Sinocalycanthus chinensis is the only representative in the genus Sinocalycanthus and an endangered species restricted in small areas of Lin′an City and Tiantai County, Zhejiang Province. Currently only two natural populations remain: the larger one is found in Lin′an City, consisting of seven subpopulations with nearly 1731 990 individuals in total; the smaller one is located at Tiantai County where 2000 individuals exist. The genetic diversity of the two natural populations and one recently introduced population at Tianmushan Natural Reserve, Lin′an City, Zhejiang Province, was assessed using allozyme markers. A population of Chimonanthus zhejiangensis from Hangzhou Botanical Gardens, Hangzhou City, Zhejiang Province, was included in this study for the purpose of comparison. The genetic diversity of S. chinensis turned out to be extremely low. Only five of 23 loci from 14 enzymes assayed were polymorphic. The polymorphism was largely due to alternative fixation of alleles on Mdh-4, Pgd-3 and Sod-1, and two mutations (Gpi-1 and Gpi-2) on one individual out of 553 in total. At species level the mean number of alleles per locus ( A ) was 1.2, the percentage of polymorphic loci ( P ) was 21.7%, and the observed heterozygosity ( H_o ) was 0.010. At population level the estimates were A =1.0～1.1, P =0～13.0%, and H_o =0～0.014. In contrast, the estimates for C. zhejiangensis were much higher ( A=1.5, P=39.1%, H_o =0.071) though there were only 16 individuals tested. Since no genetic variation was detected in the introduced population of S. chinensis at Tianmushan Natural Reserve, the introduction of the plant should not be considered as a success of ex situ conservation of the endangered species. Moreover, the range of subpopulations within Longtangshan National Natural Reserve is diminishing due to the growth of evergreen forests. So far no measures have been taken to stop this subpopulation from shrinking because of lack of knowledge of ecology and biology of the plant. This study exemplifies that we are unable to conduct in situ conservation and to practise ex situ conservation properly if we have no knowledge of the biology of the species we intend to conserve.

Measurements of species diversity of plant communities along both DCCA axis 1 and an altitudinal gradient in the northern slopes of Qilian mountains was carried out. The results showed that: 1) Both species richness and diversity in the herb layer significantly peaked at the intermediate elevations.The same trend was also suggested in the shrub layer, but the curves of both richness and diversity were not significant. Both richness and diversity in the tree layer showed no changes with increased altitude, suggesting that the order of sensitivity in terms of the responses of richness and diversity to altitudinal gradients was herb layer, then shrub layer and tree layer. 2) Evenness of the three layers showed no noticeable trend with altitude, suggesting that the dynamics of evenness of a given plant community may be strongly influenced by some fundamental characteristics of plant community rather than resource availability. 3) The fitted curve of both diversity and richness of herb layer with DCCA axis 1 was more significant than that fitted with altitudinal gradient, while that of shrub layer showed the opposite trend. 4) Of all the comparisons between shrub and herb layer in terms of richness, diversity and evenness, the differentiation was significant for both richness and diversity in the lower altitudinal zone ( p <0.01), the mid lower to mid-altitudinal zone ( p <0.01)(excluding Simpson diversity index ( D ) and in the high altitudinal zone ( p <0.05)(excluding both Shannon Wiener diversity index ( H ′) and Simpson diversity index). The differentiation of evenness between shrub layer and herb layer was not significant in any of the comparisons. The pattern of species diversity altitudinal gradient reported here demonstrates a monotonic relationship between productivity and species diversity related to resource availability.

Zhejiang Province is rich in plant resources. There live a total of 215 families, 1196 genera and 3283 species of wild vascular plants, including 49 genera endemic to China and 200 species endemic to Zhejiang. Many species have become rare and threatened, and therefore, should be conserved as soon as possible. However, these rare and endangered plant species are not distributed evenly. Attention should be given to the regions where more plant species deserving protection exist. According to plant diversity, species richness of rare and endangered plants, and their individual quantitative features, imperiled status, and the distribution of endemic plant in Zhejiang Province, seven critical reserve regions for plant species diversity protection are suggested. They are northwest mountains (centered around Xitianmu Mountain), west mountains (centered around Gutian Mountain), southwest mountains (centered around Jiulong Mountain), south mountains (centered around Fengyang and Baishanzu Mountains), east mountains (centered around Kuocang Mountain), east hills (centered around Tiantai hill land), and Zhoushan Archipelago (centered around Putuoshan Island). Measures to protect plant diversity in Zhejiang are suggested.

Studying the sibship of 11 genus of Liliaceae by focusing on their parasitic fungi,we found Peronosporales can only parasitize the Allium ,while Meliola can parasitize the Ｓmilax . The result shows that the sibships between Allium and Smilax, Allium and Samilax are distant from the other nine genus. Which coincide with the J. Hutchiuson Taxomomy system. It is important to clarify the taxonomy of Liliaceae because of its high ecomonic value. Our study provides new evidence for classification of Liliaceae.

We studied, through field survey, field inoculation experiments and hand inoculation experiments, whether Geranium sylvaticum plants differed in resistance against a macrocyclic pathogenic rust, Uromyces geranii, when they were healthy or diseased by one of two microcyclic pathogenic rusts, Puccinia leveillei and P. morthieri, and whether the macrocyclic rust interacted with the two microcyclic rusts when they infected the same host plants at the same season. The results indicated that P. morthieri diseased plants were much more resistant to U. geranii than P. leveillei-diseased plants and healthy plants. Furthermore, P. leveillei-diseased plants were more resistant than healthy plants. The results suggest that P. leveillei induces a short-term resistance, while P. morthieri induces a long-term resistance. Induced protective resistance may be one important factor in explaining disease patterns in natural plant populations.

Gahai Salt Lake, which is situated in the Qaidam Basin of the Qinghai-Tibet Plateau at an elevation of 2849.6 m above sea level, is a saline lake with high salinity and abundant biological resources of Artemia (brine shrimp). An investigation on the characteristics of community diversity of plankton with relation to salinity was conducted in the summer of 1997. Forty-six species of phytoplankton and twelve species of zooplankton have been identified in the major body of water in the in-lake area with 22 sampling sites at 5 sections. The differences of the species composition, richness , individual abundance and biomass of plankton were compared between two sampling area with a big change of salinity in the waters. The results show that the salinity is an important limiting factor in determining the structure of biological communities in the inland saline lakes.

The arid regions of China include Mongolian- Xinjiang warm-temperate arid region and Qinghai-Xizang frigid arid region, located in western China, host 120 species of small mammals including Largomorpha and Rodentia. We collected all of the available distributional data for these species in these regions. Based on GIS models of species range which were predicted by a wildlife-habitat model, we researched the distribution patterns of rodent diversity there. A total of 766 equal-area quadrangle grids that each had an area of 6,470 square kilometers were used as geographic units to collect distributional data of the species, supported by MapInfo Professional Version 4.0. Based on these grid data we obtained the number of genera and families, and calculated the small mammal species diversity of genera and families by Shannon-Winner index and G-F index. In order to explain the species differentiation tendency of small mammals, we introduced number ratios of species to genera and of genera to families as differentiation indices. The results indicate that more genera occurred in mountains around the Junggar Basin, Qilian Mountains, Helan Mountains and the west slopes of Da Hinggan Mountains, where species richness was higher, as might be explained by an edge effect. In contrast, richness was least on the Ordos Plateau and Zhangbei Plateau. There were more families on the south slopes of the Altay Mountains, Tianshan Mountains of Ili and East Qilian Mountains, but fewer on the Ordos Plateau and Zhangbei Plateau. High species diversity often occurred in ecotones such as those among or between frigid desert and warm-temperate desert, desert and mountains, plateaus and basins, desert and steppes, and mountains and steppes. In the Qinghai-Xizang Plateau, number ratios of genera to families were much lower than in the Mongolian-Xinjiang region. In contrast,, there were higher ratios of species to genera in the former region. The G-F index was higher in Qinghai-Xizang Plateau, where a great species differentiation was implied. Since small mammals can be used as indicators of biodiversity, the distributional patterns of their species diversity could be helpful for assessment of biodiversity in arid regions of West China.

The relationship between biodiversity and ecosystem functioning has emerged as a major scientific issue today. Concerns over the unprecedented loss of biodiversity have motivated ecologists to conduct considerable research, describing the relationship between biodiversity and ecosystem function, and detecting the mechanisms by which diversity impacts ecosystem functioning. Statistical and biological hypotheses have been proposed to explain the observed relationship between biodiversity and ecosystem functioning. The former, including hypotheses related to sampling and statistical averaging effects, are inclined to view empirical results from a purely statistical perspective, while the latter are built on biological effects of biodiversity, including niche complementarity, positive interactions between species, and insurance effects. This paper presents a review of several representative experimental studies, including. Ecotron, Cedar Creek, microbial microcosm and BIODEPTH, and the associated debates about the interpretation of experimental observations.

Conservation genetics is a new field of research focusing on the studies and practices of biodiversity conservation based on the principles and techniques of population genetics. During the past decades, genetic studies have made increasingly great contributions to biodiversity conservation in theory and practice. In this paper, we briefly introduce the concept and history of conservation genetics, and highlight progress in plant conservation genetics. Four major aspects of conservation genetics in plants are addressed, including plant phylogenetic reconstruction and identification of conservation units, the relationship between genetic diversity and species fitness, population genetic structure and conservation strategies, as well as the identification and utilization of plant genetic resources. In addition, the great importance of genetic studies in plant conservation is discussed.

Biological invasions are a continuous feature of a non equilibrium world, ever more so as a result of accidental and deliberate introductions by mankind. While many of these introductions are apparently harmless, others have significant consequences for organisms native to the invaded range, and entire communities may be affected. Here we provide a survey of common models of range expansion, and outline the consequences these models have for patterns in genetic diversity and population structure. We describe how patterns of genetic diversity at a range of markers can be used to infer invasion routes, and to reveal the roles of selection and drift in shaping population genetic patterns that accompany range expansion. We summarise a growing range of population genetic techniques that allow large changes in population size (bottlenecks and population expansions) to be inferred over a range of timescales. Finally, we illustrate some of the approaches described using data for a suite of invasions by oak gallwasps (Hymenoptera, Cynipidae, Cynipini) in Europe. We show that over timescales ranging from 500～10000 years, allele frequency data for polymorphic allozymes reveal (a) a consistent loss of genetic diversity along invasion routes, confirming the role of glacial refugia as centres of genetic diversity over these timescales, and (b) that populations in the invaded range are more subdivided genetically than those in the native range of each species. This spatial variation in population structure may be the result of variation in the patchiness of resources exploited by gallwasps, particularly host oak plants.

Brushtail possums ( Trichosurus vulpecula ) were introduced into New Zealand from Australia in the mid 1800′s to establish a fur industry. They became a major invasive pest damaging native biodiversity by browsing and predation, and harming the farm industry by acting as reservoir of bovine tuberculosis. Management of possums includes eradication from some offshore islands and control by trapping, shooting and poisoning on the mainland. Although successfully eradicated from some islands and greatly reduced in abundance in some areas with high conservation value, possum distribution on the mainland has continued to expand. They are still at very high density in some areas and continue to cause biodiversity loss in this country. The efficiency of conventional control methods is affected by limited funding and rapid population recovery caused by re colonisation, higher reproduction rate and survival rate of possums in response to reduced density. Biological control, especially immunocontraception, is now being investigated as a cheaper and more effective option. Recent studies indicate that the polygynous mating system and some responses of male possums to female sterilisation would help the success of a potential virus vectored immunocontraception method.

Understanding the biology of alien invasive species (AIS) is a problem for pure, as well as applied biology. However, it is obviously not possible to conduct designed experiments to further our understanding. We can, however, study actual invasions; the next best thing. We used historical data from New Zealand to explore the correlates of successful establishment of species in a new environment. Surprisingly, biological differences between species explained little of the variation in establishment success. Instead, what matters is how often, and in what numbers, a species is introduced into the new environment.

The flora of Hong Kong has been well-surveyed since the mid nineteenth century and has had a long history of alien plant invasions. To the present day, more than 2130 wild plant species have been recorded, including 238 species that are probably naturalized alien species. Among them, Mikania micrantha, Ipomoea cairica, Eupatorium catarium, and Panicum maximum are most abundant. Naturalized alien plants are most prominent in human-disturbed habitats, such as abandoned farmland, wasteland and roadsides, and are rarely important in relatively undisturbed forest habitats, or in fire-maintained impoverished shrubland and grassland. Impacts of naturalized alien plants on local ecosystems are so far limited to lowland habitats, including wetlands and forest margins, where they form monospecific thickets, outcompete native plant species, and reduce local habitat and animal diversity. The biggest impact on the local flora by an alien species, however, was caused by the Pinewood Nematode introduced in the 1970s. Introduction of alien vertebrates may also have an impact on Hong Kong's vegetation. As the biggest port on the southern coast of China, Hong Kong has probably been an important entry point for alien species to China. Among Hong Kong's naturalized alien plants, some have only recently been noticed, and have few or no records from the mainland. The potential for these species to invade the mainland should not be neglected. Appropriate measures to control spread of these plants, both locally and regionally, are essential.

The impacts and invasion method of alien invasive species (AIS), and prevention and management of biological invasion are discussed. Biological invasion is becoming one of the most important factors threatening biodiversity and stability of various ecological systems in China. The impacts of these biological invasions are becoming a more serious problems with development and increase of global trade, transportation, international travel and ecological tourism. Harmful AIS often leads to irreversible species extinction, and results in substantial economic losses within managed and natural ecosystems, including agriculture, forestry, fishery and animal production. Newly invading weeds, insect pests and plant diseases frequently result in large scale outbreaks and persistent use of chemical pesticides. Successful invasion and spread of some major insect pests and weeds in China were caused by man made factors. These include decision mistakes and unintentional introduction of some plants, such as water hyacinth and alligator weed as pig food, irresponsible introduction actions taken by individual/group without any ecological concerns, and lack of rapid response mechanism for eradicating potentially AIS as soon as they appear. China is an agricultural country. Any biological invasion will be a "big bomb" for our agriculture and inevitably result in ecological and economic losses in specific ecosystem and specific geographic regions. Prevention of biological invasion is an important aspect for safeguarding the state′s ecological safety. Development and researches should focus on building the state capacity, research capacity, and management capacity for addressing AIS problem. Based on the urgent situation of AIS in China, priority for research and action plans concentrate on: developing methods to identify the origin and pathways of invasive population; understanding the biological and ecological bases of AIS; developing environmentally friendly methods for control of AIS; developing environmental impact assessment and risk analysis methods for AIS; and developing methods for the recovery of habitats after control of AIS.

The idea that greater diversity leads to increased community stability has long been contentious as a result of lack of consensus over the meanings of both diversity and stability in empirical studies and unrealistic models of communities in theoretical studies. Diversity and stability can occur in each biological structure level in ecosystems. However, only species diversity and community stability were involved in most of previous studies, which might be another major reason that there is no consensus on the issue. This paper presents an exploration of the relationship between diversity and stability of community and population, attaching great importance to the biological structure level of ecosystems in which diversity and stability are examined. We conclude, firstly, that prior to investigation on the relationship between diversity and stability, the biological structural level of both diversity and stability should be clearly identified, and some terms with respect to both diversity and stability should be recognized, such as phenotypic diversity, population diversity, species diversity, community diversity as well as population stability, community stability, ecosystem stability, etc. Secondly, four major properties included under the concept of stability, i.e., resistance, resilience, persistence and temporal variability, all contribute to stability and yet may have very different relationships with diversity under different disturbance regimes. We redefine these properties of stability in terms of the characteristics of disturbances, dividing them into two types. Resistance and resilience are measurements of stability when ecosystems are disturbed by abnormal disturbances, such as fire, drought, grazing, attack by insects or diseases, invasion of exotic species, etc. Persistence and temporal variability are measurements of stability under normal environmental fluctuations. Thirdly, the dynamics of stability at a given level of ecosystem may be strongly influenced by the patterns of diversity within this level. For example, community stability may be favored by population diversity as well as phenotypic diversity, while population stability ultimately depends on phenotypic diversity. Finally, with the discussions of related issues on diversity and stability in both community and population, this paper holds that, under specific premises, diversity may give rise to stability. Additionally, an assembly interpretation model with respect to the long term debate over the issue on diversity and stability is proposed. We analogise diversity and stability as two assemblies, and three basic corresponding relations may exist among the elements between this two assemblies. The first two are efficient correspondence and inefficient correspondence. The former implies that diversity would lead to stability, the latter implies that it would not. The third relation is unknown correspondence. In this case, the properties underlying these corresponding relations are still unknown due to our limited knowledge. This simple model is promising to reconcile the long term dispute over the issue on diversity and stability.