Knowledge Resource Center for Ecological Environment in Arid Area
| 鄂尔多斯高原弃耕农田植被与土壤物理性质动态 | |
| 其他题名 | Dynamics of the vegetation and soil physical property in the abandoned croplands in Ordos Plateau |
| 蔡文涛 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 郑元润 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 草地灌丛化是近一个世纪以来干旱半干旱区的主要表现形式，可能会导致生态系统结构和功能的改变，甚至可能导致干旱区土地退化和荒漠化。然而以灌丛化草地为背景的弃耕农田植被、土壤物理性质与生物结皮动态的研究尚显不足。在鄂尔多斯高原软梁、硬梁上选取一系列不同时限的弃耕农田，研究弃耕演替过程中群落生物量、盖度、密度、重要值、根系分布、凋落物、地表生物结皮以及不同土层土壤含水量、容重和机械组成的变化。结果表明： 软梁弃耕农田在20年的时间内群落演替经历了杂草群落、半灌木油蒿（Artemisia ordosica）群落和多年生草本群落三个阶段。硬梁弃耕农田在20年时间内经历了杂草群落、本氏针茅（Stipa bungeana）+冷蒿（A. frigida）群落、本氏针茅群落三个阶段，多年生草本植物在整个演替过程中占主导地位。软梁弃耕农田草本植物根系主要分布在0-20cm土层，半灌木油蒿根系主要分布在0-30cm土层，且可深入地下达100cm；硬梁弃耕农田植物根系主要分布在0-5cm土层。 软梁弃耕农田表层（0-10cm）土壤物理性质随弃耕年限增加明显改善，土壤黏粒含量、地表凋落物随弃耕年限增加而明显增加，土壤容重明显降低，土壤含水量略微升高；中层（10-30cm）土壤物理性质随弃耕年限增加稍显恶化，土壤黏粒含量升高，但土壤含水量略微降低；深层（30-50cm）土壤物理性质变异较大。硬梁弃耕农田土壤表面凋落物盖度、生物结皮盖度和生物结皮厚度随弃耕年限增加而增加，表层（0-10cm）土壤容重、黏粒含量、含水量随弃耕年限增加变化不明显，深层（10-40cm）土壤物理性质变异较大。 软梁弃耕农田表层（0-5cm）土壤黏粒随弃耕年限的积累可能会延缓水分向深层入渗，凋落物盖度的增加会减少表层水分的蒸发并提高表层土壤有机质，从而提高表层土壤保水能力。硬梁弃耕农田较高的黏粒粉粒含量可能使生物结皮得到较好发育，而生物结皮的发育会促使降雨分配的浅层化。地表凋落物和土壤黏粒物质的累积导致软梁弃耕农田土壤水分浅层化可能是浅根性多年生草本植物群落取代半灌木油蒿群落的关键因素。硬梁较高的浅层土壤含水量可能是浅根性本氏针茅草地未被半灌木植物油蒿入侵的原因之一。 |
| 英文摘要 | Shrub encroachment was a main phenomenon in the last century in arid and semi-arid regions which could lead to the change of ecosystem structure and function and even lead to land degradation or desertification. However, few researches were focused on the vegetation, soil physical property and biological soil crust dynamics in the abandoned cropland in shrub-encroached grasslands. Series of different typical abandoned croplands with different abandoned years in Ruanliang and Yingliang in Ordos Plateau were selected. The communities biomass, coverage, density, species important value (IV), root distribution pattern, litter, biological soil crust and soil moisture, soil bulk density, soil texture in different soil layers were studied. The results were as follows. Within 20 years abandonment the croplands in Ruanliang experienced 3 community types including weeds, semi-shrub Artemisia ordosica and perennial grass, while cropland in Yingliang experienced 3 types including perennial weeds, the perennial Stipa bungeana with A. frigida and S. bungeana. The grass root in Ruanliang abandoned croplands mainly distributed in 0-20cm soil layer, while the semi-shrub A. ordosica distributed in 0-30cm with an expanding of 100cm. The grass root in Yingliang abandoned croplands mainly distributed in 0-5cm. There were an obvious improvement of the surface (0-10cm) soil physical conditions during the abandonment of Ruanliang cropland. The clay particle content at 0-5cm soil layer and litter on the ground clearly accumulated, soil bulk density went down, while soil moisture went up slightly during the process. The physical conditions at 10-30cm soil layer deteriorated slightly showing a phenomenon of the clay particle content at this layer up, but soil moisture down. The physical properties at 30-50cm soil layer varied a lot compared to others. In Yingliang abandoned cropland the litter coverage, biological soil crust coverage and thickness went up during the abandonment process. Soil bulk density, clay particle content and soil moisture remain constant at 0-10cm soil layer, varied at 10-40cm soil layer. The accumulation of soil clay particle at 0-5cm soil layer during the abandonment process of Ruanliang might prevent the water infiltration to deep soil layers, and the accumulation of litter could slow down the water evaporation and increase the organic carbon content of the surface soil, thus enhancing the water retaining capacity. The high clay particle content in Yingliang abandoned cropland improved the growing of the biological soil crust, and the soil crust would retain the rainfall to the surface soil layer. The high surface soil layer water moisture caused by the accumulation of litter and clay particle might be the reason why the shallow-rootedness perennial grass replaced the semi-shrub A. ordosica. Similarly, the high water moisture at surface soil layer might also be one of the reasons why S. bungeana grassland were not invaded by A. ordosica. |
| 中文关键词 | 灌丛化 ; 弃耕 ; 植被动态 ; 土壤动态 ; 鄂尔多斯高原 |
| 英文关键词 | shrub encroachment abandonment vegetation dynamics soil dynamics Ordos Plateau |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院植物研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287849 |
| 推荐引用方式 GB/T 7714 | 蔡文涛. 鄂尔多斯高原弃耕农田植被与土壤物理性质动态[D]. 中国科学院大学,2017. |
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