WEST LAFAYETTE, Ind. - Elaine Jacobs of Purdue University has received a three-year, $911,000 grant from the US Department of Energy to study how tree roots help redistribute water in the soil. He studies how water flows from the soil through plants to the atmosphere and how increased drought affects this process.
"Plants can easily transport water from wet soil to dry areas through their roots. Using the roots as straw, they absorb water from wet areas and release it to dry areas. They usually do this in order to get water," he said. Associate Professor, Department of Forestry and Natural Resources.
This allows the wet soil to be close to where most of the nutrients are.
"When water is mixed with these nutrients, they become more accessible to plants, which allows them to grow better and photosynthesize, technically, despite drought or drought," Jacobs said.
Working with Jacob on this project were Zoe Cardon, Marine Biological Laboratory, Woods Hole, MA; Jeff Dukes, Carnegie Institution for Science, Stanford, CA; Lisa Welp, Earth, Atmospheric and Planetary Sciences, Purdue; Welin Fang, Pacific Northwest National Laboratory, Richland, Washington.
Fieldwork will be conducted in Martell Forest , 8 miles (13 km) west of Purdue University's West Lafayette campus. Jacob works on the Bell Supercomputer at Purdue and in the Power Supercomputer Department for large-scale simulations. This information helps inform computer simulations of the planets' Earth operations. The model includes elements from the atmosphere, oceans, sea ice, land, and subterranean ecosystems.
The modeling effort began in 2011. It follows a 2013 report from the US Department of Energy on the vulnerability of the US energy sector to climate change and extreme weather. The report also covers the effects of climate change on climate and energy systems and the types of energy used by countries.
Hydraulic plant models are too complex to fit into large terrestrial systems models such as DOE. Jacobs says today's bigger and faster computers can do it, but there's little data to prove the model actually works.
In the first year, the team defines a field project based on the model's requirements. In the second year, the team makes sure the simulations match what they see on the ground, then adjusts parameters as needed.
"We simulate drought and create environmental conditions and put plastic edging around the trees to reduce the water to some trees," said Teresa Hudson, a field research technician for Forestry and Natural Resources. "Then we look at how well the trees use hydraulic redistribution to compensate for the reduced rainfall."
Using sensors and radioactive isotopes, researchers track the flow of water from the ground to the roots and then to the tops of trees. The main goal of this project is to measure the amount of water that moves trees.
"There is evidence that trees and other plants do this, especially in climates with distinct wet and dry seasons — like the western United States," Jacobs said. "We've never seen much drought here before, but the climate is changing and repeating."
Jacob's team will evaluate which tree species can redistribute water, when and under what conditions. Does the tree have to reach a certain size or age? It may be due to root depth. Some types of trees have tap roots, while others have shallow tap roots.
The study tracks red oak, black walnut and sugar maple. All are common in this region and the eastern forest. The researchers chose the three species because they respond differently to drought.
When plants perform photosynthesis, they open the leaf pores called stomata to let carbon dioxide into the leaves. However, they lose water through respiration, Jacobs says. - During the dry season, when there is not enough water, some trees close their stomata or narrow their openings to reduce water loss. But because of this, the amount of carbon dioxide goes out into the tree through the leaves, and they don't grow.'
However, some trees store as much carbon as possible in order to grow. Despite the loss of water, photosynthesis continues as much as possible.
"The three types represent a spectrum of these strategies, and we think that the degree to which these species are able to redistribute groundwater is related to the strategies they use," he said.
Author: Steve Kubis
Source: Elin Jacobs, ekarlsson@purdue.edu
Media Contact : Maureen Manier, mmanier@purdue.edu
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Maureen Manier, Department Chair, mmanier@purdue.edu
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