围垦对滨海湿地氮循环的影响研究

发布时间：2018-04-29 14:56

本文选题：围垦 + 氮循环　；参考：《南京大学》2015年博士论文

【摘要】：氮循环是滨海湿地最重要的物质循环之一。它不仅影响了湿地系统自身的调节机制,其在地球表层系统中所表现出的特殊动力学过程还与一系列全球环境问题息息相关。围垦是解决中国人口与土地资源短缺问题的一种有效手段,它能显著改变滨海湿地土壤的理化性质,影响植物的生长,进而影响生态系统的氮循环过程。为揭示围垦对滨海湿地氮循环的影响,从而将围垦活动对滨海湿地氮循环产生的不良影响减弱或缓解,本文以江苏盐城湿地珍禽国家级自然保护区的芦苇湿地和江苏省大丰麋鹿国家级自然保护区的碱蓬及互花米草湿地为研究对象,对比研究了自然湿地和被围垦湿地的氮循环特征,揭示了围垦对滨海湿地氮储存、迁移转化的影响过程;通过建立围垦影响下的植物-土壤系统的氮循环分室模型,揭示了围垦对滨海湿地氮循环的影响机制。结果表明:(1)围垦显著改变了滨海湿地的土壤理化性质,但对不同的生态系统具有不同的影响。围垦可以显著提高芦苇湿地表层土的含水量、有机碳、微生物量碳、碳氮比和微生物量碳氮比,但也使其土壤容重、pH、电导率和氧化还原电位显著降低。在碱蓬湿地中,围垦只显著降低了其土壤氧化还原电位,对其他土壤理化性质没有明显影响。与芦苇湿地相反,围垦可以显著提高互花米草土壤的容重、pH和氧化还原电位,而降低其含水量、电导率、有机碳、微生物量碳、碳氮比和微生物量碳氮比。(2)围垦对不同生态系统的土壤氮含量具有不同的影响。在芦苇湿地中,围垦显著提高了表层土的总氮、酸不溶性氮(惰性有机氮)、酸溶性氮(活性有机氮)、氨态氮、亚硝态氮和硝态氮含量。而在互花米草湿地中,围垦则显著降低了土壤的总氮、酸不溶性氮、酸溶性氮、水溶性有机氮、氨态氮、亚硝态氮和硝态氮含量。围垦对碱蓬湿地的土壤氮含量没有产生显著影响。逐步回归分析表明:在围垦影响下,滨海湿地土壤有机氮的主要影响因子为有机碳和微生物量碳,而无机氮的主要影响因子为含水量和电导率(盐度)。此外,围垦对三种典型湿地的土壤无机氮贮量没有显著影响;但显著提高了芦苇湿地的有机氮贮量,却降低了互花米草湿地的有机氮贮量,对碱蓬湿地的有机氮贮量则没有影响。这表明围垦是通过改变滨海湿地的土壤有机氮贮量,从而影响了其土壤总氮贮量。(3)围垦显著提高了芦苇湿地的土壤净氮矿化速率、氨化速率和硝化速率。与此相反,围垦显著降低了互花米草湿地的土壤净氮矿化速率和氨化速率。而由于围垦没有对碱蓬湿地的土壤理化性质产生影响,所以对其氮矿化过程也没有显著作用。逐步回归分析表明:在围垦影响下,土壤含水量是芦苇湿地土壤氮矿化的主要影响因子。此外,三种湿地中,土壤的氨化速率均远远大于硝化速率,这是由于滨海湿地的土壤含水量很高,土壤氮的氨化过程占主导,进而造成净氮矿化速率主要取决于氨化速率。(4)围垦显著提高了芦苇的根、茎、叶、种穗的生物量和氮贮量,但围垦后芦苇湿地的枯落物生物量和氮贮量有显著下降,这可能与其秋季的地上部分被收割有关。围垦没有改变碱蓬的生物量和氮贮量。但围垦显著降低了互花米草各器官的生物量和氮贮量。逐步回归分析表明:在围垦影响下,土壤电导率(盐度)是植物生物量的主要影响因子。同时,由于围垦没有影响三种植物各器官的氮含量,植物的氮贮量则主要由其生物量决定。(5)围垦极大地提高了芦苇植物-土壤系统的氮循环流通量,但对碱蓬植物-土壤系统的氮通量没有显著影响。与芦苇相反,围垦显著减少了互花米草植物-土壤系统的氮循环流通量。此外,在三种典型植物-土壤系统中,围垦区域均具有较高的氮素利用效率和氮再转移率,而其循环速度较慢,这表明围垦可以促进氮素的保留,防止氮素流失。基于本文的研究成果,作者认为围垦可以显著改变滨海湿地的氮循环过程。围垦通过改变滨海湿地的土壤理化性质,进而改变湿地土壤和植物氮含量,最终影响滨海湿地的氮循环过程。围垦对不同类型的滨海湿地氮循环具有不同影响。
[Abstract]:Nitrogen cycle is one of the most important material cycles in coastal wetlands. It not only affects the regulation mechanism of the wetland system itself. Its special dynamic process in the earth surface system is also closely related to a series of global environmental problems. Reclamation is an effective means to solve the shortage of China's population and land resources. It can be used as an effective means. The physical and chemical properties of the coastal wetland soil, the growth of the plants and the nitrogen cycle of the ecosystem were affected, and the effects of reclamation on the nitrogen cycle of coastal wetlands were revealed, and the adverse effects of reclamation on the nitrogen cycle of coastal wetlands were weakened or alleviated. This article was based on the National Nature Reserve of Jiangsu Yancheng wetland rare birds. The reed wetland and the wetland of Dafeng elk National Nature Reserve in Jiangsu province were studied. The nitrogen cycle characteristics of natural and reclaimed wetlands were compared and studied. The effects of reclamation on nitrogen storage and migration and transformation of coastal wetlands were revealed, and nitrogen based in plant soil system under the influence of reclamation was established. The effects of reclamation on nitrogen cycling in coastal wetlands were revealed. The results showed that: (1) reclamation significantly changed the physical and chemical properties of the coastal wetlands, but had different effects on different ecosystems. Reclamation could significantly increase the water content, organic carbon, microbial biomass carbon, carbon and nitrogen ratio and microbial biomass in the surface soil of reed wetland. The ratio of carbon and nitrogen, but also the soil bulk density, pH, electrical conductivity and redox potential decreased significantly. In the wetland, reclamation only significantly reduced the redox potential of the soil, and had no obvious influence on the physical and chemical properties of other soils. Water content, electrical conductivity, organic carbon, microbial biomass carbon, carbon and nitrogen ratio and microbial biomass carbon and nitrogen ratio. (2) reclamation has different effects on the soil nitrogen content in different ecosystems. In reed wetland, reclamation significantly improves the total nitrogen, acid insoluble nitrogen (inert organic nitrogen), acid soluble nitrogen (active organic nitrogen), ammonia nitrogen, nitrite in the reed wetland. Soil nitrogen, acid insoluble nitrogen, acid soluble nitrogen, water-soluble organic nitrogen, ammonia nitrogen, nitrite nitrogen and nitrate nitrogen content were significantly reduced in the wetland of alterniflora. The soil nitrogen content in the wetland was not significantly affected by reclamation. The stepwise regression analysis showed that under the influence of reclamation, the coastal wetness was wet. The main influencing factors of soil organic nitrogen are organic carbon and microbial biomass carbon, while the main influencing factors of inorganic nitrogen are water content and electrical conductivity (salinity). In addition, reclamation has no significant influence on the soil inorganic nitrogen storage of three typical wetlands, but it significantly improves the organic nitrogen storage of reed wetland, but reduces the wetland of alterniflora. Nitrogen storage has no effect on the organic nitrogen storage of the seashore wetland. This indicates that reclamation is by changing the soil organic nitrogen storage of the coastal wetland, thus affecting the total nitrogen storage of the soil. (3) reclamation significantly improves the soil net nitrogen mineralization rate, ammoniation rate and nitrification rate in reed wetland. The net nitrogen mineralization rate and ammoniation rate of the soil in the marsh were not affected by the soil physicochemical properties of the alkaline soil, so the stepwise regression analysis showed that under the influence of reclamation, the soil water content was the main influence factor of nitrogen mineralization in the reed wetland soil. In addition, three kinds of soil nitrogen mineralization were found. In wetland, the ammonification rate of soil is far greater than nitrification rate, which is due to the high soil water content in coastal wetland, the dominant of ammoniation process of soil nitrogen, and the net nitrogen mineralization rate mainly depends on the ammoniation rate. (4) reclamation significantly improves the biomass and nitrogen storage of reed roots, stems, leaves, spikes, but reed reed wet after reclamation. The biomass and the nitrogen storage of the litter decreased significantly, which may be related to the reaping of the aboveground part of the autumn. Reclamation did not change the biomass and the nitrogen storage of the Suaeda. But reclamation significantly reduced the biomass and the nitrogen storage of each organ of the plant. Stepwise regression analysis showed that under the influence of reclamation, the soil conductivity (salinity) was a plant. At the same time, since reclamation did not affect the nitrogen content of the three plant organs, the nitrogen storage of the plant was mainly determined by its biomass. (5) reclamation greatly improved the nitrogen circulation in the reed plant soil system, but had no significant influence on the nitrogen flux of the plant soil system. Reclamation significantly reduced the nitrogen circulation in the plant soil system of M. alterniflora. In addition, in the three typical plant soil systems, the reclamation area had higher nitrogen use efficiency and nitrogen retransfer rate, and its circulation rate was slow, which indicated that reclamation could promote nitrogen retention and prevent nitrogen loss. The author believes that reclamation can significantly change the nitrogen cycling process in coastal wetlands. Reclamation by changing the physical and chemical properties of the coastal wetlands, then changing the nitrogen content of the wetland soil and plant, and ultimately affecting the nitrogen cycle of the coastal wetlands, has different effects on the nitrogen cycle of different types of coastal wetlands.

【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：X171;S154.4

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