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The modelling activities within BIO-ECO aim to assess the impacts of human activity and climate change and variability on ecosystems at short and long timescales, in conjunction with ecosystem manipulation experiments and long-term eddy flux monitoring stations. In general, they aim to evaluate the impacts of anthropogenic climate change on ecosystems and the feedback to atmospheric greenhouse gas (GHG) budgets from terrestrial ecosystems. The difference between the specific objectives is predominantly in the temporal and spatial scales that they consider and the methods that are applied.
Ecosystem manipulation experiments
BIO-ECO operates a number of ecosystem manipulation experiments that are part of national projects (CLIMAITE) and European networks (nitroeurope; INCREASE; CARBO-Extreme). One aim of these projects is to improve the prediction of the carbon balance of terrestrial ecosystems under future climate regimes. Many ecosystem properties are important in determining the terrestrial carbon balance; different ecosystem processes respond differently to changes in temperature, water availability and atmospheric CO2 concentration. For example the processes of photosynthesis and ecosystem respiration determine net ecosystem production (NEP) and therefore the feedback to atmospheric carbon dioxide concentration. Further feedbacks on atmospheric radiative forcing may be generated by changes in the rates of production of non-CO2 GHGs such as methane and nitrous oxide. There are many physical, chemical and biological processes that are affected by climate change factors and can be investigated using at the annual to decadal scale with manipulation experiments.
Longer term climatic shifts, however, may result in change in the community composition through changes in the success of different species (growth, fecundity, mortality, etc). These community changes are significant from the perspective of conservation of threatened species and cultural landscapes. Changes in community composition may also alter the biogeochemical cycling of elements at a given site. Therefore, as future climate projections are made at timescales beyond the time required for succession to take place in many ecosystems, meaningful predictions should include ecosystem community composition shifts. As these shifts occur over periods beyond the scope of experimental studies (in general, but see Graglia et al. 2001, Zaveleta et al. 2003 and Rinnan et al. 2007), they can only be informed by observational studies of niche differentiation and habitat preference (Hijmans and Graham 2006; Ellenberg values etc.).
The different models applied
Modelling of biogeochemical cycling in ecosystems at shorter timescales is performed with more process based or mechanistic models, such as MAESTRA (Wang and Jarvis 1990, Medlyn 2004, Ibrom et al. 2006 ), CoupModel (Jansson and Karlberg 2004), while longer term modelling studies are performed using ForSAFE-VEG (Wallman et al. 2005, Belyazid et al. 2006). Inter-model comparison is an especially useful tool for parameterisation and validation of lumped parameter models using mechanistic model outputs. Empirical statistical models are used for upscaling measurement data, gap filling and to develop understanding of important system drivers (Larsen et al. 2007). Static network models and budgets are used to conceptualise system properties and evaluate the significance of different ecosystem stocks and fluxes.
References
- Larsen, K.S., A. Ibrom, C. Beier, S. Jonasson and A. Michelsen 2007. Ecosystem respiration depends strongly on photosynthesis in a temperate heath. Biogeochemistry. 85:201-213.
- Jansson, P.-E. And L. Karlberg 2004. Coupled Heat and Mass Transfer Model for Soil–Plant–Atmosphere Systems. Royal Institute of Technology, Dept. of Civil and Environmental Engineering, Stockholm, Sweden, 435 pp. Available at: ftp://www.lwr.kth.se/CoupModel/CoupModel.pdf.
- Graglia, E., S. Jonasson, A. Michelsen, I.K. Schmidt, M. Havstrom and L. Gustavsson 2001. Effects of environmental perturbations on abundance of subarctic plants after three, seven and ten years of treatments. Ecography. 24:5-12.
- Rinnan, R., A. Michelsen, E. Baath and S. Jonasson 2007. Fifteen years of climate change manipulations alter soil microbial communities in a subarctic heath ecosystem. Global Change Biology. 13:28-39.
- Zavaleta, E.S., M.R. Shaw, N.R. Chiariello, B.D. Thomas, E.E. Cleland, C.B. Field and H.A. Mooney 2003. Grassland responses to three years of elevated temperature, CO2, precipitation, and N deposition. Ecological Monographs. 73:585-604.
- Hijmans, R.J. and C.H. Graham 2006. The ability of climate envelope models to predict the effect of climate change on species distributions. Global Change Biology. 12:2272-2281.
- Belyazid, S., O. Westling and H. Sverdrup 2006. Modelling changes in forest soil chemistry at 16 Swedish coniferous forest sites following deposition reduction. Environmental Pollution. 144:596-609.
- Wallman, P., M.G.E. Svensson, H. Sverdrup and S. Belyazid 2005. ForSAFE - an integrated process-oriented forest model for long-term sustainability assessments. Forest Ecology and Management. 207:19-36.
- Gerten, D., S. Schaphoff and W. Lucht 2007. Potential future changes in water limitations of the terrestrial biosphere. Climatic Change. 80:277-299.
- Ibrom, A., P.G. Jarvis, R.B. Clement, K. Morgenstern, A. Oltchev, B. Medlyn, Y.P. Wang, L. Wingate, J. Moncrieff and G. Gravenhorst 2006. A comparative analysis of simulated and observed photosynthetic CO2 uptake in two coniferous forest canopies. Tree Physiology. 26:845 - 864.
- Medlyn, B. 2004. A MAESTRO retrospective. In Forests at the Land-Atmosphere Interface Eds. M. Mencuccini, J. Grace, J. Moncrieff and K.G. McNaughton. CAB International, Wallingford, pp. 105-121.
- Wang, Y.P. and P.G. Jarvis 1990. Description and validation of an array model - MAESTRO. Agricultural and Forest Meteorology. 51:257-280.
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