| Macrobenthic community is an important part of tidal flat ecosystem. Macrobentic community determines many significant ecological processes in the tidal flat wetland ecosystem. Studying on the macrobenthic community is important to improve our knowledge on the community ecology and the theory of ecology, then it has affirmative significance to wetland resource exploitation and biodiversity conservation.The dissertation based on the research on the macrobenthic community in the middle scale at the tidal flat wetland in Zhejiang Province, discussed on the structure characters, spatio-temporal variation of the nature tidal flat wetland and the different of the macrobenthic community in different habitats, then the different status of the creeks dyked in different years.Major conclusions from the research are:1. Since Nov., 2003 to Aug., 2004, the authors studied the macrobenthic community at east tidal flat of Lingkun Island, Wenzhou Bay. We found a total of 33 in the investigation, belonging to 21 families, 8 classes and 7 phyla, most of them being the arthropods and the mollusks. The number of species found at high tidal flat, middle tidal flat and low tidal flat was 25, 30 and 14. The density and biomass of the high, middle and low tidal flat were 185.00±25.67ind./m~2, 55.82±13.96 g/m~2; 188.00±40.78ind./m~2, 35.31±8.75 g/m~2 and 41.50±8.73 ind./m~2, 3.06±0.83 g/m~2. The result of Paird Samples T Test of the density and biomass of the different tidal flat in same seasons showed that the difference has achieved to the distinct level, expect the density of the high and middle tidal flat. The result of Paird Samples T Test of density and biomass of the same site of tidal flat in different seasons showed that the difference hasn't achieved to the distinct level. The value of Margalef's species richness index and Shannon-Wiener's index were following that: high > middle > low, the value of Pielou's index and Simpson's index were following that: high < middle < low. Base on the date of the four times extraction of the density of macrobenthic communities, using the Hierarchical Cluster of between-groups linkage method and the Non-matric Multidimentional Scaling method, the 12 communities were displayed that the macrobenthic communities of high and middle tidal flat had not distinct dividing line, the macrobenthic communities of high and low tidal flat had distinct distinct dividing line, the result revealed the character of middle tidal flat as the joint of high and low tidal flat, then the result related to the factor of season. The analysis of paper indicated that the the habitatcharacters difference was the reason of the macrobenthic communities difference, the difference of the macrobentic communities at same site of tidal flat in different season hasn't achieved to the distinct level.2. Since Nov., 2003 to Aug., 2004, the authors studied the macrobenthic community at tida flat of Tianhe, Wenzhou Bay. We found a total of 38 species in the investigation, belonging to 23 families, 8 classes and 7 phyla, most of them being the arthropods and the mollusks. The density and biomass of the upper, high, middle and low tidal flat were 144.50±14.24ind./m2, 58.56±13.23 g/ m2; 171±16.52ind./m2, 40.57+12.60 g/ m2; 182.50±39.38ind./m2, 50.26+10.57 g/ m2; 94+28.88ind./m2, 16.55±7.27 g/ m2. The value of Margalefs species richness index and Shannon-Wiener's index were following that: high > middle > low > upper, the value of Pielou's index was following that: upper < high < middle < low, Simpson's index was following that: upper < low < high < middle. Base on the date of the four times extraction of the density of macrobenthic communities, using the Hierarchical Cluster of between-groups linkage method and the Non-matric Multidimentional Scaling method, the 16 communities were displayed that the macrobenthic communities of high and middle tidal flat had not distinct dividing line, the macrobenthic communities of upper and low tidal flat had distinct distinct dividing line, the result revealed the character of high and middle tidal flat as the joint of upper and low tidal flat, then the result related to the factor of season.3. In Jan., 2003, the authors studied the macrobenthic community ecology in various dyked tidal flat habitats at Andong, Cixi City, Zhejiang Province, China. Based on the data collected from 9 types of habitat samplings on the macrobenthic community in the diked tidal flats at the south bank of Hangzhou Bay in Jan 2004, the composition of species, diversity, and community structure were studied, and 9 types of habitats selected were Spartina alterniflora moist soil (SAMS), Phragmites commvnis moist soil (PCMS), S. alterniflora dry soil (SADS), P. communis dry soil (PCDS), S. alterniflora inundated soil (SAIS), P. communis inundated soil (PCIS), admixture dry soil (ADS), using pond (UP), and desolation pond (DP). From 9 types of habitats, total 13 species were collected, which are belonged to 7 order, 3 classes, 2 phyla and dominated by the living types of surface and surface below, and most of them are the arthropod and Crustacea. Shannon-Wiener indexes {H' ) of the macrobenthic communities are followed SAMS > PCMS > SADS > PCDS = SAIS > PCIS > ADS > DP > UP, Pielou indexes (J) are SAMS > PCMS > SADS > PCDS > ADS > SAIS > PCIS > DP > UP, and Simpson indexes (D) are PCMS > SAMS > SADS > PCDS > ADS > SAIS > PCIS > DP > UP.Base on the data of four times extracting from the density of macrobenthic communities, using the hierarchical cluster of between-groups linkage method, 9 types of habitats are classed four groups, i.e. the moist soil, dry soil, water soil and pond groups. The numbers of species of the moist soil, dry soil, water soil and pond are 10, 6, 10 and 5, the average densities are 45, 40, 87 and 240 ind./m2, and the biomasses are 23.67, 15.11, 14.81 and 8.23g/m2, respectively; H' , ./and D tend towards moist soil > dry soil > water soil > pond. Using the Non-matric Multi-Dimensional Scaling method, 9 macrobenthic communities are displayed in the 2-dimensional ordinal configuration, and the dimension 1 implies being concern to the hydrology, the dimension 2 to the complexity of habitats. Also the analysis suggests that the macrobenthic community at the diked tidal flat may be affected by the complex power of hydrology condition, characteristics of sediment, succession of vegetation and relation among the species.4. In the autumn of 2003, the authors studied the macrobenthic community ecology in various habitats of different creeks dyked in different years on a tidal flat at Lingkun Island, Wenzhou City, Zhejiang Province, China. There are the following major conclusions:(l) We found a total of 33 species belonging to 20 families, 8 classes and 6 phyla, most of them being arthropods and the mollusks. In the different habitats of the creeks (the grass flat, the bank of creek and the bottom of the creek), the composition and quantity of the macrobenthos were different from one other. There were 18 species in the grass flat, 23 species in the bank of the creek and 13 species at the bottom of creek. Most of the grass flat species were arthropods and mollusks, with more mollusk species than arthropods. Most of the species were slow moving types belonging to the surface species (GS) group. Most of the bank species were arthropods, mollusks and polychaetes, mostly burrowing infaunal species belonging to the below surface (GSB) group. Most of the bottom species were crustaceans and arthropods, belonging to the swimming and infaunal groups. The ratio of GS to GSB for the grass flat, the bank of the creek and the bottom of the creek was 1.43, 0.44 and 0.44 respectively. (2) The average ratio of the density GS/GSB in different habitats of the 3 creeks was grass flat 3.86, bank of creek 1.14, and bottom of creek 0.21. (3) The average of biomass in each habitat of the 3 creeks was grass flat 58.81g/m2, bank of creek 67.07 g/m2 and bottom of creek 14.38 g/m2. The average biomass in the same creek of the 3 sites dyked in different years was 1987 30.15g/m2, 1992 47.65g/m2 and 1997 57.56g/m2., showing a trend of decreasing biomass with increasing length of time that the site had been dyked.(4) Four species diversity indices (Margalefs species richness index, the Shannon-Wiener index, Pielou's...
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