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绿洲化过程中塔北灌区农田土壤固碳速率及潜力研究
鲁晶晶
学位类型硕士
导师周智彬
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
关键词塔北灌区 农田土壤有机碳含量及密度 变化速率 影响因素 潜力估算
摘要绿洲化作为干旱半干旱地区的一种独特生态演变机制,是人类活动与自然条件共同作用下由荒漠向绿洲转变的过程。新疆塔北灌区作为典型的绿洲农业区,伴随着绿洲化过程,其农田土壤理化性质及有机碳含量发生改变,进而影响到农田土壤碳库的变化。本研究通过对不同时期塔北灌区农田样地土壤采样及剖面分析,同时结合第二次全国土壤普查和塔北灌区相关农业资料,利用Arc GIS软件分析农田土壤有机碳密度和储量的变化,揭示绿洲化过程中塔北灌区农田土壤有机碳库的演变规律,并分析影响土壤有机碳变化的主要因素,估算塔北灌区及南疆地区的农田土壤固碳潜力。研究旨在为塔北灌区改善土壤质量、提高农作物产量提供科学指导,对新疆乃至西北地区的碳估算提供理论支撑,从而服务于国家气候谈判。本研究主要研究结果如下: (1)不同类型土壤有机碳含量差异显著 塔北灌区不同类型土壤有机碳含量(SOC)之间存在差异,从高到低依次为林灌草甸土、草甸土、潮土、盐土和风沙土,其中风沙土有机碳含量远低于该区平均水平。土壤剖面有机碳含量从上而下递减,这与长期耕作及农田管理等关系密切。塔北灌区土壤有机碳密度(SOCD)的空间分布差异显著,总体呈现出自西南向东北递减的分布格局;不同类型土壤有机碳密度(SOCD)差异显著,与SOC含量分布规律一致;对同一土壤类型而言,不同土属间有机碳密度(SOCD)差异不显著。塔北灌区的有机碳库总量约为87.64*107 kg。不同类型土壤的储碳能力从高到底依次为林灌草甸土、草甸土、潮土、盐土和风沙土;草甸土碳库是灌区最大的碳库,其有机碳储量为46.31*107 kg,所占比例高达52.85%。 (2)近30年(1981-2011年)有机碳含量呈增加趋势 30年来,塔北灌区有机碳含量及密度均呈上升趋势,西南、中南和东南部的SOCD增量明显,最高可达0.9503 kg·m-2,中北及东北部等区域则呈负增长。农田有机碳含量以不足0.01 kg·hm-2·a-1的变化速率缓慢增长,土壤固碳、丢碳、相对平衡面积分别占总面积的61%、25%和14%。 (3)土壤有机碳变化是多种因素综合作用的结果 影响农田有机碳固存的主要因素包括农田开垦年限、农田管理措施和土壤理化性质三个方面。农田开垦年限对土壤有机碳积累影响显著。以新开垦地为对照,耕作年限达30年以上的农田有机碳含量显著高于耕作年限小于30年的农田。以土壤有机碳含量为因变量(y),耕作年限为自变量(x),做回归分析,得y = 0.002x2 + 0.0737x + 1.9883,R² = 0.9014。农田管理措施是塔北灌区农田土壤有机碳固存的重要影响因子。较高的秸秆还田比例,有机肥及化肥的配施,充足的灌溉水源,均有效地提高了土壤有机碳的含量。土壤有机碳含量与容重、粉粒及黏粒含量呈显著正相关,与砂粒含量呈显著负相关;全氮、全磷、全钾及有效磷含量与土壤有机碳含量的相关性显著,pH值及速效钾对土壤有机碳含量影响不显著。土壤有机碳与养分元素相关性由高到为:全氮(TN)>全磷(TP)>有效磷(AP)>全钾(TK)>速效钾(AK);建立土壤有机碳含量(y)与全氮(x1)、全磷(x2)、全钾(x3)和有效磷(x5)的最优回归方程,y=5.464x1+31.603x2+0.1771x3+23.552x5-3.184,R2=0. 653,P<0.001。 (4)农田土壤有机碳潜力巨大 塔北灌区不同类型土壤有机碳固碳潜力差异显著。盐土的固碳潜力为1.69 kg·m-2,远高于其他4种类型的土壤,因此要加强塔北灌区的次生盐碱化治理和盐碱土改良。塔北灌区5种土壤类型的总固碳潜力为59.32*107 kg,固碳潜力较大。总体而言,南疆地区的土壤有机碳固碳潜力巨大,为22.96*109 kg。固碳潜力最大的3种土壤类型依次为盐土(1.64 kg·m-2)、境漠盐土(1.06 kg·m-2)和灌淤土(0.98 kg·m-2),固碳潜力不足0.5 kg·m-2的为棕钙土,其他土壤类型的固碳潜力均在0.5~1.0 kg·m-2之间。
其他摘要Oasisization,as a unique ecological evolution mechanism of arid and semiarid regions, is a transition process that changes from desert to oasis,which is caused by human activities and natural factors together.The irrigation area in Northern Tarim Basin,as a typical oasis agriculture area,of which the soil physical and chemical properties and organic carbon content changes along with the process of oasisization,affecting the changes of cropland soil organic carbon pool.Based on analyzing the typical sampling sites of the irrigation area in Northern Tarim Basin in different periods and combined with the data from the second national soil survey and agricultural information of this area, the storage and density fluctuation of soil organic carbon were analyzed by Arc GIS, revealing the evolvement rules of cropland soil organic pools, analyzing the relevantly impacting factors of soil carbon sequestration and estimating the carbon sequestration potential of the irrigation area in Northern Tarim Basin and South Xinjiang. The research is aimed at providing scientific guidance to improve the soil quality and increase crop yields of this area. Moreover, it can provide theoretical support for carbon estimate of Xinjiang as well as Northwest Territories in China, serving for national climate negotiations. The results are as follows: (1)The soil organic carbon content of different soil types were of great significance The capacities of cropland carbon sequestration for different soil types were of great difference,and from high to low, the organic carbon content were meadow soil, solonchak soil, fluvo-aquic soil and aeolian sandy soil, respectively, and the content of organic carbon for aeolian sandy soil was far less than the average content of the region. On the scale of soil profile, the content of organic carbon were decreased from epipedon to bottom,which was closed related with long-term cultivation and cropland management . The space distribution of soil organic carbon density in the irrigation area in Northern Tarim Basin was of significant difference, showing a distribution pattern which decreased from the southwest to the northeast generally. The soil organic carbon density change laws were in line with soil organic carbon content. The soil organic carbon density of different soil genus in one soil type was not significantly different.The total organic carbon pool of the irrigation area in Northern Tarim Basin was about 87.64 * 107 kg. The capacities of carbon storage in different types were of great difference, which decreased from shrubby meadow soil, meadow soil, saline soil to aeolian sandy soil in turn; meadow soil carbon pool, whose carbon storage was about 46.31*107 kg, occupying the proportion as high as 52.85%, was the largest carbon pool in this area. (2)Soil organic carbon content increased in 30 years (1981-2011) Soil organic carbon content and density of the irrigation area in Northern Tarim Basin increased from 1981 to 2011. Soil organic carbon density in southwest, south central and southeast area increased with the increment of 0.9503 kg·m-2, while the north central and northeast showed negative growth at the same time. The carbon storage increased with the average rate of 0.01 kg·hm-2·a-1 slowly, and topsoil carbon sequestration increased area rated 61 %, decreased area rated 25%, with the relative balance of the area accounted for 14%. (3)The change of soil organic carbon content was the result of many impacting factors The main impacting factors that affected the agricultural organic carbon sequestration included three aspects: cropland reclamation duration, cropland management measures and soil physical and chemical properties.Reclamation duration had a significant impact on soil organic carbon accumulation. Compared with newly-reclaimed land, the soil organic carbon of croplands which were reclaimed for more than 30 years was significantly higher than those whose reclamation duration were less than 30 years. A regression equation of soil organic carbon(y) and reclamation duration(x) was obtained (y = 0.002x2 + 0.0737x + 1.9883, R² = 0.9014).Cropland management measures were important impacting factors of soil organic carbon sequestration of the irrigation area in Northern Tarim Basin. The high proportion of straw mulching of different crop types,combined organic manure and chemical fertilizers application, and the adequate irrigation water, were improving the content of soil organic carbon effectively.Soil organic content had significant positive correlations with soil bulk density, percentage of clay and particle, but negative correlations with percentage of sand. The content of SOC had significant positive correlations with total N, P, K and soil available P, and had no significant correlations with pH and soil available K. In general, the correlation coefficients of SOC and soil nutrients were in a decreasing order of TN >TP>AP>TK>AK. An optimal stepwise regression equation of soil organic carbon(y) and TN (x1),TP (x2),AP (x3) and TK (x5) was obtained (y=5.464x1+31.603x2+0.1771x3+23.552x5-3.184,R2=0. 653,P<0.001) (4)The soil carbon sequestration potential was great The carbon sequestration potential of cropland soil organic carbon for different soil types were of great difference in the irrigation area in Northern Tarim Basin. The carbon sequestration potential of solonchak soil was 1.69 kg·m-2, which was much higher than other four soil types. Therefore, more management of salinization and amendment of solonchak soil would greatly improve the carbon sequestration potential of the irrigation area in Northern Tarim Basin. The total carbon sequestration potential of the irrigation area in Northern Tarim Basin was large, with the capacity of 59.32*107 kg.In general, the carbon sequestration potential of south Xinjiang was huge, with the capacity of 22.96*109 kg. The top 3 soil types of the carbon sequestration potential were solonchak soil, deserty solonchak soil and luvo-aquic soil, with the values 1.64 kg·m-2, 1.06 kg·m-2 and 0.98 kg·m-2, respectively. The carbon sequestration potential of calcic brown soil was less than0.05 kg·m-2, and the carbon sequestration potential of the remaining soil types were between 0.5~1.0 kg·m-2.
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/365004/14720
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
鲁晶晶. 绿洲化过程中塔北灌区农田土壤固碳速率及潜力研究[D]. 北京. 中国科学院大学,2016.
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