Developing an integrated terrestrial ecosystem model for global

Developing an integrated terrestrial ecosystem model for global changing predictions 陸域統合モデルへの結合を念頭にした 植生動態モデルの構築（設計と進捗状況の報告） Hisashi SATO (FRSGC) & Takashi KOHYAMA (Hokkaido Univ. )

Toward developing the land surface model Land surface physical process model Land surface carbon cycle model Vegetation dynamics model For simulating long time scales, vegetation dynamics model must be added to predict changes in vegetation distribution 原図：伊藤昭彦

Feature of the DGVM (1) Major advances from the previous DGVMs * (1) Individual Based Model (except for herbaceous PFTs) (2) Explicitly simulate spatial structures of vegetations A snap shot of the simulated forest stand (30 m× 30 m). Individual tree is composed of crown, stem, and root. Shape of crown and stem are approximated by cylinder. --- Individual characteristics for woody PFTs --- Crown Stem Root : biomass, diameter, depth : biomass, height, sapwood & heartwood diameter : biomass + reserve resource for sprouting * Plant Functional Types

Feature of the DGVM (2) By explicitly treating forest 3 D structure, the model can reasonably calculate individual light conditions Estimate light intensity on the top of the crown by using canopy location within the forest stand (SORTIE like) Estimate light distribution within canopy using leaf area concentration and light attenuation index Estimated light intensity Calculate NPP, and adjust bole height by perishing deficit crown layer NPP 0. 0 To avoid ‘edge effect’, this scanning is performed among replicated forest stands, which surround the examining area.

Feature of the DGVM (3) Characteristics of herbaceous PFTs Leaf Stem Root : biomass in a forest stand Competition between woody PFTs and herbaceous PFTs 木 本 の 定 着 率 Grass layer can only use light on the forest floor 草本PFTsのバイオマス Luxuriant grass layer inhibit establishment of woody PFTs.

Output example (1): Dynamics of temperate summer-green forest Current version uses ・tentative modules for daily processes, mortality, and phenology ・parameters, which have not adjusted yet

Output examples (2): Dynamics of temperate summer-green forest 200 years Litter production ( Kg / ha year ) Biomass ( Kg / ha ) Leaf Area Index ( m 2 / m 2 ) Sum of stem diameter at breast height ( m / ha )

To see more details of the DGVM …. Module that comprise the dynamic global vegetation models, and its computation time steps. Use modules of Sim-CYCLE

Scheme for connecting phenology module and photosynthesis module

Simulation procedure (1) Simulation will be conducted on the T 42 global grid (128× 64), each of which includes 10 replication forest stands. Thus, assuming 1/3 of the earth surface is terrene, about 27000 independent forest stand will be independently simulated. To date, this would be the most complex ecosystem model that have ever made. 小サイズの林分を複数シミュレートさせる主な理由としては、攪乱の問題があげられる。 例えば寒帯林で頻発する森林火災は、一度生じると、シミュレートしている林分の大きさ が30× 30ｍだろうが1 haだろうが、その殆ど全てが壊滅してしまう。このように機会的に大 きく変動する単一の林分をもって、グリッドの代表値とさせることは適当ではない。

Simulation procedure (2) Simulation 1 (free seed dispersal) assumes that all PFTs establish all grid, irrespective of previous or current vegetation distribution Simulation 2 (no seed dispersal) assumes that PFTs that currently distribute for each grid only establish in the grid permanently The former simulation should provide maximum estimate of vegetation change, while the latter should provide minimum estimate.

Procedure for parameter estimation and tuning (1) Estimate parameters and algorithm of a tree growth so that tree-form and leaf-density are reasonably simulated for each PFT (2) Estimate dynamics parameters (Establishment, Mortality, Disturbance): so that density and age distribution of tree are reasonably simulated when only one PFT composes the forest (3) Estimate metabolic parameters (Photosynthesis, Respiration, Allocation): So that biomass, LAI, and distribution of DBH are reasonably simulated. This will be conducted on forest that was composed of only one PFT. (4) By repeating above (2) and (3), convergence parameters (5) Conduct test run on global grid then examine that distribution of vegetation and GPP at equilibrium are reasonably simulated.

Schedule ・ within Oct Complete to develop the DGVM program except daily processes ・ 2 to 4 month Link it with daily process modules of Sim-CYCLE ・ 1 to 3 month Parameter estimation and tuning ・? Vectorize the program and conduct simulation at global scale on the earth simulator