To understand the stories of our witness trees we have to ask the right questions.

Every summer our researchers observe critical functions in our trees which will tell us about their health, and ability to capture particulate matter pollution. This involves assessing parameters directly from field observations, and later in the lab using collected leaf samples. For questions that may arise in the future, every year we make voucher leaf specimens and archive them in Trinity College herbarium, as a snapshot in time for future researchers.

Beyond that, we want our science to be open, and we strive to make our processes and raw data available for everyone to read. You can find more information at the following links:

Stomatal Conductance

Stomatal conductance (gs) is the measure of the rate of exchange of water and CO2 between the plant and the atmosphere. As this process is central for the plant to stay alive, it can be used as an indicator for their general health. Different plants have naturally low or high values, depending on the strategies they have developed to thrive in the environment in which they have evolved.

However, stomatal conductance is also a dynamic process, responding  when environmental conditions, such as temperature or the concentration of CO2 in the atmosphere, change. Observing/monitoring  how stomatal conductance in our trees changes every year will give us vital information to answer important questions: how are they responding as their environment changes? Are they thriving or are they struggling to adapt? And, as a consequence, what will this mean for the forest landscape of the future?

Particulate Matter

Particular matter (PM) refers to  any particles that can be found suspended in the air, from dust and pollution to pollen. Depending on the size of the particle, it is categorised in ‘inhalable particles’ (PM10), and fine inhalable particles (PM2.5), with each having a different impact on human health when inhaled. But while in the air, particulates can be intercepted by trees: they stick to the leaves or bark, effectively being subtracted from the air until the first rain will wash them away in the ground. Figuring out which trees act better as a ‘filter’ over the years will be important for the future of our cities.