| In typical sites of Chinese fir planted forest, Cryptomeria japonica planted forest and Fokienia hodginsii planted forest in Guanzhuang national farm in Sha xian, the plots which area were 18 000 m2 were set and investigated. The plots were divided into 5 types, such as different index classes sites, different density sites, different cultivation goal sites, different age sites, different type forest. According to the analysis, it researched and discussed forest growth, forest distribution, forest volume and forest wood. And it appraised the economic effect of different forests, using NPV, IRR, B/C, N/K, NPV. Finally it put forward some proposals to keep Chinese fir planted forest sustainable development. Findings as follows:(1)Under the different condition of sites, with the site index increase, the Chinese fir forest average diameter growth gradually increased, the average tree diameter growth quantity difference remarkable level achieves 0.01. And the average high growth were obvious along with the site index change, the difference were remarkable. Different condition of sites had obviously affected the forests diameter level and highly level structure, which displayed for the sites index higher, the structure quality was better. Using the Weibull distribution function to fit the different sites index Chinese fir's diameter and height, the research indicate d that, in different sites index Chinese fir forests, index 16 forest tree diameter distribution's c value≈3.6, nearly to normal distribution, but high's cvalue>3.6, negative mountain shape distribution; index 18 tree diameter distribution's c value 1<c<3.6, active mountain shape distribution, but high's c value≈3.6, nearly to normal distribution; index 20 forest tree diameter distribution's cvalue 1<c<3.6, active mountain shape distribution, but high's c value> 3.6, negative mountain shape distribution. The site index higher, the production of woods, the specification woods, the stand volume higher. The economic analysis results indicated that,3 kind of site indexes IRR>12, index 20's economic efficiency was the largest, index 18's being next, index 16's was the smallest.(2) In different density condition, the Chinese fir forest average tree diameter growth reduced with the density increase; the forest average tree high growth fell with the density increase as well; based on the difference analysis and the Q examination, different density Chinese fir forest average tree diameter and the average tree high growth difference was remarkable, the difference level reached 0.001. Among different density Chinese fir forest, the density 450's stand structure was the most superior; the density 540's was second. The Weibull distribution model study indicated that, in different density Chinese fir forests, density 450 forest tree diameter distribution's cvalue 1<c<3.6, active mountain shape distribution, and high's cvalue 1<c <3.6, active mountain shape distribution; density 540 tree diameter distribution's c value 1<c<3.6, active mountain shape distribution, but high's c value>3.6, negative mountain shape distribution; density 240 forest tree diameter distribution's c value≈3.6, nearly to normal distribution, but high's cvalue>3.6, negative mountain shape distribution. Density 450's forest's stand volume weighs out compared to density 540's and density 630's 9.7% and 48.2%, and density 540's forest was 35.1% bigger than the initial density 630's. Based on the growth contrast, it carried on the forests economic effect comparative analysis. The result indicated that, density 450's forest's profits rate was the highest, the effect of fund use best. Above all, density 450's forest was the best, density 540's forest was next, density 630's forest was the worst.(3) The stand increment presented the obvious rise with the cultivation goal enhancement. Based on the difference analysis and the Q examination, it showed that in different cultivate goal's forests average tree diameter growth and the average tree high growth's difference were remarkable. Different cultivation goal condition had the obvious influence to the Chinese fir forest diameter and height distribution, the concrete manifestation was: cultivation goal higher, the proportion of tree diameter above 20cm was larger, also the main diameter level was higher; cultivation goal higher, the proportion of tree height above 16m was larger, also the predominant height level was higher. The Weibull distribution function was used to simulate diameter and height distribution of different cultivation goal Chinese fir forest, it indicated that the fitting effects were well. Goal 211's forest tree diameter distribution's c value> 3.6, negative mountain shape distribution, and high's c value> 3.6, negative mountain shape distribution; goal 212 tree diameter distribution's c value≈3.6, nearly to normal distribution, but high's c value 1<c<3.6, active mountain shape distribution; goal 222 forest tree diameter distribution's c value 1<c<3.6, active mountain shape distribution, and high's c value 1<c<3.6, active mountain shape distribution. Where cultivation goal higher, the average volume and stand volume higher, the production of woods and the specification material forestry outturn was higher. Further uses several dynamic economy analysis target to carry on the appraisal to the different cultivation goal forest, it indicated that the higher cultivation goal, although its invests was high, its obtains profit rate was high too, fund use effect was the best.(4) With the age growth, the average tree diameter and the average tree high gradually gr ew. Based on the difference analysis and the Q examination, it indicated that average tree diameter and average tree high growth in different age forest were remarkably different, the difference remarkable level achieve d 0.01. With the age growth, the forests'structure quality gradually enhanced.13 years old forest tree diameter distribution's cvalue> 3.6, negative mountain shape distribution, and high's cvalue 1<c<3.6, active mountain shape distribution; 24 years old forest tree diameter distribution's c value≈3.6, nearly to normal distribution, and high's c value≈3.6, nearly to normal distribution; 35 years old forest tree diameter distribution's c value >3.6, negative mountain shape distribution, and high's cvalue>3.6, negative mountain shape distribution. With the age increasing, the forest average volume increased, but, as a result of 13 years forest density was bigger, made its stand volume greater than 24 years old forest, therefore the 35 years old forest' volume was the most,13 years old forest was next, while the 24 years'was the smallest.35 years old forest's NPV,LEV,B/C,N/K were the biggest,13 years old forest's IRR was the biggest,24 years old forest's NPV and LEV were bigger than 13 years', but IRR,B/Cå'ŒN/K were less.(5) In Chinese fir planted forest, Cryptomeria japonica planted forest and Fokienia hodginsii planted forest, Chinese fir forest average tree diameter growth and average tree height growth were the biggest. Based on the difference analysis and the Q examination, it showed that 3 kinds of types forest average tree diameters growth difference was remarkable; the average tree height difference was remarkable too, but its difference mainly displayed between Chinese fir forest and Fokienia hodginsii forest, Cryptomeria japonica forest and Fokienia hodginsii forest, but Chinese fir forest and Cryptomeria japonica forest's difference was not remarkable. Different type of forest had obviously different diameter and height distribution, among the three forests Chinese forest's structure quality was the best. The research indicated, the three different types of forests' tree diameter distribution's c valuel<c< 3.6, active mountain shape distribution; but height's c value>3.6, negative mountain shape distribution. Chinese fir forest average volume, stand volume, the production of wood and the economic indexes were the highest. In brief, Chinese fir forest's economic effect was the best. |
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