Staying on Top of Climate Impact on Forests

Forests cover almost one-third of the earth and are the respiratory system for our planet.

Trees absorb carbon dioxide and emit oxygen, making them vital for all life on the planet.

But until now researchers have only been able to study trees from the ground, getting only half the picture.

Enter the mechanical crane.

University of Washington researcher Matt Schrader says tree tops have been the hardest for scientists to access, yet are considered the most important to examine the health of trees.

[Matt Schrader, Arbornaut, University of Washington]:
"That's where the tree is actively responding to the  environment, that's where the tree interacts with other plants and animals and so accessing the crown safely and being able to do it often is important."

Tree deaths have reportedly been increasing by one to two percent per year.

This increase in mortality will have profound effects on the size of trees and the density of the forest.

The forest that Schrader is studying is in the perfect location to measure the effects of global warming on trees.

It contains hundreds of years of data.

[Matt Schrader, Arbornaut, University of Washington]:
"So being up here at the branch level in the canopy we're able to see these subtle changes that occur from year to year and you just wouldn't be able to do that from the ground looking up with binoculars."

The Wind River crane is 285 feet tall with a jib arm that reaches out almost that far over the top canopy layer of the forest.

The jib is outfitted with an ultrasonic anemometer, which measures wind speed and direction in three dimensions.

An ultra-sensitive intake tube draws in air samples, measuring how much carbon dioxide is present in samples of air.

Other sensors monitor temperature and relative humidity to help researchers determine whether or not CO2 is being drawn into the forest, or being released into the atmosphere.

Dr. Ken Bible, the site director at the Wind River Canopy Crane research facility, says that the crane and sensors amount to having a "controlled experiment on planet earth."

[Dr. Ken Bible, Site Director, Wind River Canopy Crane Facility]:
"If it's continuous and automated no matter what pattern is going on naturally in the forest you're going to capture it.  It's not going to be dependent on when you can go out into the forest and get that sample, that sample is being taken.  Respiration is going down or respiration is coming up, or whatever variable you're looking for, it's taken care of for you and taken care of so quickly you're pretty much guaranteed you're going to capture it."

In the past tree growth and yield were assessed on a five-year basis.

But now Bible and his team of arbornauts are able to make observations about the flow of carbon dioxide at a 30-minute time interval, by monitoring the sensor data and the needles at the tops of trees.

[Matt Schrader, Arbornaut, University of Washington]:
"Only by continuously monitoring a forest in such a way can you find these seasonal changes. To contrast that against a yearly visit or coming to the forest every 5 years for a measurement we've been able to tell a better story and understand the seasonal dynamics of this old growth forests."

With the ability to conduct long-term studies in forests like this one, scientists hope to gain a more complete story about the mortality rate of trees.

This will leave researchers better equipped to manage the effects of global warming.