The Canopy Rainfall Interception Of Chinese Fir Forest And Response Of Its Tree Ring Growth With Climatic Factors In Dagangshan Area

Chinese fir forest is one of the important artificial forest vegetation in southern Subtropical area of China. For the research of the rainfall interception characteristics of Chinese fir forest, and explore the relationship between Chinese fir tree ring width and climatic factors, and investigate the impact of climatic factors on tree ring growth of Chinese fir in subtropical regions, the atmospheric rainfall, the throughfall and the stemflow of the sample plots of Chinese fir forest were observed in the forest ecosystem research station of Dagangshan area of Jiangxi province, and the rainfall interception process was simulated by Gash model. The Dendrochronology analysis methods was applied to establish the chronology of Chinese fir forest, the response analysis between tree ring width and climatic factors was carried out, the grey correlation analysis method was applied to find out the dominant climatic factors on the tree ring growth of Chinese fir forest. The main results were:(1) The atmospheric rainfall was 1289.5 mm, the throughfall, the stemflow and the canopy interception were 955.2, 57.1 and 277.2 mm during the observation period,which accounted for 74.1%, 4.4% and 21.5% of the atmospheric rainfall. There were a large amount of rainfall in the observation period. The rain was mainly moderate and drizzle main, but the rainfall was mainly heavy rain and rainstorm. The rate of canopy interception of moderate and drizzle main was more than that of heavy rain and rainstorm.(2) The simulated values of througfall, stemflow and canopy interception by Gash model were 946.4, 53.6 and 289.5 mm, which accounted for 73.4%, 4.2% and22.4% of the atmospheric rainfall, and the relative error was 1.0%, 6.1% and 4.4%,respectively. The good consistency of the simulated values and measured values indicated that the Gash model is suitable for estimating the rainfall interception ofChinese fir forest in Dagangshan area of Jiangxi Province.(3) The Signal-to-Noise Ratio(SNR) and Mean Sensitivity(MS) were large and the First Order Autocorrelation Coefficient(FOAC) was small, and the chronology of Chinese fir contains abundant climatic information.(4) The tree ring width index of Chinese fir was significantly positively correlated with the precipitation in previous December and current June, significantly negatively correlated with that in current May and August. The tree ring width index was significantly positively correlated with the temperature in current April and May but significantly negatively correlated with that in current July.(5) The order of the relational degree of the climatic factors with the tree ring growth was mean annual humidity index > mean annual evaporation > mean annual precipitation > mean annual temperature > annual extreme minimum temperature>annual extreme maximum temperature. Mean annual humidity index is the main factor affecting the tree ring growth of Chinese fir, followed by precipitation and then temperature.(6) The change trends between the tree ring width index of Chinese fir and the warmth index(Wi) and humidity index(Hi) fit with good consistency. The response function of Chinese fir ring width analysis shows that the warmth index is the main factor affecting the tree ring growth, followed by the humidity index, mean annual precipitation and mean annual temperature. Results can provide a scientific basis for studying the quantitative evaluation of hydrological and ecological functions of Chinese fir and the effect of climatic factors on it's growth in sub-tropical regions in China.