The top layer of soil is often wet to some extent, but is not totally saturated. In many places, plant roots are found in the top layer of soil, above the water table. How does transpiration affect groundwater? Wind will move the air around, with the result that the more saturated air close to the leaf is replaced by drier air. Wind & air movement: Increased movement of the air around a plant will result in a higher transpiration rate. Higher temperatures cause the plant cells which control the openings (stoma) where water is released to the atmosphere to open, whereas colder temperatures cause the openings to close. Temperature: Transpiration rates go up as the temperature goes up, especially during the growing season, when the air is warmer due to stronger sunlight and warmer air masses.

It is easier for water to evaporate into dryer air than into more saturated air. Humidity: As the relative humidity of the air surrounding the plant rises the transpiration rate falls. Precipitation: During dry periods, transpiration can contribute to the loss of moisture in the upper soil zone, which can have an effect on vegetation and food-crop fields. When moisture is lacking, plants can begin to senesce (premature aging, which can result in leaf loss) and transpire less water. Soil type and saturation: Clay particles are small (smaller than 0.002 mm), holding onto water whereas sand particles which are large (0.05-2 mm) release water readily (think of how water disappears into the sand quickly at the beach).

Some plants which grow in arid regions, such as cacti and succulents, conserve precious water by transpiring less water than other plants. Type of plant: Plants transpire water at different rates. Transpiration rates vary widely depending on weather and other conditions, such as Some of this water is returned to the air by transpiration. Plants put down roots into the soil to draw up water and nutrients into its stems and leaves. Since water vapor also evaporates from the soil, we would have seen even more water vapor captured if we had wrapped the plastic bag around the soil as well. An acre of corn gives off about 3,000-4,000 gallons (11,400-15,100 liters) of water each day, and a large oak tree can transpire 40,000 gallons (151,000 liters) per year. During a growing season, a leaf will transpire many times more water than its own weight. As this picture shows, transpired water will condense on the inside of the bag (this photo shows transpiration after 1 hour). One way to visualize transpiration is to put a plastic bag around some plant leaves. Just because you can't see the water doesn't mean it is not being put into the air, though. Since the water is evaporating from the leaf surfaces, you don't just go out and see the leaves 'breathing'. Plant transpiration is pretty much an invisible process. Visit Media to see details.Īfter a plastic bag is wrapped around part of a plant, the inside of the bag becomes misty with transpired water vapor.Ĭredit: Ming Kei College How much water do plants transpire? In order to understand evapotranspiration, let’s explore what transpiration is in more detail. Transpiration occurs when plants take up liquid water from the soil and release water vapor into the air from their leaves. Evapotranspiration also includes transpiration, which is the water movement from the soil to the atmosphere via plants. Evapotranspiration includes water evaporation into the atmosphere from the soil surface, evaporation from the capillary fringe of the groundwater table, and evaporation from water bodies on land. Surface runoff What is evapotranspiration?Įvapotranspiration is the sum of all processes by which water moves from the land surface to the atmosphere via evaporation and transpiration.

Absorb water