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  本文關(guān)鍵詞：崇明東灘土壤總氮含量對環(huán)境因子的響應及對植物生理生長的影響　出處：《華東師范大學》2017年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 崇明東灘 鹽沼植物 土壤總氮含量 氮儲量

【摘要】：氮過剩引起的水體富營養(yǎng)化已成為我國近海海域面臨的主要環(huán)境問題之一。潮灘濕地處于海陸交錯地帶,與近海海域交互作用復雜且強烈,各環(huán)境因子分異性高且快速更替,對土壤的固氮過程有著重要影響。本研究選取長江口典型潮灘濕地崇明東灘,結(jié)合野外采樣和控制實驗,探究定植植被、鹽度與灘面高程對土壤總氮含量的影響;并通過氮添加試驗,模擬長江口不同濃度氮素含量對潮灘植物生長及生理特征指標的影響。主要研究結(jié)果如下:1)在崇明東灘,表層土壤總氮含量與鹽度和灘面高程分布規(guī)律相近,表現(xiàn)為北高南低,西高東低。表層30 cm 土壤總氮含量在空間分布上存在顯著性差異。其中北部土壤總氮含量約為南部的1.5倍;西部(植被發(fā)育14年)土壤總氮含量約為東部(植被發(fā)育1年)的1.2～1.5倍。定植植被類型及群落演替模式在南北顯示出明顯的不同,但均呈現(xiàn)出低生物量群落向高生物量群落演替的規(guī)律,北部定植植被生物量高于南部。國內(nèi)濱海濕地多為新生濕地,因此土壤總氮含量普遍低于內(nèi)陸濕地。但崇明東灘相比國內(nèi)其他濱海濕地土壤總氮含量較低,可能是由于過度放牧、采集等人為干擾所致。因此,保護和恢復濱海濕地將增加氮素匯聚能力,對提高長江口濕地氮儲量具有重要意義。2)不同鹽沼植物對鹽度和淹水的耐受性差異,會對土壤總氮含量和植物氮儲量產(chǎn)生重要的影響。隨著鹽度的增加,強耐鹽性植物生長區(qū)域的土壤總氮含量升高;而耐鹽性弱的植物在鹽度增加時,土壤總氮含量會在一定程度上降低。此外,隨著鹽度的升高,植物氮儲量會不斷降低。隨淹水深度的增加,蘆葦和海三棱叇草的植物氮儲量均有顯著降低。其中,蘆葦?shù)耐寥揽偟�含量無顯著性變化,海三棱叇草的土壤總氮含量顯著降低,而互花米草的土壤總氮含量和植物氮儲量均無明顯變化趨勢。野外采樣中土壤總氮含量和環(huán)境因子的分布規(guī)律與控制實驗得出結(jié)果存在較大差異,說明鹽度和灘面高程作為潮灘濕地的典型環(huán)境因子,對土壤總氮含量的作用效果有限,可能受定植植被類型、微生物群落、發(fā)育年限等其他環(huán)境因子的影響更大。3)過高的氮素含量會抑制潮灘植物的生長,從而降低植物對氮素的去除和凈化能力,但目前長江口的水體富營養(yǎng)化問題尚未達到如上水平。隨施氮濃度的增加,海三棱呰草的生長總體呈低濃度促進、高濃度抑制的規(guī)律。其中100～200 mg.kg-1的氮素施加量顯著提高了海三棱叇草的各項生長指標和葉片葉綠素含量,相比無施氮處理,植株高度提高約35%;植株密度提高約50%;總生物量提高約40%;葉片總?cè)~綠素濃度提升約37%。海三棱叇草植株的氮儲量在施氮水平200 mg kg-1(實際土壤總氮水平:131.3±6.4 mg N kg-1)處理時達到最大值5.9 gm-2"。,超過該水平后,氮儲量顯著降低,對濕地中氮素的凈化能力逐漸減弱。目前崇明東灘海三棱呰草群落帶土壤總氮水平約為50 mgN·kg-1,尚未達到抑制海三棱叇草生長的程度(約130mgN·kg-1),因此仍可在長江口富營養(yǎng)化加劇的背景下較好地生長發(fā)育,并發(fā)揮其氮素吸收和凈化功能。
[Abstract]:Nitrogen surplus caused by eutrophication has become one of the main environmental problems in China's coastal waters. The tidal wetlands in the ecotone between the sea and sea areas, the interaction is complex and intense, each environmental factor difference high and rapid turnover, has an important influence on the process of nitrogen fixation in soil. This study selected the typical Yangtze River estuary the intertidal wetland of Chongming Dongtan, combined with field sampling and control experiments, explore planting vegetation, effects of salinity and tidal elevations on the total nitrogen content of soil; and through nitrogen addition experiment, effects of simulated nitrogen content in different concentrations in Yangtze River Estuary on tidal plant growth and physiological characteristics. The main results are as follows: 1) in Chongming Dongtan, surface soil total nitrogen content and salinity and tidal elevations showed similar distribution, from north to south, East West High low. The total nitrogen content in surface soil of 30 cm in spatial distribution have significant The difference. The total nitrogen content of soil in North South for about 1.5 times; the western (vegetation development 14 years) the total nitrogen content of the soil around the eastern (vegetation 1 years) from 1.2 to 1.5 times. The colonization of vegetation types and community succession patterns in the north and south is obviously different, but both showed the rule of life the volume to high biomass community succession, northern planting vegetation biomass was higher than that in the south. Many domestic coastal wetland wetland, so the soil total nitrogen content is lower than that of inland wetlands in Chongming Dongtan. But compared to other domestic coastal wetland soil total nitrogen content is low, may be due to excessive grazing, such as acquisition caused by interference. Therefore, the protection and will increase the nitrogen accumulation capability of coastal wetland restoration, to improve the Yangtze River Estuary Wetland nitrogen reserves has important significance to.2) different salt marsh plant tolerance to salinity and waterlogging difference, the soil total nitrogen content and plant Influence of nitrogen reserves. With the increase of salinity, increased soil total nitrogen content of strong salt tolerant plant growth area; and the salt tolerance of weak plants increase in salinity, soil total nitrogen content decreased to a certain extent. In addition, with the increase of salinity, plant nitrogen reserves will continue to reduce the increase. With the water depth, reed and bulrush cloudy sky grass nitrogen content of plant decreased significantly. The soil total nitrogen content of reed no significant changes, the soil total nitrogen content of Scirpus grass significantly reduced the cloudy sky, there was no significant change in soil total nitrogen content and plant nitrogen reserves spartinaalterniflora distribution trend. The experimental and control field sampling total nitrogen content of soil and environmental factors that results are quite different, that of salinity and tidal elevations as the typical environmental factors of tidal wetlands, the effect of the total nitrogen content of the soil can be limited. By planting vegetation types, microbial community, life and other environmental factors affect the development of the greater.3) nitrogen content is too high will inhibit the intertidal plant growth, thereby reducing plant nitrogen removal and purification ability, but the problem of eutrophication of the Yangtze Estuary has not reached the above level. With the increase of nitrogen the concentration of Scirpus Zi grass growth generally showed a low concentration promoted, high concentrations inhibited the law. Among them 100 ~ 200 mg.kg-1 nitrogen application rate significantly increased the growth index and chlorophyll content of the bulrush cloudy sky grass, no nitrogen treatment compared, plant height increased about 35%; plant density increased about 50%; the total biomass increased by 40%; total leaf chlorophyll concentration increased by approximately 37%. of Scirpus grass plant nitrogen reserves in the cloudy sky n 200 mg kg-1 (total nitrogen level: 131.3 + 6.4 mg N actual soil kg-1) reaches the maximum value of 5.9 when processing GM-2., exceed this level, nitrogen reserves decreased significantly and the purification ability of wetland nitrogen gradually weakened. At present, Chongming East tidal flat Zi grass community zone total nitrogen level in soil is about 50 mgN kg-1, has not yet reached the inhibition of Scirpus grass growth degree of cloudy sky (about 130mgN kg-1), it is still in the the mouth of the Yangtze River eutrophication intensified under the background of better growth and development, and play the function of nitrogen absorption and purification.

【學位授予單位】：華東師范大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：Q948.1

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