Application of a computationally efficient method to approximate gap model results with a probabilistic approach
To be able to simulate climate change effects on forest dynamics over the whole of Switzerland, we adapted the second-generation DGVM (dynamic global vegetation model) LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator) to the Alpine environment. We modified model functions, tuned model parame...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-07-01
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| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/7/1543/2014/gmd-7-1543-2014.pdf |
| Summary: | To be able to simulate climate change effects on forest dynamics over the
whole of Switzerland, we adapted the second-generation DGVM (dynamic global vegetation model) LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator) to the
Alpine environment. We modified model functions, tuned model parameters, and
implemented new tree species to represent the potential natural vegetation of
Alpine landscapes. Furthermore, we increased the computational efficiency of
the model to enable area-covering simulations in a fine resolution
(1 km) sufficient for the complex topography of the Alps, which
resulted in more than 32 000 simulation grid cells. To this aim, we applied
the recently developed method GAPPARD (approximating GAP model results with a
Probabilistic Approach to account for stand Replacing Disturbances) (Scherstjanoi et al., 2013) to
LPJ-GUESS. GAPPARD derives mean output values from a combination of
simulation runs without disturbances and a patch age distribution defined by
the disturbance frequency. With this computationally efficient method, which
increased the model's speed by approximately the factor 8, we were able to
faster detect the shortcomings of LPJ-GUESS functions and parameters. We used the
adapted LPJ-GUESS together with GAPPARD to assess the influence of one
climate change scenario on dynamics of tree species composition and biomass
throughout the 21st century in Switzerland. To allow for comparison with the
original model, we additionally simulated forest dynamics along a
north–south transect through Switzerland. The results from this transect
confirmed the high value of the GAPPARD method despite some
limitations towards extreme climatic events. It allowed for the first time to
obtain area-wide, detailed high-resolution LPJ-GUESS simulation results for a
large part of the Alpine region. |
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| ISSN: | 1991-959X 1991-9603 |