【摘要】：全球氣候變暖已是毋容置疑的事實(shí)。IPCC第五次氣候評(píng)估報(bào)告指出,到本世紀(jì)末,全球平均地表溫度將在1986-2005年的基礎(chǔ)上升高0.3-4.8℃,在未來(lái)全球變暖的背景下,極端曖事件將進(jìn)一步增多,熱浪發(fā)生的頻率更高,時(shí)間更長(zhǎng)。云南高原濕地是我國(guó)的重要生態(tài)屏障,濕地生態(tài)系統(tǒng)極為脆弱,由于地處較高的海拔,對(duì)氣候變化高度敏感,更容易受到全球氣候變暖的影響。高原濕地植物作為生產(chǎn)者,是整個(gè)濕地生態(tài)系統(tǒng)功能得以維持的核心和基礎(chǔ),是濕地環(huán)境質(zhì)量的重要指示者,也是對(duì)氣候變化響應(yīng)最強(qiáng)烈的組分。本研究利用云南高原獨(dú)特的立體地形與立體氣候特點(diǎn),采用原位異地技術(shù)和空間代時(shí)間的方法,選擇納帕海(海拔3260m)湖濱帶代表性水生植物水蔥、茭草,連同其生長(zhǎng)的原位土壤單元,一起移至隨海拔梯度變化而產(chǎn)生氣候條件差異的拉市海濕地(海拔2437m)和昆明滇池流域(海拔1891m),以轉(zhuǎn)移空間研究對(duì)象來(lái)解決時(shí)間尺度限制問(wèn)題,進(jìn)而研究氣候變化對(duì)高原濕地植物的影響,探討氣候變暖對(duì)高原濕地生態(tài)系統(tǒng)碳平衡的影響途徑和作用規(guī)律。得到的主要研究結(jié)論如下:(1)隨著海拔梯度下降的氣候條件改變,氣溫、水溫顯著升高,光照強(qiáng)度顯著降低,降雨量差異顯著,CO_2濃度和相對(duì)濕度變化不顯著。在氣候變化對(duì)高原濕地水生植物的影響研究中,氣溫、水溫、光照強(qiáng)度是應(yīng)該考慮的環(huán)境影響因子。CO_2既是植物光合作用的必須原料之一,又是構(gòu)成植物生存環(huán)境的一種環(huán)境因子,因此,CO_2濃度也作為一個(gè)考慮的環(huán)境因子。(2)隨著氣候條件的改變,水蔥、茭草兩種植物的凈光合速率顯著升高:水蔥由移出地納帕海移至拉市海濕地和昆明滇池研究地點(diǎn)后,其生長(zhǎng)階段的平均凈光合速率,分別增加了19.1%和18.4%;茭草的平均凈光合速率,分別增加了43.5%和44.2%。同時(shí),氣孔導(dǎo)度、胞間CO_2濃度以及蒸騰速率也隨之顯著升高;最大凈光合速率、光補(bǔ)償點(diǎn)、表觀量子效率顯著升高,而光飽和點(diǎn)顯著降低;CO_2補(bǔ)償點(diǎn)顯著降低,而CO_2飽和點(diǎn)和羧化效率顯著升高。研究表明,不同氣候條件下兩種植物的凈光合速率與氣孔導(dǎo)度、胞間CO_2濃度以及蒸騰速率等生理因子均呈顯著或極顯著正相關(guān);而不同氣候條件下的氣溫,是影響兩種濕地植物光合作用的最主要環(huán)境因子。兩種供試植物雖然都是廣布種,但茭草的氣孔導(dǎo)度調(diào)節(jié)機(jī)制優(yōu)于水蔥,使得凈光合速率與氣溫的相關(guān)性高于水蔥,呈現(xiàn)出茭草對(duì)氣溫升高的高適應(yīng)性。氣候變化引起的溫度升高極大地促進(jìn)了水蔥、茭草對(duì)光能的利用能力,兩種植物的光合固碳能力都得到了很大的提高。(3)隨著氣候條件的改變,水蔥、茭草兩種植物的株高、生物量均顯著增加。其中,水蔥由移出地納帕海移至拉市海濕地和昆明滇池研究地點(diǎn)后,其生長(zhǎng)后期的生物量(生物量最大的生長(zhǎng)階段)分別提高了20.3%和22.5%;茭草生長(zhǎng)后期的的生物量,分別提高了42.2%和45.3%。但基徑的變化卻不顯著,因此兩種植物的莖不夠健壯,甚至容易倒伏,從而不利于抵抗外界環(huán)境。另外,茭草的株高、生物量對(duì)氣溫升高的適應(yīng)能力要大于水蔥。研究表明,不同氣候條件下的氣溫,是影響兩種濕地植物株高、生物量的最主要環(huán)境因子。耐受溫度范圍寬、適應(yīng)力強(qiáng)的物種能積極響應(yīng)氣候變暖,光合固碳能力也得到較大提高,生物量顯著增加,從而對(duì)生態(tài)系統(tǒng)的碳輸入產(chǎn)生積極的影響。(4)隨著氣候條件的改變,水蔥、茭草兩種植物的葉綠素含量均顯著增加,丙二醛、過(guò)氧化物酶、游離脯氨酸以及可溶性糖的含量均有不同程度的降低。隨著氣候條件的改變,水蔥游離脯氨酸含量的季節(jié)動(dòng)態(tài)變化幅度逐漸變小;而茭草游離脯氨酸含量的季節(jié)動(dòng)態(tài)變化幅度仍然很大;除此之外的其他生理生化特性,茭草升高或降低的幅度均大于水蔥。研究表明,不同氣候條件下的氣溫,是影響兩種濕地植物生理生化特性(過(guò)氧化物酶除外)的最主要環(huán)境因子�？傮w來(lái)看,茭草和水蔥均體現(xiàn)了廣布種對(duì)氣候變暖的適應(yīng)能力,但茭草對(duì)環(huán)境脅迫的適應(yīng)能力更強(qiáng),這有利于該物種的進(jìn)一步生長(zhǎng)和擴(kuò)張,使其在濕地生態(tài)系統(tǒng)中持續(xù)保持優(yōu)勢(shì)地位。(5)隨著氣候條件的改變,水蔥、茭草兩種植物的凋落物分解速率均顯著增加:水蔥由移出地納帕海移至拉市海濕地和昆明滇池研究地點(diǎn)后,其凋落物的分解速率分別提高了31.9%和28.9%;茭草的分解速率,分別提高了44.7%和43.6%。溫度敏感性(Q_(10))的大小順序?yàn)?混合凋落物(3.48)茭草凋落物(3.06)水蔥凋落物(2.52),因此,水溫升高對(duì)茭草凋落物分解的影響要大于水蔥。在生長(zhǎng)季,水溫對(duì)凋落物的分解速率影響較大;在冬季,凋落物的基質(zhì)質(zhì)量對(duì)分解速率影響較大。C含量、N含量、lignin含量、C:N和lignin:N是水蔥、茭草凋落物分解的重要預(yù)測(cè)因子,但在不同的分解時(shí)期,這些凋落物基質(zhì)質(zhì)量的重要性也存在著差異:N含量、C:N是第1個(gè)冬季最重要的影響因子,lignin:N是第2個(gè)冬季最重要的影響因子。研究表明,不同氣候條件下的水溫,是影響兩種濕地植物凋落物分解的最重要環(huán)境因子,其次是凋落物的基質(zhì)質(zhì)量。氣候變暖可以加快水蔥、茭草等濕地水生植物廣布種的凋落物分解,尤其是混合凋落物的分解,進(jìn)而可能促進(jìn)高原濕地生態(tài)系統(tǒng)的碳輸出。(6)氣候變暖對(duì)高原濕地生態(tài)系統(tǒng)碳庫(kù)的影響不是單方面的,它通過(guò)碳輸入和輸出影響著濕地土壤碳庫(kù)的平衡。氣候因子決定了植被種類的分布、光合產(chǎn)物生成量和凋落物的分解速度,因此對(duì)土壤有機(jī)碳的固定和礦化分解過(guò)程有極大的影響。從整體上講,氣候變化對(duì)水蔥凋落物分解的促進(jìn)要大于對(duì)其光合固碳能力的促進(jìn),而對(duì)茭草凋落物分解的促進(jìn)基本上等于對(duì)其光合固碳能力的促進(jìn)。在氣候變暖的大背景下,水蔥可能會(huì)削弱高原濕地生態(tài)系統(tǒng)的碳匯功能,而茭草對(duì)生態(tài)系統(tǒng)碳匯功能的影響可能并不大。氣候變暖對(duì)高原濕地生態(tài)系統(tǒng)碳平衡的影響,是一個(gè)復(fù)雜而又綜合的過(guò)程,還需進(jìn)一步的深入研究。
[Abstract]:The fifth IPCC Climate Assessment Report pointed out that by the end of this century, the global average surface temperature will rise by 0.3-4.8 degrees Celsius on the basis of 1986-2005. Under the background of global warming in the future, extreme warming events will increase further, the frequency of heat waves will be higher and the time will be longer. Wetland ecosystem is very fragile and sensitive to climate change because of its high altitude. As a producer, plateau wetland plants are the core and foundation of maintaining the function of the whole wetland ecosystem and an important indicator of wetland environmental quality. Using the unique three-dimensional topography and climatic characteristics of the Yunnan Plateau, the representative aquatic plants of the Napa Sea (3260m above sea level) lacustrine zone, including onion and stubble, were selected to move to the altitude along with the in situ soil units. The Lashihai Wetland (2437m above sea level) and the Dianchi Lake Basin (1891m above sea level) with different climatic conditions caused by gradient change were used to solve the time-scale limitation problem by transferring spatial research objects. The effects of climate change on plants in plateau wetland were studied, and the ways and effects of climate warming on carbon balance in plateau wetland ecosystem were discussed. The main conclusions are as follows: (1) With the change of climatic conditions, the temperature, water temperature, light intensity, rainfall, CO_2 concentration and relative humidity are not significantly different. CO_2 is not only one of the necessary raw materials for plant photosynthesis, but also an environmental factor for plant survival environment. Therefore, CO_2 concentration is also considered as an environmental factor. (2) With the change of climate conditions, the net photosynthetic rate of water onion and stubble plants increased significantly: water onion moved from Dinapa. Meanwhile, stomatal conductance, intercellular CO_2 concentration and transpiration rate also increased significantly. Maximum net photosynthetic rate, light compensation point, and surface photosynthetic rate increased by 19.1% and 18.4% respectively. The results showed that the net photosynthetic rate was significantly positively correlated with stomatal conductance, intercellular CO_2 concentration and transpiration rate under different climatic conditions. Temperature under climatic conditions is the most important environmental factor affecting the photosynthesis of the two wetland plants. Although both species are widely distributed, the regulation mechanism of stomatal conductance of the sturgeon is superior to that of the onion, which makes the correlation between net photosynthetic rate and air temperature higher than that of the onion, showing a high adaptability of the sturgeon to temperature rise. With the change of climate conditions, the plant height and biomass of water onion and stubble increased significantly. Among them, water onion moved from Dinapa Sea to Lashihai Wetland and Kunming Dianchi Lake. After the location, the biomass of the late growth stage (the maximum biomass growth stage) increased by 20.3% and 22.5% respectively, and the biomass of the late growth stage increased by 42.2% and 45.3% respectively. But the change of basal diameter was not significant, so the stems of the two plants were not strong enough, and even lodging easily, which was not conducive to resistance to the external environment. The results showed that the temperature under different climatic conditions was the most important environmental factor affecting the plant height and biomass of the two wetland plants. (4) With the change of climate conditions, the chlorophyll content of Allium mongolicum and Zizania latifolia increased significantly, while the contents of malondialdehyde, peroxidase, free proline and soluble sugar decreased to some extent. The seasonal variation range of acid content decreased gradually, while the seasonal variation range of free proline content of the sturgeon was still very large; in addition to other physiological and biochemical characteristics, the increase or decrease range of the sturgeon was greater than that of the onion. On the whole, the adaptability of the widespread species to climate warming is reflected in the water onion and the sturgeon, but the adaptability of the sturgeon to environmental stress is stronger, which is conducive to the further growth and expansion of the species, making it maintain a dominant position in the wetland ecosystem. The litter decomposition rates of Allium mongolicum and Zizania latifolia both increased significantly: the litter decomposition rates of Allium mongolicum increased by 31.9% and 28.9% respectively after it moved from Dinapa Sea to Lashihai Wetland and Kunming Dianchi Lake, and the decomposition rates of Zizania latifolia increased by 44.7% and 43.6% respectively. Water temperature had a greater influence on litter decomposition rate than water onion. In the growing season, water temperature had a greater influence on litter decomposition rate; in winter, litter substrate quality had a greater impact on litter decomposition rate. C content, N content, lignin content, C: N and lignin: N content. It is an important predictor of litter decomposition of Allium mongolicum and Zizania latifolia, but the importance of litter substrate quality varies in different decomposition stages: N content, C:N is the most important influencing factor in the first winter, and lignin:N is the most important influencing factor in the second winter. Climate warming can accelerate litter decomposition, especially the decomposition of mixed litter, which may promote carbon output of plateau wetland ecosystem. (6) Climate warming can accelerate the decomposition of litter of aquatic plants in Plateau wetland. Climate factors determine the distribution of vegetation species, photosynthate production and litter decomposition rate, so they have a great impact on the process of soil organic carbon fixation and mineralization decomposition. The promotion of litter decomposition was greater than that of photosynthetic carbon sequestration, but the promotion of litter decomposition was basically equal to that of photosynthetic carbon sequestration. The effect of climate warming on carbon balance in plateau wetland ecosystem is a complex and comprehensive process, which needs further study.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：Q948.112

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