内蒙古奈曼草地热量平衡的研究

内蒙古奈曼草地热量平衡的研究李胜功,何宗颖,申建友（中国科学院兰州沙漠研究所,兰州７３００００）原　芳信（日本农业环境技术研究所,筑波３０５）ＨｅａｔｂｕｄｇｅｔｏｒＮａｉｍａｎｇｒａｓｓｌａｎｄｉｎｉｎｎｅｒＭｏｎｇｏｌｉａ．￥ＬｉＳｈｅｎｇｇｏｎ...     

第17届国际草地会议在新西兰、澳大利亚召开

第17届国际草地会议于1993年2月7日—21日在新西兰、澳大利亚召开。参加这次草地科学家盛会的1500多名代表来自90多个国家和地区。中国代表49人,来自内蒙古、黑龙江、吉林、北京、宁夏等省区,其中还包括台湾的5名代表。大会得到新西兰、澳大利亚和FAO等国际组织的支持并得到其赞助数十万美元。大会分三阶段举行。2月7日—2月12日开始阶段的会议在新西兰北帕麦尔斯顿城召开。2月13日—16日的会议分别在新西兰的林肯、北帕麦尔斯顿和赫密尔顿举行。而结束阶段的会议则移往澳大利亚的热带地区昆士兰省的诺克哈默顿城召开。与以往历次会议不同,这次会议除一天大会报告外,分成近60个专题组报告、讨论和     

磷在羊草草地植物－土壤中积累、分布及转移规律

本文在研究磷素几种形态的动态变化基础上,运用生态系统理论,利用系统分析的方法,分析了磷在植物－土壤系统中的流通、积累和归还的特点,得出如下结果：１．磷素在系统内９９％以上分布在土壤中。２．群落内磷的再利用量为３．６７５５ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）。３．群落每年吸收的磷为３．４０６３ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）,地上部归还土壤为０．１４４７ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）,地下部归还土壤为１．８１１１ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）,输出仅占吸收量的４２．２４％,磷素在群落中每年净积累为０．３５ｋｓ·ｈａ￣（－１）·ｙｒ￣（－１）。４．磷在各库内的周转时间是：地上植物活体为１．３３６４年,立枯体为６．４３５０年,活根为１．０８８７年,死根为２．４３７８年,有机磷为８３３．３年。     

松嫩草原碱化羊草草地放牧空间演替规律的研究

研究了不同放牧强度对羊草草地的影响。结果表明,过牧条件下,群落地上、地下生物量分别比较牧阶段下降了６７．９６和７５．００％,羊草种群根茎分蘖数和种子产量下降１．０和３．３％,极牧条件下,土壤有机质和水分含量分别下降到轻牧阶段的２１．１和６６．５％,而碱化度和全盐量却分别增加了１倍和８倍。     

草地群落的土壤呼吸

通过土壤呼吸作用向大气释放ＣＯ２是陆地生态系统碳循环的一个最主要的环节,也是人类活动影响下陆地生态系统对大气中ＣＯ２浓度产生影响,从而导致全球气候变化的关键生态学过程,因而成为全球碳循环研究中倍受关注的核心问题［３３,３７,３８］。１土壤呼吸的测定方...     

火烧和放牧影响下羊草草地微气候的比较研究

对羊草草地火烧、未火烧、过度放牧和禁牧区植物群落温度、土壤温度、土壤湿度、大气温度、相对湿度进行了测定．结果表明,白天火烧区群落温度比未火烧区低２．５～５℃,而夜晚则高于未火烧区０．１～１℃．白天火烧区土壤温度比未火烧区高５～７,５℃,夜晚为１～２．５℃．过牧区群落温度与禁牧区差异不显著,但过牧区土壤温度基本高于禁牧区,土壤湿度小于禁牧区．同一区中,白天群落温度变化为低处大于高处,夜晚则相反,而白天土壤温度为表层大于深层,夜晚则基本为深层大于表层．     

黄河三角洲草地退化的研究

黄河三角洲位于东经118°7′—119°10′,北纬36°56′—38°12′;东自山东省小清河口,西至徒骇河口,以利津县宁海为顶点向渤海湾呈扇形分布。自50年代以来,随着国营及地方农场的建立以及人口的不断增长,这一地区的草地资源得到了广泛的开发利用。但是,由于一些单位只顾盲目地开垦草地和过度放牧、割草,30多年来整个黄河三角洲盐碱化、退化草地达6.67×10~4ha多,约占当地草地总面积的40%。本文研究了该地区草地退化的现状并就退化程度与累计开发时间的关系初步进行了数     

宁夏东部农牧交错区可持续发展草地生态农业体系建设研究

1　研究地区概况宁夏盐池四墩子试区位于盐池县中北部城郊乡四墩子行政村 ,地处毛乌素沙漠西南缘 ,为黄土高原向鄂尔多斯台地过渡地带。海拔高度在 1 380～ 1 6 0 0ｍ之间 ,年平均气温 7 7℃ ,1月份平均气温为-8 9℃ ,7月份平均气温 2 2 5℃、绝对最高和最低气温分别为 38 1℃和 -2 9 6℃ ,≥ 0℃的年积温为 3430 3℃ ,≥ 1 0℃年积温为 2 949 9℃ ,年日照时数 2 86 7 9ｈ ,日照率 6 5%。年均降水量为 2 89 4ｍｍ ,年蒸发量 2 1 31 8ｍｍ ,年无霜期 1 6 2天左右 ,为典型大陆性气候。地貌为缓坡丘陵 ,地带性土壤为灰钙土和风沙…     

从北美区系看上海辰山植物园植物配置

辰山植物园绿环洲际植物地理展示区规划为黑海落叶阔叶林、日本温带区系植物林、澳大利亚和新西兰温带雨林、瓦尔底安雨林、巴西南洋杉林、北美洲西南的针叶林、北美洲东南部的温带落叶和常绿林,以及马可洛尼常绿阔叶林等。     

东北师范大学国家草地生态工程实验室简介

1　概况东北师范大学国家草地生态工程实验室于1989年6月经国家计划委员会批准,由世界银行贷款,在东北师范大学草地研究所的基础上建立。它是目前我国唯一的草地生态学研究国家实验室。该实验室拥有测试分析和数据处理等各类实验室6个及野外永久观测实验站一座,配备LC-8A型制备液相色谱仪、HP1050型高效液相色谱仪、DX-300型离子色谱仪、原子吸收分光光度计、910型差示扫描热量仪、Pharmacia多功能电泳系统等大中型仪器设备20余台套,具备了完整的野外和室内生态学研究设备体系。实验室还设有硕士点、博士点和博士后流动站,接纳国内外各…     

利用草场健康指数监测典型草原的植被退化

利用表征群落总量、放牧退化的主成份和草场健康指数(Grassland Health Index,GHI)与样方光谱反射率之间的相关性,建立了GHI与可见光、红外光因子的回归模型。应用此模型结合TM卫星遥感数据计算GHI,并与同一TM影像的计算出的NDVI作对比研究。研究发现GHI在反映放牧等人为干扰因素对草原植被的影响效应方面比NDVI有明显的优点。此外,GHI对植被分布格局,特别是斑块结构有更好的显示效果。应用GHI到历史TM数据,对所研究地域的植被覆盖变化、农牧业的变迁模式等进行了定性研究。研究发现,有较长放牧史的过度放牧区的植被类型没有沿牧压梯度的规律性分布,而是呈随机斑块模式分布。     

草地生态学领域空斑研究进展

空斑(gap)是近几十年来草地生态学领域的重点研究对象之一,在草地植被更新、群落结构和草地生态系统物种多样性维持方面起着重要作用。本文在介绍空斑的概念、功能分类和形成的基础上,总结分析了国内外对空斑的研究现状,发现目前对草地空斑的研究主要集中在空斑大小、空斑类型对物种更新以及空斑对群落结构和物种多样性影响等方面,而对空斑小环境和土壤的研究较少,对空斑内生理生态学、机理和机制性的问题尚缺乏深入探讨;建议在今后加强对空斑内环境变化、空斑内物种的生理生态学特性和物种对空斑更新的响应机制等方面的研究。     

人工草地在退化草地恢复中的作用及其研究现状

分析了草地类型生态系统退化的现状、原因及其恢复途径,提出人工草地的建立是恢复退化天然草地的有效途径;综述了人工草地的研究进展。提出高效型人工草地的建立是缓解草原压力、促进牧区可持续发展的良策;从高效角度出发。种植饲用玉米可以作为建立人工草地的一个有益尝试．     

Patch colonisation in a savanna grassland

Patches (1 m diameter) were cleared in a heavily grazed and a lightly grazed savanna in South Africa; half of them were covered once with grass litter. The greatest colonisation over three years occurred on heavily grazed patches with litter, the least on open, lightly grazed patches. Annual rainfall affected colonisation rate. Basal cover was lower on patches than in the surrounding vegetation. Patch composition was weakly affected by treatment, and was partly related to the composition of adjacent vegetation, but the proportional representation of species on patches differed from the surrounding vegetation. The stoloniferous Digitaria eriantha and the obligate seed reproducers Aristida bipartita and Heteropogon contortus were major components of patch communities but were uncommon in the surrounding vegetation and in the seed bank. Setaria incrassata and Themeda triandra were the predominant components of the surrounding vegetation and of the seed bank, but Setaria established very poorly and Themeda established well only on heavily grazed patches with litter. The pattern of seedling establishment was the same as that of colonisation. Most seedlings emerged atthe beginning of the wet season, with ca. 50% mortality soon thereafter. The colonising species can be partly predicted from the availability of propagules (vegetative or seed), emergence and establishment success, and subsequent growth.     

Problems in heathland and grassland dynamics

A review of factors governing vegetation change in heathlands and grasslands is presented, with emphasis on soil factors. Climate, microclimate, fire, fauna, grazing by vertebrates, grazing by invertebrates, disease, dispersal, establishment, competition, allelopathy, stabilization, soil formation and podzolization are discussed with emphasis on inconsistencies and lacks in our present knowledge. Examples are mainly from NW European Calluna heath and related woodlands.Nomenclature follows Clapham, Tutin & Warburg (1962) for vascular plants; species not included in this work have authorities cited in the text.     

Plant-water relationships in a mixed grassland

Summary Seasonal and diurnal patterns of osmotic and leaf water potential of several mixed grassland species were studied. The osmotic potential (OP) of Agropyron dasystachyum ranged from about-15 bars early in the growing season to about-30 bars during late summer droughts. Seasonal trends in A. smithii and Koeleria cristata were similar. Minimum osmotic potentials of Eurotia lanata and Artemisia frigida were-42 and-35 bars, respectively. The mesophytes Geum triflorum and Lomatium foeniculaceum did not exhibit OP below-20 bars. Soil water, particularly in the 0–15 cm layer, strongly influenced OP and leaf water potential (WP). Seasonal trends in WP were similar to OP. Under low stress, WP was about 10 bars greater than OP; under high stress WP was equal or even lower then OP (negative turgor). Diurnal fluctuations in WP were greater than those of OP when low stress conditions existed. Diurnal changes in potential were related to global radiation which was an index of atmospheric evaporative demand. Ecological implications of water status are discussed.     

Biodiversity and invasibility in grassland microcosms

In the years since Charles Elton proposed that more diverse communities should be less susceptible to invasion by exotic species, empirical studies have both supported and refuted Elton's hypothesis. Here, I use grassland community microcosms to test the effect of functional diversity on the success of an invasive annual weed (Centaurea solstitialis L.). I found that high functional diversity reduced the success of Centaurea by reducing resource availability. An equally important, but unstudied, question is whether diversity can buffer a community against the impacts of invasive species. In this experiment, although species diversity (independent of functional diversity) did not affect the success of the invader, the invader suppressed growth of species-poor communities more strongly. Invasion of Centaurea also increased summer evapotranspiration in species-poor communities. These results suggest that loss of species diversity alone does not affect community invasibility, but that communities with fewer species may be more likely to decline as a consequence of invasion.