若尔盖退化、沙化草地的治理

草地大面积退化、沙化导致草原生产力下降,环境恶化,生物多样性减少,直接威胁牧区经济的长远发展。如何恢复退化、沙化草地植被和协调利用、保护和管理草地资源之间的关系已经成为亟待解决的问题。根据若尔盖退化、沙化草地的现状和成因,利用科学的手段对其进行重建,从中探寻具有针对性的有效治理方法,并对先进技术和经验进行推广示范。     

Geographical patterns in openland cover and hayfield mowing in the Upper Great Lakes region: implications for grassland bird conservation

Populations of many grassland bird species such as Grasshopper Sparrow (Ammodramus savannarum), Henslow’s Sparrow (A. henslowii), and Bobolink (Dolichonyx oryzivorus) have experienced considerable declines over the last century. To foster multi-species grassland bird conservation in the Upper Great Lakes (UGL) states of Michigan, Minnesota, and Wisconsin, we quantified geographic patterns within three sub-regional zones (e.g., North, Central, and South) of the UGL. Patterns of interest included the distribution and abundance of openland cover type (including managed pasture-hayland), the distribution, phenology, habitat affinity, and long-term population trends of ten grassland bird species, and (in particular) the geographic patterns in hayfield mowing and the temporal changes in hayfield cover. Approximately 10, 38, and 53% of the UGL openland was proportioned in the North, Central, and South zones, respectively. The distribution of hayland also varied by zone: North, 17%; Central, 46%; and South, 37%. In the central portion of the UGL where the greatest area is devoted to hay production, alfalfa—more intensively managed than mixed-grass hay—predominates. Although we found significance differences (P < 0.05) in hayfield mowing intensity between zones (with the majority of land under relatively low-intensity mowing found in the North Zone, particularly the Upper Peninsula of Michigan) no strong relationships were found between hayfield mowing patterns, other land cover-land use variables, and bird population trends at finer scales of study. Nonetheless, we suggest that the geographic patterns illustrated here provide useful information for grassland bird conservation planning across the UGL.     

兴海县草地保护建议

经调查,兴海县退化草地面积占可利用草地面积的22．31％。其中,严重退化草地面积为1．14×104hm2,中度退化草地8．8×104hm2,轻度退化草地10．97×104hm2;草地退化使草地产草量从1982年的2760kg／hm2下降到2002年的1575kg／hm2,下降了42％;掠夺式放牧、鼠虫害严重、毒杂草蔓延、“四滥”不禁及人口快速增长是导致草地退化的主要原因;建议采取依法治草,加强草地建设,科学合理利用草地,加强教育等措施保护草地。     

青海草地载畜量计算方法与载畜压力评价

青海草地资源理论载畜量为1608．08×10^4羊单位。其中,天然草地载畜量为1282．84×10^4羊单位,人工草地载畜量为224．78×10^4羊单位,农作物秸秆载畜量为104．45×10^4羊单位,分别占理论载畜总量的79．77％、13．73％和6．50％。与全省2009年度存栏牲畜3020．05×10^4羊单位...     

库鲁斯台草地资源及其利用

文章介绍了库鲁斯台草原的自然概况，对该区的平原草甸草原，平原森林草甸草原，平原沼泽甸草原，平原荒漠草原等草地类型的分布，面积，植被盖度，草层高度，产草量，理论载畜量，植物组成，着生土壤等进行了比较详细的阐述，同时分析了该区草地利用现状和存在问题，在此基础上，提出了加强草地管理和保护，加快退化草地改良和建设，普及草业科技改变传统生产模式及治理额敏河，合理利用河水资源等方面的建议。     

Microbial biomass,N mineralization,and the activities of various enzymes in relation to nitrate leaching and root distribution in a slurry-amended grassland

High rates of cattle slurry application induce NO _inf3 ^sup- leaching from grassland soils. Therefore, field and lysimeter trials were conducted at Gumpenstein (Austria) to determine the residual effect of various rates of cattle slurry on microbial biomass, N mineralization, activities of soil enzymes, root densities, and N leaching in a grassland soil profile (Orthic Luvisol, sandy silt, pH 6.6). The cattle slurry applications corresponded to rates of 0, 96, 240, and 480 kg N ha^-1. N leaching was estimated in the lysimeter trial from 1981 to 1991. At a depth of 0.50 m, N leaching was elevated in the plot with the highest slurry application. In October 1991, deeper soil layers (0–10, 10–20, 20–30, 30–40, and 40–50 cm) from control and slurry-amended plots (480 kg N ha^-1) were investigated. Soil biological properties decreased with soil depth. N mineralization, nitrification, and enzymes involved in N cycling (protease, deaminase, and urease) were enhanced significantly (P<0.05) at all soil depths of the slurry-amended grassland. High rates of cattle slurry application reduced the weight of root dry matter and changed the root distribution in the different soil layers. In the slurry-amended plots the roots were mainly located in the topsoil (0–10 cm). As a result of this study, low root densities and high N mineralization rates are held to be the main reasons for NO _inf3 ^sup- leaching after heavy slurry applications on grassland.     

草地退化演替过程及诊断研究进展

随着人口的不断增加和现代工农业文明的冲击,草地生态系统出现不同程度的退化,导致草地生态系统组成、结构、过程和功能等方面发生量和质的变化;对草地退化的系统理解是进行草地恢复与重建的基础与前提。本文综述了草地退化的内涵、驱动力、退化过程与特点,以及草地生态系统退化程度诊断等一系列问题,绘制了描述草地退化程度的概念模型;建议从生态学角度研究草地退化程度诊断时选择相应的气候顶级系统或受干扰程度较轻的"自然生态系统";从草地经营学角度研究草地退化程度诊断时选择适度放牧草地作为参照系统。归纳了退化草地生态系统诊断的生物途径、生境途径和功能服务途径;分析了草地退化程度诊断的方法与可选择的指标体系,并对草地退化程度诊断及草地恢复中应注意的事项进行了讨论。     

三江源草地载畜压力时空动态分析

对三江源地区1988～2005年草地载畜压力变化的时空动态进行了分析,结果表明,18年来该地区草地平均超载1.5倍,其中冬春草场超载2倍以上.另一方面,草地载畜压力具有逐年下降的趋势,特别以冬春场的下降趋势更为明显,表明三江源地区草地利用逐年向合理的方向发展.研究认为,该地区近几十年来的连续过度放牧是造成草地退化的最主要因素之一,因此建议该地区草地恢复和治理工作的重点应该继续放在减畜减压上,在维持三江源草地畜牧业适度规模的同时,根据该区在国家主体功能区中的功能定位,促进其他重要生态功能的发挥.     

Markov models of land cover dynamics in a southern Great Plains grassland region

Grassland regions of the southern Great Plains are fragmented by agricultural activity and many habitat remnants have experienced encroachment by juniper (Juniperus virginiana L.). Recently, many cropland areas have been converted to monoculture grassland (pastures) and enrolled into the Conservation Reserve Program (CRP). Our objectives were to develop spatial and temporal Markov models to characterize land cover dynamics relative to juniper expansion and CRP using aerial photography from 1965, 1981, and 1995. We used landscapes surrounding three Breeding Bird Survey routes with varying levels of juniper encroachment in Oklahoma as study areas. As expected, land cover changes from 1965 to 1995 included increases in juniper woodland, mixed juniper-deciduous woodland, and pastures from CRP activity. Markov models revealed that juniper had a low likelihood of self-replacement in early stages of encroachment. In all areas, relatively little native grassland was lost to juniper encroachment, but other native habitat types such as deciduous woodland were heavily impacted. Transition probabilities for land cover dynamics varied significantly both spatially and temporally. Projections of these raw transition matrices produced widely varying models of future land cover conditions. By modifying the matrices to account for recent and potential socio-political and ecological changes occurring in this region, a number of more plausible land cover scenarios were produced than those resulting from simple projections of raw transition matrices.     

草地生态系统动态演化机制研究综述

对国内外关于草地生态系统演化机制的主要研究进行了综述。国内研究者强调自然因素和人为因素是两大驱动因素,其中人口压力及不合理的人类活动是主要驱动因素。国外草地生态学范式经历了均衡草地生态学向非均衡草地生态学的转变,从强调生态系统生物因素是草原退化的主要驱动力发展到强调强烈的环境波动控制草原的动态演化。相比较国内研究,国外研究更系统和深入,不仅仅注重分析单一因素,认为包括人口、经济、社会政治、科学和技术、文化与宗教以及物理、生物、化学等方面的驱动力是导致草地生态系统演变的全球驱动力。