A recent study published in the latest issue of Nature established that future climate change and fresh water availability predictions will be strongly impacted by the large amounts of water taken up by plants.
The research was conducted by Scott Jasechko, an University of New Mexico doctoral student, and funded by UNM Caswell Silver Foundation graduate fellowship program. The findings show that movement of fresh water from soil through plant stems accounts for almost twice the amount of water moved as part of all river systems on the planet.
According to Jasechko, future climate change and water availability predictions should emphasize on the transport of water in plants.
The study separates the two aspect of evapo-transpiration, and looks into the behavior of oxygen and hydrogen isotopes during of the individual processes of evaporation, or movement of water from the surface to the atmosphere, and transpiration, or plant “breathing.”
As part of the research, Jasechko and his supervisory team, consisting of Professor Zach Sharp and Associate Professor Peter Fawcett, both from the Department of Earth and Planetary Sciences, analysed water samples from rivers and lakes and estimated the amount of evaporated and transpired isotopes. They then calculated the evaporation in transpiration of water used by plants.
The results show striking numbers. The amount of water transpired by plants per year is 60,000 km3, which equals the flows of ten rivers of the size of the Amazon.
Jesechko explains that since the process of transpiration is directly linked to the amount of carbon dioxide, it was possible to establish a direct relationship between water transpiration and carbon assimilation.
The study pays key attention to the importance of plants in the global water cycle. Most studies in the field emphasize on changes in precipitation rates caused by increase in temperatures, but the study suggests that changes in land use, deforestation and other factors disturbing the global flora, should be considered when future predictions of fresh water availability are made.