广东湛江沿海木麻黄防护林生态系统的辐射通量特征

摘要

Casuarina shelterbelt is a typical forest ecosystem in tropical and south subtropical coastal zone and island of China. The main purpose of the establishment of coastal shelterbelt is to improve the ecological environment such as microclimate for human beings and plant growthing. Solar radiation is an important factor for forest carbon sequestration and microclimate formation. Based on the radiation data of a typical Casuarina equisetifolia shelter forest in Zhanjiang, Guangdong province, from January to December 2010, the radiation flux characteristics were analyzed. The results showed that: (1) Gross short-wave radiation ( K↓ ) and Net radiation (Rn) in 2010 were 5 537.42 and 6 027.17 MJ · m- 2,of which 62.72% and 61.73% in monsoon respectively. (2) The short-wave reflectivity of the ecosystem changes mainly within the range of 8% to 15% throughout the year. (3) Effective long-wave radiation ( Ln ) was negative throughout the year. It showed that the air temperature is higher than canopy surface temperature all the year round. This is helpful to the water vapor condensation on the plant surface. And it is a major water source of the coastal and island ecosystem.%木麻黄（Casuarina）防护林是我国热带、南亚热带海岸带及岛屿防护林的典型代表，建立海岸带防护林的主要目的是改善包括局域小气候在内的海陆交错带的生态环境，太阳辐射因子是森林固碳和森林小气候形成的重要基础。该研究基于广东省湛江沿海岛屿典型木麻黄（Casuarina equisetifolia）防护林2010年1—12月共1 a 的辐射观测数据，分析了其辐射通量特征。结果表明：（1）2010年太阳短波辐射总量是5537.42 MJ · m-2，净辐射总量是6027.17 MJ · m-2，其中4—9月雨季太阳短波辐射总量和净辐射总量占全年的比例分别为62.72%和61.73%。（2）生态系统太阳短波辐射反射率全年变化集中在8%~15%之间。（3）长波有效辐射全年均为负值，说明大气温度常年高于下垫面防护林生态系统的冠层表面温度，在夜间太阳辐射为零时有利于大气中所含大量水汽在植被表面的凝结，这是沿海和岛屿生态系统重要的水分来源。