Study of “disturbance refugia”

This is a press release from Oregon State U. The referenced study is open access.

Areas of mature forest that serve as refugia for the northern spotted owl are “slowly being nibbled away by recent high-severity fires.” Do we increase and improve the management of these refugia to help them, and the species that depend on them, be resilient to the “increased frequency, severity and/or types of forest disturbances”? Or do we leave them largely alone? We’ve discussed this here numerous times over the years.

Refugia may be younger forest stands, too — even plantations.

“Developing a disturbance refugia framework that recognizes multiple types of forest disturbance under one banner is an important step for research and management of forest ecosystems that are changing as the planet warms.”


June 9, 2020

Nature’s ‘slow lanes’ offer hope for species feeling heat of climate change, other pressures

By Steve Lundeberg, 541-737-4039, [email protected]
Source: Meg Krawchuk, 541-737-1483, [email protected]

CORVALLIS, Ore. – Pockets of landscape less prone than adjacent areas to disturbances like fire and drought may hold the key for scientists, conservationists and land managers seeking to preserve vulnerable species in a changing climate.

These areas, categorized as “disturbance refugia,” are becoming a focal point for ecologists trying to learn why change doesn’t occur as quickly in some landscapes as it does in others nearby.

“In the Pacific Northwest, the iconic northern spotted owl relies on refugia in the form of old-growth forests,” said Oregon State University forest ecologist Meg Krawchuk. “These forests are refugia from previous stand-replacing disturbances – that’s how they got to be old – but they’re slowly being nibbled away by recent high-severity fires.”

Known informally as the “lifeboats” or “slow lanes” of biodiversity, refugia have spawned the new field of refugia science, which is the theme of the June issue of Frontiers in Ecology and the Environment.

Krawchuk, who contributed to the issue with a study of forest refugia in the combined context of fire, drought and insect outbreaks, says research shows that some locations have inherent characteristics – such as terrain, vegetation, proximity to bodies of water, and slope-face direction – that buffer them from disturbances in a predictable manner.

“Scientists and land managers working together on refugia science and implementation will help to conserve forest landscapes, and biodiversity, here in the Pacific Northwest and around the globe that are dear to our hearts,” Krawchuk said. “Some disturbances are important ecosystem processes that support biodiversity; however, there is increasing worry about the erosion of biodiversity due to the increased frequency, severity and/or types of forest disturbances, and how they overlap.”

Natural disturbances can create mosaics across a landscape that support biodiversity, but disturbances outside the historical range of frequency and severity can do short- and long-term ecosystem damage.

Recent studies of disturbance refugia in forest ecosystems have focused mainly on fire, Krawchuk said, but the wide range of disturbances in forests necessitates developing a broader understanding of refugia, particularly against the backdrop of climate change.

“With climate change, forest disturbances like wildfire, drought and insect outbreaks are expected to become more frequent or severe, changing the recipe of these natural disturbances that historically contributed important variety and flavor to ecosystems,” she said.

The study jointly led by Krawchuk and College of Forestry colleague Garrett Meigs shows how the overlap of disturbances generates a multitude of complex feedbacks, both positive and negative, that affect the structure of refugia and how they work.

“Detecting refugia in multiple places and at different times and understanding what’s behind their occurrence, persistence and value in sustaining biodiversity are important frontiers in science and land management,” Krawchuk said. “Developing a disturbance refugia framework that recognizes multiple types of forest disturbance under one banner is an important step for research and management of forest ecosystems that are changing as the planet warms.”

Thinking in terms of only two types of land categories – refugia and non-refugia – is tempting but an oversimplification that scientists and land managers should avoid, she said.

“The people who study forests and manage them need to recognize there are varying types and qualities of refugia, and the variance will only grow as climate and disturbance regimes continue to change,” Krawchuk said. “Considering a broad palette of disturbance refugia together will be critical to management strategies that create and protect refugia. And continued research is necessary to fill out the framework.”

Disturbance refugia figure to play an increasingly important role in the ability of climate change refugia to help save species from extinction, she said.

“Identifying disturbance refugia locations within climate change refugia spots would lead to a deeper understanding of refugia,” Krawchuk said. “In this era of rapid environmental change, disturbance refugia within mosaics of fire, drought and insect outbreaks will shape the patterns of persistence of forest biodiversity and ecosystem function around the world. There are many iconic and special forest landscapes being confronted with increasing disturbance pressures, including harvest and conversion to agriculture or other uses.”

Disturbance refugia science is broadly applicable, she added, because many disturbance processes are global – including pressure from climate change. And the ideas underpinning refugia science go beyond forests and disturbance refugia.

“We’re increasingly realizing that refugia science might provide theory and analysis of the critical role of refugia in social and ecological resilience,” Krawchuk said. “For example, as resistance to diseases that can be transmitted from animals to humans, pandemics like COVID-19, political turmoil, violence and land use issues, particularly in the context of extreme events. Refugia are areas of resistance that contribute to system-level resilience.”

Collaborating with Krawchuk and Meigs were researchers from the University of Idaho, Portland State University, Western Colorado University, the United States Forest Service and the U.S. Geological Survey.

Supporting this research were the Forest Service, the USGS and the National Science Foundation.


8 thoughts on “Study of “disturbance refugia””

  1. In the face of inevitable permanent climate change, and all that that involves there are times when I question the practicality of attempting to “preserve” selected species. Seems that we’ll have our hands full with Homo sapiens.

  2. I’m stepping back here.. do we need a new field of “refugia science” with abstract ideas, models and the perceived need for global relevance, or maybe just need to get scientists who understand fires, plants, animals, bugs, climate projections to work together to understand what might work for a given area.

    My observation: the more disciplines you have, the more meetings, conferences, pubs and less funding there is for each.

    There’s also much rediscovery of what people in other disciplines have known. And it’s harder for practitioners to keep up with/influence the direction of/be in dialogue with the research and researchers.

  3. This is about “inherent characteristics – such as terrain, vegetation, proximity to bodies of water, and slope-face direction – that buffer them from disturbances in a predictable manner.” This reminds me of “conserving nature’s stage,” a planning approach led by The Nature Conservancy: “Enduring geophysical features such as topography, soil, rocks and water, form the stage on which nature’s play is enacted and can be used to prioritize sites for conservation.”'s%20Stage%20(CNS)%20refers,for%20current%20and%20future%20biodiversity.

    I’d generally agree with Sharon that, more than we need another permutation of science, we need to make what we know more operational. “At a minimum, incorporating geodiversity is a low-cost type of bet hedging which results in conservation networks more robust to climate changes and also compatible and complementary to existing plans.” This came along a little too late to recognize in the Planning Rule, but I hoped it would get used during forest planning to “prioritize sites for conservation.” I don’t think that has happened.

    • Jon, I’m glad you found that. As a vegetation person myself, I know that vegetation will do what it will, for the most part, and our efforts are relatively puny. But if we have soil and protect our water, something will always grow there. Imagine how much simpler forest planning would be if we just said “we need to protect soils, wildlife and water” and leave out the NRV vegetation and coarse filter stuff.

      • I would say NRV gives you something to manage for, but it should be based on geodiversity (and informed by historic vegetation). And the alternative to protecting wildlife with a vegetation coarse filter is a whole lot of “thou shalt nots,” which the Forest Service doesn’t seem to like.

  4. Pre-human ecology seems to be of very limited usefulness in today’s real world forests. In the Sierra Nevada, the inevitable re-burns make ‘refugia’ more and more rare. We simply cannot preserve our way to resilient and ‘natural’ forests, here. (Although some advocate for “larger and more intense wildfires”)

  5. I don’t think plantations provide much of a buffer unless they are regularly thinned. Thousands of acres of plantations of various ages that were planted after previous wildfires burned in the Rim Fire just fine, because the terrain and the fire weather were in alignment. Those lush little trees carry fire really well, because they are dense and even-aged.

    I’ve always advocated for treatment in owl territories, but we generally walked away from them, because commercial harvest wasn’t an option to “pay for it”. Now there are external funding sources, partnerships, and even state climate change offset money to cover some non-commercial treatments such as hand thinning and prescribed burning, to potentially complete these important fuels reduction and thinning projects. If we can just implement fastly enough.

    • There were also large acreages of lands that “were left to recover on their own”. The results were contiguous dense acres of highly-flammable 8 foot high brush. Even the plantations that were thinned before the Rim Fire suffered serious scorch along the edges adjacent to those ‘No Treatment’ areas, from the early 70’s. I also think that some of the trees that survived the fire didn’t survive the bark beetles.

      I’ve worked in a CASPO PAC before, marking actual timber, with a 14.9 inch dbh limit. There wasn’t a whole lot of trees to mark but, the rest of the timber sale would pay for this one unit, with minimal volume. I’ve also worked on other timber projects that had non-commercial units embedded. It does weigh down the package, and that is always reflected in the bid (which in the Sierra Nevada, is just one solitary bid).


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