【作者】 田晶会；

【导师】 贺康宁；

【作者基本信息】 北京林业大学 ， 水土保持， 2005， 博士

【摘要】 本文针对干旱半干旱地区植被建设中植被与水资源关系不协调的问题,以土壤—植物—大气连续系统(SPAC)理论为基础,在山西省方山县北京林业大学径流林业试验基地上,选择主要的水土保持造林树种作为研究对象,在2002～2004年的生长季期间,利用先进的仪器和设备,同时运用多种方法和手段,分析不同水分环境条件与林木生长的关系,系统地研究该地区主要造林树种蒸腾耗水的水分生理生态学特征和耗水规律,其结果不仅有助于干旱半干旱地区植被建设中生态用水定额的确定;而且也将对今后该地区森林植被建设中物种选择和合理林分密度设计的起到科学的指导作用。 本文主要开展了以下几方面的研究: ◆ 半干旱区的降水资源环境与植被建设的关系 ◆ 8个主要造林树种的水分生理生态学特性研究 ◆ 黄土半干旱区适宜林木生长的最佳土壤水分条件 ◆ 林木的土壤水分环境条件及土壤水分生产力特征分级 ◆ 试验林地土壤蒸发耗水规律 ◆ 林木的蒸腾耗水量的模拟与预测 ◆ 试验林分的蒸散量及分量组成比例 水量平衡原理、土壤物理学、SPAC理论、森林水文学、森林培育学是本研究试验设计和结果分析的理论基础;Farquhar气孔限制理论、土壤水动力学原理、空气动力学能量平衡理论是具体数据估算的理论依据。 主要研究结果如下: ◆ 研究地区近50年来多年平均年降水量504mm,降水量总体上呈现下降的趋势;降水主要集中在植物生长季节(5～9月);降水四季分配中降水集中于盛夏,春末夏初降水偏少,秋冬土壤补墒不足,是长期影响该地区春季造林成活率的关键所在;各季节的降水变率冬季最大,春季次之,秋季大于夏季;28%变率的降水年际变化是造成该地区防护林林分不稳定的重要原因之一。降水资源及其年际动态仍然是影响林木生长的关键因素。 ◆ 在无水分胁迫盆栽试验条件下,研究和对比了树种的蒸腾耗水特性,结果表明,苗木蒸腾速率和气孔导度的的日变化曲线呈单峰型,水分利用效率的日变化趋势为上午时段的水分利用效率明显高于下午时段的水分利用效率,针叶树种的蒸腾速率和气孔导度最低,阔叶树种最高,灌木树种位于中间;各树种苗木的蒸腾速率和气孔导度值由高到低的排序依次为刺槐、白榆、紫穗槐、黄土半干旱区水土保持林主要树种耗水特性研究沙棘、山杏、柠条、油松和侧柏;水分利用效率由高到低的排序依次为侧柏、柠条、油松、刺槐、紫穗槐、白榆、沙棘和山杏。对不同土壤水分条件下树种苗木的各项生理指标研究表明:随着土壤含水量的增加,大部分树种苗木的蒸腾速率、气孔导度和水分利用效率随着增加。 ,在不同的土壤水分条件下,光合速率对光强的响应曲线不相同,其光合速率的光响应变化趋势遵循二次项模型。在高土壤水分条件下,光合作用对光强变化的响应与土壤水分条件基本无关,敏感性较低;随着水分胁迫的加重,光合作用对光强响应的敏感性增强。 .确定了刺槐与侧柏在干早、半干旱地区以提高水分利用效率为核心的适宜土壤水分条件和林地土壤水分管理标准: 刺槐适宜的SwC闭值为11.0%~15.5%(近似于田间持水量的52.0%~74.0%),最适SWC为13.0%(近似于田间持水量的62.0%)左右;所允许的最大土壤水分亏缺SWC为1众O%(近于田间持水量的48.0%)左右;土壤水合补偿点为4.55%(近似于田间持水量的21.7%)左右。 侧柏适宜的SwC闭值在9.5%~13.5%(近似于田间持水量的45.0%一64.0%之间;最适的SwC在10.5%(近似于田间持水量的50.0%)。所允许的最大土壤水分亏缺SwC为8.5%左右(田间持水量的40.5%);土壤水合补偿点3.91% (近似于田间持水量的18.6%)左右。 ,林地土壤水分季节性变化划分为:冬季土壤水分稳定期(头年12月至翌年3月上旬)、春季土壤水分损耗期(3月中旬至6月下旬)、夏季土壤水分恢复期(7月、8月和9月上旬)、秋季土壤水分消退期(9月中旬至n月下旬)4个阶段。林地土壤水分的季节性垂直变化划分为:土壤水分速变层(0~30cm左右的土层)、土壤水分活跃层(30~SOcm左右的土层)、土壤水分过渡层(80~18Ocm的土层)、土壤水分相对稳定层(180cm或更低土层以下)4个层次。 .调查不同密度刺槐林分林下植物状况,研究林下植被对林地土壤水分环境的指示作用,随着林分密度的增大,其土壤水分、光照强度有显著减小的趋势,林下植被的种类和数量减少,物种丰富度和物种多样性指数降低,逐步由典型的中生植物向早生植物过渡,反映出高密度林分林地土壤的水分竞争激烈,渐渐出现干早、半干早地区成龄人工林土壤干化的现象。 .提出以光合速率和叶片水分利用效率为指标的土壤水分生产力分级标准,界定出“无产无效水”、“低产低效水”、“中产高效水”、“高产中效水”“高产高效水”的概念及其土壤水分临界含水量。 分析表明:各试验林分绝大部分时间林木生长都处于较严重的土壤水分胁迫状态;除在水分条件较好的8月、9月时间里,土壤含水量能达到或接近“高产高效”土壤含水量之外,其它时间均处于“低产低效水”的水分范围之内。摘要 .通过土壤蒸发与水面蒸发、土壤水分的关系,建立了土壤蒸发模型,并根据林内外的太阳辐射比例关系计算相应的林地土壤蒸发?更多还原

【Abstract】 Aiming to solve the contradiction between demand for the extension of forest vegetation and the limited water supply in arid and semi-arid area and based on the theory of soil-plant-atmosphere continuum, the dissertation chose the main afforestation tree species of soil and water conservation in the station of "Runoff Forestry" of Beijing Forestry University in Fangshan Country, Shanxi Province in Growing Seasons from 2002 to 2004, utilized advanced apparatus, equipments and various approaches, systematically analyzed of relationship between wood production with water consumption and studied the ecophysiological characteristics of tree transpiration and water consumption. These studies could provides the scientific bases for accurately estimating ecological water consumption and the choice of tree species and the properly arrangement of stand density. The dissertation involved following aspects: Relationship between precipitation resource in semi-arid region and forest construction. The study on ecophysiological characteristics of eight main afforestation tree species. The suitable soil moisture condition of tree growth in semi-arid region on Loess Plateau. The soil moisture circumstance of woodland and woodland soil’s water availability and productivity. The rule of testing woodland soil evaporation. The simulation and prediction of stand transpiration and water consumption. Total and component proportion of woodland evapotranspiration.The theoretical basis of the experimental design and conclusion analysis are the theory of water balance, soil physics, soil-plant-atmosphere continuum, foresthydrology and silviculture. The theoretical providence of factual data estimation arethe theory of soil hydrodynamics and aerodynamic principle and energy balanceequation.Major conclusions are summarized as follows:? Under the condition of free soil water stress, the diurnal changes of transpiration rate and stomatal conductance of eight main afforestation tree species display a signal-peak curve and that of water use efficiency peak in the early morning. The transpiration rate of coniferous trees was the lowest, whilst the broad leaved trees were the highest, and the shrub species fell between coniferous species and broad leaved species. When sorted by potential transpiration rate and stomatal conductance, the decreasing orders were: Robinia pseudoacacie、Ulmus pumilas Amorpha fruticosa、 Hippophae rhamnoides、 Primus armeniaca 、 Caragana korshinskii、 Pinus tabulaeformis and Platycladus orientalis. The decreasing orders of water use efficiency were: Platycladus orientalis、 Caragana korshinski、 Pinus tabulaeformis 、 Robinia pseudoacacie 、 Amorpha fruticosa % Ulmus pumila 、 Hippophae rhamnoides 、 Prunus armeniaca. With the increase of soil water content the transpiration rate, stomatal conductance and water use efficiency increase under the different soil water content. Under the different soil water content the curve of photosynthesis with irradiance is different and presents a quadratic relation model. Under the high soil water content the sensitivity of photosynthesis with irradiance is low and has little or no relation with water and with the increase of water stress the sensitivity of photosynthesis with irradiance increases.? To increase water use efficiency, the suitable soil water condition and rules of woodland soil moisture of Robinia pseudoacacia and Platycladus oriental in semi-arid region on Loess Plateau are determined. The range of SWC being suitable to tree’s growth of Robinia pseudoacacia and Platycladus oriental are respectively 11.0%-15.5% (52.0%-74.0% of saturated soil water content) and 9.5%-13.5% (45.0%-64.0% of saturated soil water content). The best SWC values are respectively 13.0% (62.0% of saturated soil water content) and 10.5% (50% of saturated soil water content) to tree’s growth of Robinia pseudoacacia and Platycladus oriental. The allowable lowest SWC are respectively 10.0% (48.0% of saturated soil water content) and 8.5% (45.0% of saturated soi更多还原