Population viability analysis(PVA)is a qulckly developing new technique and has become a central issue of conservation biology．It mainly probes into effects of extinction for small polulations by stochastic perturba-tions and its goal is to establish a minimum viable population that reduces risk of an extinction to an acceptable level．The stochastic perturbations can be classified into four kinds:demographic stochasticity,environmental stochasticity,natural catastrophes and genetic stochasticity．There are three approaches to determining MVP:theoretical models,simulation models and isldand biogeography method．The theoretical models mainly analysize effects of stochastilc perturbations on MVP under ideal or given conditions．The simulation models use computer to simulate the extinction processes for populations, and the island biogeography method analy - sizes distribution and survival of species on islands,and testifies theoretical models and simulation models． There are a great number of literatures that study behavior characteristics of demographic stochasticity,envi - ronmental stochasticity and natural catastrophes. But the relationships between genetic factors and population viability are not clearly known．The developmental trend of population viability analysis is to build a compre - hensive model that includes four kinds of stochasticity,widely to test PVA models,systematically to study genetic and ecological characteristics of target species and explore PVA's application in conservation practices．

Cathaya argyrophylla is a China endemic and rare species distributed in Sichuan,Guizhou,Hunan and Guangxi Provinces．This leads to four geographic distribution centers of this species:Daloushan, Yuechenglin．Bamianshan and Dayaoshan．All Cathaya argyrophylla forests are normally mixed and there are seven Cathaya community types．Cathaya argyrophlla is one of the dominant species in these types,but its natural regenerations are poor．Cathaya argyrophylla is theatened by the invasion of broad-leaved species and is likely to be replaced by them during the succession．To preserve Cathaya argyrophylla,two effective methods are suggested in the present paper:the preliminary thinning of the broad-leafed species and the transplanting of the sapling of Cathaya argyrophylla in gaps．

Bird banding is the simpliest,but most efficent scientific means to reveal avian migration．Since the construc-tion of National Bird Banding Centre of China in 1982,more than 60 banding stations and sites have been set up under the leadership of the Ministry of Forestry until 1990,and 62 755individals of 186 migrants species have been banded,413 of them recovered in China or abroad．The recoveries of migrants have offered mo - mentous information for East Asia avian migration studies．It has been proved that:1 ．Birds can fly over Hi- malayas on their passage ways;2．The speculation of Chinese bird migration routines is correct; 3．White - naped Cranes breeding in Northeast China fly to Kiushu in Ssouthern Japan for Wintering．japanese Cranes and some others migrate along eastern coast and winter in lower part of Yangtze River wetlands,sharing the same places with cranes from Siberia in Russia ; 4．Comparison of passage ways of some species with those of the same ones in Japan indicated that,there are two parallel from - south- to- north routines through China and Japan in West Pacific region．There are more data to show more conlusions;in the mean while,they also in- dicated the key position China stands in migration studies of West Pacific．

The Crested Ibis is one of the rarest birds in the world,with number in dozens．The population declined sharply because of changes of environment and weak vitality of itself．Artificial rearing and breeding have conducted in China since 1986．Three chicks were firstly hatched and alive in 1992．This paper summarizes the wild survey,laboratory researches,artificial rearing and breeding of Crested Ibis systematically.

Some strains of soil bacteria were isolated by their ability to grow on ACC as a sole nitrogen source．ACC deaminase activity of these strains were determined by growth assaying,confirmed by chromatograthically identifying to decrease of ACC in the medium．Then systematic identification was done．

The application of multimedia information system on microbiology research is microbiology resource database constructed by writiongs,graphs,sounds and pictures etc．．The graph and writing database of the two group of Streptomyces and Thermophilic actinomycetes will be estabilished first．This database is consisted of software and results from species classification research,research works,as morphological graph(aerial mucelium,spore,spore ultrathin-section),graphic spectrum(analisis graph spectrum of constituents of wall Chemotypes,segments of DNA and RNA,ultraviolet graph spectrum of metabolite),value(UPGMA analysis of different species),writing(names, characteristics of physiology and biochemistry,culture medium and preservation,habitat products)．The pictures byusing scanner and writing information will be edited and transfered．This resource can be utilized for classification research,resourse inquiry,domestic and international exchange．

The concept of allozyme and the application of the allozyme analysis technique in the studies of plant genetic diversity and systematics are introduced and discussed with comments on its advantage and weakness．Allozyme analysis is an important method to studying the genetic diversity of organisms,and has opened a broad prospects for the studying of systematics and evolution with molecular data．However,the use of the molecular data does not mean that the morphological,cyological and other data can be Iistead,but they are complementary each other．

Biodiversity is a kind of precious natural resource and becomes cornerstone of mankind society's sustainable development．This paper at first introduces the present situaiton of the loss in the world's biodiversity,analyses that the source resulting in biodiversity to lose is not in species and habitats themselves,but in the current e- conomic system leading to the economic action of mankind,especially the price system in which doesn't complitely,exactly reflect all kinds of value in biodiversity．Finally,putting forward some economic measures of conserving biodiversity．