COF professor is on a mission to build better for a more sustainable future.

The building sector is a major contributor to human environmental impacts on the planet – and the College of Forestry’s Mariapaola Riggio is researching ways to mitigate that impact through more sustainable building practices. She’s currently working on projects that take a more environmentally-friendly approach to building through the use of mass timber technologies and what’s known as a “circular economy” model.

Riggio, associate professor of wood design and architecture in the department of wood science and engineering, describes the concept of “circular economy” as a necessary shift in the construction industry, which will help extend the life of buildings and promote more sustainable building practices.

“The current linear consumption model of raw material extraction, production, use, and disposal, which dominates the global economy, is no longer sustainable,” she explains. “In contrast to this model, circular economy aims to slow the consumption loop by designing products that can last longer, be reused, remanufactured or recycled. It also looks at narrowing resource flows, using for instance waste or underutilized materials.”

She describes how these approaches are applied in some of her recent projects:

The first project focuses on how to use an underutilized forest resource to construct affordable, reusable shelters. The material that Riggio’s team worked with is ponderosa pine. Specifically, ponderosa pine taken from restoration programs that harvest trees in order to prevent or mitigate wildfires. These smaller ponderosa pines are removed from forests to preserve larger trees.

Ponderosa pines harvested from restoration programs are generally not considered very marketable for construction as they’re small, knotty, and the resulting boards are often warped or twisted. Riggio wanted to investigate whether they could actually be useful building material, if they were directed at the right type of structure.

She looked into building low-rise modular homes with cross-laminated timber panels made of ponderosa pine lumber. Through working on a prototype, she found that this could be an effective way to utilize this low-value lumber. The smaller dimensions of the structure are more suitable to ponderosa pine’s characteristics and the structure itself is sustainable, as it can be broken down and reconstructed as needed.

One potential use for such structures would be to house populations displaced by disasters or conflicts, as there’s often a need to provide quick and affordable shelter in the wake of disruptive and catastrophic events. Using ponderosa pine from restoration projects adds value to costly wildfire prevention and mitigation work.

“This is a promising way to use waste to engineer wood products – and build structures with a long service life,” she said. She explains that this project is an example of what is called a “narrow-close loop” in the building process, because it optimizes use of resources and reuses materials disrupting the need to demolish and dispose of buildings.

In another project, Riggio transformed the College of Forestry’s Peavy Forest Science Center (PFSC) into a living laboratory to examine the long-term performance of mass timber buildings. She installed structural health monitoring systems around the PFSC to track different factors that could affect the life of the building, like moisture levels that could lead to rot or decay.

“This project will help us understand how a building performs over time,” she said. “And, it will help us make informed decisions about how to extend the service life of the building, through preventative or remedial actions, thus “slowing the loop” of a building life”

The monitoring project proved its usefulness already during the building construction stage, and helped the building team to make informed decisions, such as ventilating roof panels to avoid mold growth and revising the installation procedure of the building shear walls to ensure proper behavior of the structure during an earthquake. Riggio plans to continue monitoring the PFSC for issues and she plans to publish takeaways from the project that can be applied to future mass timber building projects.

Riggio also teaches the concept of a circular economy and offers students hands-on experience in this model through a collaborative course with the University of Oregon’s department of architecture. This course challenges a multi-disciplinary group of students to design small-scale timber structures using materials like recycled mass timber panels. They work together to assume the roles of manufacturer, engineer, and architect to create buildings that maximize future re-use of materials. In one recent class, students designed a Nomadic Hospitality Suite, which is a portable space that can be easily disassembled and reused.

Riggio will continue to build upon her research and academic work focusing on the circular economy and how to manufacture smarter buildings. “We hope to keep learning more and contribute to the conversation about how to build better for a more sustainable future,” she said.

College of Forestry professor Gerald Presley is working to develop a new method to clean up agricultural plastic pollution

The use of a plastic film in agriculture is increasingly being considered as an option for water conservation. The use of plastic films comes with the risk of contamination of soil with non-biodegradable plastics and threatens the long-term fertility of farmlands. College of Forestry’s Gerald Presley is investigating whether fungi could help clean up this environmental issue.

“Remediation methods must be developed to efficiently remove these materials from land and we believe fungi can help,” he said.

Presley, assistant professor in the department of wood science and engineering, just launched a new four-year project to explore the possibility of using fungi to help decompose agricultural plastics pollution. The project is a joint venture with the United States Department of Agriculture’s Natural Resources Conservation Service, which supports the development of new work that can contribute to natural resource conservation.

Presley’s lab specializes in wood durability and applied mycology and he saw this as opportunity to build on that work and explore a new use of fungi. Fungi are known for being biodegrading powerhouses. There are many different species of fungi with really diverse metabolic capabilities, so there’s a fungi available to break down most any natural, organic material, he explains.

“It’s their job in the global ecosystem to degrade stuff,” he said. “We’re always interested in looking more deeply into the capabilities of fungal metabolism and finding fungal processes that can be advantageous for human use.”

Presley has worked with fungi to break down other challenging material and he saw potential for it to be helpful with polyethylene mulch. The plastic pollution he’s working with comes from polyethylene film residue, which is getting used more and more for water conservation on agricultural lands around the globe.

Plastic is notoriously difficult to turn into biodegradable material, so cleaning it up won’t be as easy as planting some extra fungi on the land, he explains. The key will be pre-treating the plastic material with another process to help break it down into something the fungi can handle.

“We’re working to develop a one-two punch to knock out agricultural plastics pollution using ultrasonic chemistry and fungi,” he said. “The plan is to develop pre-treatments for plastics that will cook up a readily digestible snack for decay fungi, who will then turn the treated plastic into innocuous and biodegradable material.”

Presley is working with Ph.D. student Leon Rogers to experiment with different combinations of ultrasonic chemistry and fungi processes in the lab to see what works best – before testing them in the field. The researchers have partnered with landowners that have a ranch outside of Stayton, Oregon for the field work side of the project. The ranch was rented out for hemp farming a few years ago, and returned to the landowners with heavy plastic pollution that must be cleaned up if the land is going to be restored to its original productive capacity. Presley and Rogers will work with the landowners to develop tools and processes to tackle the pollution on the ranch – with the hope of being able to translate their findings into a broader application for agricultural pollution and environmental cleanup.

“Our long-term goal is to develop technology that can enable farmers to pull polyethylene contaminants out of their soil and dispose of it on-site in an environmentally friendly manner,” said Presley.

The Oregon State University Research Forests are a valuable asset for long-term research projects

Sometimes, the best strategy for scientific work is to play the long game – because a short-term study can’t always offer the same insights as a multi-year endeavor.

That’s one of the many reasons that the OSU Research Forests are such an asset. They provide a venue for researchers to run long-term studies that can offer meaningful insights into an array of research questions that examine forestry practices, forests, and ecosystems.

Here are a few examples of the long-term research projects that started years ago in the Research Forests – and are still happening today – but couldn’t have happened at all, without a place to watch science unfold over decades.  

Purple Martin Habitat Patrol

The purple martin is picky about where it lives. It likes to nest in a good hole – like a dead tree cavity. And, it also needs an open canopy for foraging insects.

While this large swallow maintains a healthy population on the East Coast, it’s a “critical” sensitive species in Oregon – and could be listed as an endangered or threatened species if its population declines more. It would’ve been difficult – if not impossible – to find a purple martin in the Willamette Valley a decade and a half ago.

But, in the late 2000s, Joan Hagar, research wildlife biologist with the United States Geological Survey (USGS) and affiliate faculty in the department of forest ecosystems and society, turned to the Research Forests to encourage purple martin habitat in the Willamette Valley. And, she set up a study to monitor how the bird’s population changed over time.

She set up artificial nests in regenerative harvest sites in the McDonald and Dunn research forests to coax purple martins into the forest. Nearby snags would eventually create lasting habitat for the birds, but they needed a few years to decompose into an ideal purple martin home. OSU initially created these snags after tree harvests, in order to provide dead wood for woodpeckers to turn into cavities, which would become homes for purple martins. The recently harvested area provided a prime habitat for insects, which the purple martins feed on.

Since setting up the nests, Hagar has been monitoring the state of the purple martin population and its use of managed forests for habitat. To do this, her team bands birds every year and monitors their nesting habits when they return from their winter migration. She says the Research Forests – and plenty of time – are vital components for this study.

“Birds can see a lot of annual variation, especially migratory birds, so you can’t always see patterns until you collect a lot of data,” she said. “By observing them for multiple years, you can see trends more clearly.”

The purple martins have thrived in the Research Forests, where they can access the maintained snags for habitat – and beyond that, they’ve helped provide insights into how other species fare when dead and decomposing trees are purposely left for habitat and biodiversity. There’s a large collection of species in the Pacific Northwest that relies on cavities in dead trees for habitat.

“Purple martins are a great indicator species for how a whole suite of species is faring in this habitat,” Hagar explained.

COF Integrated Research Project

Back in 1989, a team of COF researchers and resource managers decided to launch a long-term study to investigate alternatives to clearcutting. They wanted to learn whether they could retain features of mature and old-growth Douglas-fir forests through a variety of types of timber harvests.

To initiate the study, they applied four different silviculture treatments across 33 different stands in the Research Forests and monitored how these treatments affected economic, social, and ecological factors over time. They published a summary of their initial findings in 2005.

Klaus Puettmann, professor in the department of forest ecosystems and society, assumed responsibility for the study a little over a decade ago, mainly to continue to facilitate teaching and research opportunities on this land – and advocated for its value as a long-term resource.

He explains that while active research has slowed in these stands over time, they provide a huge opportunity for education and research as the installations contain forest structures that are unique in the region. He personally brings a number of his classes to these stands on the Research Forests because they’re such a great resource for teaching.

“They offer examples of a wide range of forest conditions and hold great value for researchers and teachers who want to consider a multitude of forestry approaches,” Puettmann says. “We just don’t have many examples of these treatments in the region, especially so close by and accessible for our students.”

One of the greatest benefits of this project is for researchers and educators who want to investigate how certain treatments affect a forest over longer time periods. This could be especially helpful for questions related to how factors like climate change have affected forests, Puettmann explains.

 “They can consult the database to see if the inventory matches their research needs – and potentially launch their project with the help of decades of data,” he said.

Mature Forest Management

For the last 25 years, OSU researchers have examined how mature forests change through different levels of thinning and understory treatment. Mature forests are stands of older and larger trees, often Douglas-fir, that resemble old growth. It’s a project that was inspired by the timber wars of the 1990s, the struggles over logging and old-growth protection, to help researchers understand how mature forests and certain tree species develop through different approaches to forest management.

“This project is so valuable for answering post-timber wars questions about forest development and how we can use different kinds of silvicultural treatments for functions other than managing plantations of trees,” said John Bailey, professor in the departments of forest engineering, resources and management and forest ecosystems and society.

The project has let researchers explore questions about the best conditions for Douglas-fir growth, how thinning in different intensities and ways affects understory vegetation, and how the use of herbicides affects the growth of saplings. They’ve utilized both the McDonald and Dunn and the Blodgett Research Forests for this work.

The researchers have published a number of findings over the course of the project, and the treatments continue to be beneficial for researchers looking to explore new issues, Bailey says. Researchers can draw from 25 years of data to consider issues like carbon storage in a forest or how plant biodiversity in the understory is impacted by herbicides.

“As new questions come up, we can keep looking at this data through different lenses,” he said.

One of Bailey’s personal research interests is how thinning and understory treatment affect wildfire spread. He can consult the decades of data to investigate how different types of thinning and understory treatment affects fuel hazards for wildfires.

“Long-term studies are great for providing a time arc of data to look at as new issues and new angles emerge,” he said.