The Yangtze River estuary is an important ecoregion. However, Spartina alterniflora, native toNorth America, was introduced to the estuary in the 1990s through both natural dispersaland humans and now it is a dominant species in the estuarine ecosystems, with its invasionsleading to multiple consequences to the estuary. S. alterniflora had great competitiveeffects on native species, including Scirpus mariqueter and Phragmites australis, and couldpotentially exclude the natives locally. The presence of S. alterniflora had little influenceon the total density of soil nematodes and macrobenthonic invertebrates, but significantlyaltered the structure of trophic functional groups of nematode and macrobenthonic invertebratecommunities. The conversion ofmudflats to Spartina meadows had significant effectson birds of Charadriidae and Scolopacidae, which might be attributable to the reductionof food resources and the physical alterations of habitats for shorebirds. S. alterniflora invasionsincreased the primary productivity of the invaded ecosystems, and altered carbonand nitrogen cycling processes. Our studies focused mainly on the effects of S. alterniflorainvasions on the structure of native ecosystems; thus further studies are clearly needed toinvestigate how ecosystem functioning is affected by the modification of the structure ofestuarine ecosystems by S. alterniflora invasions.

Horizontal spatial patterns of chlorophyll a in Meiziya Reservoir, Hubei Province, China were analyzed once each month during May, June and July 1997. Two geostatistical techniques, semivariance and fractal analysis, were used to determine variation in chlorophyll a over the whole study area (isotropic) and in different directions (anisotropic). Both techniques provided useful information for detecting and assessing spatial pattern changes of chlorophyll a in freshwater environments. Based on our case study, the distribution of chlorophyll a shifted from aggregated to random distribution in the case of small rainfall event, and then returned to the aggregated distribution after a large rainfall event. On the other hand, the distribution of chlorophyll a became more heterogeneous or random in the direction of water flow (S-N direction) when rainfall events occurred, which was enhanced by rainfall intensity. In contrast, the influence of water flow on the spatial patterns was weak in the E-W direction, and thus the distribution of chlorophyll a remained aggregate with a moderate spatial heterogeneity.

Chongming Island is the world’s largest alluvial island. Its coastal wetland and tidal flats provide many important ecological services including buffers against tidal surges and staging areas for migratory birds. Due to its extraordinary resources, scenic qualities, and its proximity to the city of Shanghai 45km away, the island is also an attractive tourist destination, and it supports important agricultural and fisheries economies. Yet, large-scale land reclamation projects that are severely affecting these ecosystems have been implemented. In this paper, we report an investigation of changes in land use and ecosystem services on Dongtan (East Beach of Chongming Island) between 1990 and 2000. We used three LANDSAT TM and/or ETM data sets to estimate changes in the size of five land-cover/land-use categories, and we also used previously published value coefficients to estimate changes in the value of ecosystem services delivered by eachland category. Finally, we ranked the contribution of various ecosystem functions to the overall value of the ecosystem services. We determined that the total value of ecosystem services in Dongtan eclined by 62% from $ 316.77 to 120.40 million per year between 1990 and 2000 (totaling $855.26-981.85 million over 10-years). This massive decrease is largely attributable to the 71% loss of wetlands/tidal flats. Our sensitivity analysis suggested that these estimates were relatively robust. We also found that the contribution of water regulation, water supply, aste treatment, and raw materials increased, while the contribution of nutrient cycling, food production, disturbance regulation, recreation, abitat/refugia, and biological control decreased during the 10-year time period. We conclude that future land-use policy formulation should give precedence to the conservation of these ecosystems over uncontrolled reclamation, and that further land reclamation should be based on rigorous environmental impact analyses.

Functional zones in cities constitute the most conspicuous components of newly developed urban areas, and have been a hot spot for domestic and foreign investors in China, which not only show the expanse of urban space accompanied by the shifts both in landscape (from rural to urban) and land use (fromless extensive to extensive), but also display the transformation of regional ecological functions. By using the theories and methods of landscape ecology, the structure of landscapes and landscape ecological planning can be analyzed and evaluated for studying the urban functional zones'layout. In 1990, the Central Government of China declared to develop and open up Pudong New Area so as to promote economic development in Shanghai. Benefited fromthe advantages of Shanghai's location and economy, the government of Pudong New Area has successively built up 7 different functional zones over the past decade according to their unctions and strategic goals. Based on the multi2spectral satellite imageries taken in 1990, 1997 and 2000, a landscape ecology analysis was carried out for Pudong New Area of Shanghai, supported by GIS technology. Green space (including croplands) and built2up areas are the major factors considered in developing urban landscape. This paper was mainly concerned with the different spatial patterns and dynamics of green space, built2up areas and new buildings in different functional zones, as influenced by different functional layouts and development strategies. The rapid urbanization in Pudong New Area resulted in a more homogeneous landscape. Agricultural landscape and suburban landscape were gradually replaced by urban landscape as the degree of urbanization increased. As a consequence of urbanization in Pudong, not only built2up patches, but also newly2built patches and green patches merged into one large patch, which should be attributed to the construction policy of extensive green space as the urban development process in Pudong New Area. The shape of green area of 7 functional zones became more and more regular because of the horticultural needs in Shanghai urban planning. Some suggestions were finally made for the study of future urban planning and layout.

Compared to other ecosystems, estuarine ecosystems have distinct carbon lux dynamics – the lateral carbon flux incurred by tidal activities, and methane generation under the anaerobic conditions of wetland soils. The conventional estimation of gross primary production (GPP) based on the light use efficiency (LUE) model used for non-wetland terrestrial ecosystems, therefore, cannot be applied directly to estuarine wetland ecosystems. In this paper, we estimated the 2005’s annual carbon budget of an estuarine wetland on Chongming Island, Shanghai, and partitioned the losses of carbon due to lateral tidal dynamics and anaerobic methane production using an innovative technique. The average GPP calculated from eddy covariance between March and November was 261.79 lmolm 2 day 1, whereas that from the LUE model was 58.84 lmolm 2 day 1. The correlation coefficient between GPP simulated from the LUE model and that calculated from flux tower data was low in the growing season (R250.55). We ypothesized that tidal activities and uncounted methane release were responsible for the difference, which can be predicted from measurements of remote sensing products such as land surface water index (LSWI), evapotranspiration (ET), and tide height (TH).We developed an integrated GPP model by combining the LUE model and an autoregression model to estimate carbon budget. The average GPP from the modified model increased to 263.38 lmolm 2 day 1, and R2 for the correlation between the simulated and calculated data increased to 0.88, demonstrating the potential of our technique for GPP estimation and quantification of seasonal variation in estuarine ecosystems. The approach developed in this study has great potential for correcting unavoidable errors when estimating carbon budget of coastal wetlands. Furthermore, global warming is expected to accelerate sea level rise, which may enhance the effect of tidal activities and increase the difficulty in estimating coastal carbon budgets using conventional methods.

As invasive plants in different life stages have different recovery potential against devegetation operation, how to optimize the proper timing (the time for single treatment or the starting time for repeated treatments) for eliminating them becomes an important topic in the management of invasive plants. The invasive plant Spartina alterniflora was selected in this study, and it was clipped as a devegetation example to examine how important treatment timing is for increasing control efficiency. The results illustrated that by either single or repeated clipping treatments within 1 year, clipping at florescence was more efficient for controlling S. alterniflora. On the other hand, increasing clipping frequency without proper timing might not enhance control fficiency, suggesting that treatments in proper timing might reduce the clipping frequency required for a specific control target. From a management point of view, each control method has its optimal treatment timing, thus, in order to improve the control efficiency, the control programs should be ideally designed in relation to the phenology of the target plant. Besides, repeated clipping showed significantly higher control efficiency in low tidal zone than in high tidal zone, implying that habitat dependence of invasive plant control efficiency is an important issue in the management of invasive plants.

Many invasive plants are highly tolerant of disturbances and can invade various habitats, leading to difficulties in managing them. Most of control techniques need to be performed repeatedly, and the efficiency of the same control method may vary along environmental gradients. To develop a control strategy for an invasive plant in heterogeneous environments, it is important not only to optimize the control regime, but also to consider the efficiency in different habitats. We conducted a field experiment to test ow clipping regime (i.e., initial treatment timing and treatment interval) and habitat type (i.e., high and low tidal zones) influence the control efficiency for invasive Spartina alterniflora in an estuarine salt marsh. Among the 12 treatments, double-clipping treatment performed in early July and mid September (9- week-interval) had the highest efficiency, which not only eliminated sexual reproduction of S. alterniflora, but also inhibited its vegetative growth in the current and following years. The clipping efficiency in low tidal zonewas higher than that in high tidal zone. Therefore, an optimized control strategy for the invasive plants could be established based on the efficient control regime and habitat types. According to our study, a recommended double-clipping control strategy for S. alterniflora is that the initial clipping treatment is performed in the flowering period and the second one is performed 9 weeks later. In order to effectively reduce proliferation of the invasive plant, we suggest that the clipping regime should be applied for at least 2–3 years in low tidal zone and 3–4 years in high tidal zone.

Invasive plants strongly affect physical and biotic environments of native ecosystems. Insects and other arthropods as one of the major components of many ecosystems are very sensitive to subtle changes in abiotic and biotic environments. We examined the effects of exotic Spartina alterniflora invasion on community structure and diets of arthropods in a saltmarsh previously dominated by native Phragmites australis in Yangtze River stuary through net sweeping and plant harvesting methods and stable isotope analysis. Our results showed that diversity indices were not significantly different between exotic and native plant communities, but the total abundance of insects estimated through plant harvesting method was found to be lower in Spartina monoculture than that in Phragmites monoculture. Community structure of insects in Spartina monoculture was dissimilar to that in Phragmites monoculture and Phragmites–Spartina mixture. Moreover, stable carbon isotope patterns of arthropods were significantly different between Phragmites and Spartina monocultures. Although some native arthropods (perhaps generalists) shifted their diets, many native taxa did prefer Phragmites to Spartina even in Spartina monoculture. Spartina invasions resulted in reduced abundances of some arthropds, and increased dominance of others feeding preferably on Spartina. This study provides vidence that invasive plants can change the community structure and diets of native arthropods, which will eventually alter the arthropod food web, and affect the integrity and functioning of native ecosystems within a nature reserve that has been set aside for conserving the native biodiversity and maintaining the ecosystem integrity. In this sense, Spartina invasions in the Yangtze River estuary need to be managed appropriately.

Frequent and continuous time series is required for the detection of plant phenology and vegetation succession. The launch of novel remote sensor MODIS (moderate resolution imaging spectroradiometer) provided us with an opportunity to make a new trial of studying the rapid vegetation succession in estuarine wetlands. In this study, the spatiotemporal variations of vegetation cover and tidal flat elevation along a transect (covering 6 pixels of MODIS) of an estuarine wetland at Dongtan, Chongming Island, in Yangtze River estuary, China were investigated to assess its rapid vegetation succession and physical conditions. By combining the field data collected, the time series of MODIS-based VIs (vegetation indices), including NDVI (normalized difference vegetation index), EVI (enhanced vegetation index) and MSAVI (modified soil adjusted vegetation index), and a water index, LSWI (land surface water index) were utilized to haracterize the rapid vegetation succession between 2001 and 2006. We found that NDVI, EVI and MSAVI exhibited significant spatial and temporal correlations with vegetation succession, while LSWI behaved in a positive manner with surface water and soil moisture along with the successional stages. In order to take the advantages of both VIs and water index, a composite index of VWR (vegetation water ratio) combining LSWI and EVI or MSAVI was proposed in this paper. This index facilitates the identification of vegetation succession by simply comparing the values of VWR at different stages, and therefore it could track vegetation succession and estimate community pread rate. Additionally, this study presented an attempt of using MODIS datasets to monitor the change of tidal flat elevation, which demonstrated a potential remote sensing application in geodesy of coastal and estuarine areas.