open access

https://doi.org/10.14943/doctoral.k13917

https://hdl.handle.net/2115/77844

SEIB-DGVM を用いた北日本の冷温帯林における森林動態と炭素収支に対する台風撹乱の影響の解明

英語

2020-03-25

Hokkaido University

101p

Large storm is a major source of natural disturbance in forest ecosystems in coastal regions of the world. Under the changing climate, some climate projection models predict that storms would become stronger in future, especially in Northwest Pacific region. Although the destruction of typhoons has a strong impact on the structure and carbon balance of forest ecosystems, leading to local climate change feedback, the long-term effect of typhoon frequency and intensity on forest and carbon dynamics has not been investigated especially from the perspective of future climate change. To elucidate these long-term effects, a SEIB-DGVM (Spatially explicit individual-based dynamic global vegetation model) was applied to a deciduous-coniferous mixed forest in southern Hokkaido, Japan, to represent the development of a larch plantation established in 1954 after typhoon Toyamaru struck a natural forest and the natural regeneration from 2004 when the plantation suffered windthrow by typhoon Songda. The model was validated to ground measurement of eddy flux and biomass. The adapted model was then forced with various combinations of typhoon scenarios with multiple frequency and intensity levels, and with the projected climatic conditions for 2017–2100 under Representative Concentration Pathways (RCPs) 2.6 and 8.5. The aims of this study are: (1) reproducing the forest structural traits and carbon dynamics in Tomakomai in the historical period by using SEIB-DGVM; and (2) evaluating the possible impact of typhoons on the forest under projected future climate changes. The validation result shows that SEIB-DGVM could reproduce the interannual variations at the Tomakomai Flux Research Site in historical period. The future projections suggest that increasing typhoon frequency and intensity have a significant effect on forest and carbon dynamics under both RCP 2.6 and RCP 8.5. As the frequency and intensity of typhoons increase, aboveground biomass (AGB) and net primary production (NPP) decrease. However, increasing typhoon frequency and intensity had a greater influence on AGB than NPP. The values of AGB and NPP are much higher under RCP 8.5 than under RCP 2.6 and at baseline. As the frequency and intensity of typhoons increase, net ecosystem production first increases and then decreases. The projection indicates that the forest at the Tomakomai site will become a carbon sink under different typhoon scenarios at the end of the 21st century. The result also predicts that if typhoon frequency is ≤ 2 (i.e., a typhoon occurs up to two times between 2017 and 2100) and intensity is ≤ 40% (i.e., up to 40% of trees damaged), then forest AGB can recover to that before typhoon Songda by the end of the 21st century. Simulation results also showed strong linear relationships among forest structural traits (AGB, tree height, tree density, and woody plant and grass leaf area indexes), carbon fluxes, and typhoon frequency and intensity.

2020-03-25

甲第13917号

博士(農学)

(主査) 准教授 加藤 知道, 教授 鮫島 良次, 教授 平野 高司

農学院（共生基盤学専攻）

博士論文

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