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LPJ-GUESS

Purpose

LPJ-GUESS is a computer model that simulates the responses of land vegetation and ecosystems to climatic and environmental variation.

Brief Description

LPJ-GUESS model (Smith et al. 2001) employs forest-gap method to model dynamics of natural vegetation. Its implementation represents forest stand as a mosaic of independent patches each 1000 sq. m that are at different successional stages and follow independent hydrological and biogeochemical histories. The difference between the patches originates in explicitly-formulated processes of establishment, mortality and competition for resources under probabilistic disturbance regime. Overall state of the forest is obtained by averaging the patch variables. Establishment of new tree individuals occurs in age groups (“cohorts”), i.e. newly established individuals have similar characteristics; however, the age-dependent and growth-stress mortality of individual trees is modelled stochastically as is patch-destroying mortality due to a disturbance (e.g., storms, fire). Typically model is run with a daily time step, meaning that daily meteorological forcing data are required and most of the physiological processes are parameterised for this time scale. Establishment, growth, mortality and disturbances are calculated annually. Vegetation is organised into groups, referred to as plant functional types (PFTs), which have specific static parameters describing their ecological niches. List of PFTs is designed to represent most relevant and common plant species and live forms; it can be expanded or adjusted as necessary to account for site-specific vegetation.

The model was successfully applied to a variety of environments and a particular attention has been paid to European conditions with a more detailed parameterisation of the relevant PFTs (Wramneby et al. 2010; Smith et al. 2011). It was used with both historical meteorological datasets as well as various climate projections. Data from manipulation experiments were successfully used to evaluate obtained results at a wider regional or global scale (Hickler et al. 2008). Therefore, LPJ-GUESS is uniquely suitable to possible wide range of applications for ecosystem research in Europe.

Availability and documentation

The model is well documented and has a number of configuration parameters that can be adjusted by the users, including duration of the simulation and optional disturbance regime. To get access to the model, including its detailed description, researchers need to contact modelling group.

An educational version of LPJ-GUESS (Windows executable, no source code) is available for download.

References

• Smith, B., P. Samuelsson, A. Wramneby and M. Rummukainen (2011). A model of the coupled dynamics of climate, vegetation and terrestrial ecosystem biogeochemistry for regional applications Tellus A 63(1): 87-106 doi:10.1111/j.1600-0870.2010.00477.x.
• Wramneby, A., B. Smith and P. Samuelsson (2010). Hot spots of vegetation-climate feedbacks under future greenhouse forcing in Europe Journal of Geophysical Research 115: D21119 doi:10.1029/2010JD014307.
• Hickler, T., B. Smith, I. C. Prentice, K. Mjöfors, P. Miller, A. Arneth and M. T. Sykes (2008). CO₂ fertilization in temperate FACE experiments not representative of boreal and tropical forests Global Change Biology 14(7): 1531-1542 doi:10.1111/j.1365-2486.2008.01598.x.
• Smith, B., I. C. Prentice and M. T. Sykes (2001). Representation of vegetation dynamics in the modelling of terrestrial ecosystems: comparing two contrasting approaches within European climate space Global Ecology and Biogeography 10(6): 621–637 doi:10.1046/j.1466-822X.2001.t01-1-00256.x.

A full list of LPJ-GUESS publications is also available.