The forest successional process is characterized by the dynamic of dominant populations in different successional stages. In this paper, the dynamic of main dominant populations in the succession process of Dinghushan forest has been studied systematically： Four communities have been selected to reprresented four different stages which are a sere. The dynamics of five dominant populations including one conifer （Pinus massoniana）, two heliophytes （Castanopsis chinertsis and Schima superba） and two mesophytes （Cryptocarya chinensis and Cryptocarya concinna） were stud- ied. Their niche breadthss, population patterns, interspecific associations and niche overlaps in 38 year＇ s change have been analyzed. The results show that the different charracteristics of dynamics and distribution of conifer, heliophyte and mesophyte populations in different succession periods reveal the position and role of each dominant population in every succession stages. The succession mechanism were revealed with population dynamic analysis.

This paper examines several major geographic patterns of species richness and related hypotheses of mechanisms. These species patterns include latitudinal gradient, elevation gradient, aridity gradient, species-area relationship, and microenvironmental pattern. Hypotheses and mechanisms to be examinedinclude time hypothesis, origination-extinction dynamics hypothesis, available energy/productivity hypothesis, habitat heterogeneity hypothesis, moderate disturbance/ stress hypothesis, and niche theory/species interaction hypothesis. There has been a lack of conceptual frameworks to integrate biodiversity studies carried out at different spatial, temporal and organizational scales. We believe that such frameworks must take a hierarchical and scale perspec- tive and explicitly consider the multiplicity of processes and mechanisms. In a rather concise fashion, we propose a hierarchical structure for relating both the patterns and hypotheses of species richness with spatial scales. This hierarchical framework helps to understand patterns, hypotheses and their relationship in terms of spatial scales and related processes. For example, patterns of species richness and responsible processes are usually scale-dependent. At continental and global scales, available energy in the environment seems to be the ultimate determinant of the number of species. However, other hypotheses must be invoked in order to satisfactorily explain the largescale patterns of species richness. Spatial heterogeneity and disturbance are significant at landscape or regional scales, whereas species interactions, disturbances, and microenvironmental factors operate most importantly on local scales.

The importance of plant genetic resources to past, present, and future crop agriculture has been recognized by scientists. Conservation of genetic resources is actually to maintain genetic diversity. The quality of any collection should not be based predominantly on size or use, but rather on how well the ex-situ collection represents, conserves, and makes accessible the genetic diversity of taxon. Curators have to make balance within range of limited funding between the relatively short-term needs of users and the long-term maintenance of maximum genetic diversity within minimum number of accessions. Addressing these challenges requires effective conservation and utilization of plant genetic resources. Part of the solution to this challenge may lie in the use of powerful, yet relatively simple and inexpensive molecular techniques to generate information to better organize the useful genetic variation within a collection. In this mini-review, three molecular techniques （RFLPs, AFLPs, and SSLPs） and their uses in the assessment of genetic diverssity are to be described.

Where does maximum species richness exist? This frequently asked question has never been answered based on a large database. We examined about 10 000 species of seed plants in the northern portion of the Northern Hemisphere in last 10 years. The results indicate that northwestern North America has the greatest species richness in both the boreal and temperate zones. But this great species pool has the smallest family richness and tree species diversity due to relatively recent origin. Maximum species richness exhibited largely in hydrie, or occasionally in xeric, but not mesie habitats as expected. Chance is the primary factor and habitat selection is a secondary factor used to interpret this species distribution pattern.

The genetic diversity of symbiotic plasmids （pSyms） and symbiotic effectiveness was investigated in 11 isolates from one field population of Rhizobium fredii that had previously been characterized for plasmid content and serogroup polymorphisms. Two cloned DNA fragments from plas- mid pSA30 and pIJ1216 were used as nil HDK and nod DABC probes respectively to identify pSym variation. Although only a single plasmid hybridized to both nil and nod probes in each strain tested, pSym size variation was great ranging from 247 to 381 MDa. In addition to pSym, all of the R. fredii strains studied carried 1 - 5 other plasmids, of which one was approximately 500MDa cryptic megaplasmid. The strains with different size of pSym significantly varied in their symbiotic effectiveness determined by their chlorophyll content, total N. dry Weight of the plant and nitrogenase activity.

Four hundred and ninety-five species of Discomycetes （cup-fungi） belonging to 136 genera are currently known in China. Studies of the Chinese cup-fungi during 1983- 1993 are briefly reviewed. Two fifths of the known species were discovered in this period of time. There is a high potential of finding a huge number of species in the near future. Although significant progress has been made, compared with the world record of Discomycetes the Chinese mycologists have a long way to go. Investigation and exploration of unknown and undescribed species are our urgent tasks.

There lives a vast number of plant and animal species in Xishuangbanna. Biodiversity plays a significant role based on its function in economy, society, culture, religion, environment and germplasm conservation in Xishuangbanna prefecture. However, the environment for organisms is worsening and many species are on the brink of extinction. More than 200 species of organisms are believed to be in rare, endangered and near endangered status around the prefecture. The preserving systems for organisms of Xishuangbanna can be divided into 3 subsystems： 1） national nature sanctuary： 2） traditional preeserving system： and 3） conservation in scientific institution, Some new methods to preserve biodiversity such as： 1） international nature sanctuariies, 2） conservation in public yards and in agroforestry, and 3） traditional conservation systems （Holy Hills of Dai, Sangpabawa of Hani, tea garden of Jinuo, Buddhist temples and homegardens） are suggested in the present paper. Also the author proposes some strategies to preserve biodiversity （egg. help the residents in and near the nature sanctuaries, replace timber with bamboo, spread traditional artificial fuelwood forest techniques and stress local participation） based on the ethnoecoLogical and humar ecological viewpoints.

The impact of the Three Gorges Hydroelectric Project on the plant diversity in the reservoir region was assessed based upon field surveys of the plant species and vegetation surrounding the reservoir area that will be influenced by this project. The reservoir area harbors known higher plants （except Bryophytes） of 190 families, 1012 genera, 3012 species （including 29 sub-species, 286 varieties and 16 forms）. Of which, 37 endemic species can onlyy be found in the reservoir region, 47 species, including 22 endangered species, 20 rare species and 5 threatened species, have been listed in the ＂Plaant Red Data Book of China＇. Vegetation types in the reservoir area, except for those found in the cultivated land, have 89 formations. The coniferous forests are most widely distributed, while broadleaf evergreen forests are only scattered in the central parts of the mountain. The plants belonging to 120 families, 358 genera and 550 species that are at present distributed under the flooded line （185 m） in the reservoir will be affected by the projject, based on their current distributional range from the established database. Moreover, 27 community types in the potentially flooded area will be eliminated from the area as well, since the original habitats of some species will be destroyed after the reservoir is filled with water. Flooding will directly lead to the extinction of species and community types in the reservoir region unless preservation strategies are to be taken. Even if it is assessed solely based on the loss of natural vegetation and the destruction of the habitats that are currently cultivated, the economic loss caused by flooding will be severe.

Total 275 quadrats with 400m² each in size were set up in the central area of Foping National Nature Reserve with elevation ranged between 1250-2400m to collect data on habitat use of the Golden takins in1991. Two checks were made on these quadrats in October 1991 and February 1992. Two hundred and seventy four quadrats were sampled in October 1991. 133 of the quadrats with tracks of the Golden takin. In February 1992. 245 quadrats were checked, and only 102 were marked by takin tracks. The takins preferred both mixed coniferous and broadleaf deciduous forest and subalpine coniferous forest during later autumn and winter. The favored slope degree of habitat for the takin was about 30-60° in the study sites. The elevations preferred by takin in miixed evergreen and deciduous broadleaf forest and coniferous forest varied from 1500 to 1900m and in coniferous forest from 1900 to 2400m in later autumn and winter, respectively. In the mixed coniferous and broadleaf deciduous forest, the preferred elevations changed from 1900-2400m to 1500 -1900m between October to February of next year. The slope aspect also influenced the habitat use by the golden takins.

In this paper, the theory of Multi-Objective Optimal Sustainable Yield is developed based on the theory of optimal sustainable yield, which makes multiple objectives about biology, environment. economy and society optimization. The Strategy of Satisfied Sustainable Yield is an approach to determine a satisfied yield close to optimum yield, resulted from the principle of Multiobjective optimal sustainable yield, and a managing strategy to aid satisfied yield. The approach provides bases for the management of biological resource. The Strategy of Satisfied Sustainable Yield for Waterhyacinth. as a case study, is discussed.

Systemactics is a science, which is very important for biodiversity conservation. In this review, the definition, main research topics, services and user needs of systematics are introduced, The information needs of biodiversity conservation are summarized, Through actual examples which apply systematic knowledge into the area of biodiversity conservation, the importance of systematics to biodiversity conservation is demonstrated. In view of the serious situation of systematic researches and problems existing in conservation activities in China, suggestions for strengthening systematic researches and its application in biodiversity conservation are proposed.

For the whole living world, the only trend in evolution is continuing to diversify-genetically, morphologically, trophically, functionally ecologically as well socially, and to radiate into any corner of the biosphere.