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The biotic pump theory may be able to help us better understand the role forests have on the water cycle. The biotic pump is a theoretical concept that shows how forests create and control winds coming up from the ocean and in doing so bring water to the forests further inland.
Transpiration is the movement of water through a plant and out of its leaves and other aerial parts into the atmosphere. This movement is driven by solar energy. [4] In the tallest trees, such as Sequoia sempervirens, the water rises well over 100 metres from root-tip to canopy leaves. Such trees also exploit evaporation to keep the surface cool.
Trees can explode when struck by lightning. [3] [15] [16] [17] The strong electric current is carried mostly by the water-conducting sapwood below the bark, heating it up and boiling the water. The pressure of the steam can make the trunk burst. [3] [17] This happens especially with trees whose trunks are already dying or rotting.
Drier surroundings give a steeper water potential gradient, and so increase the rate of transpiration. Wind: In still air, water lost due to transpiration can accumulate in the form of vapor close to the leaf surface. This will reduce the rate of water loss, as the water potential gradient from inside to outside of the leaf is then slightly less.
Pressure flow hypothesis: Sugars produced in the leaves and other green tissues are kept in the phloem system, creating a solute pressure differential versus the xylem system carrying a far lower load of solutes—water and minerals. The phloem pressure can rise to several MPa, [12] far higher than atmospheric pressure. Selective inter ...
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The force pushing the water towards the low pressure region is called the pressure gradient force. In a geostrophic flow, instead of water moving from a region of high pressure (or high sea level) to a region of low pressure (or low sea level), it moves along the lines of equal pressure . This occurs because the Earth is rotating.
The continuity of the water column remains intact due to the cohesion between the molecules and it acts as a rope. Roots simply act as a passive organ of absorption. As transpiration proceeds, water absorption occurs simultaneously to compensate the water loss from the leaf end. Most volume of water entering plants is by means of passive ...