| Summary: | 碩士 === 國立中興大學 === 森林學系 === 92 === The purpose of this study was to discuss crown structure and biomass of mature China-fir (Cunninghamia lanceolata). The study area is location in the central part of Taiwan, at compartment no.111, Pa-Hsien-Sha working circle and Shyr-Wen-Shi demonstration zone. Data of this study were collected from stand and 16 sample trees of a mature China-fir plantation. This study is based on theory way, and use forest measure method and statistics software, to analysis the relationships of DBH and the other attributes, and characteristic of crown form and crown structure, and estimate the of net productivity, and analysis leaf area amount. The analyzed results are summarized as follows.
In the vertical distribution of crown, the relationship among crown-length(LC), clear-length(HB) and tree DBH of open-growth tree were found positively linear. LC and HB were increased as DBH increased. The mean crown ratio(CR) about 0.58, which have certain proportionate relationships, and growth condition was very well.
The crown form and crown structure of mature China-fir, which the crown form shown cone or cylinder, and the leaf weight can to discriminate upper crown and down crown by maximum leaf density distribution on vertical layer. The maximum leaf density distribution is 1.7~2.0 kg/m on the from top to 3~5 m.
The net productivity of China-fir, the net production of stem and branch were increased as DBH increased, the maximum net productivity of aboveground was diameter classⅡ about 1.46 ton/ha/yr. The major dry-matter distributions of China-fir stem increase with DBH, the branch dry-matter increase with height on the vertical distribution, the leaf dry-matter was concentrated in the upper or middle parts of the crown, and it is similar to the broad leaf type dry-matter distribution.
The crown leaf area of China-fir individual tree increase with diameter class, so diameter class Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ of leaf area were 74.15, 104.13, 133.11, 164.31, 206.34 m2/tree, respectively. And it is estimate China-fir leaf area index about 3.87. The highly positive correlations were found between leaf area and sapwood, accord with the pipe model theory.
The pruning operation might be useful maximum leaf density distribution on the vertical distribution of the China-fir plantation, and CR keep to 0.20~0.30 was expediency. The leaf spatial density was diameter class Ⅱ, and it have maximum biomass. The results will provide detailed information for China-fir plantation management.
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