【作者】 徐军亮；

【导师】 马履一；

【作者基本信息】 北京林业大学 ， 森林培育， 2006， 博士

【摘要】 森林生态系统在发挥其巨大水文生态功能的同时，为了满足自身生长的需要，常常需要消耗林地的一部分水分，从而使有林流域的产流减少，影响了水资源的综合利用。为此，本篇论文以北京市水源保护林主要造林树种油松和侧柏为研究对象，利用热扩散式边材茎流测定系统和自动气象站对北京西山地区油松和侧柏林木的边材液流及其环境影响因子进行了为期一年的连续同步监测，在树干边材液流活动规律分析的基础上，对其环境影响因子进行综合评价，找到了树干边材液流年变化过程中影响液流年启动、年停止、瞬态变化、日平均值变化和月平均值变化的主导环境因子，并建立了相应边材液流速率的简易环境因子制约模型。在对北京市连年降雨特征分析以及树木蒸腾耗水尺度扩展的基础上，对油松和侧柏单木的年耗水量进行了推算，提出了特定立地条件下的油松和侧柏的合理造林和经营密度，以期为水源保护林低耗水造林树种选择和林分结构优化和调整提供一定的理论依据。 太阳辐射强度、空气温湿度、土壤温湿度、风速等主要环境因子对边材液流速率变化的作用：太阳辐射强度是影响液流活动最主要的因子，决定着液流日变化的启动、停止时刻以及日变化格局，边材液流的日变化整体要滞后于太阳辐射3h左右或更长的时间。在太阳辐射强度、空气温度、空气湿度以及大气饱和水汽压亏缺等环境因子各自的不同计算和测定参数中，林冠上层参数的作用最大。不同土层温度对液流速率的作用，春季表层土壤最大，夏季深层土壤最大，秋季的最大影响土层间于春夏之间；土壤温度对树干液流活动的影响与靠近植物最适吸水温度的土层和树种的根系分布特征有关。在限定土壤含水量的前提下，空气温度、空气湿度和大气饱和水汽压亏缺均为影响树干边材液流活动最主要、最直接的因子。风速对液流活动的作用较为复杂，大风抑制蒸腾，减缓液流活动，弱风和微风加快植物蒸腾，加快液流运转速率。 影响液流速率日时间进程特征变化的主导环境因子：液流的启动时刻和停止时刻主要受太阳辐射强度影响；液流上升和下降的快慢、所需要的时间以及达到高峰的时刻，则主要受空气温湿度和大气饱和水汽压亏缺的影响。 影响液流速率瞬态、日平均值和月平均值变化的主导环境因子：影响年液流启动和停止的最主要的因子是温度，即土壤温度和空气温度。年内影响油松和侧柏液流速率瞬态变化的主导环境因子主要为大气饱和水汽压亏缺和太阳辐射，春季空气温度和土壤温度的作用要比大气饱和水汽压亏缺更强一些。不同季节影响液流速率日平均值更多还原

【Abstract】 Water consumption is needed for forest ecosystem to satisfy its growth while its substantial hydrographic functions are displayed. As a result, runoff yield in a watershed with forest are usually reduced and multi-utilization of water resource are often affected. In order to coordinate this contradiction, Sap Flow Velocity of Pinus tabulaeformis and Platycladus orientalis, and coherent environmental factors were synchronously monitored for one year in Beijing Western Mountains by using TDP systems (TDP-30) and automatic weather station. On the analysis of regulation of sap flow velocity, influencing environmental factors were individually evaluated, and furthermore, main factors which influencing annually starting and stopping, transient changes, daily and monthly averaged values of sap flow velocity were found and relevant daily, seasonally and annually sap flow velocity models were established. On the basis of Beijing rainfall characters’ analysis and tree water consumption scaling up, annually water consumption for the model tree of Pinus tabulaeformis and Platycladus orientalis were calculated. In the end, appropriate planting and tending densities were proposed. The purpose of this article is to provide some theoretical references for low water consumption tree species selection, forest structure adjustment and optimization of water protection forests in Beijing.Effect of solar radiation intensity, air temperature, air humidity, soil temperature, soil moisture, wind speed and other environmental factors on the change of sap flow velocity: Solar radiation intensity was the uppermost factor which determined starting time, stopping time and configuration of daily change of sap flow. Daily change configuration of sap flow were generally 0-3 hours later than that of solar radiation. Parameters above the crown usually had the maximal effects on the sap flow change among different measured and calculated parameters of solar radiation intensity, air temperature, air relative humidity and vapor pressure deficit. The soil layers in which soil temperature had the best effect on sap flow velocity were different with surface layer in spring, deep layer in summer and middle layer in autumn. Those were related with soil layers where had the optimal temperature for water absorption and root distribution. On the precondition of limitation of soil moisture, the most important and direct environmental factors which influencing sap flow velocity of trees were air temperature, air moisture and vapor pressure deficit. Wind had more complex effects on sap flow activity. Sap flow velocity were restrained in the condition of higher wind speed and speeded up in the condition of lower wind speed and moderate breeze.更多还原