Heat Exchange in a Conifer Canopy

Abstract

Forests cover a large part of the globe, and are responsible for a large amount of evaporation and the fixation of carbon. To be able to better understand this atmospheric exchange of forests, and how the forests will behave under future climate change, both accurate measurements as well as models are required. However, due to their height and heterogeneity they are difficult to model and measure. Standard theories do not apply well to forests, and as such more effort is required to understand the exchange between the forests and the atmosphere. However, precise measurements are made difficult due to a number of issues. The most prominent are the non-closure of the energy balance, and so-called ‘decoupling’ of the canopy. Non-closure of the energy balance is where all the measured inflows and outflows of energy do not add up to the measured change in energy storage in the forest system. The size and heterogeneity of forests makes this difficult to assess. Second is ‘decoupling’, where the vertical mixing of air within the canopy is hampered, and measurements performed above the canopy are not representative of what happens in the entire canopy down to the forest floor.