Based on gel electrophoresis method,the gene diversity of Fagus lucida,F.pashanica and F.engleriana was studied in this paper.The allozymes determined include peroxydase(PX₁ and PX_２), phosphogluconate dehydrogenase(PGD), superoxyde dismutase(SOD), glutamate oxaloacetate transaminase(GOT₁ and GOT₂),isocitrate dehydrogenase(IDH),menadione reductase(MNR),phosphoglucomutase(PGM_１ and PGM₂), and malate dehydrogenase (MDH₂). We have determined and analysed the allelic frequency and the genetic distances of the three beeches, and provided some scientific information for the further studies of taxonomic relations and systematic evolution of the beeches.

Only one wild population of the Crested Ibis (Nipponia nippon)survives by now, and its size has been no more than twenty since being rediscovered in 1981. We put forward the population dynamics and endangered level by Population Viability Analysis (PVA) with the help of a computer simulation model——VORTEX model on the basis of the data from 14 year long monitoring. The result indicated with probability of 98.5 % that the Crested Ibis would be extinct 50 years later. The mean extinction time is 15.72 years. The population is so small that the fate of this species is strongly influenced by demography stochasticity. Sensitive analysis showed that the survival probability was sensitive to catastrophes and environmental variations.Consequently, the prior conservation project is controlling hunting and predating, as well as artificial intervention on behalf of the birds to improve the survival rate.

This paper reports 8 taxa of Emericella Berk & Br.and Neosartorya Malloch & Cain as follows :E.quadrilineata (Thom & Raper) Brnjamin,E.rugulosa(Thom & Raper) Benjamin,N.fischeri (Wehmer) Malloch & Cain,N.glabra (Fenn. & Raper) Kozak., N.spinosa (Raper & Fenn.) Kozak., N.stramenia (Novak & Raper) Malloch & Cain,N.aureola (Fenn. & Raper) Malloch & Cain and N.quadricincta (Yuill) Malloch & Cain.Among them three are new records in China.

Since Darwin and the earliest theory of population genetics, it has been well known that breeding system plays an important role in genetic diversity and evolution of organisms. After elucidation of the rationale for the use of protein electrophoresis in assesment of breeding system of plants, experimental results obtained by Chinese and foreign scientists has been cited. Although many characters of plants such as life form, mode of reproduction etc. do influence genetic structure of populations, the most significant matter is the relationship between breeding system and population genetic differentiation. Since that we can make a deduction from breeding system to population genetic structure, and further to sample strategies which are critically important to monitoring genetic diversity of in situ conservation and ex situ conservation.

Gene flow is an important factor influencing the genetic structure of plant populations and plays role in the conservation of endangered plants. This paper introduced different methods for measurement of gene flow in plants, analyzed the patterns of gene flow within and among populations. Relation between gene flow and population differentiation was also discussed. At last, implications of gene flow in the conservation of endangered plants were introduced.

This paper deals with the diversity of species, of the microorganisms in human oral cavity, and with the microbiota changes. The relation between the complexity of the small habitat in human oral cavity and diversity of the microorganisms, and the relation between the microbiota changes and human health.

In freshwater ecosystems,higher trophic level group may influence lower trophic levels strongly,leading to a change of the whole enviroment,which is called top down effect.The top-down effects in freshwater ecosystems especially that of fish and their consequences were analized in the present paper,and it was suggested that the lack of high trophic level group which existed before can also make top-down effect.Top-down effect is the most important characteristic of freshwater ecosystem.While dealing with biodiversity conservation in freshwater ecosystem,much attention should be paid to conservation of high trophic level group and cautious to introduction of extra species.

Paths are flow channels of energy and matter in ecosystems. The structures and functions of ecosystems are supported by the flow paths passing energy and matter. The path diversity is one aspect of the trophic structure diversity of ecosystems. In the present paper, the measure reflecting the flow path diversity in ecosystems along the path length are formulated by defining base paths and equivalent base paths.

Ophiopogon xylorrhizus is an endangered species,restrictedly distributed in tropical rain forest of Xishuangbanna,Yunnan,China,whihc is especially significant to studies on systematics and conservation biology of plants.RAPD is a rapid and simple method to reveal genetic diversity of populations.DNA as templets was generally isolated from fresh materials,which has difficulties in dealing with materials from remote districts.Total DNAs of 49 individuals among 4 populations were extracted using High salt low pH method from Ophiopogon xylorrhizus leaves dried through silica gel in the field.Quantity of the DNA ranged from 80 to 160 μg/dried leaves of 1 gram of fresh leaves.Compared with DNA from fresh materials,the DNA from dried leaves was not even in molecular weight and partly took place reduction,which affected PCR amplification.Good results and high production of amplification were achieved through different treatments to templet DNAs and adjustment of PCR programs.This research lays the foundation for extracting DNA from other tax using materials dried in the field for RAPD analyses.