Based on remote sensing and GIS technology,the authors analyzed two-way succession processes of natural and man-made wetlands and impacts of natural environmental features on the processes in Sanjiang Plain during 1986-2005.Results showed that two-way succession processes of wetland in Sanjiang Plain were characterized with mutual transformation between marsh and paddy field from 1986 to 2005.During the periods of 1986-1995,1995-2000 and 2000-2005,ratios of transformation area from marsh to paddy field to total area of transformed marsh were 7.61%,37.99% and 28.81%,respectively,while ratios of transformation area from paddy field to marsh to total area of transformed paddy field were 4.83%,13.69% and 4.84% respectively.Main natural environmental features in relation to two-way succession between marsh and paddy field in Sanjiang Plain were characterized by being the regions of meadow soil and marsh soil,elevation of 0-100 m,slope gradient of 0-1°,physiognomies of low flood plain,high flood plain,depression and first terrace.

Based on the research in 36 different sites with different pinus massoniana mixed proportion and invasion extent of Bursaphelenchus xylophilus in Fuyang,Zhejiang Province,the authors analyzed the change of community diversity of all forest types in arbor,shrub and herb layers after invaded by Bursaphelenchus xylophilus.The results showed that invasion of B.xylophilus tended to reduce the differences in diversity of arbor,shrub and herb layers in pinus massoniana community of different forest types.However,much heavier invasion of B.xylophilus resulted in a new feature in diversity indexes of all forest types,showing a trend of reciprocating between polarization and consistency.Furthermore,successional stages of community in Fuyang,Zhejiang Province were processing from early stage to middle stage of evergreen broadleaved forest;whilst the increase of composite disturbance accelerated such successional stages.

Handeliodendron bodinieri is an epibiotic single-species of plant unique to China in limestone regions.Because of destructive human activities,its peculiar habitat and its own characteristic,this rare species is endangered,and hence it has been listed as one of the first-level preservation plant species under state protection.Handeliodendron bodinieri population in Mulun Nature Reserve was investigated based on sampling plot and sampling line in order to clarify its population structure,dynamic character and distribution pattern.Size structure and height structure of Handeliodendron bodinieri population were analyzed.Point pattern analysis was applied and the spatial characteristics were described effectively by Ripley s K(d) function in this paper.The results showed that population of Handeliodendron bodinieri was declining due to lack of its seedlings,and distribution pattern of population was mainly random.Distribution pattern of Handeliodendron bodinieri population was primarily affected by the factors including its reproduction characteristics,habitat feature of limestone region,intraspecific and interspecific competition and so on.

The authors investigate the effects 01 three different substrates on physiological characteristics of Fagus longipetiolata seedlings with pot experiments in this study.The results show that emergence rate of F.longipetiolata seedlings planted in substrate of general garden soil mixed with common sand reaches to 93.33%,followed by those planted in general garden soil substrate,with emergence rate of 90%,and the rate of those planted in common sand substrate is the lowest,which is at 76.67%.F.longipetiolata seedlings planted in substrate of general garden soil mixed with common sand have the earliest first euphylla time of 26 days,maximum averaged euphylla number of 6 pieces,and the highest averaged plant height of 16.87 cm.They are remarkably superior to those planted in substrate of general garden soil,while common sand substrate is not suitable for the growth of F.longipetiolata seedlings.The experiments reveal that F.longipetiolata seedlings are fairly sensitive to substrates,and that F.longipetiolata seedlings planted in substrate of general garden soil mixed with common sand have the advantages of high germination rate and growth rate.

Through systematic sampling surveys along altitudinal gradient,the authors analyze the trend of changes of species diversity of wood and herb layers of plant communities along altitudinal gradient,meanwhile preliminarily explore the correlation between species diversity of plant communities and soil characteristics on the northern slope of Laotudingzi Mountain,Liaoning Province by using species richness index,a diversity index and β diversity index.The results show that species diversity of wood layers declines with fluctuation with an increasing altitude,while species diversity of herb layers shows a trend of decreasing first but increasing later.Replacing speed of species diversity index is high in the transition zone between different communities.Major soil types are brown forest soil and dark brown forest soil with high organic matter content on the northern slope of Laotudingzi Mountain.There is a negative correlation between species diversity of plant communities and soil characteristics.

Monitoring of marine environment was conducted in Weizhou Island,Guangxi in late September,2008 after an oil spilling event occurred,and community structure of phytoplankton was analyzed based on investigation data.The results showed that 106 species belonging to 44 genera were identified,including diatoms of 92 species in 35 genera,pyrrophyta of 12 species in 7 genera,cyanobacteria and chromophyta of 1 species in 1 genus each.The main dominant species included Chaetoceros curvisetus,Thalassionema nitzschioides and Chaetoceros lorenzianus.Distribution of phytoplankton was homogeneous.Average density of phytoplankton was 2 645.32×10⁴cells×m^-3 with a relatively higher cell density in the northwest,lower in the southwest around Weizhou Island.Abundance distribution of dominant species was generally similar with phytoplankton density.Shannon-Wiener(H') and Pielou(J') indices indicated that phytoplankton community was stable.In contrast to other relative researches,reports and data from State Oceanic Administration,our results suggest that in oil spilling ocean phytoplankton composition varied little,and phytoplankton density decreased less.Main dominant species were obviously subrogated and community structure was stable.Quick response to oil spilling emergency in marine ecosystem must be required.

The authors study landscape pattern and ecological value of shelter forests in Dongshan Island by landscape ecological theory and quantitative valuation method of forest environmental value.Some landscape indicators including patch density,edge density,fractal dimension of patches,landscape diversity,landscape dominance and Shannon's evenness index were selected to analyze the spatial distribution and spatial pattern feature of shelter forest landscape types in Dongshan Island.The service function of the forest ecosystem was evaluated using market valuation method etc.from the viewpoints of small scale shelter forest ecosystem and important ecological service function.Results showed that landscape pattern of shelter forests in Dongshan Island was greatly affected by human activities,and that averaged value of service function of shelter forests in Dongshan Island adds up to 39.45×10⁶-92.55×10⁶ yuan in terms of CO₂ fixation,O₂ release,wind protection and sand stabilization.

One thousand and twenty nine bp sequence of partial mitochondrial cytochrome b gene of 21 individuals representing 2 populations in the Pearl River(PR) system and 1 population in Han River(HR) in South China was sequenced,and 11 haplotypes and 14 variable sites were detected.Haplotype diversity(h) and nucleotide diversity(π) were much lower in population from HR (h=0.464 and π=0.000 97) than those in populations from Zuojiang and Yujiang in the PR system(h=0.929-1,π=0.023 6-0.036 9).Individuals from different locations in neighbor-joining tree were intertwined showing neither genealogical nor geographic clusters.Pairwise comparison of Fst and AMOVA analysis indicated that there was no significant genetic divergence among 3 populations.As expected from star-like networks,F_S tests and Tajima's D tests of whole population were significantly negative,and mismatch distributions were unimodal,indicating a Pleistocene population expansion at about 164 000-66 000Ka BP.

Data of 1024 samples (0-20cm) collected from a 10.24 hm² cropland in a dense grid of 10m×10m were used to analyze and quantify spatial variability of soil organic matter(SOM) by geostatistical method.Within the study area,soil organic matter had weak variability as CV = 1.84%,but it was entirely low in the content no more than 1.04%.The semi-variogram of soil organic matter after eliminating the trend had low nugget variance 0.00005,small ratio of nugget to sill 0.135 and long range 145.5m.The standard variance of Kriging estimation 0.00943% was also extremely low.Our results showed soil organic matter had strong spatial dependence across the cropland and the spatial correlation range was very large.

Caragana korshinskii,C.leucophloea,C.acanthophylla and Atraphaxis virgata are four important species composed of vegetation around Urumqi,and they have a great potential in recovering degraded vegetation.In this study,physiological responses of four shrub seedlings to artificially simulated drought stress were studied.The results showed that leaf water content and chlorophyll content of four shrub seedlings decreased with increased drought stress.Proline accumulation was much more significant than soluble sugars under drought stress conditions.MDA accumulation was not significant (P>0.05) for all shrub seedlings except C.acanthophylla.Our results indicated that four shrubs can adapt to arid environments by adopting different strategies under drought stress conditions,and that drought resistance in descending order of four shrubs was C.leucophloe>C.korshinskii>A.virgata>C.acanthophylla.

An extreme disaster of snow and cold took place at the beginning of 2008 and caused great damage to vegetation in South China.Taking Guangdong as an example,the authors analyze NDVI changes of damaged vegetation and healthy vegetation using MODIS data,extract distribution information of damaged vegetation through ISODATA algorithm of unsupervised classification method,and study the relationships between damaged vegetation and topography factors using 90 m SRTM DEM data.The results showed that vegetation in Guangdong was damaged seriously,with a damaged area reaching to 19 011.06 km²,and it was greatly affected by topography factors such as elevation,slope and aspect.Damaged vegetation mainly distributed in shady hillside with elevation higher than 400 m and slope less than 15°Through overlap analysis between IGBP vegetation map and damaged vegetation,it was found that damaged vegetation mainly covered the evergreen broadleaf forest,mixed forest,deciduous broadleaf forest,shrubbery,deciduous coniferous forest and evergreen coniferous forest.

Five hundred and thirty three bp sequence of partial mitochondrial ND4-tRNA^Ser gene of 18 individuals of lacustrine Plecoglossus altivelis population from Dongzhang Reservoir,Fujiang Province was determined,and 4 haplotypes,2 variable sites and 2 parsimony-informative sites were detected.Genetic distance based on Kimura 2-parameter model among 4 haplotypes ranged from 0.001 9 to 0.003 9.No obvious genealogical clusters were found in neighbor-joining tree.Haplotype diversity(Hd) and nucleotide diversity(Pi) were 0.627 and 0.001 37 respectively with average nucleotide difference 0.732 in the population,which were much lower than in Plecoglossus altivelis altivelis in Japan(Hd=0.793,Pi=0.002 94),but similar as compared with Plecoglossus altivelis ryukyuensis,an endangered subspecies listed in IUCN(Hd=0.519,Pi=0.001 11).Further studies are still needed to make clear the reasons responsible for such poor genetic diversities in Dongzhang reservoir populations;meanwhile urgent measures should be taken to conserve the valuable fishes.

Land use change is a major factor affecting ecosystem services.Taking Xiamen Island as an example,the authors examine the land use patterns from 1950 to 2007 by integrating remote sensing data and evaluate the regional ecosystem services based on two revised methods so as to identify the effects and mechanisms of land use change on ecosystem services.The results showed that during 1950-2007 land use intensity of Xiamen Island had been annually rising generally.The changing trends of ecosystem service value of Xiamen Island obtained by two methods were consistent,which were decreased with the decreasing of land use intensity.Before 1987,ecosystem service value of Xiamen Island had increased by about 1.07 million yuan due to the expanding of 12.87km² water and wetland areas.Since the establishment of Xiamen Special Economic Zone in 1984,rapid urbanization has resulted in a sharp decline in ecosystem service value,and average annual loss reached to 619 773 yuan after 1987.With the utilization of land reaching saturation and launching of ecological projects,such as the Xiamen Eastern Sea Comprehensive Improvement Project,it can be predicted that decreasing trend of ecosystem service value is going to slow down in the near future.The problem of overestimating service value by correction made from a single aspect can be solved by applying ESV total correction method.

Landscape pattern and its change in the Pearl River Delta (PRD) are very complicated.Especially,within three decades of reform and opening-up,the landscape pattern of the PRD has changed with rapid economic growth and urbanization process.With an increasing concern to development of ecological environment,greater attention of many scholars and researchers is being paid to investigating change of ecological landscape in the PRD.In addition,with the rapid development of remote sensing (RS),geographic information system (GIS) and global positioning system (GPS) technologies,it has been a hot spot to monitor and study landscape pattern and change by integrating 3S technology.Meanwhile,many studies have been carried out and some results have been obtained based on 3S technology concerning dynamic changes of landscape pattern in the PRD.However,because application of landscape ecology in the PRD is in an early stage,not all issues have been systematically explored.In this paper,the application of 3S technology used in studying landscape pattern and change of the PRD is discussed,and then some expectations are also put forward,so as to provide some necessary references and support for monitoring and studying changes of landscape pattern in the PRD.

With the rapid development of urbanization,urban air pollution,which exacerbates degradation of urban vegetation and loss of ecological services,becomes more serious.Pollutants in air such as O₃,UV-B radiation,heavy metals,SO₂ and their compound pollutions induce ecological stress on urban vegetation in different levels of molecule,cellule,individual,population,community and ecosystem.In this paper,the authors analyze and summarize the results and methods of previous researches related to ecological stress effects of air pollution on urban vegetation.At the same time,some important research areas,which should be paid more attention to in the future,are proposed including field and long-term stress experiments,combined stress effects,action mechanism for air stress on plants and important role of buildings on ecological stress of urban air pollution,and so on.Finally,the authors point out that related research on urban street trees should be strengthened particularly.