【作者】 牛俊杰；

【导师】 赵景波；

【作者基本信息】 陕西师范大学 ， 自然地理学， 2008， 博士

【摘要】 人工植被土壤水环境研究对认识土壤干化原因与土壤干层分布规律有重要科学意义,对认识土壤干化对地下水的影响、防止新的生态退化、成功实施生态环境建设和农林业发展具有重要现实意义。现代黄土高原土壤含水量及其区域变化受已经发生了变化的现代气候控制,植被建设必须能够适应现代土壤含水量状况,所以将土壤中、下部含水量状况作为植树种草以及确定人工林植株密度的依据是科学的、可靠的。因此,本项研究对成功实施太原及其周边地区黄土高原生态建设和确保其环境与经济效益有重要的应用价值。以全球变化为背景,以区域响应作主线,研究太原及其周边地区人工植被土壤水分特征,探讨土壤干层的发生过程、形成机理。本项研究采用实地调查、打钻采取6m深度土层剖面样品、实验分析的方法测定土壤含水量,将野外考证与理论分析、定性分析与定量分析相结合进行综合研究。通过对实验结果的理论分析与模型计算得出以下结论和认识:(1)研究地区季节性土壤干层形成时间主要是在秋、冬、春季。由于太原及其周边地区降水量少,黄土丘陵起伏不平,在四季都可能出现暂时性干层,但在秋、冬、春季暂时性干层发生的几率大。(2)太原及其周边地区的人工植被土壤干化具有普遍性。在长治等晋东南半湿润区人工植被土壤存在弱干层,临猗、芮城等晋南重半干旱区人工植被土壤存在严重干层,太原、忻州、榆次、太谷等晋中、晋北重半干旱黄土丘陵区人工植被土壤存在严重干层,平川地带存在弱干层,寿阳等晋东北轻半干旱地区人工植被大部分存在轻度干层,大同等雁北重半干旱地区人工植被下出现了严重干层,离石等晋西轻半干旱地区人工植被下出现了严重干层。(3)人工乔木林长期性土壤干层的分布深度。在太原及其周边地区绝大多数人工乔木林土壤干层发育深度超过了6m,坡地梯田土壤干层分布深度达到了7m以下。在较干旱区(近年平均降水量395mm)长期性干层分布上界为100cm左右,在一般干旱区(近年平均降水量440-490mm)为150cm左右。(4)太原及其周边地区农田深部存在土壤干层。在太原及其周边地区玉米、小麦等农田中普遍存在轻度或中度干层。在晋中玉米地轻度干层发育到了600cm以下,晋南轻度土壤干层发育深度也达到600cm,晋西玉米地400cm深度接近轻度干化,晋北玉米地轻度干层分布深度超过了600cm。农田季节性干层、深部长期性土壤干层的出现严重影响了农田土壤的水循环,季节性干层的存在是该地区农作物易于发生干旱灾害的主要原因。降水量少是本区农田干层产生的主要原因,但农田生产力提高、作物密度大是不可忽视的因素。(5)运用GIS软件,依据土壤含水量等主要影响因素将太原及其周边地区的土壤水分环境划分为:土壤水分相对丰富区、土壤水分一般区、土壤水分相对缺乏区;依据土壤干层程度将太原及其周边地区人工林的土壤干层划分为:土壤轻微干层区、土壤中等干层区、土壤严重干层区。(6)基于水分消耗的土壤干层指标—水分缺失度模型:水分缺失度R=(田间持水量W-土壤含水量W_h)/田间持水量W(7)太原及其周边地区的植被建设模式。遵循演替规律,自然恢复为主,水分条件好的地方发展人工林。结合植被带的变化,人工植被种类、密度为:在半湿润的长治地区,杨树、核桃及与之耗水接近的落叶阔叶乔木适宜种植密度应略小于1111株/hm~2,静乐沟谷和阴坡杨树的种植密度应为500-600株/hm~2,岚县平川地杏树的种植密度为600-700株/hm~2,梁峁地油松密度为500-600株/hm~2。轻半干旱地区杨树、核桃、油松等植被适宜种植密度应略小于900株/hm~2;重半干旱地区的太原平川地段苹果、梨树种植密度应在700-800株/hm~2,梧桐应为500-600/hm~2,白皮松、柏树应为600-700株/hm~2,枣树应略小于1000株/hm~2,平川地区杨树应略小于1000株/hm~2。在阳曲阴坡、沟谷可以种植密度小于600株/hm~2的杨树。更多还原

【Abstract】 Studies concerning soil water environment under plantation have their scientificsignificances to realize causes of soil desiccation and dried soil layers’ spatial distribution in aeration zone. Simultaneously, they have their practical significances to realize soil desiccation’s affection on groundwater and to prevent new ecological degeneration, to construct ecological environment and develop agriculture and forestry effectively. It is reasonable and dependable to put soil moisture of layers in the middle and deep position as criterions to grow plantation and discover a proper plant density because of the phenomenon that modern loess plateau’s soil moisture is controlled by the changed modern climate and the principle that vegetation’s setting must correspond with current soil moisture situation. Therefore, our study is practically valuable for ecological construction around Taiyuan, to ensure its environmental or economic benefits and to prevent new ecological degeneration.Based on the theory that soil moisture manifests the relation between global change and regional response, this thesis studies soil water’s characteristics under plantation around Taiyuan and takes a further discussion of dried layer’s occurrence.The study’s field works include drilling soil samples from 0-6ms underground. Based on these samples, we take a method which combines field works and theoretical analysis, as well as qualitative means and quantitative means.After our theoretical analyses and calculation with corresponding models to the samples, we reach some recognitions as the following:1. Seasonal dried soil layers in our research area usually form in fall or spring and winter. Because of a low precipitation and a rough landform around Taiyuan, seasonal dried soil layers may occur in all the four seasons, but may occur in summer with a lower probability.2. It is a common phenomenon that soil under plantation around Taiyuan has a dried soil layer. In the southeast of Shanxi like in Changzhi, located in the semi-humid zone, there exist weak dried soil layers. In the south of Shanxi like Linyi and Ruicheng, located in severe-semi-arid zone, there exist severe dried soil layers. The middle Shanxi and north of Shanxi like Taiyuan, Xinzhou, Yuci, Taigu in loess hilly region or plain, located in the severe-semi-arid zone, there exists severe dried soil layer or weak dried soil layer. The northeast of Shanxi like Shouyang, located in weak-semi-arid zone, there mostly exist weak dried soil layers. The Yanbei region like Datong, located in the severe-semi-arid zone, there exist severe dried soil layer. The west of Shanxi like Lishi, located in weak-semi-arid zone, there exist the severe dried soil layers.3. Made sure the depth of lasting dried soil layer under arbor forests. Most arbor forests or farmlands around Taiyuan have dried soil layers exceeding the depth of 6m, while terrace in slope field have dried layers exceeding the depth of 7m. Dried soil layer’s upper bound has a depth of 100cm in medium arid zone (mean precipitation: 395mm) and a depth of 150cm in normal arid zone (mean precipitation: 440mm-490mm).4. Find the deep dried soil layer in farmlands in Taiyuan and surrounding areas. There are weak or medium dried soil layers in corn fields and wheat fields etc. all around Taiyuan. The main cause that makes vegetation prone to suffer drought is seasonal dried soil layer. Weak dried soil layer in corn fields in middle of Shanxi reaches below 6ms. Weak dried soil layer in south Shanxi also reaches 6ms because of lasting drought. 4m depth of corn fields in west Shanxi is close to the weak dried soil layer. Weak dried soil layer in corn fields in north Shanxi also reaches 6ms. The seasonal dried soil layers and depth soil layers have seriously influenced the water cycle of farmland soil. Low precipitation is a main cause of dried soil layers. But attentions should be also paid to the rise of farm productivity and the increase of plant density.5. Using GIS software and indexes of soil moisture and other factors, soil moisture environment of Taiyuan and its surrounding areas will be divided into three different parts: area with abundant soil moisture, area with general soil moisture, area with low soil moisture. Based on extent of soil desiccation, Taiyuan and its surrounding areas will be divided into three different parts: area with slightly dried soil layers, area with medium dried soil layers, area with severely dried soil layers.6. Based on an index portraying dried soil layer of the loss of moisture, we raised a model:Soil moisture lack extent R = (Field capacity W- Soil moisture W_h) / Field capacity W.7. The model of vegetation construction in Taiyuan and surrounding area. Plantation should be restored in a place which is sufficient for water. We should follow the rules of deduction, and mainly resort to natural reconstruction. For instance, we can plant poplar, walnut or trees with similar water rate in a density less than 1111 plant/hm~2 in Changzhi. We can plant poplar in a density of 500-600 plant/hm~2 in valleys or shady slope in Jingle, almond in a density of 600-700 plant/hm~2 in plains of Lanxian. We can plant Chinese pine in a density of 500-600 plant/hm~2 in loess liang and loess mao. We can plant poplar or walnut or Chinese pine in a density less than 900 plant/hm~2 in weak-semi-arid zone. We can plant apple tree or pear tree in a density of 700-800 plant/hm~2, or phoenix tree in a density of 500-600 plant/hm~2, or bark pine or cypress in a density of 600-700 plant/hm~2, or Chinese jujube in a density less than 1000 plant/hm~2, or poplar in a density less than 1000 plant/hm~2 in plains of Taiyuan. We can plant poplar in a density less than 600 plant/hm~2 in valleys or shady slope in Yangqu.更多还原