The sheer size of the giant sequoia trees in California has always begged to question, how do these trees provide sufficient resources for the upper branches? Sid Perkins, a freelancer science writer, decided to investigate this phenomenon. He wondered how these tall trees can consume thousands of liters and distribute them to every inch of the plant. Not only does the tree need to counteract the force of gravity but also overcome the resistance of the tissues.
Climatologist Gregory Quetin explains this mechanism plants use as an “evaporation of water from foliage” as the primary conductor for pulling sap upwards. He found that on average for all the world’s plants, .03 watts per square meter are used for sap pumping power which could double in areas like “rainforests.” To put that into context this is around “90% of the amount of hydroelectric energy produced in 2019”
In the larger picture, plants are heavily reliant on this evaporation method as a means of pumping liquid up. If they didn’t, they’d have to “expend 14% of the energy they generated via photosynthesis.” This obviously differs from each species and its climate as illustrated by Quetin who notes that more power is utilized in hotter regions. Regardless the power to pull sap or liquid up a tree like a sequoia seems impossible looking from the outside. These plants aren’t just powerlifters on the inside but also flex a range of ways to reduce global warming’s effects. Nikk Ogasa, MD for geology, elaborates on the roles of these trees as not just “carbon sponges,” but more. In an extensive research study, Ogasa concluded that scientists “should refrain from focusing on carbon emissions” as their role is much bigger than that.
In the scope of Biology, we learned as a class a technique called adhesion which is a cool property in plants that allows water to stick to tissue. Furthermore, we learned how essential water is to facilitating photosynthesis as it is a key component in the light-dependent reactions to create NADPH and ATP. This ATP and NADPH is then used in the Calvin Cycle to create glucose molecules. So if these trees need to grow even in the upper parts they need these resources key to photosynthesis provided by this pumping technique in these trees. There are two components that make the vascular system of the sequoia trees so powerful. The xylem transports water through cohesion, water molecules creating hydrogen bonds with each other, and adhesion, the property that allows the water to stick on the wall. Phloem transports the sugars made from photosynthesis up the tree to provide nutrients all across the organism.
Nikk Ogasa couldn’t have emphasized the point better. When we think of global warming we jump straight to carbon emissions and try to reduce them, but we tend to overlook how these large areas of forest are essential in maintaining soil health, promoting biodiversity, and cleaning the air. Trees are truly deeply rooted in our society and environment.