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采用样地调查法,对日本冲绳岛北部的亚热带常绿阔叶林的林分结构,树种组成以及土壤特性等进行了调查分析。结果表明,该亚热带林具有林冠低矮、小径木多等特点。林分的平均林冠高度仅10m,平均立木密度达5400株·hm2(≥3.0cmDBH),其中胸径小于10cm的立木占64%。林分胸高断面积为54.4m2·hm-2。30个调查样地共出现树种数(≥3.0cmDBH)达80种,分属31个科。根据树种的重要值,Castanopsis sieboldii和Schima wallichii分别为优势树种和亚优势树种。树种多样性指数(H’)平均达3.63,均衡度指数(J’)为0.71,丰富度指数(S’)为4.72。这些多样性指数都随着优势树种重要值的增加而显著降低。土壤养分测定结果表明,该森林的土壤肥力低,异质性大,并可能存在Al毒害。由相关分析知,林分密度和优势树高均与土壤pH值呈显著正相关关系;多样性指数则与土壤交换性K+,Ca2+以及Ca2+/Al3+比呈显著的正相关,而与土壤有机碳,全氮和磷呈显著的负相关。这些结果说明土壤性质是影响冲绳亚热带常绿阔叶林林分结构和树种组成多样性的重要因素。图3表4参38。
By means of plots survey, the sub-tropical evergreen broad-leaved forest in northern Okinawa, Japan, the stand structure, tree species composition and soil characteristics were investigated and analyzed. The results showed that the subtropical forest has the characteristics of low canopy and small diameter wood. The average canopy height of the stands was only 10m, and the average stand density was 5400 plants · hm2 (≥3.0cmDBH), of which 64% had stand diameter less than 10cm. Forest area of chest height of 54.4m2 · hm-2.30 species were found in the total number of species (≥3.0cmDBH) up to 80 species, belonging to 31 families. Castanopsis sieboldii and Schima wallichii are the dominant species and the subdominant species, respectively, according to their importance. The tree species diversity index (H ’) averaged 3.63, the balance index (J’) was 0.71, and the abundance index (S ’) was 4.72. These diversity indices all decreased significantly with the increase of the important value of dominant tree species. Soil nutrient measurements show that the forest has low soil fertility, large heterogeneity, and possible Al toxicity. According to the correlation analysis, the stand density and the dominant tree height had a significant positive correlation with the soil pH. The diversity index had a significant positive correlation with soil exchangeable K +, Ca2 + and Ca2 + / Al3 + ratios, but with soil organic carbon , Total nitrogen and phosphorus showed a significant negative correlation. These results indicate that soil properties are important factors affecting the sub-tropical evergreen broad-leaved forest stand structure and tree species diversity in Okinawa. Figure 3 Table 4 参 38.