| The paper studies the storage and distribution pattern of soil carbon and nitrogen, seasonal variation of soil respiration rate, total nitrification rate and denitrification rate.seasonal variation characteristics of influencing factors on transformation of element C and N as well as the relevance based on different species forest following as Bamboo,Eucalyptus,Casuarina,Slash Pine. It aims to provide a theoretical basis for coastal protection forest experience, carbon and nitrogen dynamics provide the appropriate data for the coastal shelterbelt ecosystems, provide appropriate data for the study of climate change in coastal areas.The results were as follows:(l)Total nitrogen and total carbon content was different within same soil layer.The contents of total nitrogen in different forest soil were different within different soil layers.The highest total carbon and nitrogen of soil is within layer between 0-10cm that showed of Casuarina>Eucalyptus>Bamboo>Slash, which the Casuarina is up to 0.86g/kg and minimum to 0.36 g/kg in Pinus elliottii,and the total carbon content of different soil layer within same forest land was showed significantly different (P<0.05).Total carbon content decreased from shallow to deep and soil carbon content in different forest land was lied in 0-30cm layer.The value of soil carbon content in different layer is different,The 0-10cm soil layer,among those,within 0-10cm layer was showed Eucalyptus>Casuarina>Bamboo>Slash The content were showed of Casuarina>Eucalyptus>Slash Pine>Bamboo with layer of 10-30cm.Total carbon content of soil were showed a significant difference in four kinds of forest land, among those the highest and lowest content was 3.91 g/kg in Casuarina,1.25g/kg in Eucalyptus respectively.(2)Soil nitrogen reserves are different in different forest land and shows Casuarina> Eucalyptus>Slash>Pine>Bamboo,which obtained 3.97t/hm2,2.64t/hm2,2.45t/hm2,2.38t/hm2 in those lands respectively.Also,soil carbon storage are different in different forest land and shows Casuarina>Eucalyptus>Slash>Pine>Bamboo,which obtained 12.05 t/hm2,12.67 t/hm2,17.30 t/hm2,26.63 t/hm2 in four lands respectively.Casuarina forest land has a better storage capacity of carbon and nitrogen when compared to rest of lands.(3)The soil respiration rate of different forest land showed obvious dynamic change with the seasons.The highest soil respiration rate of four forest land was in June and within the same forest land it changed significant with seasons.Also.in the same forest land, the difference of soil respiration rate were showed significant along with month.In addition to Slash Pine land,the rest of forest lands were showed a significant positive correlation in soil respiration rate and moisture content,the soil respiration in this area was mainly affected by plant root respiration, which had showed no significant relationship with the number of microorganisms.Affected by different characteristics of forest lands, different enzymes have different effects on soil respiration of it.(4)There was showed a obvious seasonal variation in denitrification rate in different forest land and the trend of it were different.Soil denitrification rate and soil water content were showed a negatively correlated in Eucalyptus and Slash Pine forest lands.Correlation between soil and water content,ph value in different forest land is not same.The rate of denitrification in soil was showed negatively correlated with the number of bacteria and fungi.Different soil enzymes have different effects on denitrification since different soil conditions.There was seasonal variation of the total nitrification rate in four Forest lands,which showed similar variation trend in Bamboo, Casuarina and Slash Pine lands.But the annual seasonal variation of Eucalyptus is smaller.(5)The total soil nitrification rate was always showed of Casuarina>Eucalyptus>Slash Pine,and reached highest value in June.In the correlation analysis, the correlation between total nitrification rate and different environmental factors was different based on different lands.Influenced by different land characteristics, different enzymes had various effects on the total nitrification rate in the four lands.The results show that soil respiration,denitrification and nitrification rates may vary with vegetation type, site condition, soil environment,etc.Therefore different lands have nothing to do with it.(6)In Bamboo.Casuarina and Slash Pine land,the soil respiration rate was significantly correlated with total nitrification rate,however,the correlation was not significant in Eucalyptus land.There were showed negative correlation between respiration rate and denitrification rate in four kinds land.Also,correlation between denitrification and nitrification rate was not obvious.The results show that correlation between soil respiration rate, total nitrification rate and denitrification rate was different within different lands.The study results in several aspect of the same land did not apply to other lands.(7)Soil microbial biomass and enzyme activities in different forest land were showed seasonal variation.Also it have different change trend. Base on correlation analysis the results show that the correlation between microbial and soil enzyme in same land was different;the correlation of soil enzyme and microorganism quantity is different in four lands.The main source of soil enzymes is the secretion of soil microbial activity, plant roots as well as the decomposition of plant residues and soil animals.The different source of soil enzyme result in difference between relevance soil enzyme and microorganism.(8)4 plant trees planted in different aspect’s ability to influence soil strength,4 species could improve the sandy soil in coastal area, stability of soil environment, improve the sand soil C and N cycling speed, adjust the coastal sandy climate environment, improve soil fertility, improve soil enzyme activity and microorganism content,4 kinds of forest category with coastal sand is fit for planting, the rich coastal sand afforestation tree species, improve the environment of coastal areas is with important significance. |
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