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Vegetation green aboveground biomass is an important parameter of terrestrial ecosystem process-based models, and is closely related to photosynthetic activity. In this paper, the hyperspectral predictors for estimating green aboveground biomass were evaluated based on field spectral and corresponding biophysical parameter measurements during the growing seasons of 2009 and 2010 in the desert steppe of Inner Mongolia. Results showed that the performance of red-edge reflectance curve area (between normalized reflectance curve and wavelength in 680–780 nm region) was better than that of traditional vegetation indices (VIs) and red-edge position (REP). The model based on red-edge reflectance curve area produced a lower standard error of prediction (26.4 g m−2) compared with the optimal narrow-band ratio vegetation index (RVI) (37.4 g m−2), normalized difference vegetation index (NDVI) (33.5 g m−2), soil-adjusted vegetation index (SAVI) (37.5 g m−2) and modified soil-adjusted vegetation index (MSAVI) (38.6 g m−2). Statistical analyses performed on the slopes and intercepts of the fitted lines between actual and predicted values demonstrated that no statistical differences (P > 0.05) were found in regards to slope = 1 and intercept = 0 for red-edge reflectance curve area and optimal SAVI and MSAVI, whereas the slope and intercept based on optimal RVI were different (P < 0.05) from 1 to 0 respectively, and the slope based on optimal NDVI was different (P < 0.05) from 1. In conclusion, the red-edge reflectance curve area method is a practical and suitable technique for complementing the existing methods on estimation of green aboveground biomass in arid and semi-arid areas. [Copyright &y& Elsevier]

Large scale process-based modeling is a useful approach to estimate distributions of global net primary productivity (NPP). In this paper, in order to validate an existing NPP model with observed data at site level, field experiments were conducted at three sites in northern China. One site is located in Qilian Mountain in Gansu Province, and the other two sites are in Changbaishan Natural Reserve and Dunhua County in Jilin Province. Detailed field experiments are discussed and field data are used to validate the simulated NPP. Remotely sensed images including Landsat Enhanced Thematic Mapper plus (ETM+, 30m spatial resolution in visible and near infrared bands) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER, 15m spatial resolution in visible and near infrared bands) are used to derive maps of land cover, leaf area index, and biomass. Based on these maps, field measured data, soil texture and daily meteorological data, NPP of these sites are simulated for year 2001 with the boreal ecosystem productivity simulator (BEPS). The NPP in these sites ranges from 80 to 800gCm−2 a−1. The observed NPP agrees well with the modeled NPP. This study suggests that BEPS can be used to estimate NPP in northern China if remotely sensed images of high spatial resolution are available. [Copyright &y& Elsevier]

Abstract: The Changjiang (Yangtze River) is known to contribute significantly to the eutrophication that has caused drastic changes to the ecosystem of the East China Sea. However, evidence for historical changes in nutrient concentrations and composition and the consequent effects on the ecosystem in the coastal water is sparse. In this paper we present some long-term data for nutrient concentrations and Si:N:P ratios in the freshwater and the river plume and the long-term response of the ecosystem structure in the river plume. These data reveal increases in the dissolved inorganic nitrogen and phosphate concentrations in the Changjiang freshwater by a factor of five from the1960s to the end of the 1990s and a reduction in dissolved silicate by two thirds over the same period. Concomitantly, an increase in DIN concentration and a reduction in silicate concentration both by a factor of two were observed in the surface water of the Changjiang plume. As an ecological consequence to such nutrient changes, the chlorophyll a concentration increased by a factor of four since the 1980s and harmful algal blooms increased rapidly since 1985 in the Changjiang estuary and adjacent sea areas. The macrozoobenthic biomass decreased sharply from the mid 1980s to the present, suggesting that the Changjiang estuary has been in a high eutrophication state since that time. We predict that, due to the continuously increasing nutrient pressure, the symptoms of eutrophication associated with nutrients will worsen in the Changjiang plume in the near future. [Copyright &y& Elsevier]

Abstract: This paper examines spatial and temporal variations of mesozooplankton abundance, biomass and community structure during three cruises of July 2002 (summer), January 2003 (winter), and April 2003 (spring) in the Pearl River estuary, China. Zooplankton abundance and biomass fluctuated widely and showed distinct heterogeneity in the Pearl River estuary. A total of 154 species were identified during three surveys. The number of zooplankton species richness was strongly linked to salinity. Hierarchical cluster analysis identified three zooplankton groups during this study. Estuarine, neritic and pelagic groups corresponded to the upper, middle and lower reaches in the Pearl River estuary. The difference among groups could be mainly ascribed to changes in the relative contributions of the dominant species. The fluctuations in the zooplankton abundance, biomass and community structure were determined by the interactive effects of freshwater inflow, tidal and coastal currents, chlorophyll a, salinity and temperature. Significant spatial variability in the distribution of zooplankton species, abundance and biomass can be ascribed to the virtual presence of a horizontal gradient in salinity. [Copyright &y& Elsevier]