Sweden：LPJ-GUESS

Sweden: LPJ-GUESS
The name of the group: Department of Physical Geography and Ecosystem Analysis
Name, title and affiliation of Principal investigator: Assoc. Prof. Almut Arneth; Assoc. Prof. Ben Smith Name and affiliation of contact point, incl. detailed address: Almut Arneth & Ben Smith, INES,
Sölvegatan12,22362Lund,*****************************.se;*******************.se
URL: http://www.nateko.lu.se/INES/Svenska/main.asp
Partner institutions: PIK, SMHI/EC-EARTH
Which components:
land sfc yes
atmospheric chemistry yes
Project Description:
LPJ-GUESS (Smith et al., 2001; Hickler et al., 2004) is a generalized, process-based model of vegetation dynamics and biogeochemistry designed for regional to global applications. It combines features of the widely used Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM; Sitch et al., 2003) with those of the General Ecosys-tem Simulator (GUESS; Smith et al., 2001) in a single, flexible modeling framework. The models have identical representations of ecophysiological and biogeochemical processes, including the hydrological cycle updates d e-scribed in Gerten et al. (2004). They differ in the level of detail with which vegetation dynamics and canopy stru c-ture are simulated: simplified, computationally efficient representations are used in the LPJ-DGVM, while in GUESS a "gap-model" approach is used which is particularly suitable for continental to regional simulations. Tepre-sentations of stochastic establishment, individual tree mortality and disturbance events ensure representation of suc-cessional vegetation dynamics which is important for vegetation response to extreme events.
LPJ-GUESS models terrestrial carbon and water cycle from days to millennia (Sitch et al. 2003; Koca et al. 2006; Morales et al. 2005, 2007) and has been shown to reproduce the CO2 fertilisation effects seen in FACE sites (Hickler et al. in press). It has been widely applied to assess impacts on carbon cycle and veg etation based on scenarios from climate models (Gritti et al. 2006; Koca et al. 2006; Morales et al. 2007; Olesen et al. 2007). In addition it has several unique features that are currently not available in any of the Earth System Models:
(1) A process-based description for the main biogenic volatile organic compounds (BVOC) emitted by vegetation. BVOC are crucial for air chemistry and climate models, since they contribute to formation and destruction of trop o-spheric O3 (depending on presence and absence of NOx), constrain the atmospheric lifetime of methane, and are key precursors to secondary organic aerosol formation. LPJ-GUESS is the only land surface model with a mechanistic BVOC representation that links their production to photosynthesis. It also uniquely accounts for the recently disco v-ered direct CO2-BVOC inhibition which has been shown to fundamentally alter future and past emissions compared to empirical BVOC algorithms that neglect this effect (Arneth et al., 2007a,b). (2) The possibility to simulate past and present vegetation description on a tree species (as well as PFT) level (Miller et al., in press, Hickler et al., 2004). This is crucial for simulations of BVOC and other reactive trace gases and allows for a much better represe ntation of vegetation heterogeneity in regional and continental atmospheric chemistry-climate studies (Arneth et al., 2007b), an important aspect since spatial heterogeneity must be accounted for with atmospherically reactive chemical species. (3) LPJ-GUESS accounts for deforestation by early human agriculture throughout the Holocene and the effects on global carbon cycle and atmospheric CO2 concentration (Olofsson & Hickler 2007). We currently investigate the impor-tance of Holocene human deforestation on BVOC and fire trace gas and aerosol emissions, and how these may affect Holocene CH4 levels, and simulations of pre-industrial O3. (4) LPJ-GUESS accounts for deforestation by early human agriculture throughout the Holocene and the effects on global carbon cycle and atmospheric CO2 concentra-tion (Olofsson & Hickler 2007). We currently investigate the importance of Holocene human deforestation on BVOC and fire trace gas and aerosol emissions, and how these may affect Holocene CH4 levels, and simulations of pre-industrial O3. (5) A novel global process-based fire description, SPITFIRE (Thonicke et al., 2007) has been incorporated; it is currently used to study effects of climate change and of human vs. natural ignition on carbon cycle and trace gas emissions in savanna ecosystems. (6) Prognostic schemes for agricultural and forest land use that p a-rameterise farmer and forestmanagement decisions under changing climate and productivity. The agricultural scheme has been implemented and applied at the global scale (Bondeau et al. 2007), the forest management scheme in a prototype form for Sweden (Koca et al. 2006). (7) Incorporation of a permafrost module, wetland processes and methane emissions, as well as vegetation nitrogen cycle is in progress.
The vegetation dynamics module of LPJ-GUESS has been coupled to the land surface scheme of the Rossby Centre regional climate model RCA3 (Jones et al. 2004a,b) and is being applied to investigate biophysical feedbacks of land surface changes on climate at the regional scale in Europe. The above listed process descriptions are also applicable and available to global ESMs.
(References available on request)。