【作者】 臧春鑫；

【导师】 杨劼； 宋炳煜；

【作者基本信息】 内蒙古大学 ， 生态学， 2010， 博士

【摘要】 在干旱半干旱地区,水分成为制约植物生长的主要限制因子。因此准确探明植物的吸收、耗水机制以及由此产生的生态水文效应对于植被的合理建植、科学管理,有着重要的指导意义。本研究,选择广泛分布于蒙古高原荒漠化草原区和黄土高原北部典型草原区的防风固沙植物中间锦鸡儿作为研究对象。在总结前人的工作基础上,采用了Granier热扩散探针法和稳定性同位素示踪法,分别以风沙土基质和黄绵土-黄土基质上生长的中间锦鸡儿为例对中间锦鸡儿的水分吸收方式、树干液流特征、蒸腾耗水量、群落特征及其水分利用状况进行了详细的调查分析,在阐明中间锦鸡儿耐旱适应机理的同时,分析了浑河流域中间锦鸡儿灌丛的水分收支状况。本研究在全面调查的基础上,将研究区选择在了毛乌素沙地腹地(行政区划位于乌审旗)和黄土丘陵沟壑区的浑河流域。结果如下：1中间锦鸡儿水分吸收特点1)中间锦鸡儿的根系形态可塑性强,可以适应不同基质的土壤含水量变化。风沙土基质中间锦鸡儿根系形态构型特点是：主根扎根较浅,侧根和吸收根(根径<1mm)主要分布在10-30cm土层中,数量占根系总量的72.2%,侧根主要以水平生长为主；黄绵土-黄土基质中间锦鸡儿根系形态构型特点是：主根扎根很深,主根直径随着土壤深度的增加逐渐减小；侧根和吸收根(根径<1mm)的数量也随土壤深度的增加呈下降趋势。侧根和吸收根(根径<1mm)主要分布于0-70cm的土层中,其中O-50cm土层中的侧根和吸收根的数量占到根系总数的91.7%。2)水力提升现象：中间锦鸡儿全天具有水力提升现象,但是在18：00到次日凌晨2：00这段时间的水力提升现象对植物的影响最大；中间锦鸡儿的水力提升现象,除了可以满足自身水分需要外还可以为邻近植物提供水分,提高了自身及邻近非水力提升植物的竞争力；根据实验,计算得出中间锦鸡儿幼苗提升水量为1.33gH2O·d-1·株-1。3)两种基质上生长的中间锦鸡儿有着不同的水分吸收方式。黄绵土-黄土基质上生长的中间锦鸡儿即可以通过主根利用深层土壤水,也可以利用表层发达的吸收根获取降水时所补充的浅层土壤水。风沙土基质上生长的中间锦鸡儿,其水分主要来源于大气降水所补充的浅层土壤水,并依靠侧根的水平生长来增加水分的吸收面积。2中间锦鸡儿树干液流特征1)中间锦鸡儿树干液流速率日变化呈明显的“几”字型宽峰曲线,没有出现“午休”现象。全天树干液流速率变化可以划分为：液流迅速上升、液流相对稳定、液流迅速下降和夜间液流四个阶段。影响中间锦鸡儿树干液流速率日变化的环境因子有太阳辐射、空气温度、水汽压亏缺、大气相对湿度、土壤温度和风速,除了大气相对湿度与树干液流速率呈显著的负相关关系以外,其余环境因子均与树干液流速率呈显著的正相关关系。2)中间锦鸡儿树干液流速率日变化同太阳辐射、水汽压亏缺的变化并不完全同步,存在时滞现象。风沙土基质上生长的中间锦鸡儿,其树干液流速率的变化要滞后于太阳辐射60min,提前于水汽压亏缺90min。黄绵土-黄土基质5月份、7月份中间锦鸡儿树干液流变化要滞后于太阳辐射30min,9月份没有出现滞后；5月份、9月份的水汽压亏缺滞后于中间锦鸡儿树干液流变化的时间均为150min,7月份滞后时间为120min。3)不同月份中间锦鸡儿的树干液流速率和液流量存在差异。5月份中间锦鸡儿在的树干液流速率(0.05kg·h-1)和液流量(36.75kgH2O·株-1)最低,7月份树干液流速率(0.08kg·h-1)和液流量(62.52kgH2O·株-1)均达到了整个生长季的最大值,8月、9月树干液流速率和液流量开始下降但整体保持在一个较高的水平。中间锦鸡儿树干液流速率季节变化与水汽压亏缺、太阳辐射、空气温度和风速呈正相关关系,与大气相对湿度呈负相关关系。4)中间锦鸡儿具有夜间水分补偿现象；中间锦鸡儿夜间仍然存在着树干液流变化,与白天树干液流相比,变化比较平缓,波动较少,液流量明显低于白天的液流量,中间锦鸡儿的夜间液流现象,是在补充白天因强烈蒸腾而导致的自身水分亏缺,而且不同月份的中间锦鸡儿夜间树干液流速率存在差异。5)不同天气条件下中间锦鸡儿树干液流变化存在差异,而且影响树干液流的环境因子也不同。但是,太阳辐射始终是影响中间锦鸡儿树干液流的主要环境因子。3中间锦鸡儿整株丛蒸腾耗水特征在利用树干液流计算中间锦鸡儿整株丛蒸腾耗水量时,要剔除夜间树干液流的数据。中间锦鸡儿整株丛蒸腾速率日变化规律呈明显的“几”字型宽峰曲线,没有出现“午休”现象；中间锦鸡儿的整株丛蒸腾速率季节变化规律呈现“抛物线”状,7月份中间锦鸡儿的蒸腾耗水量最高,5月份最低,9月份虽然进入中间锦鸡儿生长的后期,但是仍然具有较高的蒸腾耗水量。不同天气情况下中间锦鸡儿的蒸腾耗水量存在差异,晴天的蒸腾耗水量要明显高于阴天的蒸腾耗水量。4中间锦鸡儿灌丛蒸腾耗水量与生态水文效应1)中间锦鸡儿灌丛7月份的蒸腾耗水量最高。黄绵土-黄土基质中间锦鸡儿灌丛整个生长季的蒸腾耗水量5月份最低(19.53mm),7月份最高(45.65mm),9月份中间锦鸡儿虽然进入生长后期,但是群落的蒸腾耗水量仍然保持较高水平(27.6mm),整个生长季变化规律呈“抛物线”状。2)中间锦鸡儿灌丛水分收支平衡,在理想的状态下,除生长中期的7月份灌丛水分出现盈余以外,生长初期的5月份和生长后期的9月份灌丛水分均不同程度的出现亏缺。说明,仅依靠当期大气降水补充到土壤中的水分无法满足中间锦鸡儿灌丛水分需求,植物仍需要从土壤中获取大量的水分,进而加剧了土壤水分亏缺现象的出现。3)中间锦鸡儿灌丛生态水文效应：①中间锦鸡儿灌丛各月份均有土壤干层现象的出现,多数情况下土壤含水量处于凋萎湿度以下,土壤水分极度匮乏。②中间锦鸡儿灌丛内外的土壤含水量存在明显差异,灌丛外没有明显的土壤干化现象而灌丛内的土壤干化现象则较为明显。③从中间锦鸡儿灌丛与毗邻其它群落土壤水分的比较中,可以看出,中间锦鸡儿灌丛各层土壤含水量均低于其他群落,整体呈下降趋势,存在明显的土壤干层。80cm以下土层的土壤含水量低于凋萎湿度,土壤水分极度匮乏,说明中间锦鸡儿更容易造成土壤干层现象的出现。④中间锦鸡儿灌丛与其他群落相比,土壤水库的调节能力较差,灌丛土壤水库88.53%的调节能力持久性地丧失。中间锦鸡儿灌丛土壤水分的交换深度在80-100cm之间,100cm以下的土壤水分无法进行有效的水分交换,土壤干层现象无法得到缓解。4)浑河流域中间锦鸡儿灌丛生长期水分收支平衡状况,在仅依靠大气降水的情况下,除7月份中间锦鸡儿灌丛存在26.9mm的水分盈余以外。5、9月份均有不同程度的水分亏缺现象,5月份水分亏缺8.58mm、9月份亏缺2.8mm。更多还原

【Abstract】 In Arid and Semi-arid Regions, water becomes the main factor to constrain plant growth. So to calculate accuvelocityly the absorption and water deprivation of plant and its eco-hydrological effects has the guiding significance to the rational planting and scientific management of plant. In this research, we choose Caragana intermedia as the object, which is an excellent wind-breaking and sand-fixing shrub species widely distributed in the Desert-steppe of Mongolian Plateau and the typical steppe region of northern Loess Plateau. On the basis of predecessors’ work and the adoption of advanced Granier’s thermal dissipation probe method and stable isotope technique, we have a detailed analysis on Caragana intermedia in sand soil and in loess about the water absorption, characteristics of stem sap flow, transpiration water consumption, community characteristics and water utilization. While clarifying the drought resistance mechanism of Caragana intermedia, we have an analysis on the water balance condition of Caragana intermedia community in the Hunhe river basin. On the basis of general investigation, we choose Maowusu sandlot and the Hunhe river basin in the hilly area of Loess Plateau as the research area. The results are as follows:1. Water absorption characteristic of Caragana intermedia1) The root system of Caragana intermedia is quite plastic, which can help the plant to adapt to different water capacity in different ground substances. The characteristic of root morphology of Caragana intermedia in sand soil is as below: the rooting depth of main root is shallow; the branch roots and absorbing roots (diameter less than lmm) mainly distribute in 10-30cm soil layer, which account for 72.2% of the total amount of roots, and the branch roots mainly grow horizontally. The characteristic of root morphology of Caragana intermedia in sand loess is different:the main root takes root deep, and its diameter becomes smaller as it goes deeper; the number of branch roots and absorbing roots (diameter less than 1mm) decreases as the depths grows. The branch roots and absorbing roots mainly distribute in the 0-70 cm soil layer and the number of those in the 0-50 cm soil layer account for 91.7% of the total amount of roots.2) There is hydraulic lift phenomenon in Caragana intermedia, but it is the most important effect plant between 18:00 and 2:00 the next day. This phenomenon can not only satisfy its own needs for water, but also provide water for plants nearby, thus improving the competitive strength of Caragana intermedia and other nearby plants without hydraulic lift. Experiments show that the amount of water lifted by young plant of Caragana intermedia is 1.33g per plant per day.3) There are different ways of water absorption for Caragana intermedia in two different ground substances. Caragana intermedia growing in sand loess can absorb water in deep soil with main root and also water in shallow layer of soil with its rich absorbing roots. Caragana intermedia in sand soil mainly makes use of water in the shallow surface and increases absorbing area by its branch roots that grow horizontally.2. Sap flow characteristics of Caragana intermedia1) The daily variation of sap flow velocity of Caragana intermedia is wide-peak curve, and there is no obvious phenomenon of "nap". It can be divided into four stages:rapid ascending period, stationary period, rapid descending period and nighttime period. The variation is mainly influenced by factors such as solar radiation, air temperature, vapor pressure deficit, relative air humidity, soil temperature and wind speed. Among these factors, relative air humidity has the obvious negative correlation with sap flow velocity, while all others have obvious positive correlation.2) The daily variation of sap flow velocity of Caragana intermedia does not keep pace with solar radiation, and vapor pressure deficit, but there is time-delay. The sap flow velocity variation of Caragana intermedia in sand soil is 60 minutes behind solar radiation and 90 minutes before vapor pressure deficit. The sap flow variation of Caragana intermedia in May and July in loess is 30 minutes behind solar radiation, and there is no time delay in September. In May and September, the vapor pressure deficit is 150 minutes behind the sap flow variation of Caragana intermedia, and the time delay in July is 120 minutes.3) There is a difference between sap flow velocity and sap flow capacity in Caragana intermedia. In May, the sap flow velocity (0.05kg·h-1), and the sap flow capacity (36.75kgH2O·strain-1) are the lowest, while that in July reach the highest in the grow season with the sap flow velocity (0.08kg·h-1) and the sap flow capacity (62.52kgH2O·strain-1). In August and September, the sap flow velocity and sap flow capacity begin to drop but still keep at a relatively high level. The seasonal sap flow velocity variation of Caragana intermedia has positive correlation with vapor pressure deficit, solar radiation, air temperature and wind speed while it has negative correlation with relative air humidity.4) There is nighttime water compensation in Caragana intermedia. Nighttime sap flow still exits in Caragana intermedia, but compared to daytime sap flow,the rate variation at night is slow, the curve is relatively smooth and the amount of sap flow is obviously lower. This is to compensate for the water deficit caused by strong transpiration during the day, and the nighttime sap flow rate in different months are different.5) The sap flow of Caragana intermedia varies in different weather conditions, and the environmental factors that affect the sap flow are different. But solar radiation is always the main environmental factor that affects the sap flow of Caragana intermedia.3. The transpiration water consumption characteristics of Caragana intermediaWhen calculating the transpiration water consumption by way of sap flow, it is necessary to get rid of the sap flow at night. The seasonal variation curve of transpiration of single Caragana intermedia is paracurve. The transpiration is the highest in July, and the lowest in May. In September, the transpiration still keeps at a high level, even though it has reached the later period of growth. Besides, the transpiration is different in different weather conditions, in which it is higher in clear days than in cloudy days.4. The transpiration water consumption of Caragana intermedia shrub and its eco-hydrological effects1) The transpiration of Caragana intermedia community is the highest in July. The transpiration of Caragana intermedia community in sand loess during the whole growth period reaches the lowest in May (19.53mm) and the highest in July (45.65mm). In September, the transpiration still keeps at a high level (27.6mm), even though it has reached the later period of growth. The seasonal variation curve of transpiration of Caragana intermedia is paracurve.2) There is a water balance in Caragana intermedia community. In an ideal state, there is a water surplus in July (middle period of growth); while there is a water deficit in varying degrees in May (early period of growth) and September (later period of growth). This explains that precipitation can not satisfy the water need of Caragana intermedia community, and the plant has to absorb water from the soil, which accelevelocitys the water deficit in the soil.3) The eco-hydrological effects of Caragana intermedia community.①There is a phenomenon of dry layer of soil every month in the Caragana intermedia community. The water content in the soil is below the point of wilting moisture most of the time. The soil is extremely lack of water.②There is an obvious difference in soil water content in and outside the Caragana intermedia community. The dry layer of soil is quite obvious in the Caragana intermedia community, but it is not the case outside the Caragana intermedia community.③Compared to other plant communities nearby, the water content in different layers of soil in the Caragana intermedia community is lower, and there is obvious dry layer of soil. The water content below 80cm is below the point of wilting moisture, and there is extreme lack of water in the soil, which means Caragana intermedia is more likely to cause dry layer of soil.④Compared to other plant communities, the soil reservoir in the Caragana intermedia community lacks the ability of the self-control, which means 88.53% of ability is permanently lost. The water exchange depth in the Caragana intermedia community is 80-100cm, below which the water can not exchange effectively and the problem of day layer of soil can not be solved.4) The water budget of Caragana intermedia community during growth period in the Hunhe River basin is as follows:if only depending on precipitation, there is a water surplus of 26.9mm in July, and there is a water deficit in varying degrees in May and September, which are 8.58mm and 2.8mm respectively.更多还原