Todays post will be to do with analysing one of the dynamic global vegetation models (DGVM) previously discussed. The one chosen is the LPJ model discussed in Sitch et al. (2003). It is one of many fully integrated DGVMs that have been developed following the criticism of bioclimate envelope models. The model describes vegetation in terms of fractional coverage of a grid cell, taking into account different plant functional types (PFTs) (Table 1).
Each PFT is then assigned bioclimatic limits (Table 2) which determines whether the species can survive/regenerate under the climatic conditions of the particular grid cell.
LPJ addresses the limitations of bioclimate envelope models be including representation of vegetation structure, dynamics, competition between PFTs and soil biogeography into the model. Figure 1 shows the model logic.
The model can predict changes on different spatial scales. My post will focus on those on the global scale. Figure 2 shows a simulated map of potential natural vegetation for the modern climate. It accurately shows the boreal evergreen forests in Canada and northern Eurasia, the boreal deciduous forests in Siberia, and the transition into temperate ecosystems of north America, western Europe and China. LPJ simulates the transition from savanna into evergreen rainforests near the equator, as well as northern tundra, and grasslands in drier areas.
Figure 2. LPJ predictions of PFT distribution
LPJ has been shown to be able to reproduce relatively accurate models of current global ecosystems. This proves the model’s effectivness and provides some reliability for its application to future modelling. Looking forward, attempts should be made to use this information to examine possible effects of climate on species on a global scale. Having shown an example of a DGVM and how they work and my next post will show how one can be applied to the modelling of a certain area, with hopefully some results.
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