摘要
树木蒸腾是森林生态系统水循环的重要组成部分。准确了解植物蒸腾的变化规律及其影响因子,有助于科学掌握和理解植被生理生态过程对气候变化的响应。我国西南山地森林生态系统植被类型丰富,环境条件复杂多变,是气候敏感区和典型生态环境脆弱地带,但已有研究更多关注区域蒸散发计算及光合作用对水分利用的响应规律,缺乏对植物蒸腾变异规律及其影响因子的深入探讨。本研究利用热扩散探针技术,获得贡嘎山峨眉冷杉2017—2018年小(20~40cm)、中(40~60cm)、大(60~80cm)3个径级的树干液流速率,采用相关分析和逐步回归分析量化环境因子对液流速率的影响。结果发现:(1)半小时尺度,液流速率呈单峰曲线变化,且增长快于回落,夜间液流活跃;(2)日尺度,液流速率变化大致呈先增后减的趋势,整体波动幅度与径级大小呈反比;(3)不同时间尺度下,各径级液流速率按大小排列均为:中径级>小径级>大径级;(4)液流主要与气象因子有关,液流速率与水汽压亏缺、空气温度、风速和光合有效辐射呈极显著正相关(p<0.01),与相对湿度呈极显著负相关(p<0.01)。同时,液流受水分条件的影响,干季缺水时,土壤湿度和降雨促进液流蒸腾,湿季水分过多则起抑制作用;(5)日尺度,中、小径级树木比大径级树木更易受环境因素的影响,且分别在干、湿季受影响最大;(6)逐步回归方程中的环境因子数量随时间尺度的增大而减少,且气象因子占主导。研究结果可为预测我国西南亚高山森林生态系统植被水分利用及循环的变化趋势提供数据支撑和理论参考。
Transpiration plays an important role in adjusting water cycle in forest ecosystems. To analyze the changes in plant transpiration and its influencing factors contributes to a comprehensive understanding of the response of vegetation physiological and ecological processes to climate change. Mountainous forest ecosystem in southwest China has rich vegetation types, complex and changeable environmental conditions. It is sensitive to climate and its ecological environment is typically fragile. Past studies of plant transpiration in southwest China mostly addressed the calculation of regional evapotranspiration and the response of photosynthesis to water use, but less attention was paid to the exploration of the patterns of plant transpiration variation and its influencing factors. In this paper, sap flow velocities of three diameter classes, small(20~40 cm), medium(40~60 cm) and large(60~80 cm) of Abies fabri were obtained by thermal dissipation probe technique(TDP) from 2017 to 2018. Correlation analysis and stepwise linear analysis were used to quantify how environmental conditions affected stem sap flow velocities. Results conclude that:(1)Diurnal sap flow velocities showed a single peak curve with a higher increasing rate than decreasing rate, and the nocturnal sap flow was active;(2)Daily mean sap flow velocity increased and then decreased, and the overall amplitude of fluctuation was negative to the size of diameter class;(3) Sap flow velocities at both diurnal and daily scales were in the order of medium class > small class > large class;(4)Sap flow velocities were affected by meteorological factors. Specifically, sap flow velocities were significantly positive correlated to vapor pressure deficit, air temperature, wind speed and photosynthetic active radiation(p<0.01), whereas significantly negative correlated to humidity at both half-hour and daily scale(p<0.01). Besides, sap flow velocities were also affected by water availability, the reduction of soil moisture and precipitation enhanced transpiration in
作者
唐子舒
王根绪
胡兆永
TANG Zishu;WANG Genxu;HU Zhaoyong(State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resource and Hydropower,Sichuan University,Chengdu 610065,China)
出处
《山地学报》
CSCD
北大核心
2022年第2期220-234,共15页
Mountain Research
基金
国家自然科学基金(41901053)
四川省科技计划项目(2021YJ0507)
中央高校基本科研业务费专项资金资助(YJ202079)。
关键词
亚高山森林
树木蒸腾
径级
树干液流
subalpine forest
transpiration of trees
diameter class
stem sap flow
