Abstract:Methane is one of the principal greenhouse gases. Irrigated rice paddies are recognized as contributing to atmospheric methane concentration. Methane emissions from rice paddies are among the most uncertain estimates in rice-growing countries. Efforts have been made over the last decade to estimate CH₄ emissions from Chinese rice paddies via the model method. However, these estimates are very vague due to different models and upscaling methods. A reduction in these uncertainties may be achieved by coupling field-scale models with regional databases. The objective of this article is to develop a methodology of coupling a CH₄ emission model with regional databases by which CH₄ emissions from Chinese rice paddies can then be estimated. CH4MOD, a model for simulating CH₄ emissions from rice paddies with minimal input by using commonly available parameters, is of great potential in terms of upscaling as it has provided a realistic estimate of the observed results from various soils, climates and agricultural practices. By linking spatial databases to CH4MOD, CH₄ emissions from Chinese rice paddies in the 2000 rice-growing season were simulated on a day-by-day basis. The spatial databases were created by GIS with a spatial resolution of 10km10km, including soil sand percentage, amounts of crop straw and roots from the previous season and farm manure, the water management pattern, dates of rice transplanting and harvesting, acreage of rice planted, rice grain yield and daily air temperature. ARCGIS software was used to meet all GIS needs, including data access, projection definition, overlaying of different vector layers, creation of grids (a raster format of ARCGIS software) by converting vector data, and the data conversion between grids and ASCII formats. Methane emissions from rice paddies in mainland China in the 2000 rice-growing season were estimated to be 6.02 Tg (1 Tg = 10⁹ kg). Of the total, approximately 49% (2.93Tg) is emitted during the single rice-growing season, and 27% (1.63Tg) and 24% (1.46Tg) are from the early and late rice-growing seasons respectively. It was concluded that regional CH4 emissions from rice paddies could be estimated by coupling CH4MOD with regional databases with a high spatial resolution. A further effort should be made to improve the quality of the spatial databases, especially in terms of the amount of added organic matter and the water regime. It is also necessary to evaluate the uncertainties of the present estimates in order to improve the overall accuracy.

Abstract:Pollution from the oil shale dump in Maoming, Guangdong Province, China, was a major social problem due to the great amount of environmental damage it caused. Therefore, a great deal of attention needed to be paid for the ecological restoration and reconstruction. The objective of this study was to investigate the species composition of soil fauna and its diversity in oil shale dumps after the application of different ecological restoration schemes in order to understand the impact they had on ecological restoration. Three plots were selected on an oil shale dump near the city of Maoming. The “north plot” was a newly-planted young forest mixed with various tree species, while the “south plot” was a 20-year-old Acacia auriculaeformis forest, and the “control plot” was a 20-year-old naturally-recovering grassland. Soil animals, mainly including macro-meso groups, were collected by hand-sorting and Tullgren funnel extraction. They were then identified to family or genus level with only a small portion to order (e.g. Chllopoda) or species (e.g. Isopoda) level. The specimens obtained in the present study was 11164 individuals, belonging to 27 orders and 110 families or genera. The Shannon index (H′), DG_s (based on species) and DG_g (based on groups) were used to analyze the diversity of soil animals between different plots. The major results were as follows: A total of 33 families or genera belonging to nine orders were found in the “north plot”. The main group was Caritermes, accounting for 63.4% of the total, followed by Tetramorium with 21.3%. Hymenoptera, mainly Formicidae, had more genera than others, accounting for 80% of the total genera in this group. The diversity of soil animals in this plot was very low because the H′ index was only 1.2, while the DG_s index was 4.0 and the DG_g index was 1.3. A total of 61 families or genera belonging to 23 orders were found in the “south plot”. Malmcoangelia and Tetramorium were the main groups, which accounted for 60.3% and 10.2%, respectively. Two genera of Annelda and two genera of Isopoda only accounted for 2.6% and 1.9%, respectively, but they were considered to be major groups due to their large body sizes and the distinct characteristics of their habitat. Acarina had a greater number of individuals and families or genera with its individual number accounting for 67.5% of the total, and the number of families or genera of this group account for 70% in this plot. The diversity indexes (H′, DG_s and DG_g) in this plot were significantly higher than those in the “north plot”, and were 1.65, 16.7 and 7.75, respectively. In the “control plot”, there were 67 families or genera of soil animals belonging to 23 orders. The main groups were Tetramorium (20%), Lasius (17.1%), Bothriomymex of Formicidae (13.8%), and Malmcoangelia of oribatid mites (14.5%). Formicidae of Hymenoptera was the group with the maximum number of individuals, accounting for 51.0%, while Diplopoda had the most families or genera. The H′ and DG_s indexes, being 2.54 and 17.7, were higher than those in the “south plot”, while the DG_g index of 7.20 was lower than that in the “south plot”. The results showed that the species composition and diversity indexes were higher in the “south plot” than in the “north plot” and the “control plot”, which demonstrated that using Acacia auriculaeformis forest to restore the oil shale dump was an effective approach in terms of soil biodiversity.

Abstract:North Dagang Wetland Nature Reserve is situated in the southeast of Tianjin, China. It is the biggest wetland nature reserve in Tianjin. An investigation into the diversity of the moth community was carried out from June 12 to October 14, 2001, and then from April 12 to October 30, 2002. The investigation was conducted in order to identify the moth species in wetlands, study their dynamic laws, select indicator insects to indicate wetland quality, and assist in the study and protection of wetlands. A total of 132 moth species were collected, which belonged to 105 genera in 17 families. The data about insects which was collected during the survey was listed and constructed in terms of species-abundance, indices of diversity (H′), evenness (J′), specific richness (S) and individual number (N) using the Microsoft Excel Program. The status of the wetlands was also analyzed using the moth community species-abundance curve, indices of diversity, the connection between evenness and richness indices, etc. The results show that moth species in the wetlands were not rich, and the moth community was unstable. In other words, the living environment of the moths and the environmental quality of the wetlands were unstable due to the serious degeneration of the wetland environment and human activities.

Abstract:The relationship between land features and their spectral characteristics is important for the interpretation of remote sensing images. In this study, the spectral characteristics of a submerged plant Vallisneria spiralis with varied coverage was measured with a ground sensor/radiometer, FieldSpec^TM Pro JR Spectroradiometer in the laboratory and in the constructed wetland of “Mengqingyuan”, Shanghai, China. The results showed that the reflectance rate of Vallisneria spiralis rose with its increasing coverage, which was exhibited both at the visible band (500–650 nm) and the near infrared band (700–900 nm). Water quality influenced the reflectance rate with the primary differences between the laboratory and field experiments mainly occurring at the near-infrared band (700–900 nm). A regression analysis was carried out respectively between the coverage of Vallisneria spiralis and the reflectance rate at the wavelengths of Quick Bird 4 bands where the coverage responded to the strongest. These results of regression analyses showed a clear linear relationship, by which the coverage of Vallisneria spiralis could be quantitatively deduced from the reflectance rate measured in situ. The implications in terms of the ability of hyperspectral remote sensing to distinguish and monitor the distribution and dynamics of submerged vegetation on a large scale are discussed.

Abstract:Four surveys were carried out in August 2001, and in August, September and October 2002 in the southern Yellow Sea, China. Bacterioplankton abundance and biomass were quantified along the transects from Qingdao, China to the Korean island of Jeju. In this paper, the author describes the distribution of bacterioplankton and predatory pressures, and also discusses the impact of Yellow Sea Cold Water Mass (YSCWM) on the distribution of bacterioplankton. The range of Synechococcus biomass was 0.78–33.49 mg C/m³ (on average 6.26 mg C/m³), and heterotrophic bacteria biomass was 1.58–21.25 mg C/m³ (on average 5.79 mg C/m³, n=197). In the vertical direction, the distribution order of Synechococcus biomass was mid-layer>surface>bottom, and the one of heterotrophic bacteria biomass was surface>mid-layer>bottom. The contribution of Synechococcus to the total phytoplankton biomass (SB/PB) ranged from 2% to 99% (on average 42.5%), and the ratio of heterotrophic bacterial biomass to phytoplankton biomass (HBB/PB) was from 5% to 637% (on average 85%). Daily variations of bacterioplankton biomass at anchor stations showed that the maximal Synechococcus biomass was 8.8 times the minimum, and it was 2.8 times in heterotrophic bacterial biomass. The distribution of bacterioplankton accorded with temperature and salinity, and the minimum of bacterioplankton biomass occurred in the YSCWM waters. At the same time, the microzooplankton (20–200 μm) preyed on Synechococcus in these waters, with the ingestion rate of about 0.20–0.42/d.