中国高山林线树木径向生长研究进展

高山林线作为树木分布的高度上限,是全球范围最重要的植被过渡带之一,目前已成为全球气候变化理想的"监视器".本文从树木年轮法、树木径向变化记录仪法、微树芯法等3种主要研究途径出发,综述了中国高山林线树木径向生长研究的进展情况,并对未来的研究方向进行了探讨.     

Diurnal and monthly variations of carbon dioxide flux in an alpine shrub on the Qinghai-Tibet Plateau

Long-term flux observation is an efficient approachto collect CO2 emission or assimilation data in an ecosys-tem. In cooperation with a series of international coopera-tion programs including those sponsored by IGBP (Inter-national Geosphere-Biosphere Program), WCRP (WorldClimate Research Program), IHDP (International HumanDimension of Global Environment Change), GCTE(Global Change and Terrestrial Ecosystem) and LUCC(Land Use and Land Cover Change), a lot of researchwork conce…     

Diversity of Plant Species of Alpine Grassland in Nakchu of Tibet, China

0Introduction Biologicaldiversityconcernedwiththesumofvariouslivingbeingsandtheirprocesses,aswellasthebasisofharmonious coexistencebetweenmanandnatureplaysanimportantroleinecology,economy,esthetics,ethics,etc.Duetodeteriorationofglobal environment,acceler…     

Formate and acetate as recorded in a mid－latitude glacier in west China

Formic (HCOOH) and acetic (CH3COOH) acids are the chief carboxylic compounds in the troposphere[1]. Although weak acids, they contribute significantly to the free acidity, ionic balance of precipitation and the chemical reactions in the atmosphere, especially in the remote areas[2—4]. General sources for formate and acetate have been identified in the past 3 decades although a satisfactory source attribution is lacking to explain atmospheric observations[5]. Possible sources include veget…     

山西五台山嵩草(Kobresia)草甸的初步研究

嵩草草甸在山西仅分布在五台山2400米以上的山地,由北方嵩草(Kobresia bellardii)和小嵩草(K. pygmaea)占优势。本文就草甸植被的组成,外貌和结构以及类型和分布作了初步分析。并将其与我国其他地区的嵩草草甸作了简单比较。最后,讨论了五台山嵩草草甸的垂直地带问题。     

Influence of land cover changes on the physical and chemical properties of alpine meadow soil

Taking the alpine cold meadow grassland in the southeastern part of the Qinghai-Tibetan Plateau as an example ,this researcdh deals with the characteristics of apline meadow soil property changes,including soil nutrients,soil physical properties and soil mositure content under differcent land coverage conditions.With the degradation of grassland vegetation and the decline of vegetation coverage ,soil compactness reduces ,gravel content increases and bulk density increases ,The originally dense root-system layer is gradually denuded,making the soil coarse and gravel .The change of the organic matter contents with the vegetation coverage change in the surface soil layer (0-20cm) has shown an obvious cubic polynomial curve process ,The organic matter contents increas rapidly when land coverage is above 60%,contrarily decreases on a large scale when land coverage is below 30%,Between 30%-60% of land coverage the organic matter contents remain stable,The total N and organic matter contents remain stable.The total N and organic matter contents in soil have shown quite similar change regularity ,Following this the mathematic equations are derived to describe such change processes ,Moisture content in soil changes sharply with the vegetation coverage change,Soil moisture content change with the vegetation coverage change,Soil moisture content change with the vegetation coverage change has shown a quadratic parabola process,Results have shown that organic matter conternt and the total N content of the apline meadow soil decrease by 14890 kg/hm^2 and 5505kg/hm^2 respectively as the vegetation coverage reduces from 90% to less than 30%,the heavey changes of soil physical and chemical proerties with grassland degradation have made the recovery of alpine meadow ecological system impossible,The protection of alpine meadow vegetation is of vital importance to the maintenance of the regional soil environment and the regional ecological system.     

营养元素添加对青藏高原亚高寒草甸物种多度分布格局的影响

以青藏高原亚高寒草甸为研究对象,基于N,P,N+P耦合营养元素添加的控制实验,研究了群落内全部物种、常见种和稀有种的物种多度分布格局以及物种丰富度对N,P,N+P耦合营养元素添加的响应规律,并选取对数正态模型、幂分割模型、几何级数模型、Zipf模型以及中性模型对物种多度数据进行拟合.结果表明:1)P添加对物种丰富度的影响不显著,全部物种、常见种与稀有种的物种多度分布曲线的陡缓程度基本相同.随N,N+P耦合添加量的增大,全部物种与常见种的物种多度分布曲线都越来越陡峭,物种丰富度也都显著下降,表明在青藏高原亚高寒草甸N,N+P耦合添加会导致物种多样性的降低.2)比较CK,N15,P15,N15P15的物种多度分布曲线发现N+P耦合处理的物种多度分布曲线的陡峭度较CK,N15,P15处理的要陡,表明N+P耦合对物种多度分布格局的影响效应要强于单独的N,P的.3)分析施肥对物种多度分布模式的影响发现,全部物种的多度分布符合统计模型的对数正态模型以及基于生态位理论的幂分割模型、几何级数模型与Zipf模型.常见种的多度分布符合几何级数模型与Zipf模型,而稀有种在同时符合这两种基于生态位分化的模型外,呈现出符合中性模型的趋势.说明多种不同模型可以拟合同一生境的物种多度分布,常见种和稀有种通过不同的响应方式共同维持着亚高寒草甸生态系统的物种多样性.     

贵州高寒山区华山松Pinus armandii Franch育苗试验

华山松是贵州高寒地区(当地)主要造林用树种,在退耕还林、还草工程和宜林荒山造林中,也是西部地区作为首选树种之一,但华山松常规育苗需要一年才能育成。本育苗试验采用"百日苗"育苗法可缩短育苗时间,经2009~2012年重复试验,100 d内苗高10 cm以上,地径0.2 cm以上,大大提高了综合效益,在高寒山区具有一定的实用性。     

高寒嵩草草甸不同土地管理措施对植被生产力的影响

将原生高寒嵩草草甸封育系统作为对照,研究了土地退化对植被生产力的影响,检验了退化土地在不同人工重建措施下对植被生产力的相对影响程度.研究结果表明:原生植被封育处理总地上生物量为265.1 g/m2,0～30cm土层地下根系生物量达6982 g/m2;而重度退化处理总地上生物量仅为139.9 g/m2,0～30 cm土层地下根系生物量为916 g/m2,仅占原生植被封育处理地下根系生物量的13%,因此重度退化地主要特征之一是天然嵩草草甸坚实而富有弹性的草皮层的丧失.土地退化使地下根系生物量的损失量大约为地上损失量的50倍.混播、松耙单播和翻耕单播人工种植处理经过7个生长季后,总地上生物量分别为原生封育处理的116%,75%,68%;自然恢复处理总地上生物量为原生植被封育处理的76%.与重度退化草地相比较,种植可以有效恢复地上生物量,尤其是禾草生物量,这对于提供冬季饲草、减少天然草地的压力是至关重要的.混播、松耙单播、翻耕单播和自然恢复处理,经过7个生长季后,地下根系生物量分别为1 323,1 094,1 169,1412 g/m2,重建措施(如混播)自然恢复处理可部分恢复地下根系生物量;恢复重建处理与原生植被封育处理相比较而言,有更多的生物量是分配在地上的.但随恢复年限的增加,恢复重建草地都是将更多的生物量分配给地下.且随恢复时间的增加,人工种植处理向地下转移生物量的速率比自然封育处理的更快.     

甘南高寒草甸物种多样性与生产力的关系

利用甘南高寒草甸植物群落丰富度、多样性、生产力的抽样调查资料,分析了不同空间范围内物种多样性与生产力的关系,探讨了其形成机制.结果显示:丰富度、Shannon-Wiener α多样性指数、Simpson α多样性指数与生产力之问的关系在合作分站和玛曲分站均呈显著正相关,在玛曲县欧拉乡为不相关;Pielou α均匀度指数与生产力的关系在玛曲分站呈显著正相关,在合作分站和玛曲县欧拉乡均为不相关;Whittakerβ多样性指数与生产力的关系在合作分站和玛曲分站均呈负相关,在玛曲县欧拉乡为不相关.综合三个地区的数据分析表明:随着空间范围的扩大,丰富度、三种α多样性指数与生产力趋向于正相关关系,Whittakerβ多样性指数与生产力趋向于负相关关系.如果要改善甘南高寒草甸草场质量、提高草场生产力,那么不仅要保护物种多样性,还要提高物种空间分布的均匀性、减少环境异质性.