Camila Tejo (blue jacket) with researchers from Orgon State University

Researchers from Chile and the United States are cooperating on a multi-year study of two iconic and similar species of old-growth tree giants from the coastal temperate rainforests of both countries to provide new data on the ecological processes of canopies and their connections to overall forest ecology.

The study –the first of its kind at this scale—is focusing on the tree-tops of ancient alerce (Fitzroya cupressoides) trees in Chile’s Valdivian Coastal Reserve and old-growth western redcedar (Thuja plicata) trees in Olympic Experimental State Forest in Washington and Oregon.

Titled “Ecosystems in the Sky: Dynamic Processes of Old-¬growth Tree Canopies in Chile and the Pacific Northwest”, the project is the result of collaboration between Universidad Austral in Chile (UACh) and Oregon State University (OSU).

“Our objective is to compare the canopies of the tree tops of the alerce and redcedar... We will analyze the climate in the canopies and how the canopy influences the capture and retention of water that reaches the forest, among other aspects”, explains Camila Tejo, research associate for the project who received her PhD working in old-¬growth canopies in Washington and is studying canopy ecology in Chile for her postdoctoral research.
Comparing the Hidden Worlds of Canopies

One of the main reasons for studying these old-growth species is that they accumulate epiphytes –material such as vines, lianas and moss—that create layers of matter different to that located in the forest floor. The study will try to determine how this material influences the functioning of the tree and other organisms and of the forest in general.

The upper canopies of these forests, both in Chile and the US, contain a world of their own, and a wealth of hidden information that will contribute to our understanding of old¬-growth forest function and its response to climate change in both countries. When not immersed in fog, the canopies experience a very different microclimate than the rest of the forest: it is often simultaneously brighter, hotter, windier, and drier. The upper canopy also contains most of the leaf area and, because it absorbs most of the solar radiation, it accounts for the great majority of carbon and water exchanges. This is also the zone where most climate variations and stress will show up.

Measuring and Monitoring, Branch by Branch

The trees selected for the project will be under study for two and a half years and the researchers will focus on selected branches of these trees, collecting information about branch height, aspect, tree diameter, depth and density of canopy soil. They will also install moisture and temperature sensors in some of the branches, connected with a data logger attached to the main trunk. The information collected by the data loggers will be retrieved periodically. Patterns of water retention and temperature will provide information about what is happening within the treetops and how this affects forest productivity.

As part of the project, a group of researchers from Oregon State University visited southern Chile in August 2016 to experience the Valdivian Coastal Reserve first-hand. “It is important to find ways to compare these forests, since we don't live in isolation in the world and it is highly relevant when we think of forest conservation. At the same time, it is also exciting”, said Oregon State University professor Dave Shaw.