Math Biology Seminar: Isabell Graf

   
Each spring the pressure in maple tree stems is so high that, for several days, maple sap can be harvested by making simple holes in the stem. The mechanisms behind this high pressure are not entirely understood. In collaboration with John Stockie and Maurizio Ceseri we developed a mathematical model which might describe the processes inside the maple tree. The model is based on the ideas of Milburn and O'Malley, where during cold nights the sap is pulled out of the vessel into the usually gas-filled fibers for freezing, and during warm days the ice melts and moves back into the vessel by osmosis and gas pressure. Thereby the water pressure in the vessel increases. The model is divided into the freezing and the thawing process, in this talk we will only consider the thawing process. First we consider the interaction of one vessel and one fiber in the fine view, later we upscale this process to the whole tree stem and describe the events for many vessels and fibers in the coarse view.