| The coastal shelter forest is an important barrier on ecological protection, the research on coastal shelter forest mainly on shelterbelt structure, soil improvement such as reduce salinity, affect physical and chemical properties, some achievements in practical experience were obtained. However, the resilience of the windstorm and soil enzymes, microbial activities were relatively weak. Based on that, this paper took the typical coastal shelter forest in Shanghai as research object, the wind-break potency and soil improvement as goal, study on the forest soil enzymes, microbial activities and forest structure on wind-break potency. The main study results were as following:(1) The regularity of seasonal variation of Soil invertase activity in different forest type was different. The seasonal variety of soil urease was January> March> July> October . The seasonal variety of soil alkaline phosphatase was March> January> October > July. The seasonal variety of soil catalase was July> March> October > January. The seasonal variety of soil protease was March> July> January> October . The soil invertase had different seasonal variation regularity in different forests. The activity of soil urease, alkaline phosphatase,protease and invertase decreased with the increased depth of the soil layer, but the distribution of soil catalase was not obvious in the soil layer and the difference among them is tiny.(2) Total number of microorganisms in 0-10 cm soil layer was much different among every forest type and the total from biggest to smallest were as follows: Populus, Populus+Quercus acutissima, Ulmus pumila+Zelkova schnideriana , Metasequoia glyptostoboides+Populus , Taxodium mucronatum×Crytomeria fortunei , Metasequoia glyptostoboides , Beach. The distribution of microorganisms was also different from each other in different forest types with month. Number from largest to smallest in order of bacteria, fungi, actinomycetes. Bacteria were the absolute superiority in soil microorganisms. The number of bacteria, fungi, actinomycetes and total decreased with the increased depth of the soil layer.(3) SMBC in 0-10 cm soil layer was much different among every forest type and the total from biggest to smallest were as follows: Metasequoia glyptostoboides, Populus+Quercus acutissima, Metasequoia glyptostoboides+ Populus, Taxodium mucronatum×Crytomeria fortunei, Ulmus pumila+Zelkova schnideriana , Populus, Beach. SMBN in 0-10 cm soil layer was much different among every forest type and the total from biggest to smallest were as follows: Metasequoia glyptostoboides, Taxodium mucronatum×Crytomeria fortunei, Metasequoia glyptostoboides+ Populus, Ulmus pumila+Zelkova schnideriana, Populus+Quercus acutissima, Populus, Beach. SMBP in 0-10 cm soil layer was much different among every forest type and the total from biggest to smallest were as follows: Metasequoia glyptostoboides+ Populus, Populus, Populus+Quercus acutissima, Metasequoia glyptostoboides, Ulmus pumila+Zelkova schnideriana, Taxodium mucronatum×Crytomeria fortunei, Beach. The seasonal variety of SMB is significant. The vertical variety is not obvious, but the soil surface had the largest ration.(4) A correlation analysis showed that soil bacteria, fungi, actinomycetes, SMBC, SMBN, SMBP were significantly correlation between most of soil physical and chemical properties indexes and 5 kinds of soil enzymes.(5)Field measurements of forest wind performance showed that: For the sparse structure Sequoia shelter forest, during summer typhoon season, the nearer to the shelterbelt it was, the bigger the wind-break potency was. In the same horizontal distance, there is a trend of wind-break potency moving to the increase with vertical increased.(6)Wind tunnel test of forest wind performance showed that: Shelterbelt porosity, wind angle and shelterbelt distance were affected the wind-break potency. Various forest of wind speed along the horizontal and vertical distribution were similar. Various factors of forest structure on orthogonal experimental analysis, select the relative optimal combination: ratio of width to height of shelterbelt =1.0, porosity of shelterbelts=35%, height of shelterbelt=24m, shelterbelt distance=14H.(7)Analyzed by using the Analytical Hierarchy Process (AHP), the results showed that: As for the total benefits, the order was as follows: Metasequoia glyptostoboides+Populus, Metasequoia glyptostoboides, Taxodium mucronatum×Crytomeria fortunei, Ulmus pumila+Zelkova schnideriana, Populus, Populus+ Quercus acutissima. That migh tbe much meaningful to the construction of the coastal shelter forest.
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