The evolution of the earth's terrestrial ecosystems is an important issue to be considered in order to predict future stresses. The community composition and species distribution of forests generate different spatial temperature patterns and supplies different services to terrestrial animals including humans. Therefore projections of future vegetation types are necessary. In this study we are using a well documented, well tested and widely used model: LPJ-GUESS.
LPJ-GUESS (Lund-Potsdam-Jena General Ecosystem Simulator) is an ecosystem modeling framework in which the simulated biological units are plant functional types (PFTs) or species. Climate changes affect plant growth in LPJ-GUESS via temperature effects on the kinetics of photosynthesis and maintenance respiration, the influence of soil water content on stomatal conductance and photosynthesis, changes in phenology. Further details of the physiological, biophysiological and biogeochemical components of the model are described in Sitch et. al (2003).
The model was applied over a window covering the entire landmass of Turkey and its region at a resolution 0.5° longitude and latitude. Gridded values of biomass, ecosystem annual net primary production and annual net ecosystem carbon exchange are considered. Most important tree species of Turkey and its region are represented and corresponding PFT parameters are chosen based on the physiology and life-history of each. Input data are the FAO soil types, and monthly climatology for temperature, precipitation and cloudiness (based on CRU05 global monthly dataset, extending from 1901 to 1998). Future climate information has been generated by downscaling the ECHAM5 global model results with RegCM3 regional model for the period 1999-2100 and for A2 and B1 emission scenarios.
Results/Conclusions
The ecosystem model represent current ecosystem distribution fairly under mean climatic and atmospheric CO2 conditions for the period 1969-1998. Results suggest that shifts in climatic zones may lead to changes in species distribution and community composition among major tree species of natural Turkish forests. Increased temperatures and a longer growing season allow mediterranean needleleaved evergreen types to expand northwards and a change from deciduous to conifer in Southern Turkey. The model also predicted substantial increases in vegetation net primary productivity (NPP) and the extension of the tree line. The economy-oriented A2 emission scenario would lead to higher NPP and stronger carbon sinks according to the simulations than the environment-oriented B1 scenario. In this study the potential natural vegetation was simulated, ignoring direct anthropogenic effects such as land use or silvicultural management.