关键词: 柳杉, 人工林, 林分空间结构, 相邻木, 近自然林, 恒续林

Abstract: This article reports a case of close-to-nature forest improvement in Cryptomeria fortunei plantation at Chongzhou forest farm, in southwestern China. In this investigation, the researchers selected some Cryptomeria fortunei which could be cultivated well as "target trees", and the companion species Cunninghamia lanceolata were reserved as "ecological target trees", other surrounding trees were selectively cut as "disturbing trees". After selective cutting, some native broad-leaved saplings, i.e. Phoebe zhennan and Cercidiphyllum japonicum were interplanted into the stand. Thereby the stand spatial structure of Cryptomeria fortunei plantation could be optimized reasonably, so that the paces of turning pure plantation into fixed forest were anticipated to be accelerated. A detailed analysis of forest spatial structure was made after the interplanting, based on Isolation Index (CS), size differentiation (T) and aggregation index (R). Through investigating spatial structures dynamic in the process of the close-to-nature forestry management, we conclude that the degree of mingling and spatial segregation was ameliorated well after the interplanting, CS indicates complete species mingling in the stands. As for as size differentiation, it was dramatically polarized after interplanting from the values of T. The to distribution pattern was characterized as uniform pattern consistently, despite selective cutting and interplanting treated. Case study also provides initial values and stand structures for single-tree models from estimated qualitative stand characteristics. It has shown that from given spatial forest structures one can possibly conduct the close-to-nature forest management in terms of the theory and practice, however, it has yet to be proved by further appropriate analysis.

Key words: Cryptomeria fortunei, plantation, forest spatial structure, neighboring tree, close-to-nature forestry, continuous cover forest