Restoring forest landscapes in the US – it’s more than just planting trees

29 July 2015

Three short stories of landscape restoration in the western United States show that restoration can mean a lot more than just planting trees. Sometimes it means cutting trees, setting fires, and unleashing destructive rodents. Perhaps we’d better explain.

A chainsaw breaks the peace of a quiet forest in central Oregon. Soon, the crash of a tree follows and the rustle of debris dragged and piled. When the weather cools the next sound will be a crackling one, as great heaps of wood are lit and fires rage.

What we are witness to is a classic scene of deforestation, right? The clearing of virgin woods to make way for cattle, crops or homes?

Wrong. In some cases, this scene is actually one of lands being restored and rejuvenated.

Restoration: It’s Not Just Tree-Planting

Landscape restoration, or bringing productivity back to degraded lands, takes many forms. In much of the western United States, it can mean cutting trees. And setting fires, removing hills, or even, sometimes, unleashing destructive rodents.

Perhaps we better explain. Restoration always comes with a purpose. In the U.S. Pacific Northwest, the purpose is often to make forest landscapes more resilient to climate change, drought or pest disturbance. Paradoxically, this is often accomplished by removing trees from dense forests to reconstruct more natural and open structures, burning undergrowth to encourage greater plant diversity, or cutting soft meandering brooks and meadows across sharp, human-altered streams.

Three short stories of landscape restoration in the western United States follow. They detail projects that are successfully bringing health and productivity back to degraded lands in unexpected ways. Each takes a landscape approach that, as you will see, goes far beyond merely planting trees.

1. Thinning and Burning

Most government agencies wish they could have a mascot as recognizable and effective as Smokey the Bear, the U.S. Forest Service’s cartoon grizzly bear who, since the 1940s, beseeched Americans to help prevent forest fires. Smokey was the face of a successful movement, begun well before the First World War, to stamp out wildfires in American forests. Today Smokey is recognized by 95 percent of American adults and nearly all forests in America bear a legacy of fire prevention.

The trouble is that fire is a natural element of the ecology of many U.S. forests, a fact any forester will happily tell you now. More than 100 years of fire suppression have left U.S. public lands—and many private lands—overstocked with dense trees that should have burned decades ago. If those lands were to catch fire now, the resulting fires would burn hotter, higher and much longer than normal, killing trees naturally designed to survive smaller fires and destroying other forest goods and services, like clean waterways.

To avoid catastrophic burns, which would kill old growth stands, threaten rural communities and clog waterways for years, the U.S. Forest Service and its partners in the Collaborative Forest Landscape Restoration Program routinely remove trees from dense stands (a process called “thinning”), and carefully burn the underbrush and litter below the trees to mimic natural fire. The resulting forest is more open – a structure that leads to greater plant diversity. Burned plant matter enriches the soil and the landscape has less wood and debris to fuel future fires.

<p>A stand of ponderosa pine still smolders from a recent prescribed fire in central Oregon. Photo by Aaron Reuben/IUCN.</p>

A stand of ponderosa pine still smolders from a recent prescribed fire in central Oregon. Photo by Aaron Reuben/IUCN.

In the last 5 years, the 23 projects of the US Forest Services’ Collaborative Forest Landscape Restoration Program have treated more than 1.45 million acres to reduce the risk of catastrophic wildfire, resulting in healthier forests with greater plant diversity and more resilience to pests and climate change. Walking through one restoration site last May, with smoke in our eyes and warm ash under our feet, it was hard to imagine that a burned forest is a restored one. But “this is what the ecosystem calls for,” said Maret Pajutee, forest ecologist for the US Forest Service in central Oregon. What is needed here, surprisingly, is not more trees, but fewer. And more fire.

2. Putting Beavers to Work

You know you are standing on the bank of a beaver managed stream when your feet start getting wet. What you thought was terra firma proves more porous, and water suddenly seems to run everywhere. Beavers hate the sound of flowing rivers and, as quickly as they arrive, subtly turn streams to wetlands and re-channel rivers by building dams. Today, with a changing climate, beavers may be what arid forest regions need.

“With the climate changing we want this system to store more water for us,” said Bob Hassmiller, a hydrologist with the U.S. Forest Service. Though many still view the aquatic rodents as pests, beavers make hydrologists like Hassmiller happy. Beaver activity alters and slows the flow of water through a watershed, he said, “providing natural reservoirs we can benefit from.”When water flows start to drop late in the summer season, beaver-dammed streams will continue to release water and, importantly, provide more flows for fish.

<p>Land managers in the western United States are increasingly letting beavers, and their dams, restore streams and waterways to more natural conditions. Photo by Aaron Reuben/IUCN.</p>

Land managers in the western United States are increasingly letting beavers, and their dams, restore streams and waterways to more natural conditions. Photo by Aaron Reuben/IUCN.

On a chilly day in May Hassmiller stood, pants tucked into tall rubber boots, beside a newly dammed stream running along the Malheur National Forest in Oregon. “Since the beavers have arrived,” he said, “we’ve seen more habitat for fish, and better stream temperatures.” Hassmiller and his colleagues in the Malheur have been using beavers to manage streamside restoration for a few years now, letting the non-human engineers transform landscapes altered by historic human uses. “We’re just glad they’re here.”

3. Aspen Restoration

Walking through eastern Oregon’s forest can be a monotonous process. The ponderosa pine (Pinus ponderosa) completely dominates hundreds of thousands of acres of forest in Oregon. With one exception. Very occasionally, you will come across a row of green and white trees, similar-looking and stacked in a pyramid, with a tall tree in the center giving way to short fellows on the sides – the quaking aspen (Populus tremuloides).

While aspen are so ubiquitous as to be a nuisance in some parts of the United States, in Oregon they are prized as biodiversity boons: Many species of woodpeckers and songbirds prefer to forage and nest in their boughs; certain mushrooms and insects favor their rich soils; and migrating deer and elk find nourishment in their sprouts and bark even in winter. That is why aspen is a key species for restoration in Oregon, said Trent Seager, PhD candidate in forest ecology at Oregon State University.

<p>Green ponderosa pine trees tower behind the young aspen shoots. Photo by Aaron Reuben/IUCN.</p>

Green ponderosa pine trees tower behind the young aspen shoots. Photo by Aaron Reuben/IUCN.

Because fire was suppressed in the region for more than 100 years, aspen, which typically return quickly from a fire and use fires to colonize new ground, have slowly disappeared from parts of Oregon’s forests. Because they prefer to grow in water-rich deep soil, and elk eat them when they are small, it can be deviously hard to plant aspen successfully.

So how do you restore a tree that is a challenge to plant?

“Slowly,” said Seager. Aspen grow in a clonal way, with a central tree sending underground root suckers outward to start new trees. This system works pretty well, and new stems in a clonal stand may appear up to 30–40 meters (98–131 feet) from a parent tree. An individual aspen can live for more than 100 years above ground, but the clones of the colony themselves can last for several hundred. The trick for aspen restoration is to find a good aspen stand and help it grow.

“We will remove the pines encroaching on an aspen stand to give the aspen more water, light and nutrients to expand,” said Seager. “And when we thin and burn across the larger landscape, that increases forage for elk and deer and frees up more water at the landscape level for aspen across the area.”

Forest landscape restoration is about more than just planting trees. It involves people coming together to identify the problems degradation causes in their area and finding the solutions that can bring a balanced mix of goods and services back to the land. In many of the forests in the Northwestern US water is a limiting factor. In a fire activated landscape, thinning makes the land healthier, taking pressure off remaining trees and allowing old growth forests to survive low-intensity fires. Allowing beavers to return to the land can bring more water year-round, improving fish stocks and forest health. And releasing old aspen stands from the encroachment of pines can increase biodiversity and wildlife forage.

We hope these stories can inspire those outside the US Northwest to think creatively about improving their landscapes. But some questions invariably arise:

  • Is the challenge facing the US, where fire was suppressed for decades, comparable to the challenges facing other countries? In many places the battle is to bring trees back to degraded lands, not remove them.
  • The US Forest Service has worked hard to change its image from a timber logging organization to an organization working towards resilience in human managed landscapes. However, are they depleting their carbon stocks by thinning and burning (as some have suggested)? Can their 15 million hectare restoration commitment to the Bonn Challenge be considered equal to the 15 million hectares of agroforestry restoration expected from Ethiopia or the eight million hectares of forest landscape restoration committed from the Democratic Republic of the Congo?
  • As we move towards more human mediated landscapes, with mounting pressures from climate change and the need for resilience, will landscape engineering become a more prevalent form of landscape restoration governance?

Maybe restoration as a concept is evolving. Before jumping into another tree planting campaign, we should remember to assess what is truly needed for a resilient landscape. It may not always be more trees.

These case studies originate from presentations made at the first International Seminar on Forest Landscape Restoration, hosted by the US Forest Service, World Resources Institute and IUCN. IUCN’s contribution to the seminar made possible through support from UK aid, from the UK government.

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Originally posted on IUCN’s blog. Reposted by the World Resources Institute (WRI).