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黄土高原半干旱区天然辽东栎林蒸腾耗水研究
张 建 国
Subtype硕士
2011-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword黄土高原 辽东栎 树干液流 热扩散探针 方位差异 径向差异 林分蒸腾耗水.
Abstract

本文以黄土高原半干旱地区辽东栎天然次生林为研究对象,利用Granier热扩散探针连续监测一个生长季(2009年4-10月)辽东栎、山杏、侧柏、大果榆等树种的树干液流通量密度,并同步监测环境因子(太阳辐射、空气温度、空气湿度、风速等),分析了树干液流通量密度对主要环境因子的响应特征,同时研究了不同方位、不同径向深度树干液流通量密度的变化规律,估算了2009年辽东栎天然次林生长季内林分蒸腾耗水量,旨在为半干旱地区植被恢复和重建提供理论依据。主要结论有以下几个方面: (1)辽东栎液流日变化总体上与太阳辐射和空气水气压亏缺呈相同趋势,但液流峰值出现时间较早,通常为上午 10:00左右。随着生长季内物候变化,液流通量密度总体表现为前期(4-6月)较低、中后期(7-9月)较高、末期(10月)迅速下降的变化趋势。采用指数饱和曲线函数对液流通量密度和空气水气压亏缺进行拟合,有效地反映了各月份液流通量密度对空气水气压亏缺的响应特征。各月份的曲线特征和拟合参数的差异表明,蒸腾耗水过程也受到土壤水分状况等其它因素的影响。 (2)辽东栎东、西、南、北4个方位测得的液流通量密度存在显著差异,并显著相关。辽东栎生长季内(5-10月)单株日蒸腾耗水量分别与日总太阳辐射和日均白天空气水气压亏缺进行指数饱和曲线拟合,拟合效果较好。采用2个方位和1个方位树干液流通量密度测算的整株蒸腾耗水量与采用4个方位的测算值分别相差约18%和30%,说明不同方位之间的液流差异可能成为蒸腾耗水测算的重要误差来源。 (3)辽东栎、侧柏不同径向深度树干液流通量密度之间存在显著的差异。辽东栎和侧柏边材径向液流通量密度变化规律表现为从形成层到心材最大液流通量密度值减小的趋势。侧柏1-2 cm和2-3 cm的树干液流通量密度变化93%可由0-1 cm的液流通量密度来解释,三者之间具有极显著的线性关系;辽东栎不同径向深度之间的树干液流通量密度没有发现明显的线性或其它曲线关系。辽东栎、侧柏1-2 cm和2-3 cm处最大液流通量密度占0-1 cm处最大液流通量密度的比例因个体不同而呈现差异。(4)利用指数饱和曲线模型可以拟合辽东栎天然次生林主要树种(辽东栎和山杏)的边材面积与胸径间的关系,结合林分调查的单木胸径可以推算相应树木边材面积。辽东栎天然次生林各树种林分平均边材液流通量密度均具有明显的季节动态变化特征。生长季内5-7月为林分蒸腾耗水量较高时期。未考虑径向和方位差异情况下估测的2009年生长季内林分蒸腾耗水总量为100.5 mm;日均林分蒸腾耗水量为0.53 mm。 关键词:黄土高原,辽东栎,树干液流,热扩散探针,方位差异,径向差异,林分蒸腾耗水.

Other Abstract

The Granier-type thermal dissipation probes (TDP) were applied to measure the tree sap flow dynamics in a natural Quercus liaotungensis forest at Mount Gonglushan located in the southern suburb of Yan’an city of Shaanxi Province in the central part of the Chinese Loess Plateau (36°25.40’N, 109°31.53’E). Air temperature, relative air humidity, solar radiation, wind speed, and soil water content were monitored at the same time. In this paper, we investigated the diurnal course of sap flow characteristics and the relationships between sap flux density and environmental factors, azimuthal and radial variations of sap flux density on xylem trunk, and estimated stand transpiration in the growing season of 2009. The main conclusions were as follows: (1) Sap flux densities in Q. liaotungensis reached their daily peaks earlier than solar radiation and vapor pressure deficit, usually around 10:00 am, though the diurnal courses of sap flux density were generally similar to the changes of environmental factors. As the season and leaf phenology progressed, the overall performance of sap flux density was relatively low at early stage (April-June), high in the mid and late period (July-September), and rapidly declining in the last stage (October). Exponential saturation function was applied to the data sets of sap flux density and vapor pressure deficit, and the fitted curves effectively reflected the sap flow characteristics for different months. The differences in fitted curves and parameters among months suggest that the transpiration process in these forest trees was also affected by soil moisture conditions or other environmental factors.
(2) Sap flux densities at four aspects (north, south, east and west) on the trunk were significantly different, but were highly linearly correlated. Daily whole-tree transpiration throughout the growing season (May to October) could be well fitted to the corresponding daily total solar radiation and average daytime air vapor pressure deficit using exponential saturation functions. The differences relative to tree transpiration estimates based on sap flux densities for four aspects were typically 30% and 18% in accordance with the sap flux densities for one and two measurement aspects, respectively. The results suggest that  azimuthal variations of sap flux density could be a large source of errors in tree transpiration estimates. (3) Radial variation (0-1 cm, 1-2 cm, 2-3 cm) of sap flux density were significantly different for both Q. liaotungensis and Platycladus orientailis, but were linearly correlated only in P. orientailis. Sap flux density in Q. liaotungensis and P. orientailis gradually decreased from cambium to heartwood. About 93% of the change in the sap flux density at the depth of 1-2 cm and 2-3 cm can be explained by that of 0-1 cm. The proportion of the maximum sap flux density for 1-2 cm and 2-3 cm in the maximum sap flux density of 0-1 cm varies by individuals. (4) The power function model can be used to fit the relationship between sapwood area and DBH of the dominant tree species in Q. liaotungensis forest. The stand average sap flux density of each tree species were differed among different months in growing season. The seasonal dynamics of stand average sap flux density in each tree species may be related to the differences in leaf phenology, meteorological factors and availability of soil water. Stand transpiration were higher from May to July. Total stand transpiration during the growing season of 2009 were roughly estimated to be 100.5 mm. Daily mean stand transpiration for Q.liaotungensis forest in the region were about 0.53 mm day-1. Key words: Loess Plateau; Quercus liaotungensis; sap flow; thermal dissipation probe; azimuthal variations; radial variations; stand transpiration

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8881
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
张 建 国. 黄土高原半干旱区天然辽东栎林蒸腾耗水研究[D]. 北京. 中国科学院研究生院,2011.
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