浙江凤阳山天然混交林林分空间结构分析

Stand spatial structure of a natural mixed forest in the Fengyang Mountains of Zhejiang

以浙江凤阳山天然混交林为研究对象,对其角尺度、混交度和大小比数3个林分空间结构参数进行测定分析,以期为该区域阔叶混交林林分结构的优化调整提供理论依据和技术支持。在凤阳山国家级自然保护区内,设置20 m×20 m的4个固定样地,采用全面调查法,调查样地内胸径大于起测径阶(5 cm)的林木特征值。结果表明:凤阳山天然混交林优势种群以木荷Schima superba,浆果椴Tilia endochrysea,亮叶水青冈Fagus lucida和多脉青冈Cyclobalanopsis multinervis为主,形成多优势种结构特征。数目最多的优势种木荷在空间大小对比上处于中庸地位,77%的水丝梨Sycopsis sinensis完全处于受压迫的状态,8%处于最优势状态,说明水丝梨分化严重。优势树种木荷的平均混交度为0.48,多呈单种聚集,短柄枹Quercus glandulifera var.brevipetiolata由于数量很少,平均混交度只有0.17,说明短柄枹呈团状分布。而其他树种平均混交度几乎都在0.50以上。以上数据说明,在该林分中,除木荷、短柄枹外,同树种聚集在一起的情况很少,树种之间的隔离程度较大,说明研究林分是由不同树种呈现弱中度混交结构状态组成的较复杂群落。从林木水平分布格局上看,该天然混交林分为团状或均匀分布,其林木分布格局会逐渐趋向于随机分布,向顶级群落即常绿阔叶林演替。

To provide a theoretical basis and provide technical support for structural adjustments in a natural mixed forest, stand spatial structure of a mixed forest in the Fengyang Mountains National Nature Reserve of Zhejiang Province was determined using three structural parameters： uniform angle index, mingling, and neighborhood comparison. Four typical plots of 20 m × 20 m were surveyed for tree diameter at breast height above 5 cm. Results showed that dominant tree populations cida, and Cyclobalanopsis muhinervis exhibited diverse of Schima superba, Berrya ammonilla, Fagus lu- and dominant species characteristics. The largest number of dominant species S. superba in the comparison of the space is in the moderation status. 77% Sycop- sis sinensis is completely oppressed and 8% is in the most dominant state, which shows that Sycopsis sinensis differentiates seriously. The average mingling of S. superba is 0.48 exhibiting aggregation of a single species. Because of less amount of Quercus glandulifera var. brevipetiolata, the average mingling is only 0.17 indicat ing Quercus glandulifera var. brevipetiolata distribution appeared as gobbets. Whereas the average mingling of other tree species is above 0.5. In addition to S. superba and Ouercus glandulifera var. brevipetiolata, the oth er species seldom cluster together and have greater degree of isolation, which indicates the stand has the less moderate mixed degree. Distribution patterns for forests gradually move toward a random distribution in climax community succession, so natural mixed forest in the Fengyang Mountain develop into evergreen broad-leaved forest. [Ch, 2 fig. 4 tab. 18 ref.]