In other words, the plant will conduct water from the soil to the atmosphere only if the atmosphere has a lower water potential than the soil. Furthermore, transpiration cools leaf surfaces because it absorbs heat energy. While transpiration is a key physiological process in plants, it is also a fundamental process characterizing terrestrial ecosystems through its contribution to evapotranspiration. In temperate deciduous forests, such as those of the northeast, transpiration is the major contributor to evapotranspiration during the growing season. Increased streamflow during autumn months is correlated with the slowing or stopping of transpiration at the end of the growing season.
Transpiration can also indirectly reduce soil erosion by reducing streamflow during storms.
While streamflow increases the export of nutrients out of the forest, transpiration can transport some nutrients to leaf surfaces, which then fall to the ground where the nutrients can then be recycled. Furthermore, transpiration serves as a soil-aerating process, which is important to aerobic soil organisms contributing to decomposition. In today's laboratory, we will investigate the role of the abiotic environment in affecting transpiration rates of plants. Before starting the lab, make some predictions about how you think each of the treatments will affect transpiration relative to the control. Place a 0.1 ml pipette tip down into a piece of tygon tubing.