Respiration and carbon flow in trees and soils
I study how carbon flows through trees and soils. I am particularly interested in linking processes to gas exchange measurements, especially in respiration. Gases provide us a “window” through which we can see the respiratory substrates, the active enzymes, and other reactive processes. For example, in my PhD, I developed the measurement of CO2/O2 fluxes ratio. By theory, this ratio shows which substrate fuels respiration. In practice, I found that in tree stems and soils, the ratio is often below substrate values. In the tree stems the low ratios can be explained by non-respiratory processes that consume CO2 like dark CO2 re-fixation, while in soils oxidative breakdown of macromolecules that consume O2 can explain the observations. Currently, I am exploring the use of this ratio in separating respiration of roots and mineral soil.
Another area I research is how aboveground tissues and fine roots use storage compounds. Fine roots consume a large portion of forests carbon budget. But because they are hidden belowground, we know surprisingly little about their carbon cycles. Here, I use radiocarbon measurements of different carbon pools to understand turnover rates and storage compounds use. The research is taking place in the Alpine tree line and in temperate forest.