Knowledge Resource Center for Ecological Environment in Arid Area
| 荒漠灌丛树干茎流与根区优先流及其土壤沃岛效应 | |
| 其他题名 | Stemflow and Root-Induced Preferential Flow of Xerophytic Shrubs and Their Contribution to Soil Fertile Islands |
| 张亚峰 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 导师 | 王新平 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 腾格里沙漠东南缘沙坡头地区人工固沙植被系统经过50余年的演化，由原来以均质流动沙丘为主的沙漠景观演变成一个复杂的人工—天然的荒漠生态系统，形成了植被斑块与裸地斑块镶嵌的景观，是干旱区生态恢复的成功模式。降水是该地区限制植物生长、制约生态系统格局和过程的关键因子。固沙植物通过对降水的再分配而影响植被—土壤系统的水文循环和生物地球化学过程。灌丛植物的漏斗效应使降水汇集于灌丛基部并通过根区优先流进入深层土壤，是植物在贫瘠环境下重要的水分及养分来源。由树干茎流和根区优先流驱动的灌丛植被与土壤水分、养分之间的动态耦合机制，是影响群落组成结构、分布格局与演变过程的重要驱动力，是干旱区生态水文学和恢复生态学研究的前沿领域，对植被重建与生态恢复具有重要的理论指导意义。 本论文以1986年春季建植的人工固沙植被区灌木柠条锦鸡儿（Caragana korshinskii）和半灌木油蒿（Artemisia ordosica）为研究对象，在2011至2013年对树干茎流和穿透雨进行观测研究。量化了树干茎流、穿透雨和冠层截留在降雨再分配中所占的比例，确定了产生树干茎流的临界降雨量。同时，通过人工降雨模拟试验确定了冠层持水力和树干茎流与降雨强度、雨滴大小的关系。首次引入单位降雨树干茎流参数，建立了树干茎流与灌木冠层结构的关系。探明了灌丛周围土壤性状空间变异特征以及土壤含水量、湿润锋动态，运用漏斗率和离子富集率分析了树干茎流对水分和养分的富集效应，实现了从单株植物向群落的尺度扩展，证实树干茎流是形成灌木“沃岛”的重要生态水文学机制，树干茎流的雨水汇流和养分富集作用具有协同效应，增强了植物对干旱贫瘠环境的适应能力和生态系统的稳定性，在植被重建方面具有重要的生态水文学意义。 本论文主要结果如下： （1）柠条灌丛的树干茎流量、穿透雨量和冠层截留损失量分别占同期降雨量的8.99 %、74.31 %和16.80 %，油蒿灌丛的分别占2.82 %、74.38 %和22.35 %。柠条灌丛树干茎流显著大于油蒿（P< 0.05），二者间穿透雨量无显著差异，柠条灌丛截留损失显著小于油蒿（P<0.05)。柠条比油蒿具有更高的树干茎流率和更低的冠层截留损失量。 （2）树干茎流量（mm）随降雨增加而增加。柠条树干茎流与降雨量具有极显著的线性相关关系（P< 0.001），而油蒿树干茎流与降雨量近似幂函数关系。通过对树干茎流与降雨量的回归分析，拟合得到柠条和油蒿产生树干茎流的临界降水量分别为1.3 mm和2.2 mm。柠条和油蒿树干茎流随降雨强度增加均呈现先增加而后减小的变化趋势。 （3）冠层持水力随降雨强度的增加而指数递增。针叶型油蒿比卵圆叶型柠条更高的单位叶面积持水量。油蒿单位叶面积冠层持水量平均为0.61 mm（范围：0.29?0.89 mm），柠条单位叶面积冠层持水量平均为0.39 mm（范围：0.24?0.53 mm）。以叶面积或地上生物量（干重或鲜重）为参数能较好地估测稳态冠层持水量。 （4）大气降雨pH值最高，穿透雨pH值次之，树干茎流pH值最低，三者间具有显著性差异。灌丛外裸地土壤pH值最高，灌丛下次之，树干基部最低。树干茎流和穿透雨的酸化作用是导致土壤pH值从灌丛间裸地到灌丛基部方向上降低的一个主要原因。 （5) 冠层截留的大部分降雨通过树干茎流汇集到灌木基部。柠条和油蒿树干基部可以汇集82和22倍的与之相应树干面积的雨水于灌木基部。灌木基部的湿润锋深度显著大于基部以外区域，比较而言，柠条基部的入渗湿润锋大于油蒿基部的湿润锋。 （6） 树干茎流富集养分于灌木茎干基部，增强灌木“沃岛效应”。在测量的离子中，柠条和油蒿树干茎流的离子富集率平均值分别为726和312。灌木基部土壤养分含量远大于直接来源于大气降雨的裸地斑块土壤养分含量。树干茎流养分的季节动态表明该地区降雨的初始冲刷效应明显。 |
| 英文摘要 | Revegetation experiments have been established for more than 50 years at Shapotou area in the southeastern fringe of the Tengger Desert, northwestern China, using mainly xerophytic shrubs such as Caragana korshinskii, Hedysarum scoparium and Artemisia ordosica, which are considered as a successful model for desertification control and ecological restoration. The former sand dune landscape has been greatly transformed into a landscape characterized by a mosaic of the sparse shrubs and herbs and the bare interspaces covered by biological soil crusts. Precipitation is the sole source of soil water replenishment, and is also the key factor limiting vegetation growth and regulating the ecosystem processes and patterns in this rainfed desert ecosystem. Therefore, the availability of water and nutrients for vegetation growth and survival is crucial to the development of this ecosystem. Vegetation canopy, by redistributing incident precipitation into interception, throughfall and stemflow, affects the hydrological and biogeochemical fluxes between vegetation and soil. Although stemflow is volumetrically insignificant when compared to throughfall at the stand scale, it can be significant in soil water replenishment along roots due to the funneling effects of vegetation canopy that collects the nutrient enriched rainwater from a large area of canopy but delivers it to the soil in a much smaller trunk or stem basal area. The dynamic mechanism by integrating stemflow with root-induced preferential flow probably plays a pivotal role in vegetation structure, distribution pattern and succession of a community in rainfed desert ecosystems, and merits great attention in the research of dryland ecohydrology and ecological restoration. In this study, stemflow were quantified for two xerophytic shrubs (C. korshinskii and A.ordosica), during growing seasons of 2011-2013, in a revegetated desert enclosure that was established in 1986 of Shapotou area. We quantified the percentages of stemflow, throughfall and interception loss for two shrubs, and determined the threshold values of precipitation for stemflow generation. Through rainfall simulation experiments, we quantified canopy water storage and stemflow of two shrubs, and their relations to rainfall intensity and rain drop size. Moreover, we, for the first time, introduced the term of stemflow volume per unit precipitation depth (SfVPP) to analyze the relationships between stemflow and the biometric variables of two shrubs. Furthermore, we characterized the spatial variations of soil physical and chemical properties, the water content and wetting front depths within soil profiles that are adjacent to shrub base, beneath shrub mid-canopy and in the bare intershrub spaces, respectively. Finally, we quantified the effects of shrubs’ stemflow on soil water and nutrient enrichment, by using funneling ratio and enrichment ratio, upscaled the nutrient flux of rainfall partitioning from individual plant to the vegetation community, and justified stemflow as an important eco-hydrological mechanism that contributes to fertile islands of shrubs. Through quantitative analysis, we concluded that stemflow can be an important localized source of soil water and nutrients that can be channeled into the deeper soil layers to favor the growth and survival of shrubs. There probably exists a synergistic effect of rainwater accumulation and nutrient enrichment on the stemflow-influenced areas, which is beneficial for the adaptability and stability of shrub communities and plays a significant positive role in the development of this rain-fed revegetated desert ecosystem of study area, and thus it is also of great hydro-ecological importance in arid and semi-arid regions for the better vegetative restoration. Main findings of this dissertation are summarized as follows: (1) Percentage of stemflow, throughfall and interception loss was 8.99, 74.31, 16.80 % for C. korshinskii, respectively; the corresponding value was 2. |
| 中文关键词 | 荒漠生态系统 ; 树干茎流 ; 穿透雨 ; 冠层截留损失 ; 沃岛效应 |
| 英文关键词 | Desert ecosystem Stemflow Throughfall Interception loss Fertile islands |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287332 |
| 推荐引用方式 GB/T 7714 | 张亚峰. 荒漠灌丛树干茎流与根区优先流及其土壤沃岛效应[D]. 中国科学院大学,2014. |
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