The annual dynamics of community structure and species diversity of rotifers in the Wuhu section of the Qingyi River was studied in the year 2003, and the relationships between rotifer density and ecological factors including water temperature, Chl-a concentration and river discharge were analyzed for further understanding of China rotifer fauna and the pattern of seasonal variation of rotifer density in rivers. One hundred and four rotifer species were identified, of which Cephalodella forceps, C. macrodactyla, C. mucronata, C. evabroedi, Lecane hornemanni, L. elsa, L. lunaris acus and Filinia camasecla were confirmed as new records in the subtropical region of China. The dominant species were Keratella cochlearis, Polyarthra vulgaris and Ascomorpha ecaudis.The total density of rotifers was positively related to water temperature and Chl-a concentration (r=0.533,P<0.05;r=0.548,P<0.05) during January-April (before flood season), but it was positively correlated with river discharge (r=0.580,P<0.01) during May-September (during flood season), and with water temperature,Chl-a concentration and river discharge (multiple-linear regression,R²=0.680,P<0.05) during October-December (after flood season). River discharge had the greatest effect on the total density of rotifers during October-December (standardized partial regression coefficient: β1=0.312, β2=0.120,β3=0.593). Across the year, species diversity index was positively associated with number of species and species evenness of the community (n=12,r₁=0.600,P<0.05; n=12,r₂=0.955,P<0.001), but negatively associated with dominance (n=12,r=-0.942,P<0.001).

Landscape has been defined as a land area with groups of plant communities or ecosystems forming an ecological unit with distinguishable structure, function, geomorphology, and disturbance regimes. Landscape diversity is the number of ecosystems, or combinations of ecosystems, and types of interactions and disturbances present within a given landscape. We explored dynamics of forest landscape diversity in Heilongjiang Province during 1949-1981. According to the map of forest resource distribution in 1949 and 1981, some representative quantitative indices of landscape diversity, including patch density, perimeter-area fractal dimension, aggregation, interspersion and juxtaposition index, Shannon′s diversity index, and dominance, were selected to describe the changes in the spatial pattern of landscape elements with the support of ESRI′S ARCGIS 8 and FRAGSTATS 3.3 software. The results showed that forest landscape spatial pattern in the region has tended to become fragmented, with Korean pine forest the most severely affected. Based on comparison of patch diversity, pattern diversity and type diversity, patches of primitive forest landscape decreased in abundance or were replaced by other landscape types, indicating that spatial variation of landscape pattern, as well as the diversity and evenness of the whole forest landscape declined over the 32 years, while dominance increased. Human irrational activities, such as unplanned logging and farming, changed landscape heterogeneity and resulted in changes in landscape diversity. Protecting natural forest resources, combining logging with afforestation, and sustainable use of forests is the only way to solve all of the problems.

The relationship between species diversity and ecosystem function is one of the core problem of biodiversity research, and productivity is an important modality of ecosystem function. The species diversity of natural communities is often strongly related to their productivity. The grassland is an important component of terrestrial ecosystems and plays a significant role in the biodiversity and ecosystem function. Understanding of how to use natural vegetation to restore deteriorated grasslands is critical for protection of grassland ecosystems. Moreover, the relationship between species richness and productivity relies on scales. At some scales, productivity affects diversity, and at other scales, species diversity also affects productivity. Thus, it is necessary to know the relationship between plant functional diversity and productivity in different grassland types. In 2003 the differences in plant functional diversity, functional composition and productivity in different grassland types of alpine meadow were analyzed. Humans are modifying both the identities and the numbers of species in ecosystems. However, the impacts of such changes on ecosystem processes are still controversial. The effects of functional diversity and composition on plant community productivity were analyzed in four types of alpine meadows. The research results show:(1) the effects of the legume functional group on productivity was greater than other functional groups in Kobresia humlis meadow and Potentilla froticosa shrub. (2) Although the biomass of forbs, C3 plants and sedge functional groups account for higher proportion of community productivity in Kobresia pygmaca meadow and K. tibetica swamp meadow, differences were not significantly different, indicating that the factors influencing community productivity were not only species diversity, but also the identity of species present and environmental resources. These factors were in turn mainly affected by species diversity and evenness among functional groups. That is, differences in functional group composition have a larger effect on ecosystem processes than functional group richness alone. (3) A significant correlation was found between the coverage per functional group and the primary productivity of communities in the four types of alpine meadows. (4) Changes in productivity with number of species per functional group showed a unimodal pattern, such that the maximum community productivity occured at an intermediate level of number of species per functional group.

We investigated ground bryophytes under artificial Pinus tabuliformis forests with four different slope aspects, i.e. NE80°(east facing slope, E), NW85°(west facing slope, W), SE10°(south facing slope, S), and NW20°(north facing slope, N) along the upper reaches of the Minjiang River, in order to explore bryophyte species composition and structural characteristics. Of the 13 bryophyte species occurring in the four artificial forests,only 6, 11, 12 and 7 species occurred in E, W, S , and N forest, respectively. Six moss species, Brachythecium glaciale, Thuidium cymbifolium, Entodon concinnus, Eurhynchium savatieri, Oxystegus cuspidatus,and Porella pinnata existed commonly in all the four forests. The highest frequency for bryophyte occurrence was 100% under W and N forests, and the lowest, under the E and S forests, was 96.7%. According to importance value, the dominant species were Brachythecium glaciale and Thuidium cymbifolium under all four Pinus tabuliformis forests, indicating that they were the most common moss species in the study area. For E, W, S and N forests, ground bryophyte coverage were 5.50%±0.90%, 25.66%±2.76%, 9.03%±1.76% and 7.93%±1.16%, respectively, while hoot density were 480.67±133.65, 2724.80±419.72, 982.00±191.33, 923.47±173.51 shoots/m2, respectively, and average bryophyte thickness were 4.73±0.31, 6.67±0.41, 6.83±0.73, 5.42±0.33 mm, respectively. No statistical differences（P>0.05）in structural parameter were found among E, S and N forests. By comprehensive analysis, it was found that W forest was the best of the four forests in bryophyte composition and synusia structures, indicating that slope aspect is one important environmental factor inducing differences of ground bryophyte composition and synusia structure, and indirectly affecting the survivorshipand growth of bryophytes.

Qinling fir, Abies chensiensis, is endemic to China and was listed in the China Plant Red Data Book as one of the third class protected plants. It is only found scattered in small forest fragments in Mts. Qinling, Bashan and Shennongjia from 1300 m to 2300 m a. s. l. in Shaanxi, Gansu，Henan, Sichuan and Hubei provinces. To assist in efforts to effectively conserve and restore this species, the geographic distribution, community structure and demographic characteristics of populations were studied through field investigations and statistical analysis. In the A. chensiensis communities in the Qinling Mountains, we recorded 102 plant species, belonging to 63 genera and 40 families. Among them, the temperate geographical elements comprise 84.21%, and the tropical geographical elements 15.79%. The communities in Qinling could be divided into five associations by cluster analysis on the importance values of the dominant species. The habitat of the communities was wet and shaded, and the coverage was relatively high. The structure of the communities was complex, and the age difference among individuals was significant. The natural regeneration of this species occurred mainly in canopy gaps on shaded slopes. The growth of young seedlings was relatively slow, but DBH increased relatively quickly during the 40－100 years stage, as did height during the 30－70 years stage. The sexual reproduction for this A. chensiensis population began at 30－40 years old, and the seed-bearing interval was about 3－5 years. Mature trees of A. chensiensis produced on average eight cones, and the mean number of seeds per cone was 56. The lack of seedlings was the main barrier for regeneration of this species. Insufficient seeds and low survival rate from seed to seedling were the weak link. In the future, in situ conservation should be considered as the most important management activity for this species, and natural regeneration should be promoted. At the same time, the artificial populations should be expanded from seeds collected in years of high seed set.

Using household-based agrobiodiversity assessment, we collected 31 upland rice varieties from three ethnic minority villages (Daka, Baka and Mannalong Villages) of Xishuangbanna, Yunnan Province, and investigated the management and utilization of them. Statistical analyses were conducted on the basis of agronomic and morphological characters. Based on the available data, we devised some in situ conservation strategies for upland rice resources. The results are as follows: (1) According to principal component analysis, the diversity of agronomic and morphological characters was mainly from the variation of production as well as the angle and shape of flag-leaf. The scatter plot diagram from the analysis of the first two principal components showed that the diversity of the upland rice varieties was much higher in Baka and Daka Villages than in Mannalong Village, and some varieties with good agronomic characters were found; (2) The cultures of different ethnic minorities, procedures of seed exchange among farmers, intercropping, and rotation of different varieties played important roles in the maintenance and improvement of upland rice variety diversity. Seed exchange among farmers of different villages or different ethnic minorities enriched the diversity of upland rice varieties, and intercropping and rotation of different varieties were beneficial to the evolution and hybridization of upland rice; and (3) protection of minority cultures and customs, promotion of indigenous knowledge of traditional management, encouragement of seed exchange, and training and guidelines from the government and institutes should be put in place for effective in situ conservation of upland rice resources in communities.

Arbuscular mycorrhizal (AM) fungi are important soil microorganisms in agroecosystems. Biodiversity among AM fungi in crop fields is influenced by many factors, including soil properties and plant species. In order to study AM fungal diversity in field soil of North China, we collected 127 soil samples from various crop fields from Shandong and Hebei provinces. Culture and purification of the mycorrhizal fungi led to the isolation of 22 species in five genera. Among these, 20 species were identified, including a new record for China, Glomus spurcum Pfeiffer, Walker & Bloss. The frequency of occurrence of the genus Glomus was the highest and Acaulospora was the second most common genus, while Glomus etunicatum and G. mosseae were dominant species. Spore density was affected by soil Olsen-P content and pH, while species diversity was little affected. Moreover, AM fungi species colonization and diversity was greatly affected by host plants. Although AM fungi hosted by maize and sweet potato had similar dominant species, there were differences in species composition.

The invasion of bullfrog (Rana catesbeiana) has become one of the main factors leading to population decline and extinction of some native amphibians. Although bullfrogs were introduced into mainland China in 1959, they were not wildly raised until 1990. Natural populations of the species in China have never been reported. We investigated bullfrogs in Zhoushan Archipelago and Ningbo area in the east of Zhejiang Province, China. Bullfrogs were found on Xiushan, Liuheng, Daishan and Fodu island. A total of 23 individuals of bullfrogs were captured on these islands from Sep. to Nov. 2003, including 4 adults, 18 juveniles and 1 tadpole. Twenty-eight tadpoles of bullfrogs were captured from Daishan between Jan. and Feb. 2004. This clearly shows that tadpoles of bullfrogs can over-winter and bullfrogs have successfully established their populations in the wild on these islands. Bullfrogs were mainly found in reservoirs, ponds and rivers, and share habitats with 6 indigenous frog species in this area. Escape from farms and release of live bullfrogs abandoned by bullfrog farmers due to falling profits are the main sources of the bullfrog invasion. There will be a great potential threat of bullfrogs to indigenous amphibians in the area. There is an urgent need for greater understanding of the diet, distribution and population dynamics of the bullfrog in China.

How the traits of invasive plants determine their invasiveness is one of the major issues in invasion biology. Invasive plants usually have broad ecological amplitudes, and hence can exploit a great diversity of habitats. Genetic differentiation and phenotypic plasticity are two major strategies that invasive plants can use to invade broad geographical areas and diverse ecosystems. Phenotypic plasticity is a trait that has a certain genetic basis and can evolve independently. Although some of the invasive plants have low genetic variation, they can still invade diverse habitats. Phenotypic plasticity may play a critical role in invasion of these species into new environments. In this review, the concept of phenotypic plasticity and its significance for adaptation were introduced. The relationship between phenotypic plasticity and the invasiveness of alien plants was discussed, supported by theoretical analysis and published experimental evidence.We also suggest some issues that might be addressed in future studies for better understanding of the mechanisms of successful invasion with reference to phenotypic plasticity. Although successful invasion cannot be explained by phenotypic plasticity alone, the positive correlation between invasiveness and phenotypic plasticity seems to be a rule rather than an exception for those invasive species with low genetic diversity but a broad geographic distribution.

In this paper, the effect of soil management practices and environmental factors on soil microbial diversity are reviewed and the methods for studying soil microbial diversity are briefly introduced. Soil microbial diversity includes microbial species diversity, genetic diversity and ecological diversity. Culturing techniques using a variety of culture media are used traditionally to analyze soil microbial communities, but only a small fraction of soil microbial community has been cultured and isolated. Recently several modern methods including Biolog analysis, phospholipid fatty acid analysis and nucleic acid-based analysis have been utilized internationally to study and characterize soil microbial diversity. Soil microbial diversity is affected by many factors including management practices. Application of pesticides usually causes declines in soil microbial diversity or changes in its structure and function. Organic manures are commonly reported to maintain soil microbial diversity and activities, but reports on the effects of inorganic fertilizers have been contradictory. Generally speaking, microbial diversity is higher and biomass is larger in agricultural soils cultivated with reduced tillage and crop rotation than in those soils cultivated with conservation tillage and monoculture. Soil microbial diversity may also be influenced by soil organic matter, vegetation, seasonal change, and usually suffer from stresses such as drought, overgrazing, and nutrient deficiencies.

Allelopathy is a phenomenon of direct or indirect, beneficial or adverse effects of a plant on its own or another plant through the release of chemicals into the environment. It affects plant distribution, community formation, and intercrop evolution. It has a consanguineous relationship with biodiversity conservation, agriculture, forestry, and horticulture and is now arousing further international interest. In China, research on plant allelopathy began relatively late and thus has been limited, particularly studies of fern allelopathy. We introduce recent advances in fern allelopathy, including studies of autotoxicity of ferns, and of allelopathic interactions occuring in two ways: (1) sporophytes acting on gametophytes and (2) gametophytes acting on gametophytes. Fern autotoxicity is a type of intraspecific allelopathy, whereby a fern species inhibits the growth of its own kind through the release of toxic chemicals into the environment. Sporophytes acting on gametophytes and gametophytes acting on gametophytes are common phenomena of interspecific fern allelopathy. In addition, allelopathic effects between ferns and seed plants are discussed. Some ferns can compete with seed plants by fern allelopathy to obtain more resources and space, while some seed plants can inhibit the growth of ferns by allelopathy. Fern allelopathy also has relationships with consumption by animals and microbial infection. Insect herbivory can amplify or dampen the effects of fern allelopathy. Activity of microbes may amplify the allelopathic effects of some ferns. Impacts of fern allelopathy on biodiversity are discussed from the different perspectives described above.