海南岛西部橡胶人工林冠层温度变化及其与微气象要素的关系

冠层温度是表征植物生理生态过程及能量平衡状况的重要参数之一。为探讨热带森林冠层温度在不同时间尺度下的变化规律并且初步分析环境因素与冠层温度的关系,本研究利用红外温度传感器测定了海南岛西部橡胶人工林2017年全年的冠层温度数据以及同步得到的冠层微气象资料,对干季和湿季下海南岛西部橡胶人工林冠层温度（T_c）与大气温度（T_a）特征进行了分析,同时结合微气象因子进行了讨论。结果表明：橡胶人工林冠层温度全年各月日变化都为单峰曲线,相比T_a,T_c具有明显的位相前移、变化加剧的特点。白天林冠边界层处于不稳定状态,林冠为土壤-植物-大气连续体（Soil-Plant-Atmosphere Continuum,SPAC）的热源;夜晚林冠边界层为逆温层结,呈稳定状态,林冠为SPAC的冷源。湿季冠层温度高于干季。若仅考虑T_a,T_c与T_a之间具有很好的线性关系,其线性方程为T_c= 1.033T_a-0.656;若同时考虑大气温度（T_a）、净辐射（R_n）、相对湿度（RH）与风速（V）等微气象因子,其复相关系数表明全年均呈极显著相关,偏相关系数表明干季冠层温度变化主要受T_a、R_n和RH的影响,其次受V的影响;湿季主要受T_a与RH的共同作用,R_n与V对其的影响相比可忽略不计。此研究结果初步揭示了橡胶人工林冠层温度的全年变化规律及其与众多微气象因子之间的关系,为进一步探究冠层温度变化及其影响机制提供科学依据。

Variations of Canopy Temperature in a Rubber Plantation in Western Hainan Island and Their Relations with Micrometeorological Factors

Canopy temperature is one of the most important parameters to characterize the physiological, ecological processes and energy balance of plants. In order to investigate the variation of the canopy temperature in tropical forests at different time scales and to preliminarily analyze the relationship between environmental factors and canopy temperature, an infrared temperature sensor was used to measure the canopy temperature of a rubber plantation in Western Hainan Island in 2017. Based on the annual canopy temperature data and synchronous canopy micrometeorological data, the characteristics of canopy temperature (T_c) and air temperature (T_a) of a rubber plantation in dry and wet seasons were analyzed, and the micrometeorological factors were discussed. The daily change of canopy temperature in a rubber plantation was a single-peak curve every month. Compared with T_a, T_c had obvious characteristics of phase forward and intensified change. During the day, the canopy boundary layer was unstable, and the canopy was the heat source of SPAC (Soil-Plant-Atmosphere Continuum), at night, the canopy boundary layer was inversion stratification, which was stable, and the canopy was the cold source of SPAC. The canopy temperature in wet seasons was higher than that in dry seasons. If only T_a was considered, T_c and T_a had a good linear relationship, and the linear equation was T_c= 1.03T_a-0.656. If the micro-meteorological factors such as atmospheric temperature (T_a), net radiation (R_n), relative humidity (RH) and wind speed (V) were taken into account, the multiple correlation coefficients showed that the annual correlation was very significant. Partial correlation coefficients showed that the change of canopy temperature in dry seasons was mainly affected by T_a, R_n and RH, and secondly by V. Wet seasons were mainly affected by T_a and RH, the influence of R_n and V was negligible. The results preliminarily revealed the annual variation of canopy temperature in rubber plantation and its relationship with many micro-meteorological factors, providing a scientific basis for further exploring the change of canopy temperature and its influencing mechanism.