The system of the tree-atmosphere continuum is spatially large, which sets challenges for trees to be capable to transport various chemical compounds within them and to exchange compounds with the atmosphere. Transport phenomena and resulting mass flows are governed only by few fundamental physical laws giving rise to different transport mechanisms. The mutual effectiveness of different transport modes depends on the spatial scale. In a way, trees utilize effectively this frame of physical laws in their functioning and interactions with environment.
By transport we especially mean the movement a certain quantity of mass or energy between the storage locations of the quantity. Storages may be apparent as sources and sinks of the quantity and unequal amounts of any entity in the storage locations lead to the concept of a non-zero gradient of the quantity. In practical terms, ecosystems store materials as mass (such as carbon, nutrients, water) and heat, and any differences in the amounts of mass and heat tend to disappear by physical mechanisms called transport phenomena. The third fundamental quantity besides mass and heat is momentum which is defined as the product of the mass and velocity of a homogenous fluid (fluid means either gas or liquid) parcel. All of these can be transported by two physically different mechanisms, which are molecular transport and bulk transport, called also convection. Transport of heat may happen also by means of a third heat transport mechanism which is electromagnetic radiation. Next we consider three transport mechanisms starting with the molecular one.
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© 2008 Springer Science + Business Media B.V
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Vesala, T., Rannik, Ü., Hari, P. (2008). Transport. In: Hari, P., Kulmala, L. (eds) Boreal Forest and Climate Change. Advances in Global Change Research, vol 34. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-8718-9_4
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DOI: https://doi.org/10.1007/978-1-4020-8718-9_4
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