2010 Fiscal Year Final Research Report
Estimation of mortality probability distribution for natural forests
| Project/Area Number |
21780142
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Forest science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HIROSHIMA Takuya The University of Tokyo, 大学院・農学生命科学研究科, 講師 (40302591)
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| Project Period (FY) |
2009 – 2010
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| Keywords | 森林管理 / 政策 |
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| Research Abstract |
The purpose of this study was to estimate a probability distribution of tree mortality and conduct yield prediction on a stand scale based on empirical data of tree age structure in a natural forest. Study area was the natural stand dominated by fir, hemlock and oak in size of 0.259 ha in the University of Tokyo Chiba Forest, Japan. First, tree age data were collected from trees with DBH≧5 cm using a RESISTOGRAPH. Tree ages were associated with the observation data as to number of dead trees and living trees by age class in the period from 1999 to 2008. Second, the probability density function was estimated by the maximum likelihood method for censored survival data. Finally, number of harvestable dead trees was predicted based on the estimated probability density function in the next 10 year period. The results showed that the mean age classes of dead trees and mortality probability distribution were 2.13 and 10.7 which implicated target stand was still young in succession midway. The results also showed that totally 71 trees were predicted to die and to be harvestable. In timber cruising, the information of age should be converted to that of diameter using the age-diameter regression functions for practical use. The suggested method showed a new approach to recognition of succession stage and prediction of yields in natural forests.
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