These are some of the themes that concern Klaus Puettmann, a proponent of “managing for complexity.” Puettmann, himself a transplant from Germany, is an associate professor of silviculture at Oregon State University. This July he took me for a stroll among the dappled shadows of soaring Douglas fir in the 11,250-acre McDonald-Dunn Research Forest, 15 minutes north of campus. There, researchers are experimenting on a grand scale of thousands of acres. They’re documenting how the forest responds to different management, such as thinning, cutting trees to open gaps in the canopy, and planting various species in the understory to create more diversity of species and structure.
In effect, researchers are asking how to create more options for an unknown future without diminishing the forest of the present. “We have questions that require a lot of space,” says Puettmann. “To address some of those issues we need bigger experiments. We can work with 300-plus species on a few hundred acres, and we feel like we have a strong story to tell.”
Puettmann doesn’t feel particularly obligated to the past. “I don’t see historical conditions as useful blueprints,” he says. “We can learn a lot, but they are not the blueprints.” The forest soaring 150 feet overhead is a case in point. The 75-year-old Douglas fir provide habitat for nearby endangered northern spotted owls. Yet, before European settlement, the ridge Puettmann is walking was open oak savanna, groomed by frequent fires set by local tribes. “We have more trees growing here than ever before,” says Puettmann, “which makes it really interesting when we talk about habitat for owls… because we never had habitat for owls.”
Rather than mimic the past, Puettmann’s goal is to create a forest of greater “adaptive capacity,” one that can provide timber, wildlife habitat, and ecosystem services no matter what nature may throw its way. “How can we set ecosystems up so that they can react to surprises while still providing clean water, habitat, spiritual values, and timber? The resilience discussion to me has always been a little too much backwards-looking.”
Even the concept of diversity falls short of what might be needed in the future, he says. “Species counting as a measure of diversity is nice, but not very insightful. We decided it’s not really what species there are, but what species do. So we’re looking at a mechanistic approach.” Puettmann and colleagues sorted 300 understory species of fauna by their function as food: Do they produce berries? Are they pollinated by insects? How palatable are the leaves? “Then we looked at our thinning studies and asked, what do our manipulations do to those species? Generally, they seem to increase them in the understory,” he says.
“The idea is that if you thin, especially if you protect some of those sensitive species, we can set up the forest so that if things get drier or warmer and we have more fires, the likelihood that the wildlife functions are maintained and that there is food for all those (species) is higher in thinned stands than in unthinned stands. That’s an example of how we increase the adaptive capacity—that if the climate changes, the system will react in a way that is desirable or acceptable,” he says. “If we start thinking about what diversity does, what species do, rather than just counting species as an indicator of diversity, I think we can be more efficient at setting the forest up to deal with future surprises.”