【作者】 刘敏；

【导师】 贺康宁；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2009， 硕士

【摘要】 随着全球经济的飞速发展,温室气体的持续增加,生态环境日趋恶化,各种资源日益紧缺,水资源的匮乏尤为明显。林业在水源涵养、水资源净化方面起着举足轻重的作用。因此,如何保证和维系林木正常生长发育的基本水分要求,确定合理的造林营林密度是本文研究的核心内容。本研究对高寒区常见树种青海云杉、华北落叶松、沙棘以及盆栽苗木银水牛果、白桦的蒸腾速率、耗水量、光合生理特性及其主要影响因子进行了深入分析。主要研究结果如下:1.推导出用于推求林分蒸腾的Penman-Momeith修正方程模型,利用该模型对试验区林分2008年生长季节内蒸腾量进行推求;并根据实测数据对模型进行了验证,结果表明计算值与实测值吻合效果较好。生长季内（5月～8月）,云杉林分模拟蒸腾量267.78mm,茎流计实测蒸腾量293.36 mm,相对误差在10%以内;而华北落叶松林分模拟蒸腾量为277.60 mm。2.2008年生长季,云杉林地各月份分摊系数值分别为1.97、1.49、1.67、1.95。潜在蒸发量988.25mm,土壤蒸发量143.90 mm,蒸散量442.59 mm。而此期间降雨量为471.7 mm,降水能够满足林木生长需求。3.不同天气条件下茎流速率变化有很大差异,晴天为“宽峰”型,阴天或雨天蒸腾高峰期持续时间短,多为“双峰”或“窄峰”型。大胸径云杉比小胸径云杉茎流速率大,前者比较稳定,后者受环境因子影响显著。成熟的云杉茎流速率最大,华北落叶松最小,沙棘介于中间。4.叶片蒸腾速率与气孔阻力和气象因子有着密切关系,在充分供水和轻度胁迫下,相关性在0.9以上;但在中度、重度干旱胁迫下其相关性显著降低,分别为0.65、0.48。不同苗木在不同土壤水分条件下,蒸腾速率高峰值、变化曲线都有所不同,且峰值出现时间也有很大差异,但是不管哪种水分条件,蒸腾速率排序都是:沙棘＞牛果＞白桦＞云杉,总体变化趋势可以预测。5.光合速率与气孔导度、胞间C0₂浓度、蒸腾速率以及土壤水分关系密切。同一水分梯度下,云杉的光合速率最小,其次是牛果,沙棘最大。充分供水和重度胁迫下云杉、牛果、沙棘光合速率分别为5.0 umol·m^-2·s^-1、5.0 umol·m^-2、s^-1、20.0umol·m^-2·s^-1;1.56 umol·m^-2·s^-1、2.0 umol·m^-2·s^-1、5.9 umol·m^-2·s^-1。云杉、牛果、沙棘维持叶片水分利用效率最高时的土壤含水量分别为10.0%、11.0%和9.5%;维持最高净光合速率的土壤含水量临界值分别为:15.5%、16.1%和15.8%。由此可以得出,三者适宜的土壤水分范围分别为10.0%～15.5%、11.O%～16.1%和9.5%～15.8%。更多还原

【Abstract】 With the rapid economical development and enhanced Greenhouse Effect and collapsed ecosystem,all kind of resources and materials are deeply in shortage,especially short of water.Forestry plays a decisive role with respect to water-absorbing and water-purging.Thereby,how to guarantee and maintain basic water requirement for the normal growth and development of the forest is the core content of study.In view of the above situation,the paper studies the transpiration rates,water consumptive using,photosynthetic physiology features and the main factors of influence about Picea Crassifolia,Laric Principis-rupprechtii,Hippophae Rhamnoides Zinn,Shepherdia argentea Nutt from abroad,Betula platyphylla Sak which growth on high cold area at Qinghai province.Main research results:1.The evaporation of the forest stand in experimental zone in 2008 was calculated on the basis of Penman-Monteith model.The comparison between the values gained from calculation and measurement shows the equations is feasible.In growth season（from May to Aug.）,simulated evaporation of the Picea Crassifolia is 267.78mm,actual evaporation which was tested by Stem Flow Gauge is 293.36mm The simulated evaporation of the Larix principis-rupprechtii is 277.60mm.The relative errors are under 10%.2.At growing season in 2008,the distribution coefficients of Picea Crassifolia are 1.97,1.49,1.67, 1.95.The potential evaporation is 988.25mm,soil evaporation is 143,90mm,and potential evapotranspiration is 471.7mm,during the whole growth season total rain fall is more than total evapotranspiration.Hence the rainfall can satisfy the demand of forest growth.3.At different weather conditions the stem flow rates have a great deal of difference.The stem flow rates graph change into broad peak in the sunny day.In the cloudy or rainy day the duration of transpiration peak persist short time and the graph become double or narrow peak.The Picea Crassifolia stem flow rate of large DBH are much higher and more stable than small DBH ones.The small DBH Picea Crassifolia is obviously influenced by environmental factors.The stem flow rate of mature Picea Crassifolia is bigger than Hippophae Rhamnoides Zinn.Larix principis-rupprechtii has the smallest stem flow rate.4.The transpiration rate of the leaves has closely relationships between stomatal resistance and meteorological factors.When there are enough water and mild stress,the relativity is above 0.9.But the relativity will sharply reduce to 0.65 and 0.48,when stresses become moderate and severe.Different nursery stock in different water conditions have diverse transpiration rate peak and curve shape.At the same time the points of the peak also have a lot of difference,the comparation of the unit area of transpiration rate is Hippophae Rhamnoides Zinn＞Shepherdia argentea Nutt＞Betula platyphylla Sak＞Picea Crassifolia.The whole variation tendency can predictable.5.The photosynthetic rates have strong ties with stomatal conductance,the CO₂ concentration of intercellular and soil moisture content.Results the difference values of moisture gradation were Betula platyphylla Sak,Shepherdia argentea Nutt and Hippophae Rhamnoides Zinn from small difference to large.When there are enough water and severe stress,the photosynthetic rate of Picea Crassifolia, Shepherdia argentea Nutt and Hippophae Rhamnoides Zinn are 5.0 umol·m^-2·s^-1,5.0 umol·m^-2·s^-1,20.0 umol·m^-2·s^-1;1.56 umol·m^-2·s^-1,2.0 umol·m^-2·s^-1,5.9 umol·m^-2·s^-1.The soil moisture content of the leaves of Picea Crassifolia,Shepherdia argentea Nutt and Hippophae Rhamnoides Zinn are 10.0%,11.0%and 9.5%,when the water utilization efficiency of leaves reach the highest.The critical values of maintain the highest net photosynthetic rates are 15.5%,16.1%and 15.8%.So the results shows that the optimum range of three tapes soil moisture content are 10.0%～15.5%,11.0%～16.1% and9.5%～15.8%.更多还原