Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM
<p>Natural and anthropogenic disturbances, in particular forest management, affect forest age structures all around the globe. Forest age structures in turn influence key land surface processes, such as photosynthesis and thus the carbon cycle. Yet, many dynamic global vegetation models (DGVMs...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-01-01
|
| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/13/185/2020/gmd-13-185-2020.pdf |
| _version_ | 1819096343695589376 |
|---|---|
| author | J. E. M. S. Nabel K. Naudts K. Naudts J. Pongratz J. Pongratz |
| author_facet | J. E. M. S. Nabel K. Naudts K. Naudts J. Pongratz J. Pongratz |
| author_sort | J. E. M. S. Nabel |
| collection | DOAJ |
| description | <p>Natural and anthropogenic disturbances, in particular forest management, affect forest age structures all around the globe. Forest age structures in turn influence key land surface processes, such as photosynthesis and thus the carbon cycle. Yet, many dynamic global vegetation models (DGVMs), including those used as land surface models (LSMs) in Earth system models (ESMs), do not account for subgrid forest age structures, despite being used to investigate land-use effects on the global carbon budget or simulating biogeochemical responses to climate change. In this paper we present a new scheme to introduce forest age classes in hierarchical tile-based DGVMs combining benefits of recently applied approaches the first being a computationally efficient age-dependent simulation of all relevant processes, such as photosynthesis and respiration, using a restricted number of age classes and the second being the tracking of the exact forest age, which is a prerequisite for any implementation of age-based forest management. This combination is achieved by using the tile hierarchy to track the area fraction for each age on an aggregated plant functional type level, whilst simulating the relevant processes for a set of age classes. We describe how we implemented this scheme in JSBACH4, the LSM of the ICOsahedral Non-hydrostatic Earth system model (ICON-ESM). Subsequently, we compare simulation output to global observation-based products for gross primary production, leaf area index, and above-ground biomass to assess the ability of simulations with and without age classes to reproduce the annual cycle and large-scale spatial patterns of these variables. The comparisons show decreasing differences and increasing computation costs with an increasing number of distinguished age classes. The results demonstrate the benefit of the introduction of age classes, with the optimal number of age classes being a compromise between computation costs and error reduction.</p> |
| first_indexed | 2024-12-21T23:57:42Z |
| format | Article |
| id | doaj.art-2263dab1e99f49c6bd666487c90d0b9b |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-12-21T23:57:42Z |
| publishDate | 2020-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-2263dab1e99f49c6bd666487c90d0b9b2022-12-21T18:45:47ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032020-01-011318520010.5194/gmd-13-185-2020Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESMJ. E. M. S. Nabel0K. Naudts1K. Naudts2J. Pongratz3J. Pongratz4Max Planck Institute for Meteorology, 20146 Hamburg, GermanyMax Planck Institute for Meteorology, 20146 Hamburg, Germanynow at: Department of Earth Sciences, VU University Amsterdam, Amsterdam, the NetherlandsMax Planck Institute for Meteorology, 20146 Hamburg, Germanynow at: Ludwig-Maximilians-Universität München, Munich, Germany<p>Natural and anthropogenic disturbances, in particular forest management, affect forest age structures all around the globe. Forest age structures in turn influence key land surface processes, such as photosynthesis and thus the carbon cycle. Yet, many dynamic global vegetation models (DGVMs), including those used as land surface models (LSMs) in Earth system models (ESMs), do not account for subgrid forest age structures, despite being used to investigate land-use effects on the global carbon budget or simulating biogeochemical responses to climate change. In this paper we present a new scheme to introduce forest age classes in hierarchical tile-based DGVMs combining benefits of recently applied approaches the first being a computationally efficient age-dependent simulation of all relevant processes, such as photosynthesis and respiration, using a restricted number of age classes and the second being the tracking of the exact forest age, which is a prerequisite for any implementation of age-based forest management. This combination is achieved by using the tile hierarchy to track the area fraction for each age on an aggregated plant functional type level, whilst simulating the relevant processes for a set of age classes. We describe how we implemented this scheme in JSBACH4, the LSM of the ICOsahedral Non-hydrostatic Earth system model (ICON-ESM). Subsequently, we compare simulation output to global observation-based products for gross primary production, leaf area index, and above-ground biomass to assess the ability of simulations with and without age classes to reproduce the annual cycle and large-scale spatial patterns of these variables. The comparisons show decreasing differences and increasing computation costs with an increasing number of distinguished age classes. The results demonstrate the benefit of the introduction of age classes, with the optimal number of age classes being a compromise between computation costs and error reduction.</p>https://www.geosci-model-dev.net/13/185/2020/gmd-13-185-2020.pdf |
| spellingShingle | J. E. M. S. Nabel K. Naudts K. Naudts J. Pongratz J. Pongratz Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM Geoscientific Model Development |
| title | Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM |
| title_full | Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM |
| title_fullStr | Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM |
| title_full_unstemmed | Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM |
| title_short | Accounting for forest age in the tile-based dynamic global vegetation model JSBACH4 (4.20p7; git feature/forests) – a land surface model for the ICON-ESM |
| title_sort | accounting for forest age in the tile based dynamic global vegetation model jsbach4 4 20p7 git feature forests a land surface model for the icon esm |
| url | https://www.geosci-model-dev.net/13/185/2020/gmd-13-185-2020.pdf |
| work_keys_str_mv | AT jemsnabel accountingforforestageinthetilebaseddynamicglobalvegetationmodeljsbach4420p7gitfeatureforestsalandsurfacemodelfortheiconesm AT knaudts accountingforforestageinthetilebaseddynamicglobalvegetationmodeljsbach4420p7gitfeatureforestsalandsurfacemodelfortheiconesm AT knaudts accountingforforestageinthetilebaseddynamicglobalvegetationmodeljsbach4420p7gitfeatureforestsalandsurfacemodelfortheiconesm AT jpongratz accountingforforestageinthetilebaseddynamicglobalvegetationmodeljsbach4420p7gitfeatureforestsalandsurfacemodelfortheiconesm AT jpongratz accountingforforestageinthetilebaseddynamicglobalvegetationmodeljsbach4420p7gitfeatureforestsalandsurfacemodelfortheiconesm |