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塔里木沙漠公路防护林土壤有机碳动态及呼吸特征研究
王迎菊
学位类型硕士
导师雷加强
2016
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词定植年限 有机碳储量 惰性有机碳 腐殖质 土壤呼吸 温度
摘要土壤碳是全球最大的碳源。土壤呼吸是全球碳循环和气候演变的关键生态过程。目前极端干旱区人工林生态系统土壤有机碳动态及呼吸特征方面的资料相对匮乏,相关资料在区域乃至全球碳循环研究中必不可少。为此,本研究立足于世界第二大流动沙漠腹地,以塔里木沙漠公路防护林生态系统中定植年限不同的防护林地为研究材料,通过研究土壤有机碳动力学特征,初步了解防护林对风沙土发育过程中土壤固碳潜力的影响;模拟咸水灌溉影响下凋落物分解过程,理解防护林对于风沙土的碳释放特征的影响。本研究成果能够丰富极端干旱区碳平衡研究的基础资料,有益于极端干旱区碳循环理论体系的完善;同时可为塔里木沙漠公路防护林生态工程的可持续性管护提供科学决策依据。本研究主要成果如下。 (1)随防护林定植年限增大,土壤有机碳储量只有柽柳林地略微升高。值介于1192-2316 g/m2之间,均值为1704 g/m2。就植物种类而言,土壤有机碳储量大小顺序为沙拐枣 > 柽柳 > 梭梭。就不同土层而言,土壤有机碳含量仅在0-50 cm范围内随土壤深度增加而减少,50 cm以下变化不明显。 (2)随防护林定植年限增大,表层土壤(0-10 cm)惰性有机碳(包括团聚体、腐殖质、抗氧化性和抗酸解性有机碳)含量增加,其中团聚体和腐殖质有机碳含量逐年增加,而抗氧化性和抗酸解性有机碳只在定植年限5-7年时增加明显。各碳组分之间极显著相关,其中团聚体、腐殖质有机碳与总有机碳的相关性较高。就各惰性碳在总有机碳中的相对含量而言,团聚体和抗氧化性有机碳的含量较高,而抗酸解性有机碳含量最低。 (3)随防护林定植年限增大,腐殖质结构中C=O的相对含量(C=O / C-O-C)先降低后升高;支链聚亚甲基碳占末端甲基碳的比例(CH2 / CH3)在7年时最高,之后略有降低并趋于稳定。 (4)在夏末、秋季和初冬季节(6月30日-11月18日),随凋落物分解时间的增加,土壤呼吸速率呈波动式降低;随土壤深度增加,土壤呼吸速率在分解过程的夏末和秋初(6月30日-9月10日)时,表层大于亚表层。在夏末和秋初(6月30日-8月10日)时,三种植物对土壤呼吸速率的影响大小为柽柳 > 沙拐枣 > 梭梭。淡水灌溉下土壤呼吸速率明显高于咸水,两种咸水灌溉下土壤差异不明显。施氮肥后土壤呼吸速率明显增加。 (5)秋季防护林土壤呼吸速率日变化呈单峰曲线模式,最大值出现在正午14-16时(北京时间),晚上22-24时(北京时间)降至最低;随土壤深度增加,土壤呼吸速率降低;随灌溉水矿化度增加,土壤呼吸速率降低, 并且亚表层表现较明显;三种植物对土壤呼吸的影响大小为梭梭 > 柽柳 > 沙拐枣。 (6)随土温和气温的变化,防护林土壤呼吸速率月变化模式较为复杂,可用复合(Compound)、增长(Growth)、指数(Exponential)和逻辑曲线(Logistic)来模拟。灌溉咸水土壤呼吸速率日变化与温度呈三次函数关系(Rs = b3T3 + b2T2 + b1T + a),并且与5 cm深度处温度的拟合曲线决定系数(R2)最高,而与气温拟合关系决定系数最低。两个分解层中,表层土壤呼吸速率的变化用温度拟合的准确性较高。三种植物中,柽柳的拟合曲线的决定系数(R2)的均值最大,梭梭最小。
其他摘要Soil carbon is the world's largest carbon source. Soil respiration has been viewed as a vital ecological progress in the global carbon cycle and climate evolution. Previous researches on dynamic changes of soil organic carbon and characteritics of soil respiration of the shelter forest ecosystem in the extreme arid region are quite inadequate, which would be necessary for carbon cycle on regional scale or world scale. Therefore, this study based on the world's second-largest flow desert hinterland,the Tarim desert highway shelter forest was chosen as the study object and the experimental design were mainly based on different plantation time of the shelter forest. The objects of this thesis are preliminarily understanding: (1) the ability of soil carbon sequestration during the process of the development of the sandy soil, by studding the dynamic changes of soil organic carbon in Tarim desert highway shelter forest; (2) the influence of shelt forst on the carbon release characteristics of sandy soil by simulating plant litter decomposition process under the influence of saline water irrigation. The study fruits of this project will enrich basic data of carbon balance in extreme arid region, help to improve theoretical system of carbon cycling in in extreme arid region, furthermore, provide scientific decision-making basis for sustainable management of the Tarim desert highway shelter forest ecological project. The main results of this study are: (1) The soil organic carbon storks increased a little with the years of plantation only in Tamarix chinensis Lour. (T.c.) Shelter forest. The range of the change is 1192-2316 g/m2, average value is 1704 g/m2. The carbon storks size order of three kinds of plant is Calligonum mongolicunl Turcz. (C.m.) > Tamarix chinensis Lour. (T.c.) > Haloxylon ammodendron (C. A. Mey.) Bunge. (H.a.). Soil organic carbon content only decreased with soil depth in 0 to 50 cm and didn’t changed obviously below 50 cm. (2) The soil passive organic carbon, including micro-aggregate organic carbon (OCMIA), humus organic carbon (OCHS), resistance to oxidation carbon (OCNaClO) and resistance to hydrolysis carbon (OCHCl) increased with years of plantation in the soil surface layer (0-10 cm). OCMIA and OCHS increased year by years, OCNaClO and OCHCl increased in 5 to 7 years and then no obvious change. The degree of correlation between all kinds of SOC fractions is with significance prominence, and the correlation between OCMIA and TOC, OCHS and TOC is higher than OCHCl and TOC, OCNaClO and TOC. The relative content of OCMIA and OCNaClO in TOC is higher than OCHS and OCHCl, the relative content of OCHCl is the lowest. (3) The relative content of functional C=O groups (C=O/C-O-C) decreased first and then increased with years of plantation; and the ratio of the polymerization methylene in carbon branched chain to methyl at the end of the carbon chain (CH2 / CH3) was highest in 7 years and decreases a little and stable gradually. (4) In the end of summer, autumn and early winter (from June 30 to November 18), with the increase of litter decomposition time, the soil respiration rate was reduced with fluctuation monthly. With soil depth increasing, in the end of summer and early autumn (from June 30 to September 10), the rate was surface layer greater than sub-surface. In the end of summer and early autumn (from June 30 to August 10), the influence of three kinds of plants to soil respiration was T.c. > C.m. > H.a.. With the increase of irrigation water salinity, fresh water soil respiration rate was significantly higher than salt. The difference between two kinds of salt- water was not obvious. The rate after applying nitrogen fertilizer will increase obviously. (5) In autumn, the daily variation of soil respiration rate was single-peak curve model. The maximum appears at 14-16 h pm, decreased to minimum 22-24 h pm. With depth increase, the rate reduced. With the increase of irrigation water salinity, the soil respiration rate decreased which showed more apparent in the sub-surface layer. The influence of three plants on soil respiration was H.a. >T.c.> C.m. (6) The monthly changes of soil respiration rate with the soil and air temperature presented complicated model, can use four kinds of curve fitting, which are compound, growth, exponential and logistic curve respectively. The relationship between daily variation of respiration rate of soil irrigated by salt water and temperature is three function of Rs = b3T3 + b2T2 + b1T + a. The decision coefficients (R2) of the fitting curve of each treat with temperature in 5 cm depth are the highest, and with the air temperature are lowest. In two decomposition layers, the fitting accuracy of the change of the surface soil respiration rate with temperature is higher. The average value of R2 in the fitting curve of T.c. is maximum than other plants; H.a. is minimal.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14742
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
王迎菊. 塔里木沙漠公路防护林土壤有机碳动态及呼吸特征研究[D]. 北京. 中国科学院大学,2016.
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