Various anthropogenic stressors have caused mire degradation in subarctic northern Japan, such as drying and the invasion of an alder-dominant shrub forest. The Japanese government recently started a nature conservation project to restore a formerly meandering river in order to prevent invasive forest species and to rehabilitate the original mire ecosystem. In this study, the process-based National Integrated Catchmentbased Eco-hydrology (NICE) model is further developed to improve accuracy in evaluation of nonlinear interactions and feedback of hydro-geomorphology and vegetation dynamics in the ecosystem. The simulated results clarify the impact of groundwater level change, sediment deposition, and nutrient availability on the complex alder invasion after refining the model to include newly-developed down-scaling and feedback processes. The model also shows the interaction between groundwater and inundated flow and its effect on vegetation change, which sheds light on two conflicting conceptualizations of peatland hydrology. This integrated system links the hydrological approach to the ecological one implicitly in the model, and throws some light on the refinement of tipping-point early warning systems for sustainable development and the improvement in boundless biogeochemical cycles along terrestrial-aquatic continuum for global environmental change.
人為活動に伴う乾燥化やハンノキ侵入という釧路湿原の劣化に対し、著者は既存論文において水循環・土砂堆積に伴う地形変化・植生遷移をシミュレーションするNICEモデルを開発し、湿原回復可能性の評価を行ってきた。本論文では既存研究をさらに拡張し、ダウンスケーリングおよびフィードバックを新たに考慮したモデル構築を行った。得られた結果をもとに表面流－地下水流間の相互作用および植生遷移へ及ぼす影響を明らかにし、従来の湿原域での水循環の概念モデルの拡張を行った。本研究で構築した統合システムは水文学的および生態学的手法を関連付け、生物地球化学的循環のさらなる解明および精度向上に有効である。
