Takuya HIROSHIMA, Associate Professor
・Standing Faculty, International Program in Agricultural Development Studies (IPADS)
Laboratory of Global Forest Environmental Studies, Department of Global Agricultural Sciences,
Department of Forest Science, Graduate School of Agricultural and Life Sciences, the University of Tokyo
http://www.gfes.ga.a.u-tokyo.ac.jp/
Contact information:
Phone +81 3 5841 7508
EMAIL hiroshim[at]g.ecc.u-tokyo.ac.jp
Professional Experience & Education
| 2021~Present: | Associate Professor, Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo |
|---|---|
| 2018: | Lecturer/Vice Director, The University of Tokyo Hokkaido Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo |
| 2016: | Lecturer/Director, Ecohydrology Research Institute, Graduate School of Agricultural and Life Sciences, The University of Tokyo |
| 2007: | Lecturer/Vice Director, The University of Tokyo Chiba Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo |
| 2004: | Ph. D., Forest Science, Graduate School of Agricultural and Life Sciences, the University of Tokyo |
| 1998: | Assistant Professor, Department of Forest Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo |
Discipline(s)
Forest Science, Geo-informatics, Growth model, Survival Analysis
Research interests
- Survival analysis of forest stand in planted forest and tree population in natural forest
- Multiple time and spatial scale simulation for timber harvest and forest growth
- Spatial analysis of forest stand based on geo-informatics
- Evaluation of carbon sequestration in forest and its offsetting credit trading
Study example
1A. Prediction of timber harvest from forest plantations: We developed the prediction system of timber harvests on national scale by combining yields of local districts (e.g. 47 prefecture in Japan) based on survival analysis techniques. The harvesting probabilities of parametric survival estimates were derived from the harvesting stats in local districts. Then timber harvesting area and volume were predicted for each district using the estimated probabilities. The validation results showed that the supposed method was successfully predicted harvesting volumes on national scale compared with the corresponding national forestry stats. The developed prediction system is widely available to predict timber harvests from forest plantations on national scale all over the world.
1B. Survival analysis of individual tree populations in uneven-aged forest stands: We performed survival analyses of individual tree populations in natural forest stands to evaluate the matured states of stands. Tree ages of living and dead trees were measured using a semi non-destructive device called the Resistograph during the observation periods, and all the changes (i.e., death and new ingrowth) during the period were recorded. In the analyses, first, we applied survival analyses to find out multi-temporal age distributions and non-parametric estimates. Secondly, we applied parametric Weibull distributions to calculate age related metrics such as mean lifetime and mean age of stands. Finally, we evaluated these calculated metrics from the viewpoints of matured states of forest stands. The developed methods is widely available to understand the stand dynamics of natural forests coherent to the morality of individual tree populations all over the world.
2. Growth prediction of forest plantations using long term growth observation data: We investigated the changes in extrapolated values of diameter at breast height (DBH) in old Sugi (Cryptomeria japonica) forest plantations with changes in the observation period of training data for model calibration. The study sites were long-term growth observation sites of Sugi forest plantations in the University of Tokyo Forests. In this study, both DBH of individual trees and mean DBH of stands were analyzed by fitting Richards growth functions. The results showed that the accuracy of growth predictions in old ages was improved by including growth data from a sufficient number of older trees. From another point of view, growth prediction in old ages tended to underestimate actual growth if growth data did not include enough older trees. The developed methods is widely available to predict the growth of forest plantations in terms of carbon stock estimation, timber harvest prediction, etc. for a long term.
3. Finding right spots to harvest using GIS thematic maps: We developed the way to automatically find out the right spots for harvest using GIS thematic maps. The map themes consisted of stand age, site quality, accessibility and slope stability, and they were combined after conversion of original units into a common scale of standard scores. Then, forest plantation stands suitable for clearcutting and reforestation were selected considering yarding feasibility check to see if there was any obstacle along the sky line of cable logging in the visible area from the neighboring yard. A standard score was useful to set several thematic maps into a common scale when they were combined. The developed method is flexible and can contribute to a wider use in sustainable forest management all over the world.
4A. Carbon stock estimation in sustainably managed forests under the Kyoto Protocol and the Paris Agreement: We predicted the amounts of carbon sequestration in the managed forests under the Kyoto Protocol on national scale. Managed forests were defined as the forest plantations that have undergone silvicultural practices such as weeding, pruning and thinning since 1990 in accordance with the Article 3.4 of Kyoto Protocol. The regression models were developed to predict the forest areas that have undergone silvicultural practices, employing silvicultural subsidies and forest worker’s wages as predictor variables. Then the time series changes in the predictor variables were provided by extending their recent trends, with the result being that the forest areas that have undergone silvicultural practices were predicted on the basis of the three scenarios of the variables. Thus the Article 3.4 forest area was predicted, and the area was converted into the amount of carbon sequestration by multiplying it by coefficients such as a volume table, biomass expansion factor, etc. The result implied that the managed forests were expected to sequester 8.16 – 8.87 Mt-C per year during the first commitment period of Kyoto Protocol. These amounts covered 63 – 68% of the carbon sequestration goal by Land-Use Change and Forestry activities capped under the Marrakesh Accords. The developed method is also available to predict the carbo sequestration/stock of sustainably managed forests under the Paris Agreement.
4B. Trends and issues on the Verified Emission Reduction (VER) credits for carbon offsetting: The case study looked back over the development of international VER schemes such as J-VER, VCS and CAR and corresponding carbon offsets to date, and discussed current issues to be hurdled for further development. VER schemes were generally designed based on the Kyoto Mechanism, and labor and time consuming. But these high requirements led to the high credibility of the schemes. To accelerate the current depressed circumstance of VER trading, it was essential to increase current share of VER in carbon offsetting market. For that purpose, it was considered important to promote public relation of carbon offsets with VER, which was a merit for interested companies to appeal their contributions to EGS investments for rural area development by purchasing VER. It was also important to relate the use of VER with the carbon offsetting based on public frameworks such as Paris Agreement legislatively.
Major publications
Hiroshima T, Toyama K, Suzuki SN, Owari T, Nakajima T, Ishibashi S (2020) Long observation period improves growth prediction in old Sugi (Cryptomeria japonica) forest plantations. J For Res 25: 183-191. DOI: 10.1080/13416979.2020.1753280
Hiroshima T, Nakajima T, Kanomata H (2018) Calculation of commercial thinning volumes in 47 prefectures in Japan. J For Res 23: 47-55. DOI: 10.1080/13416979.2017.1391367
Hiroshima T (2015) Finding Suitable Stands for Clearcutting and Reforestation by Combining GIS Thematic Maps Expressed by Standard Scores: A Case Study in the University of Tokyo Chiba Forest. J For Plann 20: 35-43. DOI: 10.20659/jfp.20.2_35
Hiroshima T (2014) Applying age-based mortality analysis to a natural forest stand in Japan. J For Res 19: 379-387. DOI: 10.1007/s10310-013-0428-8
Hiroshima T (2012) Trends and issues on the Japan Verified Emission Reduction (J-VER) scheme and corresponding carbon offset in Japan. Bull Tokyo Univ For 127: 1-16. Permalink : http://hdl.handle.net/2261/51963
Hiroshima T (2011) Calculation of yields on a national level by combining yields of each prefecture using the Gentan probability. J For Res 16: 98-107. DOI: 10.1007/s10310-010-0216-7
Hiroshima T, Nakajima T (2006) Estimation of sequestered carbon in Article-3.4 private planted forests in the first commitment period in Japan. J For Res 11: 427-437 DOI: 10.1007/s10310-006-0236-5
Hiroshima, T (2004) Strategy for implementing silvicultural practices in Japanese plantation forests to meet a carbon sequestration goal. J For Res 9: 141-146 DOI: 10.1007/s10310-003-0070-y