BOZEMAN, Mont. — A study by Montana State University scientists created the first global estimates of water stored in plants and how long it takes water to flow through them.
The study was published on Jan. 9 in the journal Nature Water and was led by MSU Department of Land Resources and Sciences assistant professor Andrew Felton.
In the study Felton found vegetation on earth stores 786 cubic kilometers of water, enough water to fill Flathead Lake about 34 times.
The process for the water to return to the atmosphere ranges from five days in croplands to 18 days in evergreen forests.
He also found the global average for water to re-enter the atmosphere is 8.1 days, while water in lakes is expected to take 17 years.
By combining different metrics Felton is able calculate the time it takes for a drop of water to move through the entire cycle.
Montana State University sent out the following:
A new study led by a scientist in the Montana State University College of Agriculture provides the first comprehensive global estimates of water stored in plants and the time it takes for that water to flow through them. The research addresses a gap in understanding of the global water cycle and how it is being changed by land use and climate.
Andrew Felton, an assistant professor in MSU’s Department of Land Resources and Environmental Sciences, is lead author of the study, which was published Jan. 9 in the journal Nature Water. The publication culminates research Felton began during a postdoctoral fellowship at Chapman University in California.
Felton found that all of Earth’s vegetation stores about 786 cubic kilometers of water, roughly enough to fill Flathead Lake 34 times. The time it takes for water to flow through plants and return to the atmosphere — referred to as “transit” or “turnover” time — ranges from five days in croplands to 18 days in evergreen forests, the paper states.
Felton said those results underscore vegetation’s dynamic role in the water cycle. The average time it takes for water to travel through plants and back to the atmosphere is 8.1 days, globally. In comparison, the water in lakes is estimated to take 17 years and the water in glaciers is estimated to take 1,600 years.
“We have known for a long time that most of the water that returns from the ground to the atmosphere does so through plants, but until now, we did not really know how long it took,” said Felton. “Our results show that the transit of water through plants occurs on the order of days, rather than months, years or centuries.”
By combining estimates of the transit of water through plants with the transit of water through the atmosphere (about 8-10 days) and through soil (about 60-90 days), scientists can begin to estimate the total time it takes for a drop of water to move through the entire terrestrial water cycle. They found that the transit time of water through vegetation varied considerably across land cover types, climate and seasons. Transit time through croplands was consistently the fastest, with water transiting through plants in less than a day during the peak of the growing season.
“One important observation is that croplands around the world tend to have very similar and very fast transit times,” said Gregory Goldsmith, another of the paper’s authors and an associate professor of biological sciences at Chapman University. “This indicates that land use change may be homogenizing the global water cycle and contributing to its intensification by more rapidly recycling water back to the atmosphere, where it can turn into heavy rain events.”
To generate the estimates, the team first calculated the amount of water stored in plants using data from NASA’s Soil Moisture Active Passive satellite mission, which provided high-resolution estimates of the water in soils. The mission originally saw plants as interfering with soil moisture measurements and corrected for their presence, but Felton’s team found that those corrections contained valuable information about the amount of water stored in plants.
“Plants are the forgotten part of the global water cycle,” said Felton. “The results suggest that the transit time of water through plants is likely to be very sensitive to events such as deforestation, drought and wildfire.”
The study has implications more locally for Montana, he added.
“Much of Montana is comprised of ecosystems with rapid transit times, such as grasslands and croplands,” said Felton. “A better understanding of the transit times of water flowing through plants in these water-limited ecosystems has important applications for water resource management, including predicting drought vulnerability and managing irrigation.”
This post was originally published on here
