Abstract:Canopy meteorological factors, including solar radiation (Rs), precipitation (P), wind speed (W), relative humidity (RH), maximum temperature (Tmax) and minimum temperature (Tmin), and soil moisture content (SMC) within 4 m soil depth were daily monitored from Oct. 1, 1999 to Sep. 30, 2000 in an eucalypt plantation in Leizhou peninsula, Guangdong, China. Canonical correlation analysis (CCA) was employed to assess impacts of canopy meteorological factors on SMC. SMC differed significantly at different layers within 4 m soil depth, which was influenced mainly by precipitation in rainy seasons. SMC in rainy seasons increased with time due to the abundant precipitation. The coefficient of variance of SMC in rainy seasons was higher than that in dry seasons. SMC at 50 cm soil depth fluctuated obviously, which had a significant correlation with some meteorological factors such as solar radiation, precipitation, wind speed, vapour pressure deficit, and maximum temperature. Meteorological factors that affected soil moisture at deep layers (150, 250, and 350 cm) had almost similar pattern but differed from that at layer of 50 cm. The values of canonical correlation coefficients in rainy seasons were significant. Among the three canonical correlation coefficients and variables, the value of the first canonical correlation and its variance in covariates explained by canonical variables was the highest, which indicated that the canopy meteorological factors affecting soil moisture content were mainly by the first canonical variables.
