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Evaluation On Environmental Factors And Simulation Of Whole Tree Water Consumption Of Pinus Tabulaeformis And Platycladus Orientalis Forests In Beijing Western Mountains

Posted on:2007-04-15Degree:DoctorType:Dissertation
Country:ChinaCandidate:J L XuFull Text:PDF
GTID:1103360185481383Subject:Forest cultivation
Abstract/Summary:PDF Full Text Request
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.
Keywords/Search Tags:Thermal Dissipation Probe System, Sap Flow Velocity, Water Consumption Evaluation, Daily Tune Process, Scaling up, Optimal Stand Density
PDF Full Text Request
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