关键词: 西双版纳, 柚木人工林, 立地分类, 立地评价, 数量化理论Ⅰ

Abstract: [Objective] Site classifications and evaluation of teak (Tectona grandis) plantation by sample plot survey and analysis is to build a scientific basis for site selection of teak plantations of Xishuangbanna or other similar regions. [Method] 51 sample plots distributed in 12-26 years old plantations were set up and growth traits of teak were measured, and site topography factors were recorded. Soil samples were collected for analyzing soil chemical and physical properties. 8 factors of soil chemical properties selected by stepwise regression method were used to divide soil nutrient grades by principal component analysis, and the relations between soil factors and the growth of teak together were analyzed by quantity theory I.[Result] The multiple correlation coefficient of quantity model fitted by the selected site factors (soil nutrient grades, soil texture, slope orientation, slope position, slope degree, soil bulk density and Elevation) was 0.865, indicating a highly significant correlation (P<0.01).Soil density, soil texture,slope degree and the soil nutrient grades consisting of 8 soil nutrient factors (pH, the contents of exchangeable acid, total K, total P, available P, exchangeable Ca²⁺, exchangeable Al³⁺ and available Fe) were highly significantly correlated with the growth (P<0.01). The contribution rate of site soil factors to height growth of dominant trees reached 58.3%,indicating a highly significant correlation in the quantity model (P<0.01). According to the scores of site factors of each sample plot obtained from the quantity regression model, site productivity levels were divided into 4 groups, and 11 site types were identified according to soil density, soil texture and soil nutrient grade. Growth and site factors for each productivity group were estimated. The average annual height growth of dominant trees of the four groups of site productivities ranked from high to low were 1.70-1.81, 1.22-1.31, 1.08-1.12, and 0.51 m respectively. [Conclusion] Teak grew better in silty loam with good drainage system than in sandy loam or heavy loam. Teak was sensitive to soil density and preferred higher soil density; Teak grew best at sites with high levels of base saturation, total potassium, available phosphorus, and exchangeable magnesium; in strong acid soil, teak grew very poor due to low nutrient and poor fertility with high concentration of soil exchangeable aluminum and available iron. Soil density, texture and soil acid should be particularly considered when selecting higher fertility sites and suitable for growth of teak in Xishuangbanna region. Teak plantations planted at unsuitable sites with poor site quality should be improved so as to reduce the loss.

Key words: Xishuangbanna, teak plantation, site classification, site evaluation, quantity theory I