Deep in the densely forested mountains and hills of the Southwestern region of the United States, researchers this year have been climbing tall trees in the name of science.
The team from the University of Arizona’s Laboratory of Tree-Ring Research, in addition to help from others, has undertaken a major project in an attempt to gain significant knowledge in the field of dendrochronology, or tree-ring dating.
The goal of the project is to observe the steps of how the cells within a tree grow firsthand as it happens, to see how their environment affects them. By collecting this information through a multitude of field samples taken over a period of time, the team is attempting to observe the certain weather and climate on a certain day or time period, and then directly observe what changes were made on a cellular level through observations in the lab after the samples are collected.
In the years since astronomer and scientist A.E. Douglass established the lab in 1937, it has gone from a series of rooms underneath the football stadium, to the newly completed Bryant Bannister Tree-Ring Building, which was finished in April of 2013 at a cost of $12 million after a year and a half under construction.
“This is something that we have been wanting to do for nearly a decade,” says Malcolm Hughes, the Regent’s Professor of Dendrochronology and one of the projects leaders.
Although there have been many advances made in tree-ring dating since the fields inception, when it comes to these four species that populate a large portion of both Arizona and the Southwestern United States, the majority of our knowledge is based off of inferences and models that have been made. As Hughes explains, the best way to observe cellular change is to collect samples making up as wide a time period as possible, and to bring them into a lab and meticulously observe the changes.
“At this point the findings are optimistic because we’ve got a couple of hints in the few samples we’ve worked through,” says Hughes, “They make us think we’ll be able to capture the timing of the growth stages pretty accurately, which is going to help us set some bounds on what changing climate might do to forest growth in this region.”
This particular project, which is funded by the National Science Foundation, is set to last for three years. 2014 marked the first year where the team went into the field to find and set up sites at the four species: Douglas-fir, ponderosa pine, limber pine, and Engelmann spruce. The next two years will be focused on both collecting and then analyzing the data.
“Some of the adjustments we’ve had to make range from the very simple up to larger changes outside our control,” explains Hughes, “One of the small initial issues came in collecting samples of the Douglas-fir. Since the tree has a pretty thick bark, we had to adjust how we inserted it (device used to extract sample) into the tree to avoid affecting the tree more than we needed to.
Among the larger issues outside of their control is a lack of available limber pine in the front range of Rockies in Colorado and Wyoming where they had previously been expected. The species there had suffered a lot of mortality, making it more difficult to find appropriate samples.
Despite some difficulties, Hughes says that the initial findings that have been brought back to the lab from the field reassure the team that they are on the right track, as well as suggesting more developments to come as more time allows for sample collecting and viewing in the lab.
While some tree species in alpine and subarctic climates have been examined, the techniques had not yet been tested on trees located in more moderated climates like the U.S. southwest.
The growth of trees radially occurs through a process where cambial cells divide and enlarge before becoming wood cells. The time and speed of those steps depend on both the environment in addition to how far from the inner layer the growth is occurring.
The funding that the team has received for the project helps not only in the costs of the process of surveying and setting up sites to collect organisms and the transporting to the lab, but also in the time it allows for the members to dedicate to the project.
Although the period for this specific project is only three years, the information and research observed and learned through this project will extend far beyond the three years designated for this project, according to Hughes.
“We’re developing a capacity here that not only with equipment, but skills in the laboratory that we will develop towards the possibility for many more projects enhanced in the future,” says Hughes.
Harrison Leff is a reporter for the Arizona Sonora News, a service offered by the school of journalism at the University of Arizona. Reach him at: hbleff@email.arizona.edu