长江中游(以湖北湖南为主)的植物生物多样性及其保护对策

在对植物调查研究的基础上,对长江中游(湖北、湖南为主)的植物区系、植被、生物多样性保护及保护对策进行了系统的论述。根据两省土著种子植物名录统计,本区共有202科1476属7037种(包括种下等级),其中裸子植物7科30属64种;被子植物196科1445属6973种。以鄂湘为代表的华中区分布类型复杂、物种丰富、起源古老,而且特有的科、属、种多,特有度高。北温带木本植物属高度集中,体现了长江中游具有古第三纪．泛北极植物区系的代表性。拥有众多的东亚特有属、东亚．北美间断分布属和中国特有属,它们既是本地植物区系的特色,也代表了中国植物区系的核心。本地中山以亮叶水青冈(Fagus lucida)为主的阔叶林系第三纪．泛北中生落叶阔叶林的后裔。在植被区划上,本区属于常绿阔叶林区域,包括北亚热带常绿阔叶．落叶阔叶混交林地带及中亚热带常绿阔叶林两个植被地带。后者分为北部典型常绿阔叶林亚地带,南部含华南植物区系成分的常绿阔叶林亚地带。本区主要的自然植被类型(以原生类型为主)有171个类型(相当于群系formations)。从生物多样性保护的三个层次上(物种、群落、景观)对保护现状、特点、保护方针和策略等进行了探讨并提出了建议。     

A pragmatic study of dansereau's universal system for recording vegetation: Application in south-east Queensland,Australia

Summary Standard Dansereau diagrams were constructed to illustrate the vegetation of part of south-east Queensland, Australia. Some problems were encountered in illus trating herbaceous lianes, in assessing seasonality, and in estimating coverage in specific instances. Although discriminating between major vegetation types the standard diagrams did not differentiate well between the various eucalypt communities. The modifications suggested in Dansereau, Buell & Dagon (1966) only partially alleviate the problem. In particular it is suggested here that further modification to include leaf angle and bark characteristics would be appropriate.

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Zusammenfassung Zur Ausbildung der Vegetation in einem Teil von südost Queensland, Australien, wurden Standard-Diagramme im Sinne Dansereaus (1958) zusammengestellt. Einige Probleme ergaben sich dabei, besonders mit den krautigen Lianen. Es war auch manchmal schwer Bedeckung und Saisonbedingungen einzuschätzen. Obwohl die Standard-Diagramme für die Unterscheidung von Vegetationstypen im allgemeinen gut brauchbar sind kommt man weniger gut aus in den verschiedenen Gemeinschaften mit Eucalyptus-Arten. Mit dem System von Dansereau, Buell & Dagon (1966) wird nur ein Teil des Problemes gelöst. In diesem Beitrag werden daher einige Änderungen vorgeschlagen, damit auch die Blattwinkel und der Charakter der Rinde zum Ausdruck kommen.

     

Ecological amplitude in Silene nutans in relation to allozyme variation at the western margin of its distribution

Abstract. At the western border of its geographical range, Silene nutans (Caryophyllaceae) has evolved two groups of parapatric populations showing distinct allozyme patterns and apparently occurring on different bedrock types. This study tests the hypothesis that these groups represent edaphic ecotypes. With this in view, the ecological amplitude of 36 populations of Silene nutans from Belgium was investigated and their synecology specified using vegetation composition and soil parameters; Ellenberg indicator values were used for ecological interpretation of the vegetation analyses. The results provide evidence that allozyme and habitat variations are correlated, the two groups occurring on contrasting soil with distinct vegetation types. One group is restricted to alkaline soils and typically occurs in open calcareous grasslands, fringes and scrub. The other group is characterized by wider autecological and synecological ranges with a bimodal pH- distribution, occurring on two kinds of siliceous soils: (1) neutral soils, supporting vegetation with a high species richness comprising many mesophilous species, and (2) CaCO₃ -free bedrocks characterized by acidophilous, species-poor, open dry grasslands and woodlands. It also appears that factors not related to soil chemistry, such as microclimate, are involved in the ecological specialization of the two ecotypes. It is argued that these ecotypes exemplify adaptive radiation and parapatric speciation at the margin of a species distribution area.     

The influence of tidal channels on the distribution of salt marsh plant species in Petaluma Marsh,CA, USA

Tidal channels influence the distribution and composition of salt marsh vegetation in a San Francisco Bay salt marsh. Two channel networks in the Petaluma Marsh, Sonoma County, CA, were mapped and characterized using global positioning and geographic information systems. Plant species abundance was sampled on transects placed perpendicular to and extending away from the channel banks. The vegetation showed significant increases in species richness along channel banks and larger areas of effect which increased approximately linearly with channel size. Composition of species assemblages varies with distance from the channel bank and channel size. These results demonstrate that salt marsh plant assemblages, composed of both major and minor species, are distributed with respect to the channel network in Petaluma Marsh.     

The antioxidation-related functional structure of plant communities: Understanding antioxidation at the plant community level

In the case of ecological stresses, reactive oxygen species (ROS) can be overproduced in plant cells, leading to lipid peroxidation that causes damage or death to cells. To prevent damage, plant tissues contain several antioxidants that scavenge ROS. However, antioxidation at the plant community level still remains unknown and may provide an insight into ecosystem functioning regarding stress resistance. To understand the property, we established the antioxidation-related functional structure based on the concept of the functional structure and the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), reduced glutathione (GSH), carotenoid (Car) and proline (Pro) and the relative abundance of component species in natural plant communities on the Chinese hilly-gullied Loess Plateau. An information-theoretic (I-T) approach was used to infer the effects of antioxidation-related functional components and stresses that we investigated on lipid peroxidation at the plant community level quantified by the community-weighted mean of malondialdehyde (MDA). We found that the induction of lipid peroxidation was more closely associated with a soil available nitrogen deficiency than it was with an available phosphorus deficiency. However, the inducing effect of soil available nitrogen was finite. The prevention of lipid peroxidation was more closely associated with the community-weighted means of GSH and Pro (CWM GSH and CWM Pro) than it was with other antioxidation-related functional components. However, the efficiency of CWM Pro was quite low; CWM GSH exhibited inefficiency. In addition, antioxidation-related functional components were affected by neither soil available nitrogen nor available phosphorus. Furthermore, by estimating the relative weights of the antioxidants and considering the feasibility of community assemblages, we proposed that Stipa grandis, Leymus secalinus, Stipa bungeana, Phragmites australis, Potentilla tanacetifolia, Artemisia gmelinii, Artemisia scoparia, Heteropappus altaicus and Syringa oblata could be utilized in community assemblages to achieve an antioxidation-functional target. Additionally, appropriate phosphorus application for A. gmelinii and H. altaicus might contribute to maintaining their antioxidation.     

Field observed relationships between biodiversity and ecosystem functioning during secondary succession in a tropical lowland rainforest

The relationship between biodiversity and ecosystem functioning (BEF) is one of the most concerned topics in ecology. However, most of the studies have been conducted in controlled experiments in grasslands, few observational field studies have been carried out in forests. In this paper, we report variations of species diversity, functional diversity and aboveground biomass (AGB) for woody plants (trees and shrubs) along a chronosequence of four successional stages (18-year-old fallow, 30-year-old fallow, 60-year-old fallow, and old-growth forest) in a tropical lowland rainforest recovered after shifting cultivation on Hainan Island, China. Fifty randomly selected sample plots of 20 m × 20 m were investigated in each of the four successional stages. Four functional traits (specific leaf area, wood density, maximum species height and leaf dry matter content) were measured for each woody plants species and the relationships between species/functional diversity and AGB during secondary succession were explored. The results showed that both plant diversity and AGB recovered gradually with the secondary succession. AGB was positively correlated with both species and functional diversity in each stage of succession. Consistent with many controlled experimental results in grasslands, our observational field study confirms that ecosystem functioning is closely related to biodiversity during secondary succession in species rich tropical forests.     

Use of the ecological information system SynBioSys for the analysis of large datasets

The rapid developments in computer techniques and the availability of large datasets open new perspectives for vegetation analysis aiming at better understanding of the ecology and functioning of ecosystems and underlying mechanisms. Information systems prove to be helpful tools in this new field. Such information systems may integrate different biological levels, viz. species, community and landscape. They incorporate a GIS platform for the visualization of the various layers of information, enabling the analysis of patterns and processes which relate the individual levels. An example of a newly developed information system is SynBioSys Europe, an initiative of the European Vegetation Survey (EVS). For the individual levels of the system, specific sources are available, notably national and regional Turboveg databases for the community level and data from the recently published European Map of Natural Vegetation for the landscape level. The structure of the system and its underlying databases allow user‐defined queries. With regard to its application, such information systems may play a vital role in European nature planning, such as the implementation the EU‐program Natura 2000. To illustrate the scope and perspectives of the program, some examples from The Netherlands are presented. They are dealing with long‐term changes in grassland ecosystems, including shifts in distribution, floristic composition, and ecological indicator values.