PhD student and forester Gregory (Greg) Harris enjoys addressing understudied ecological questions with real-world management implications. Under his advisor Associate Professor Marcella Windmuller- Campione and with funding from Forest Carbon Works, he’s researching snag dynamics. Harris took a moment to describe his research, the role it plays in forest carbon accounting, and how it blossomed his newfound interest in mycology.
What research question are you asking?
My core question is: What factors determine how long a snag (a standing dead tree) remains standing and how it decays? I’m particularly interested in whether the cause of death and the tree’s structural role at time of death predict these outcomes. I’m examining these dynamics in managed forest systems, in two cover types in Minnesota: red pine dominated mixed woods and oak savannas. We already know quite a bit about tree mortality patterns (the processes that create the snags) within these systems, but we know much less about their fate. For example, paper birches are fast-growing, short-lived, shade-intolerant trees that do not invest as much in structurally stable wood and decay resistant heartwood as do the slower growing trees that will later dominate the stand. When these birches start to be overtopped and die, this transitional mortality will likely create snags that decay, break apart, and fall relatively quickly.
Why is this important?
Snags are an important structural component of forests that support biodiversity and play a key role in the forest carbon budget. They provide critical structural habitat for wildlife, particularly cavity-nesting birds like woodpeckers. Snags are also the substrate and main energy source for an entire community of invertebrate and microbial species that develop within the decaying tree. Wood-decaying fungi are the main drivers of this system because they are essentially the only organisms that have evolved ways to break down and recycle the rich carbon source locked up in wood. Intensive forest management generally reduces both the quantity and quality of snags. Meanwhile, increases in the intensity and frequency of disturbances driven by climate change will likely cause unprecedented numbers of snags in some forests. It’s imperative to better understand snag dynamics so that we can find ways to mitigate losses and actively cultivate this resource in the face of different management and climate scenarios.
How are you approaching the topic?
I am taking a process-oriented approach, which forms the basis for my newfound interest in mycology. As a silviculturist, I have focused on understanding how different living tree species respond to their environment and interact with each other. There are also wood-decaying fungi responding to the environment and acting on the tree. It’s crucial to better understand the fungi’s composition, structure, and dynamics within the deadwood.
I am also taking an integrative approach with deadwood management and silviculture. About 25 years ago, Mark Harmon at Oregon State University coined the term “morticulture” while calling attention to the fact that deadwood is a dynamic system that we can learn how to cultivate. This parallels with silviculture, which already gives us a lot of information and techniques for managing deadwood. Foresters can protect and enhance deadwood resources, like snags, while pursuing other management objectives by integrating morticultural operations within their activities. No need for zero-sum thinking here. Snags are a component to healthy forests, and we have the tools to help maintain their function.