齐岳山人工草地土壤微生物时空变化研究

为探究齐岳山三叶草草地土壤微生物与时空变化的关系,为山地土壤生态重建和草地资源可持续利用提供重要参考价值,本研究采用平板培养法对齐岳山人工草地不同季节、不同土层土壤微生物数量、种类及其变化规律进行了研究。结果显示:齐岳山人工草地土壤微生物种类在4月和8月数量最多,且各土层无明显差异;土壤微生物数量最多出现在7月和8月,各土层的数量变化因菌种而异。     

江河源区退化高寒草地土壤微生物与地上植被及土壤环境的关系

对青藏高原江河源区退化高寒草地土壤微生物与地上植被、土壤环境的相关性进行分析。结果表明,退化高寒草地植物多样性、物种组成、地上植被盖度、草地生产力的变化引起土壤微生物数量发生变化,土壤微生物特别是细菌生理类群受土壤环境因子影响较大。江河源区退化高寒草地土壤中非有益性微生物功能群处于增加趋势,限制了土壤养分供给和转化能力,不利于草地土壤肥力维持和提高,给受损高寒草地,特别是“黑土滩”退化草地的生态恢复带来困难。因此,在修复受损高寒草地生态系统时,不仅要恢复地上部分的植被,而且要恢复地下部分的土壤微生物群落,重建土壤微生物生态系统。     

草地土壤微生物生态研究概况

土壤微生物在草原生态系统物质转化和能量流动中起着非常重要的作用,文章从牧草与土壤微生物相互作用、草地土壤微生物研究方法及不同季节放牧、施肥和不同草地类型对土壤微生物的影响等方面进行了综述和浅评,并对未来研究进行了展望。     

放牧对草地土壤微生物影响的研究述评

综述了我国不同放牧强度对草地土壤微生物区系组成、微生物数量及土壤微生物的时空分布变化研究,草地的不同利用方式对土壤微生物的影响。草地土壤微生物类群主要由真菌、细菌和放线菌等组成,它们也是草地土壤微生物中数量最大的3个类群,其中,细菌数量最多,放线菌次之,真菌最少。在空间上,草地土壤微生物数量表现为随土层的加深逐渐减少,季节分布表现为春季随温度的上升逐渐增高,最高峰出现在8月中旬,冬季降到最低。因此微生物在草地生态系统的能量流动和物质转化中起着重要的作用。     

放牧对草地生态系统温室气体的影响

放牧主要通过影响草地生态系统中土壤的理化性质(土壤含水率、孔隙度、微生物和有机物含量的构成)来影响整个生态系统温室气体的排放。草地生态系统土壤中,植物根系的呼吸作用、土壤微生物的活动以及各种物理、化学和生物作用为温室气体的主要来源。本文在阐述草地生态系统温室气体排放机制和作用的基础上,主要从放牧管理模式、放牧强度、放牧动物等放牧作用对草地生态系统温室气体的排放情况进行了综述,就今后放牧对草地生态温室气体的研究重点和方向进行了展望,总结了适合不同放牧条件下整个生态系统温室气体的减排措施。     

气候变化对青藏高原高寒草地生态系统草丛-地境界面微生物的影响研究进展

由于自然因素或人类因素驱动,以CO₂浓度增加、气候变暖、大气氮沉降等为主要特征的生态效应对草地生态系统产生了复杂的影响。草丛-地境界面中草地植被和土壤环境对全球变化的响应十分敏感,土壤微生物与草地植被和土壤环境之间的关系密切,不同层面上微生物对全球变化的响应特征不同。气候变化的各个因素对土壤微生物有直接或间接的作用,且目前作用机制尚不明确。本文综述了全球变化因子,包括CO₂浓度、气温及氮沉降等因素对草地土壤微生物影响的相关研究进展,在此基础上分析评述了全球变化对草地生态系统微生物多样性的影响及微生物的响应机制,并对未来研究需关注的问题和方向进行了探讨和展望。     

新疆平原荒漠盐渍草地土壤微生物生态分布的研究

对新疆平原荒漠盐渍草地土壤微生物生态分布的研究结果表明，新疆平原荒漠盐渍草地中分布的微生物数以细菌占绝对优势，占总菌数的９９．８％。０－４０ｃｍ土层是该类草地土壤微生物数量分布及生物学活性最大的区域。土壤微生物呈明显的季节变化３规律。氮素生理群微生物以氨化细菌最多，芽孢细菌次之，硝化细菌极少，好固氮菌未测定到。平原荒漠盐渍草地中各类微生物的数量及分布密度均低于同地区的耕地土壤。     

天然草地的另类资源--土壤微生物

天然草地除固有的生态作用和生产资料性质外，土壤中种类繁多、数量巨大的微生物尚未作为资源被认识和利用。从自然资源角度对天然草地土壤微生物的特点、潜在价值和利用途径进行探讨，对充分利用这一资源和维护环境健康有重要的参考价值。     

玉树高寒草甸不同利用方式下土壤微生物的特征

连续2年对青海玉树高寒草甸的3种不同利用草地(天然草地、灭鼠草地、灭鼠+围封草地)的微生物类群及微生物量碳、氮、磷空间含量及变化特征进行了研究,分析不同利用方式下土壤微生物特征及其变化规律.以探讨不同利用措施对玉树退化草地土壤微生物的影响.结果表明:同一利用方式下,不同土壤层(0~5, 5~10和10~15 cm)土壤各微生物类群主要分布在土壤表层,且数量均随着土壤深度增加而减少.不同利用方式下,同一土壤层内,灭鼠和灭鼠+围封草地对土壤细菌、真菌与放线菌和微生物各氮素类群数量有一定的促进作用;微生物量碳、氮和磷含量均表现为灭鼠和灭鼠+围封草地显著高于天然草地;各草地类型中微生物数量是细菌>放线菌>真菌.表明天然草地经灭鼠和围封处理利用时均有利于草地土壤中微生物的活动,有利于草地的自然更新和保护物种多样性.     

甘南草原不同退化草地植被和土壤微生物特性

为研究草地退化对植被和土壤微生物的影响,本试验以甘南州碌曲县高寒草地为研究对象,调查研究不同退化程度草地植被特征,并测定土壤微生物呼吸、土壤微生物量碳、土壤微生物代谢熵及土壤微生物群落结构变化。结果表明：随着草地退化程度的加重,高寒草地植物种类减少,优势植物种类发生变化,植被高度、盖度、植株数、鲜草产量下降;土壤基础呼吸和诱导呼吸、土壤微生物量碳及土壤代谢熵等指标均有不同程度的下降;土壤总磷脂脂肪酸（Phospholipid fatty acid,PLFA）、土壤细菌、放线菌含量减少,真菌含量增多,土壤微生物群落结构发生变化,压力指数增高;植被与土壤微生物各指数呈一定的相关性。本研究说明高寒草地退化过程中植被演替与土壤微生物变化密切相关。     

美国草原管理法律法规发展概况

草地资源的立法管理是各国管理草地资源防止草地退化的主要人为调控手段。美国草原立法开始早,立法体系完善,对美国公共草地合理管理做出了巨大贡献。美国草地立法经历了3个阶段:首先是草原立法和管理主要在各州层面上,对公共草地管理作用不大,使西部公共草地处于无序利用状态,草地退化严重;第二是《泰勒放牧法》颁布后,开始了公共草地管理,建立了有照放牧和放牧收费制度;第三是美国草地的多用途管理,出台了与草地资源管理相关的一系列法律,主要是《环境政策法》和《联邦土地政策管理法》,草地资源相关价值受到高度重视。在国家立法规定下,对草地资源的价值进行评估。研究美国草地立法过程和立法思想,对于合理管理中国草地资源具有重要指导意义。     

北方农牧交错区草地生态系统服务间接价值的初步评估——以太仆寺旗和沽源县境内为例

以草地地上生物量为基础,运用经济学的市场价值法、物质量法、水量平衡法等方法对太仆寺旗和沽源县境内的农牧交错区草地的固定CO2、释放O2、土壤侵蚀控制、涵养水源、营养物质循环5项生态系统服务功能进行初步的评估。结果表明：由这5项功能构成的生态系统服务的间接价值在农区为16 668元/（hm2·a）,在草原区为17 223元/（hm2·a）。尽管草原区的间接价值比农区的高3.33%,但研究所选的农牧交错区由于农业活动的干扰,并没有导致草地生态系统服务功能间接价值的显著下降。这说明维持现阶段的农业活动或退耕还草可能促进草地生态系统生态经济价值的可持续性发展;但若继续开垦和破坏草地,草地生态系统的服务功能可能会显著下降,草地所具有的生态屏障作用也会减弱甚至消失。     

草原的生态系统服务:IV.降低服务功能的主要因素和关爱草原的重要意义

草原/草地生态系统服务的价值大小取决于草地的自然资本大小和生态系统功能。影响草原生态系统服务功能的最主要因素是,1.改变草地生态系统的用途,2.草地破碎化,3.火,4.草原退化;对它们影响草原生态系统服务功能的原因和机制进行了论述。草原分布广泛,约占地球陆地面积的40%,有40个国家的草地面积占国土面积的50%以上。世界上有17%,即9.38亿人生活在各类草地上并以草地为生,尽管已经证实草原对全世界和全国人民极其重要,但草原提供的生态系统服务———生态服务和产品服务仍没有得到应有的认识和足够的重视。由于生态系统服务的影响深远,健康的草原及其生态系统服务惠及全国和全世界人民;相反,破坏、损失草原自然资本殃及全国和全世界人民。因此,关爱草原,使草原走可持续发展的道路,是全人类共同的责任和义务。     

Effect of Plateau Zokor (Myospalax fontanierii) Disturbance on Plant Community Structure and Soil Properties in the Eastern Qinghai-Tibet Plateau,China

Plateau zokor (Myospalax fontanierii) is a native subterranean rodent in alpine rangeland on Qinghai-Tibet Plateau (QTP) in China, and its foraging, digging, and mounds building cause the unique disturbance pattern to alpine rangeland ecosystem. Over the past decades, the zokors have been regarded as major pests who result in the degradation of the rangeland ecosystem in the QTP and have been simply eliminated by rodenticides or traps. Understanding the function of zokors and evaluating the zokors’ impacts on alpine rangeland systems should be the solid scientific basis for zokor control. In this study, we considered the average nearest neighbor indices of zokor mounds to represent the disturbance intensity of zokor to alpine rangeland and surveyed the plant species richness, diversity indices, biomass, and soil physicochemical properties in intermound areas under different zokor disturbance intensities in alpine rangeland in Tianzhu Tibet Autonomous County, located in eastern QTP. Our results indicated that 1) the plant species diversity indices were positively correlated with zokor disturbance intensity and aboveground and belowground biomasses were not significantly different under the different disturbance intensities; 2) the importance value of the forb functional group increased as the disturbance intensities increased, and the sedge functional group showed the opposite trend. The proportions of aboveground and belowground biomasses of forbs increased as the disturbance level increased; 3) there were no changes in the dominant plant species among the different disturbance intensities, but new plant species (Polygonum viviparum and Equisetum arvense) occurred in the plots with high disturbance intensities; 4) a significant positive correlation was observed between soil moisture in the 0-20 cm layer and disturbance intensity, while soil temperature exhibited a significantly negative relationship with the disturbance intensity; however, no differences in soil chemical properties were observed; and 5) redundancy analysis identified that mound building changed soil physical properties, especially soil moisture, in intermound areas, which influenced the plant community structure. In conclusion, the plateau zokor in our study area increased plant species diversity and did not decrease plant biomass, which is beneficial for alpine rangeland systems. We suggest that rangeland managers should consider the multiple functions of zokors to an alpine rangeland ecosystem instead of simply eliminating them.     

Phytomass estimation using eMODIS NDVI and ground data in arid rangelands of Morocco

The assessment of rangeland productivity in semi-extensively grazed arid rangelands is a prerequisite for livestock management in relation to sustainable use of pastoral resources. The objective of this study was to assess rangeland productivity based on normalised difference vegetation index (NDVI) images. Data on phytomass were measured on 61 field samples in arid rangelands of Morocco, covering various rangeland categories during autumn (November) and spring (April), i.e. when phytomass is at low and high levels, respectively, for two consecutive years (2008 and 2009). Dekadal EROS Moderate Resolution Imaging Spectroradiometer (eMODIS) NDVI data were linearly regressed to field measurements for these four periods. Results show that phytomass values were correlated with NDVI during spring, with R² and RMSE values of 0.82 and 0.3 t ha^?1, respectively. This study indicates there is a high potential for operational use of remotely sensed data to estimate rangeland phytomass of semi-extensively grazed rangelands.     

青海省三江源区天然草地改良与合理利用建议

阐述了青海省三江源区草地畜牧业与草地利用的现状和存在的问题。在分析其他地区草地利用经验的基础上,提出了该地区退化草地改良与合理利用的建议,供有关人员参考。     

Patterns of seed production and shrub association in two palatable Karoo shrub species under contrasting land use intensities

Seed production and shrub association patterns of the two palatable shrubs. Tripteris sinuatum and Tetragoma froticosa were investigated on heavily grazed communal and lightly grazed commercial rangeland in the succulent karoo, Namaqualand. Seed production in both these species was substantially reduced on the communal rangeland relative to the commercial rangeland. Seed production in T. sinuatum was most severely affected, with seed production on the communal rangeland two orders of magnitude lower than on the commercial rangeland. The proportion of T. sinuatum and T. froticosa shrubs growing unassociated with other shrubs on the communal rangeland was reduced by approximately 50%. Lycium ferocissimum was most effective as a refuge plant for T. sinuatum in terms of the mean seed production per plant. Ruschia robusta was however most important in terms of the overall amount of seed produced by T. sinuatum and T. froticosa on the communal rangeland, due to the large number of times this association occurred. Refuge plants did not appear to be particularly important for T. froticosa in terms of seed production, but were important in terms of providing safe sites for recruitment. The results of this study suggest that unpalatable or thorny species such as L. ferocissimum play an important role in providing refuge sites for palatable species that might otherwise become entirely lost from overgrazed rangelands.     

Geospatial Assessment of Grazing Regime Shifts and Sociopolitical Changes in a Mongolian Rangeland

Drastic changes have occurred in Mongolia’s grazing land management over the last two decades, but their effects on rangelands are ambiguous. Temporal trends in Mongolia’s rangeland condition have not been well documented relative to the effects of long-term management changes. This study examined changes in grazing land use and rangeland biomass associated with the transition from the socialist collective to the current management systems in the Tsahiriin tal area of northern Mongolia. Grazing lands in Tsahiriin tal that were formerly managed by the socialist collective are now used by numerous nomadic households with their privately owned herds, although the lands remain publicly owned. Grazing pressure has more than tripled and herd distribution has changed from a few spatially clustered large herds of sheep to numerous smaller herds of multiple species. Landsat image–derived normalized-difference vegetation index estimates suggest that rangeland biomass significantly decreased (P < 0.001) from the collective to the postcollective periods. The observed decrease was significantly correlated with changes in the grazing management system and increased stocking density (P < 0.001), even when potential climate-induced changes were considered. Furthermore, field- and Satellite Pour l’Observation de la Terre imagery–based rangeland assessments in 2007 and 2008 indicate that current rangeland biomass is low. Spatial pattern analyses show that the low biomass is uniform throughout the study site. The observed decrease in rangeland biomass might be further accelerated if current grazing land use continues with no formal rangeland management institution or organized, well-structured efforts by the local herding households.     

青海省海南州草地资源分析评价

通过对海南州草地资源调查资料研究分析 ,结果表明 :2 0世纪 90年代海南州天然草地各类型产草量除高寒草甸外 ,均有不同程度的下降 ,草地植被退化较严重 ;全州各县天然草地单位面积载畜量减少 ,严重阻碍了草地畜牧业的持续发展     

The quantification of rangeland condition in a semi-arid grassland of southern Africa

The degradation gradient technique was used to quantify rangeland, condition in areas ranging from poor, trampled areas close to watering points to well managed areas in a semi-arid, sweet grassland of southern Africa. Ecological values were linked to species by means of their individual positions on the degradation gradient. These species were further classified according to ecological index values. Identification of indicator species for purposes of rangeland condition assessment was done by using the correlations between the relative composition and the rangeland condition value of a species. Index values and Gaussian distribution curves were used in calculations to determine rangeland condition. The accuracy of these methods was tested and the best results were obtained by using the species curves of Themeda triandra and other species which dominate at other positions along the gradient. The advantage of this technique lies in its simplicity and ease of use. Another advantage is the fact that only the most important indicator and dominant species in the study area are used to determine rangeland condition.