中国水土流失敏感性分布规律及其区划研究

以水土流失通用方程为理论基础,利用我国已有的水土流失研究成果及地貌、土壤和植被分布图,分析了降水、土壤质地、地形坡度增长和地表覆盖因子对我国水土流失敏感性的影响及其形成的区域差异。在综合评价我国水土流失敏感性区域差异基础上,提出了中国水土流失敏感性区划方案。     

Structure and expression of three Emx genes in the dogfish Scyliorhinus canicula: functional and evolutionary implications

We report the characterization of three Emx genes in a chondrichthyan, the dogfish Scyliorhinus canicula. Comparisons of these genes with their osteichthyan counterparts indicate that the gnathostome Emx genes belong to three distinct orthology classes, each containing one of the dogfish genes and either the tetrapod Emx1 genes (Emx1 class), the osteichthyan Emx2 genes (Emx2 class) or the zebrafish Emx1 gene (Emx3 class). While the three classes could be retrieved from the pufferfish genome data, no indication of an Emx3-related gene in tetrapods could be found in the databases, suggesting that this class may have been lost in this taxon. Expression pattern comparisons of the three dogfish Emx genes and their osteichthyan counterparts indicate that not only telencephalic, but also diencephalic Emx expression territories are highly conserved among gnathostomes. In particular, all gnathostomes share an early, dynamic phase of Emx expression, spanning presumptive dorsal diencephalic territories, which involves Emx3 in the dogfish, but another orthology class, Emx2, in tetrapods. In addition, the dogfish Emx2 gene shows a highly specific expression domain in the cephalic paraxial mesoderm from the end of gastrulation and throughout neurulation, which suggests a role in the segmentation of the cephalic mesoderm.     

Regional application of PnET-N-DNDC for estimating the N2O source strength of tropical rainforests in the Wet Tropics of Australia

In contrast to the significant importance of tropical rainforest ecosystems as one of the major sources within the global atmospheric N₂O budget (2.2–3.7 Tg N yr^?1), regional estimates of their N₂O source strength are still limited and highly uncertain. To contribute toward more reliable estimates of the N₂O source strength of tropical rainforest ecosystems on a regional scale, we modified a process‐oriented biogeochemical model, PnET‐N‐DNDC, and parameterized it to simulate C and N turnover and associated N₂O emissions in and from tropical rainforest ecosystems. Model modifications included: (1) new parameterizations associated with plant physiology and soil hydrology and the addition of algorithms relating daily leaf litterfall to water stress as well as to daily rainfall to account for the effects of heavy rainfall damage; (2) the development of a denitrifier activity index that depends on soil moisture conditions and influences N turnover by denitrification; and (3) the addition of a biological N fixation algorithm. Daily simulated N₂O emissions based on site data were in good agreement (model efficiencies up to 0.83) with field observations in the Wet Tropics of Australia and Costa Rica. The model was even able to reproduce the highly dynamic pattern of N₂O emissions with short‐term increases during the wet season. Sensitivity analyses demonstrated that the PnET‐N‐DNDC model was sensitive to changes in soil properties such as pH, clay content, soil organic carbon and climatic factors such as rainfall and temperature. By linking the PnET‐N‐DNDC model to a geographic information systems database, tropical rainforests in a 9000 km² area of the Wet Tropics of Australia are estimated to emit 962 t N₂O‐N yr^?1 (2.4 kg N₂O‐N ha^?1 yr^?1) between July 1997 and June 1998.     

Characteristics of paravertebral muscles – fibre type distribution pattern in the pika, Ochotona rufescens (Mammalia: Lagomorpha)

The evolution of the locomotor apparatus in vertebrates is marked by major reorganizations in trunk's musculature. The hypothesized functions of mammalian back muscles in the literature are discussed under consideration of the distribution and proportion of oxidative, type‐I‐fibres, oxidative‐glycolytic, type‐IIa‐fibres and glycolytic, type‐IIb‐fibres in paravertebral muscles of a small mammal. The fibre type distribution was examined from a complete series of histological sections maintaining topographical relationships between the muscles as well as within the muscle, in order to establish the overall distribution pattern. The deep and short muscles showed the highest percentage of oxidative fibres. The larger, superficial paravertebral muscles contained the highest percentage of glycolytic fibres. Two muscles were intermediate in their proportion of fibre types. All epaxial muscles together can be interpreted as an antigravity muscle–complex counteracting enduringly against the rebound tendency caused by gravitation, comparable with antigravity muscles in limbs. A gradient from deep to superficial, or a clear regionalization of oxidative muscle fibres in central deep regions around a large intramuscular tendon was found in the m. spinalis and the m. quadratus lumborum, respectively. Concepts of the function of human back muscles as those of A. Bergmark (1989: Acta Orthop. Scand. 230 , 1) or S.G.T. Gibbons & M.J. Comerford (2001: Orthop. Division Rev. March/April, 21) were exposed to be more general within mammals. Functional specializations of different muscles and muscle parts are discussed under the consideration of evolutionary reorganization of the paravertebral musculature in tetrapods. Along the cranio‐caudal axis, the percentage of oxidative fibres was decreased in caudal direction within the same muscles, whereas the proportion of glycolytic fibres was increased. Therefore, classifications of muscles as ‘glycolytic’ or ‘oxidative’ based on biopsies or analyses of single cross‐sections may result in wrong interpretations. Changes in the proportions of the fibre type distribution pattern were mostly due to oxidative and glycolytic fibre types, whereas the percentage of oxidative‐glycolytic fibres had only minor influence. A significant positive correlation between the cross‐sectional area of the single fibre and its percentage in the area investigated were observed for oxidative fibres, whereby the size was positive correlated to the proportion of the oxidative fibres.     

植被气候关系与我国的植被分区(英文)

气候制约着植被的地理分布 ,植被是区域气候特征的反映和指示 ,两者之间存在密不可分的联系。揭示植被与气候之间的关系是正确认识植被分布的前提 ,是进行植被区划的理论基础。植被区划是植被研究的归纳和总结 ,是其他自然地理区划和农林业区划的基础。本文在简要回顾中国植被气候关系及植被分区的研究历史的基础上 ,对我国以往的主要植被分区原则、依据和方案进行了评述 ,对有争议的主要植被界线进行了讨论。我们认为 ,在当今我国大部分地区的原生植被已遭到破坏的现实情况下 ,根据原生植被及其衍生植被类型的分布 ,确定其分布与限制性气候因子的关系 ,以此来进行植被带 (区 )的划分 ,不仅反映植被气候间密不可分的关系 ,在实践上也便于操作。尽管在一些植被带的命名、具体界线的划定上有分歧 ,但最近的中国植被分区方案大都认为我国基本的植被区有 8至 9个 ,即针叶林、针阔叶混交林、落叶阔叶林、常绿落叶阔叶混交林、常绿阔叶林以及雨林季雨林、草原、荒漠以及高寒植被。通过分析主要植被带附近的植被、气候等特征 ,本文认为 ,1)秦岭淮河线是一条重要的水分气候带 ,而不是温度带 ,不是亚热带植被的北界 ;2 )我国亚热带植被的北界基本上沿长江北岸 ,从杭州湾经太湖、安徽宣城、铜陵经大别山南坡到武汉     

安徽大别山北坡植物区系与邻近地区植物区系关系探讨

安徽大别山北坡是大别山的主体部分,也是目前大别山森林植被保存较好的地区之一。作者通过对该区植物区系与邻近地区植物区系之间共有种和区系成分的对比分析,以及通过与邻近山地森林植物区系之间相似性系数的对比分析,初步得出下列结论:(1) 该区植物区系与华东植物区系的关系最密切,其次是华中,再次依次为日本、华北、华南、西南、东北,与西北和青藏高原植物区系之间很少有联系。(2) 该区植物区系与日本植物区系之间的关系比与我国西南植物区系之间的关系要密切。(3) 该区植物区系与天目山、神农架、中条山、庐山、武夷山诸山地森林植物区系之间关系紧密程度依次为天目山、庐山、神农架、武夷山、中条山。(4) 大别山植物区系在我国植物区系分区上应属于华东区。(5) 在我国植物区系分区上,华东区与华中区的分界线在湖北省境内应位于“襄樊—宜昌”一线,华东区与华北区的分界线在安徽省境内应位于“霍丘—滁县”一线。     

中国生物多样性的生态地理区划

生态地理区划是生物多样性研究的空间分异基础。以国际上的生态地区划原则为依据,采用多无分析与地理信息系统等手段,利用各种生态地理因子,包括气候指标如与植物耐寒性有关的绝对是低温度、最冷月平均气温、最冷月日平均温度的最在值和最值;与需热性有产的植物生长季积温;年降水量的季节分配,最冷月降水、最热月降水、年降水量、年降水的统计标准差和变异系数（年变率;植被指标如植被类型、植被区划类型、植物被的净第一生产     

The structure of the vegetation of Khakasia

A diagram of the vegetation structure of Khakasia, made up with the use of a generalized large-scale map, shows the main variety of the phytocoenoses. It is particularly important for the analysis of the vegetation of mountaincous regions.Differentiated areas of phytocoenoses are used to distinguish the region borders in fractional geobotanical regionalization.Khakasia belongs to three geobotanical provinces of the Altal-Saijan geobotanical region — provinces of Minusinsk depression, West Saijan and Kuznetsk Alatau. In Khakasia, geobotanical districts are distinguished by altitudinal zonation and phytocoenotic structure. The vegetation cover is comprehensively described in a special monograph.Nomenclature follows (Flora USSR. Ed. Acad. Sc. Leningrad Vol. I–XXX, 1934–1960). This paper was presented at the International Botanical Congress, USSR, Leningrad, July 1975.     

三北防护林体系建设工程区森林水源涵养格局变化研究

三北防护林体系水源涵养功能是三北地区生态环境状况的重要指示器,然而,三北防护林体系水源涵养研究仍较缺乏。动态评估三北防护林体系建设工程区(三北工程区)森林水源涵养功能及其影响因素,对科学认识、保护和调控三北防护林体系森林水源涵养,制定三北工程植被建设与保护决策具有重要意义。以三北工程区森林为研究对象,通过收集和分析相关数据,在植被分区的基础上,分析三北工程区森林水源涵养时空格局与变化特征,对比研究各区不同森林类型水源涵养功能差异,揭示各区森林水源涵养功能与地形及森林状况与质量的定量关系。结果表明:(1)三北工程区森林水源涵养功能持续增强,单位面积水源涵养量从1990年的73.92mm增加到2015年的75.14mm,空间格局呈东高西低、南高北低态势。(2)森林水源涵养功能在植被分区和森林类型间差异显著,森林植被区是三北工程区森林水源涵养的主体;针阔混交林是三北工程区水源涵养功能最强的森林类型。(3)三北工程区森林水源涵养受其地形、状况与质量的影响显著,除个别植被区外,各区森林水源涵养量随坡度、覆盖度和NPP增加而增大,随生物量增加而降低,这是区域植被适应及滥砍滥伐、毁林开垦、植被建设与保护等人为干扰共同作用的结果。因此,可通过调整与优化林分结构,调控区域森林水源涵养功能。     

青海茶卡-共和盆地及其毗邻地区种子植物区系

茶卡-共和盆地及其毗邻地区位于青海省的东部,约处于北纬34°45′～37°00′,东经98°45′～101°30′。海拔2800～5305m,面积约38300km2,属于高原大陆性气候类型。本区共有野生种子植物59科、277属、854种。分别占青海省总科数的65.56%、总属数的54.53%、总种数的37.37%。区系特征如下:1、种类相对较贫乏,木本更贫乏。2、就属的层面而言,本区属于以北温带成分,特别是欧亚大陆温、寒地带典型成分为优势的,兼具旱生温性、耐寒温性和高寒类型的温带区系性质。3、许多种、属和热带类型均以本区为边缘分布区,因而区系的边缘性质明显。4、为青藏高原高寒区系、黄土高原温性(草原)植物区系和亚洲东部荒漠区系在我国的交汇过渡区,区系的过渡性质明显。5、是青藏高原植物亚区唐古特地区的一部分。6、是青海植物区系或“唐古特植物地区”划分植物亚地区的关键区域。