【摘要】：濕地生態(tài)系統(tǒng)具有獨(dú)特的水文歷史和生物特征,具有較高的生態(tài)多樣性、物種多樣性和生物生產(chǎn)力。而水文過(guò)程是影響濕地生態(tài)系統(tǒng)穩(wěn)定和退化的關(guān)鍵因素,對(duì)濕地生態(tài)系統(tǒng)的物質(zhì)循環(huán)和能量轉(zhuǎn)化具有重要影響,而土壤微生物作為濕地生態(tài)系統(tǒng)的分解者,其群落結(jié)構(gòu)和功能活性是如何響應(yīng)水分變化的,我們知之甚少。本研究以鄱陽(yáng)湖灰化苔草濕地表層土壤為研究材料,采用室內(nèi)水分控制實(shí)驗(yàn),模擬濕地水分條件,設(shè)置五種水分處理:自然干燥、濕潤(rùn)(含水量約30%)、淹水0cm、10cm和100cm。采用多種研究方法,對(duì)土壤理化因子、微生物生物量、細(xì)菌群落結(jié)構(gòu)、胞外酶活性、碳源代謝活性進(jìn)行分析。以期為濕地生態(tài)系統(tǒng)的保護(hù)與改善提供科學(xué)的理論依據(jù)。主要研究結(jié)果如下:(1)淹水條件能夠顯著提高土壤有機(jī)質(zhì)和銨態(tài)氮含量,同時(shí)會(huì)升高土壤pH。土壤理化因子在處理的第72d達(dá)到了相對(duì)穩(wěn)定的狀態(tài),同時(shí)研究發(fā)現(xiàn)除硝態(tài)氮含量外,土壤理化因子在不同淹水深度間無(wú)顯著性差異。(2)濕潤(rùn)處理下的土壤微生物生物量最高,淹水處理次之,自然干燥處理最低,而不同的淹水深度間無(wú)顯著差異。在不同的水分條件下,濕地土壤細(xì)菌群落結(jié)構(gòu)在處理的前21d發(fā)生了劇烈變化呢,之后趨于穩(wěn)定。同時(shí)研究還發(fā)現(xiàn)淹水環(huán)境中的土壤細(xì)菌群落結(jié)構(gòu)顯著不同于自然干燥和濕潤(rùn)處理。在對(duì)處理21d土壤微生物群落組成的研究中發(fā)現(xiàn),自然干燥環(huán)境中含有較高豐度的細(xì)菌為Acidobacteriaceae_(Subgroup_1)和細(xì)球菌科(Micrococcaceae),濕潤(rùn)土壤環(huán)境中以草酸桿菌科(Oxalobacteraceae)和黃單胞桿菌科(Xanthomonadaceae)豐度最高;而淹水土壤中梭菌科(Clostridiaceae_1)的豐度相對(duì)較高。但淹水深度對(duì)細(xì)菌群落組成無(wú)顯著影響。(3)土壤酶活性在處理的前21d未發(fā)生顯著變化,之后分異變化明顯。其中在自然干燥條件下土壤酶活性最低,濕潤(rùn)處理?xiàng)l件下的β-葡萄糖苷酶(Bglu)活性較高,而淹水條件下?lián)碛休^高的酚氧化酶(PERO)和過(guò)氧化物酶(PHOX)活性,但淹水深度對(duì)土壤酶活性無(wú)顯著影響。選擇自然干燥、濕潤(rùn)和淹水100cm三組水分條件處理的樣品進(jìn)行碳源利用測(cè)定分析,結(jié)果表明土壤碳源代謝能力在處理的前21d出現(xiàn)了顯著的變化,之后趨于穩(wěn)定。最終表現(xiàn)為,濕潤(rùn)處理的碳源代謝能力最強(qiáng),淹水100cm次之,自然干燥處理最低。進(jìn)一步研究發(fā)現(xiàn)在淹水條件下利用的主要碳源為氨基酸類(lèi)。綜上所述,濕潤(rùn)的土壤環(huán)境最有利于微生物生長(zhǎng)代謝,淹水條件顯著改變了土壤理化環(huán)境、細(xì)菌群落結(jié)構(gòu)和組成,而干燥的土壤環(huán)境顯著降低了土壤酶活性和碳源代謝能力。研究結(jié)果提示,維持大面積的洲灘濕地對(duì)濕地生態(tài)系統(tǒng)的保護(hù)至關(guān)重要,未來(lái)濕地保護(hù)不僅要關(guān)注濕地土壤的淹水深度,更要關(guān)注濕地的淹水面積和淹水時(shí)長(zhǎng)。
[Abstract]:Wetland ecosystem has unique hydrological history and biological characteristics, with high ecological diversity, species diversity and biological productivity. Hydrological process is the key factor that affects the stability and degradation of wetland ecosystem, and it has an important influence on the material cycle and energy transformation of wetland ecosystem, and soil microorganism is the decomposer of wetland ecosystem. We know little about how the community structure and functional activities respond to water changes. In this study, the surface soil of Poyang Lake ash Carex marsh was used as the research material. The indoor water control experiment was used to simulate the moisture condition of the wetland. Five kinds of water treatments were set up: natural drying, wetting (about 30% water content), flooding 0 cm, 10 cm and 100 cm. Soil physical and chemical factors, microbial biomass, bacterial community structure, extracellular enzyme activity and carbon source metabolic activity were analyzed by various methods. In order to provide scientific theoretical basis for the protection and improvement of wetland ecosystem. The main results are as follows: (1) the content of soil organic matter and ammonium nitrogen can be significantly increased by flooding conditions, and the soil pH. will be increased at the same time. The soil physical and chemical factors reached a relatively stable state at 72 days after treatment, and it was found that except for nitrate nitrogen content, There was no significant difference in soil physical and chemical factors among different flooding depths. (2) the soil microbial biomass was the highest in wet treatment, followed by flooding treatment, and the lowest in natural drying treatment, while there was no significant difference among different flooding depths. Under different water conditions, the bacterial community structure of wetland soil changed dramatically in the first 21 days, and then stabilized. At the same time, it was found that the community structure of soil bacteria in flooded environment was significantly different from that of natural drying and wetting treatment. In the study of soil microbial community composition for 21 days, it was found that Acidobacteriaceae_ (Subgroup_1) and (Micrococcaceae), were the most abundant bacteria in natural dry environment. In the moist soil environment, the highest abundance of (Oxalobacteraceae) and Xanthomonas were found in the two families. The abundance of Clostridiaceae_1 was relatively high in flooded soil. However, the depth of flooding had no significant effect on the composition of bacterial community. (3) there was no significant change in soil enzyme activity in the first 21 days of treatment, but the variation of soil enzyme activity was obvious in the first 21 days of treatment. Under the condition of natural drying, the activity of soil enzyme was the lowest, the activity of 尾-glucosidase (Bglu) was higher under the condition of wet treatment, but the activity of phenoloxidase (PERO) and peroxidase (PHOX) was higher under the condition of flooding. However, the depth of flooding had no significant effect on soil enzyme activity. Carbon source utilization analysis of the samples treated with natural drying, wetting and flooded 100cm showed that the metabolic capacity of soil carbon sources changed significantly in the first 21 days after treatment, and then tended to be stable. Finally, the ability of carbon metabolism was the strongest in wet treatment, followed by flooded 100cm, and the lowest in natural drying treatment. Further study found that the main carbon source used under flooded condition was amino acid. In conclusion, moist soil environment is the most favorable for microbial growth and metabolism, flooding condition significantly changed soil physical and chemical environment, bacterial community structure and composition, while dry soil environment significantly decreased soil enzyme activity and carbon source metabolism ability. The results suggest that maintaining a large area of Zhoutan wetland is very important to the protection of wetland ecosystem. In the future wetland protection should not only pay attention to the flooding depth of wetland soil, but also pay attention to the flooded area and duration of wetland flooding.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：S154.3

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