【作者】 华娟；

【导师】 赵世伟；

【作者基本信息】 中国科学院研究生院（教育部水土保持与生态环境研究中心） ， 土壤学， 2009， 硕士

【摘要】 植被恢复是宁南山区治理土壤退化及保持水土的主要措施,这个地区的植被恢复措施主要分为天然草地封育、牧荒坡短期封禁草地和人工柠条的种植。本研究针对宁南黄土丘陵区植被恢复措施的现状,选取植被恢复过程中典型样点进行试验,揭示了研究区植被恢复过程中土壤有机碳库特征、碳汇效应及团聚体的物理保护机制。1.植被恢复措施能显著提高土壤的总有机碳含量和有机碳密度,表现为封育草地>牧荒坡短期封禁草地>人工柠条。植被演替的影响在演替初期(坡耕地至百里香群落)主要表现在0～100 cm土层,演替后期(百里香群落至大针茅群落)在0～20 cm土层有机碳表聚作用更为明显。2.植被恢复措施对土壤活性有机碳组分(易氧化有机碳、颗粒有机碳和轻组有机碳)含量均有显著提高,封育草地效果最好,显著高于牧荒坡短期封禁草地和人工柠条,并随植被恢复演替而增加。演替初期的影响表现在整个测定剖面,演替后期土壤易氧化有机碳、颗粒有机碳和轻组有机碳含量的表聚作用更加明显,分别为0～20 cm、0～40 cm和5～10 cm土层。3.植被恢复措施对土壤稳定性有机碳(惰性有机碳、重组有机碳和矿物结合态有机碳)含量均有显著改善,封育草地效果最好,牧荒坡短期封禁草地和人工柠条次之,并随植被恢复演替过程而增加。植被恢复的影响在演替初期表现在整个剖面,演替后期土壤重组有机碳和惰性有机碳含量表聚作用更加明显,分别为0～5 cm和0～10 cm土层。4.土壤水稳性团聚体形成过程表现为:在坡耕地阶段的基础上,随植被演替逐步由微团聚体(<0.25 mm)向大团聚体转移,最终形成>5 mm粒径团聚体,并形成以>5 mm和<0.25 mm粒径团聚体为主的分布格局。5.植被恢复措施对土壤团聚体有机碳及其活性有机碳组分的改善效果均表现为封育草地>牧荒坡短期封禁草地>人工柠条。植被演替对团聚体有机碳的影响在演替初期和后期分别表现在0～70 cm和0～40 cm土层,主要分布在1～0.25 mm粒径。植被恢复促进了0.5～0.25 mm粒径易氧化有机碳、>5 mm粒径轻组有机碳、2～0.5 mm粒径颗粒有机碳含量的增加。6.植被恢复措施能显著提高土壤团聚体稳定性有机碳组分含量,封育草地效果最好,牧荒坡短期封禁草地和人工柠条次之,表明植被的天然恢复更有利于提高稳定性有机碳库容。草地土壤固碳机制表现为:植被演替初期,稳定性有机碳主要固定在<0.25 mm粒径中,演替后期主要固定在>5 mm粒径中。更多还原

【Abstract】 Vegetation restoration is a main measure to controll soil degradation and conserve soil water in Southern Mountainous Areas of Ningxia. The mearsures of vegetation restoration include natural restored grassland,short-term non-grazing on pasture and wastelandand planting caragana. We seleceted the typical samples of defferent vegetation restoration and researched characteristics and carbon sink of organic carbon in soil and aggregates. Furthmore,the study was conducted to discuss the carbon sequestration mechanism of glassland. The main results and conclusions were presented as follows:1. Different vegetation restoration measures(natural restored grassland,short-term non-grazing on pasture and wastelandand caragana) could significantly improve both the content and density of SOC,which followed the order natural restored grassland> short-term restored after grazing glassland> caragana. Effects of SOC on soil depths were 0～100 cm in early succession (slope land - Thymus mongolicus) while the depths of 0～20 cm of SOC was higher than other in later succession(Thymus mongolicus- Stipa grandis).2.Soil active organic carbon(AOC) (including labile organic carbon(LOC),particulate organic carbon(POC) and light fraction organic carbon(LFC))had also been significantly improved under the three measures. Moreover,the improvement effect of natural restored grassland was more significant than short-term non-grazing on pasture and wastelandand caragana. Effects of AOC on soil depths were 0～100 cm in early succession. LOC,POC and LFC were higher in 0～20 cm, 0～40 cm and 5～10 cm.3. Soil stable organic carbon (including inactive organic carbon(IOC), heavy fraction organic carbon(HFC) and mineral organic carbon(MOC))had also been significantly improved under the three measures. Moreover,the improvement effect of natural restored grassland was more significant than short-term non-grazing on pasture and wastelandand caragana. Effects of stable organic carbon on soil depths were 0～100 cm in early succession. HFC and IOC were higher in 0～5 cm and 0～10 cm.4. Formation of soil aggregates in grassland showed that it firstly formad micro-aggregates(<0.25 mm) in slope land. With the vegetation succession,micro-aggregates gradually formed larger size of aggregates. >5 mm particle size of aggregates ultimately formed.5. Different vegetation restoration measures could all significantly improve the content of SOC and AOC in aggregates, which followed the order natural restored grassland> short-term restored after grazing glassland> caragana. Effects on SOC in aggregates was 0～70 cm in early succession and 0～40 cm in later succession. Content of SOC in aggregates mainly inhanced in the particle size of 1-0.25 mm. In the process of glassland vegeration restoration,content of LOC reached maximum in the size of 0.5-0.25 mm,the size of >5 mm was highest for LFC as well as 2-0.5 mm for POC.6. Different vegetation restoration measures could significantly improve the contents of stable components of organic carbon in aggregates. Moreover,the improvement effect of natural restored grassland was more significant than short-term non-grazing on pasture and wastelandand caragana,which showed that natural restored grassland was more conductive to improving stable organic carbon in aggregates. Soil carbon sequestration mechanism in glassland showed the following changes. Stable organic carbon in aggregates maily fixed in the size of <0.25 mm in early succession while in >5 mm in later succession.更多还原