My general interest is predicting what vegetation at the global land surface does, given some information about climate and other controlling factors.
Currently, I am trying to find out which factors determine the global distribution of vegetation on the ground (e.g. mosses). This may be important, for instance, at high latitudes, where vegetation at the ground acts as an insulating layer for the frozen soil below (permafrost). If the soil warms up due to a reduction in vegetation, considerable amounts of CO2 may be released which would further enhance global warming.
As a tool to make these predictions I use numerical models which represent the complex processes and interactions associated with global vegetation in a simplified way.
In my PhD thesis, I developed a model which predicts the global productivity of lichens and mosses as a function of climate. The motivation for this model was to estimate the contribution of these organisms to the global carbon cycle. The model is similar to other global dynamic vegetation models, but it explicitly simulates characteristic properties of lichens and mosses, such as poikilohydry. Moreover, it takes into account the great functional variation of these organisms at the global scale. This is achieved by generating many different physiological strategies in the model instead of using one globally uniform parameterisation. Trade-offs within the biochemical machinery as well as climate constrain the possible physiological strategies. These constraints act as a filter to reduce the uncertainty of the model estimates.
As an application of this model, I quantified further influences of lichens and bryophytes on global biogeochemical cycles. Based on their carbon uptake, I estimated global nitrogen and phosphorus requirements of lichens and mosses and their potential for weathering of surface rocks. This work showed that lichens and mosses have the potential for significant impacts on global cycles of nitrogen, phosphorus and weathering.
Another part of my work is the modelling of soil hydrological processes. Using a global land surface model I tested if soil water flows can be predicted by the Principle of Maximum Entropy Production (MEP).
Since 2014: Max-Planck-Institute for Biogeochemistry (Department Biogeochemical Integration) - Postdoc
2009 - 2013: Max-Planck-Institute for Biogeochemistry (Biospheric Theory and Modelling Group) - Ph.D.
Thesis: Process-based modeling of lichens and bryophytes and their role in global biogeochemical cycles
2004 - 2009 : Universitaet Potsdam - Geoecology (Diplom)
Thesis: Entropy Budget of the Soil Hydrological Cycle
Porada P, Weber B, Elbert W, Pöschl U, Kleidon A, (2014) Estimating Impacts of Lichens and Bryophytes on Global Biogeochemical Cycles of Nitrogen and Phosphorus and on Chemical Weathering, Global Biogeochemical Cycles, in Press
Kleidon A, Renner M, Porada P, (2014) Estimates of the climatological land surface energy and water balance derived from maximum convective power Hydrol. Earth Syst. Sci. Discuss., 11, 265-306
Buendia C, Arens S, Hickler T, Higgins S, Porada P, Kleidon A, (2013) On the potential vegetation feedbacks that enhance phosphorus availability - insights from a process-based model linking geological and ecological time scales Biogeosciences Discuss., 10, 19347-19407
Porada P, Weber B, Elbert W, Pöschl U, Kleidon A, (2013) Estimating global carbon uptake by lichens and bryophytes with a process-based model, Biogeosciences, 10, 6989-7033
Porada P, Kleidon A, Schymanski S J, (2011) Entropy production of soil hydrological processes and its maximisation, Earth Syst. Dynam., 2, 179-190, doi:10.5194/esd-2-179-2011