Comparative analysis of the gas exchange of mountain meadows

The steady rise in atmospheric carbon dioxide concentrations since the industrial revolution and the anticipated adverse consequences on the global climate system, have triggered a strong scientific interest in the global cycles of carbon, water and energy. Several European and international projects are currently trying to quantify the fluxes of carbon dioxide, water vapour, energy and other green house gases to/from terrestrial ecosystems using the eddy covariance method and to understand how these are affected by biotic, abiotic and anthropogenic controls. The ultimate goal of all these efforts is a realistic assessment of the role terrestrial ecosystems will play in the global carbon, hydrological and biogeochemical cycles under likely future climate and land-use scenarios and to infer appropriate abatement strategies. However, all these efforts are strongly biased towards forest ecosystems, with a consequent shortage of flux data for grassland ecosystems. Globally, grasslands cover approximately 40 % of the ice-free terrestrial surface area, but less than 10 % of the present study sites are grassland ecosystems. Semi-natural grasslands in the Alps, i.e. pastures and meadows, form the economic basis for local dairy farming and have become characteristic elements of the Alpine landscape. Long-term measurements at a meadow in the vicinity of the village Neustift (Stubai Valley/Austria) since 2001 have revealed that the investigated meadow acts as a net source of the greenhouse gas carbon dioxide. The reasons for this are currently unclear, also because no results from comparable sites are available. Aim of the proposed project is thus to improve the existing knowledge on the carbon dioxide, water vapour and energy exchange of mountain grassland ecosystems in the Greater Tyrol in order to put the results from the study site Neustift into perspective and to draw scientifically sound conclusions about the gas exchange of mountain grasslands. To this end it is planed to employ a combined experimental and modelling approach: The carbon dioxide, water vapour and energy exchange will be measured by means of the eddy covariance method in a continuous fashion at the study site Neustift and episodically by means of a mobile eddy covariance station at several meadows within the Greater Tyrol. A causal analysis of these data will be accomplished by means of an extant soil-vegetation atmosphere-transfer (SVAT) model. The necessary input data will be derived from soil/plant physiological/ecological field experiments and by means of remote sensing, i.e. the interpretation of satellite images.

The steady rise in atmospheric carbon dioxide concentrations since the industrial revolution and the anticipated adverse consequences on the global climate system, have triggered a strong scientific interest in the global cycles of carbon, water and energy. Several European and international projects are currently trying to quantify the fluxes of carbon dioxide, water vapour, energy and other green house gases to/from terrestrial ecosystems using the eddy covariance method and to understand how these are affected by biotic, abiotic and anthropogenic controls. The ultimate goal of all these efforts is a realistic assessment of the role terrestrial ecosystems will play in the global carbon, hydrological and biogeochemical cycles under likely future climate and land-use scenarios and to infer appropriate abatement strategies. However, all these efforts are strongly biased towards forest ecosystems, with a consequent shortage of flux data for grassland ecosystems. Globally, grasslands cover approximately 40 % of the ice-free terrestrial surface area, but less than 10 % of the present study sites are grassland ecosystems. Semi-natural grasslands in the Alps, i.e. pastures and meadows, form the economic basis for local dairy farming and have become characteristic elements of the Alpine landscape. Long-term measurements at a meadow in the vicinity of the village Neustift (Stubai Valley/Austria) since 2001 have revealed that the investigated meadow acts as a net source of the greenhouse gas carbon dioxide. The reasons for this are currently unclear, also because no results from comparable sites are available. Aim of the proposed project is thus to improve the existing knowledge on the carbon dioxide, water vapour and energy exchange of mountain grassland ecosystems in the Greater Tyrol in order to put the results from the study site Neustift into perspective and to draw scientifically sound conclusions about the gas exchange of mountain grasslands. To this end it is planed to employ a combined experimental and modelling approach: The carbon dioxide, water vapour and energy exchange will be measured by means of the eddy covariance method in a continuous fashion at the study site Neustift and episodically by means of a mobile eddy covariance station at several meadows within the Greater Tyrol. A causal analysis of these data will be accomplished by means of an extant soil-vegetation atmosphere-transfer (SVAT) model. The necessary input data will be derived from soil/plant physiological/ecological field experiments and by means of remote sensing, i.e. the interpretation of satellite images.