崇明东滩土壤总氮含量对环境因子的响应及对植物生理生长的影响

发布时间：2018-01-05 04:12

本文关键词：崇明东滩土壤总氮含量对环境因子的响应及对植物生理生长的影响　出处：《华东师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：氮过剩引起的水体富营养化已成为我国近海海域面临的主要环境问题之一。潮滩湿地处于海陆交错地带,与近海海域交互作用复杂且强烈,各环境因子分异性高且快速更替,对土壤的固氮过程有着重要影响。本研究选取长江口典型潮滩湿地崇明东滩,结合野外采样和控制实验,探究定植植被、盐度与滩面高程对土壤总氮含量的影响;并通过氮添加试验,模拟长江口不同浓度氮素含量对潮滩植物生长及生理特征指标的影响。主要研究结果如下:1)在崇明东滩,表层土壤总氮含量与盐度和滩面高程分布规律相近,表现为北高南低,西高东低。表层30 cm 土壤总氮含量在空间分布上存在显著性差异。其中北部土壤总氮含量约为南部的1.5倍;西部(植被发育14年)土壤总氮含量约为东部(植被发育1年)的1.2～1.5倍。定植植被类型及群落演替模式在南北显示出明显的不同,但均呈现出低生物量群落向高生物量群落演替的规律,北部定植植被生物量高于南部。国内滨海湿地多为新生湿地,因此土壤总氮含量普遍低于内陆湿地。但崇明东滩相比国内其他滨海湿地土壤总氮含量较低,可能是由于过度放牧、采集等人为干扰所致。因此,保护和恢复滨海湿地将增加氮素汇聚能力,对提高长江口湿地氮储量具有重要意义。2)不同盐沼植物对盐度和淹水的耐受性差异,会对土壤总氮含量和植物氮储量产生重要的影响。随着盐度的增加,强耐盐性植物生长区域的土壤总氮含量升高;而耐盐性弱的植物在盐度增加时,土壤总氮含量会在一定程度上降低。此外,随着盐度的升高,植物氮储量会不断降低。随淹水深度的增加,芦苇和海三棱叇草的植物氮储量均有显著降低。其中,芦苇的土壤总氮含量无显著性变化,海三棱叇草的土壤总氮含量显著降低,而互花米草的土壤总氮含量和植物氮储量均无明显变化趋势。野外采样中土壤总氮含量和环境因子的分布规律与控制实验得出结果存在较大差异,说明盐度和滩面高程作为潮滩湿地的典型环境因子,对土壤总氮含量的作用效果有限,可能受定植植被类型、微生物群落、发育年限等其他环境因子的影响更大。3)过高的氮素含量会抑制潮滩植物的生长,从而降低植物对氮素的去除和净化能力,但目前长江口的水体富营养化问题尚未达到如上水平。随施氮浓度的增加,海三棱呰草的生长总体呈低浓度促进、高浓度抑制的规律。其中100～200 mg.kg-1的氮素施加量显著提高了海三棱叇草的各项生长指标和叶片叶绿素含量,相比无施氮处理,植株高度提高约35%;植株密度提高约50%;总生物量提高约40%;叶片总叶绿素浓度提升约37%。海三棱叇草植株的氮储量在施氮水平200 mg kg-1(实际土壤总氮水平:131.3±6.4 mg N kg-1)处理时达到最大值5.9 gm-2"。,超过该水平后,氮储量显著降低,对湿地中氮素的净化能力逐渐减弱。目前崇明东滩海三棱呰草群落带土壤总氮水平约为50 mgN·kg-1,尚未达到抑制海三棱叇草生长的程度(约130mgN·kg-1),因此仍可在长江口富营养化加剧的背景下较好地生长发育,并发挥其氮素吸收和净化功能。
[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.

【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948.1

【参考文献】