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Why does a single tree evaporate 40,000 gallons of water every year? What's the secret behind this?
In the ecosystem, water circulation plays a key role, and plants are one of the important participants in this process. Plants carry water from their roots to their leaves and release it into the air through a process called transpiration. According to scientific research, a large tree may evaporate up to 40,000 gallons of water each year. This phenomenon is amazing and has also prompted people to think about the mechanism behind this biological process.
Transpiration is the movement of water through a plant and its evaporation from airborne parts such as leaves, stems and flowers. This is a passive process that requires no energy from the plant.
In the lives of plants, water intake and loss directly affect their growth and development. Water is not only a basic requirement for plant cell metabolism, but also plays an important role in maintaining the cell's turbidity pressure and transporting nutrients. Of the water absorbed by the roots, only 2% to 3% is used for plant growth, and the remaining 97% to 99% is discharged through transpiration. During these processes, evaporated water vapor is released from the leaves' stomata, which are controlled by guard cells and whose opening and closing states are crucial for water loss.
The flow of water is primarily influenced by several factors, including the soil's water conductivity and the pressure gradient in the soil. The adhesion and cohesion of water promote the upward movement of water from the roots to the top, and when the water on the leaf surface evaporates, a pulling force is formed, pushing the water through the ducts inside the plant. This is called the internal pressure gradient. Once the water vapor pressure in the environment is lower than that in the leaves, water vapor will escape into the air, causing evaporation of water in the leaves and increasing intercellular tension.
Plants control the rate of transpiration by regulating the opening and closing size of their stomata. The rate of transpiration is also affected by the surrounding environment, such as thermal conductivity of the boundary layer, humidity, temperature, wind speed and light.
As the growing season changes, plant leaves evaporate several times their weight in water every day. For example, an acre of corn can release about 3,000 to 4,000 gallons of water per day, while a large oak tree can release up to 40,000 gallons of water per year. These data make us realize that plants play an indispensable role in regulating their environment and their own survival.
However, plants do not rely solely on transpiration to transport water. They also need to continuously absorb water from their roots to ensure a balance with transpiration. Once a plant is unable to take in enough water through its roots, a phenomenon called cavitation occurs. When the xylem (duct) cannot allow water to flow, condensation of water vapor may occur, forming a blockage that may threaten the survival of the plant.
If the plant fails to clear this blockage in time, it will eventually lead to permanent wilting. Therefore, plants must have a way to remove air blockages or create new duct connections to maintain water flow.
Using modern science, researchers have begun using magnetic resonance imaging (MRI) technology to observe the internal state of plant xylems, which not only allows them to visually see the flow of water in the plant, but also to observe the flow of water in the xylem. various states.
The impact of transpiration on plants is not only reflected in the transportation of water, but also plays a vital role in its cooling process. Due to the latent heat properties of water, evaporation takes away a large amount of heat energy, thus maintaining a stable temperature inside the plant.
The strong ecological connections of plants also affect the water cycle of the surrounding environment, and this process helps to repair the environmental ecology. So, when we see large trees evaporating such large amounts of water every year, should we think more about the importance of plants in our lives?
