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Killing trees in name of climate research

Staci Matlock/The (Santa Fe) New Mexican Los Alamos National Labs plant physiologist Nate McDowell and his team hope to devise a system to predict tree die-off around the world and the potential climate impacts as the forests die.

By Staci Matlock
The (Santa Fe) New Mexican

SANTA FE (AP) – For a plant physiologist whose research points to a looming disaster in the world as we know it, Nate G. McDowell is a surprisingly upbeat guy.

”I’m excited. This is such an awesome project,” said McDowell, a Los Alamos National laboratory staff scientist, as he gave a tour of his latest research site near Bandelier National Monument.

In a way, McDowell’s getting to do what he loved as a boy growing up in Washington state’s Olympic rainforest – run around in the woods. Only now, his play has evolved into critical research modeling the death of New Mexico pińons and junipers as temperatures climb and drought deepens.

McDowell steps inside one of the cylindrical plexiglass and steel chambers near two of the trees he’s likely to kill in his research. It is blisteringly hot inside already at 9:30 a.m. He confesses to loving trees, “dead or alive.”

“I do think about that (killing trees),” McDowell said, acknowledging a twinge of guilt now and then. “But we have to kill the trees to understand how they die. Not a lot of them, just a few.”

Trees in forests all over the world, from the Arctic to semi-arid New Mexico, are dying at an alarming rate. Combine drought with warmer temperatures, and it’s no surprise trees are croaking. But how fast do they die? Does it depend on the species? Will some species survive no matter what? What will be the impact of massive tree die-offs on the climate, agriculture, watersheds and people?

McDowell’s team is working on answers to some of those questions. It hopes to devise a system that will help predict tree die-off around the world and the potential climate impacts as the forests die. McDowell was among five Los Alamos National Laboratory scientists to receive federal ARRA funding for their individual projects along with Andrew Gaunt, Christopher Mauger, Evgenya Smirnova and Tsuyoshi Tajima.

McDowell received $2.5 million to cover the first five years of the project, most of which went to designing and building the test site.

“I have $100,000 left,” McDowell said.

McDowell’s work at the Los Alamos plot will build on a similar project he’s had down at the Sevilleta National Wildlife Refuge for the last half-dozen years.

His projects document exactly how juniper and pińon die, and how long it takes, if temperatures and precipitation follow what climate scientists predict for the area in 50 to 80 years.

Climate scientists believe ambient temperatures will be 5 degrees Celsius hotter than the average now. McDowell based precipitation on 2002 records for Los Alamos when the region received half its 30-year average moisture. The Los Alamos research plot contains 18 chambers.

Researchers control the precipitation that falls in some, the temperature in others and both in some. Some chambers, the controls, have no conditions changed other than those caused by the structures themselves. Precipitation around some of the chambers is controlled by a series of plexiglass troughs that direct rainwater and snow away from the sites.

The temperature is controlled by a sophisticated heating and air conditioning system designed by Santa Fe technician Heath Powers.

“When the temperature is more than a few degrees off target, the HVAC kicks on and heats or cools the chamber to the desired level,” he said.

Instruments inside and outside the chambers measure temperature, tree moisture and transpiration, soil moisture and respiration, and more.

Traps collect insects. One of McDowell’s postdocs found four pinon bark beetles inside one trap for the first time last week. A thermal camera measures heat coming off surfaces around the research plot trees, ground, people.

Most of the measurements are taken automatically by the machines, 24 hours a day, and the information is sent to the research team’s computers. Once a month, the researchers go out at 4 a.m. to take readings manually.

If the heat- and drought-stressed trees at Los Alamos react similar to the ones at McDowell’s Sevilleta plots, the pińon will die in about 11 months. The junipers will hold on longer, up to three years. The shrubby oak are likely to live the longest or not die at all.

The team is mapping out the exact process by which a tree dies when stressed by lack of water and prolonged heat. One hypothesis they’re testing is that a long, hot drought damages a tree’s foliage and the photosynthetic mechanism that maintains the tree’s metabolism.

“If a plant is starving for carbon, it can’t repair that damaged tissue,” McDowell said. “It’s a hypothesis that makes sense but has never been tested. It could be the final straw that breaks the camel’s back. If the leaves get cooked and the plant can’t rebuild them because it has no carbohydrates to use as energy sources to rebuild them, that could be the end of it.”

McDowell said it is important to find out not just how the trees die, but what happens to the climate when they do. He has no doubt about what is happening to Earth’s climate right now.

“Carbon dioxide is rising and that’s a fact. Temperatures are rising and that’s a fact. Third, the rising greenhouse gas levels do drive a large, large part of the temperature rise. The only people who debate these things are contrarians or people who have an ulterior motive.

“Now, are trees dying because of (rising carbon dioxide and temperature levels)? That’s what we can’t say for sure,” McDowell said. “But, there’s a bunch of lines of evidence suggesting that they are.

“I can’t say this with absolute certainty, but I don’t expect there to be conifers in Los Alamos or Santa Fe County in 50 years,” McDowell said.

McDowell’s work is among many projects at LANL that aren’t related to nuclear research. The lab’s overseer at the Department of Energy, especially within the Division of Climate and Environmental Science, wants to know what kind of impact America’s energy choices will have on water availability, trees and agriculture. The United States largely relies on coal-fired power plants, oil and natural gas for electricity and transportation. The three are considered the largest contributors of greenhouse gas emissions linked to climate change.

Scientists believe climate change is the likely reason temperatures will keep rising, droughts will last longer and a lot more trees are bound to die.

Plus, said McDowell, “it’s going to make skiing really rough.”

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