进土壤的氮循环;重度利用则导致草原土壤中氮素...     

放牧对典型草原土壤中几种生态因子影响的研究

研究了放牧强度对典型草原土壤中的微生物量氮、碳,微生物数量,五种酶活性和土壤理化性状的影响。结果表明:放牧对草原土壤中微生物量以及微生物数量的影响很显著,围栏和轻度放牧有利于保持或提高土壤中各类微生物数量,过度放牧则使土壤中的微生物量和微生物数量显著降低,同时,随放牧强度的增加,土壤的呼吸强度显著降低;轻度放牧使三类水解酶活性增加或极显著增加,中度和重度放牧导致此三类酶活性显著降低,不同程度的放牧均导致土壤中两类氧化酶活性增加;适度放牧有利于速磷的增加,而过度放牧则导致全磷、全氮和速效氮的显著降低。     

不同利用程度对典型草原植被空间异质性的影响

在生态学研究中,植被空间异质性一直是众多研究者关心的主要问题之一。但是不同植被指数空间异质性的多尺度效应尚未引起人们的重视。因此,文中采用Mann-Kendall秩次相关法在内蒙古鄂温克旗对典型草原不同利用程度的植被空间异质性进行了分析。研究结果表明:Mann-kendal秩次相关法用于植被异质性分析可解释异质性的多尺度特征。禁牧可导致典型草原NDVI的异质性增加,在50m的样线内出现显著性变化的拐点5次,从禁牧到重牧过程异质性呈降低趋势。轻度放牧可促进植物种丰富空间异质性增加,在样线内出现显著性变化的拐点2次,高于其他放牧强度。过度放牧使植被的丰富度和均匀度异质性程度极大降低,使植被特质趋向均质化。不同放牧强度对植物多样性空间异质性影响较小,在样线内都未出现显著性的拐点。     

不同放牧制度对荒漠草原短花针茅空间异质性的影响

在不同放牧制度下,以荒漠草原短花针茅植物种群为研究对象,采用GS＋软件和地统计学分析方法对其空间异质性分布进行了研究。结果显示：对照区和划区轮牧区或自由放牧区都表现出很强的空间自相关性,且结构是导致短花针茅空间变异的主要因素。对照区、划区轮牧区和自由放牧区,短花针茅空间格局的分形维数相近,都接近于2。不同放牧制度下短花...     

Impact of Parthenium hysterophorus on grazing land communities in north‐eastern Ethiopia

An investigation into the impact of Parthenium hysterophorus infestation was conducted in 2007 in the north‐eastern grazing lands of Ethiopia. Data on the above‐ground and seedbank species diversity were collected from five areas, each having sites with low, medium, or high levels of weed infestation. A total of 72 species was found in all areas. They were categorized into grass species (23), other species (48), or P. hysterophorus for ease of interpretation. A regression analysis showed a highly significant, but negative, relationship between the above‐ground species diversity and evenness with P. hysterophorus abundance. The mean cover abundance for the three infestation levels was 33.4% for P. hysterophorus, 41.0% for the grass species, and 26.5% for the other species. The most dominant grass species under all infestation levels were Cynodon dactylon, Urochloa panicoides, and Chloris gayana, while Andropogon abyssinicus and Eragrostis spp. were dominant under the low and medium infestation levels, respectively, and Hyparrhenia hirta was dominant under the low infestation level. Among the other species, Solanum nigrum was the most dominant under the low infestation level and Datura stramonium and Xanthium spp. were the most dominant under the medium and high infestation levels, respectively. The above‐ground dry biomass of P. hysterophorus increased between the low and high infestation levels, while that of the grass or other species reduced in the high, as compared to the low, infestation level. Although the grass species density decreased significantly with successive increases in the P. hysterophorus infestation level, no such trend could be seen for the other species. Within the soil seed bank, the viable seed density for the grass species, other species, and P. hysterophorus were 25.7, 5.8, and 68.5%, respectively. Similarly, the soil seed bank under the low‐, medium‐, and high‐infestation sites was dominated by P. hysterophorus, which contributed 25.1, 65.4, and 87.4% of the viable seed bank, respectively. Although the overall similarity between the above‐ground vegetation composition and the soil seed bank was low, it was similar at the low‐infested site. Thus, the invasion by P. hysterophorus was found to critically endanger the biodiversity of the grazing lands, particularly for the different grass and forbs species in the area. These changes might adversely affect not only future agriculture, but also food security, unless appropriate practises are developed and implemented for P. hysterophorus management.