关键词: 光皮桦（Betula luminifera）, 人工林, 立地条件, 生长特征, 土壤理化性质

Abstract: The experiment was conducted to study the growth and soil physical and chemical properties of Betula luminifera plantation under different site conditions, providing reference for cultivation and promotion of Betula luminifera plantation and cultivation of large-diameter timber in southern mountainous areas. Four standard plots of different site conditions including sunlit slope （top and bottom） and shaded slope （top and bottom） were set up in Betula luminifera plantation, and tree height, DBH, height under branches and crown width were measured under different site types. The soil enzyme activity and nutrient content were measured. Single factor analysis of variance（ANOVA） was used to analyze the differences of growth and soil physical and chemical properties of Betula luminifera plantation in different types. Pearson correlation coefficient and principal component analysis （PCA） were used to comprehensively evaluate the soil quality of Betula luminifera plantation under different site types. The results showed that, the growth of tree height, DBH, height under branches and crown width of Betula luminifera plantation at the lower and upper parts of the sunny slope was better than that at the lower and upper parts of the shady slope. Under different site types, there were significant differences in soil enzyme activity and soil nutrient content of Betula luminifera plantation（P<0.05）. Generally, the lower part of the sunny slope was higher than the upper part of the sunny slope, and the lower part of the shady slope was higher than the upper part of the shady slope. With the decline of slope position, the soil fertility of Betula luminifera plantation increased. The results of correlation analysis showed that the growth of tree height, DBH and crown width of Betula luminifera plantation was highly positively correlated with most soil enzyme activities and soil nutrient indexes （r>0.800）, indicating that the growth of Betula luminifera plantation was consistent with the spatial change of soil fertility. Principal component analysis showed that the comprehensive score of soil quality of Betula luminifera plantation under different site types from high to low was lower part of sunny slope > upper part of sunny slope > lower part of shady slope > upper part of shady slope. Different slope positions and directions had significant effects on the growth and soil fertility of Betula luminifera plantation. The lower part of the sunny slope was the best area for the growth of Betula luminifera plantation.

Key words: Betula luminifera, plantation, site conditions, growth characteristics, physical and chemical properties of soil