For the love of trees
by Michelle Nijhuis
Last summer, after 15 years in western Colorado, my family moved back to the Pacific Northwest. The move was a shock in many ways, taking us from dry to wet, rural to town, red politics to blue. The topography here is different, the wildlife is different, and the trees are very, very different.
But our neighbors' attachment to the forests is familiar. Whether surrounded by graceful aspen or scrubby juniper or majestic Douglas fir and western hemlocks, people care about trees in a way that goes beyond politics and logic. For most of us, forests are part of the personality of our places, and when they change, we change, too.
In recent years, Western forests have undergone profound changes. Deep drought in the Southwest, beetle attacks throughout the Rockies, and warming average temperatures worldwide have led to record-breaking forest die-offs. Many familiar species – lodgepole pine, whitebark pine, even the hardy juniper – are dying in huge numbers.
For most of us, the carnage is unsettling. For scientists, it's also a mystery worth solving.
Death is a complicated matter, and it turns out that tree death is no exception. As HCN assistant editor Cally Carswell writes in this issue's cover story, Western forest researchers are finding that what look like simple cases of beetle kill or drought-induced starvation are not really simple at all. Heat, changes in rainfall patterns, fire, insects and disease can all contribute to a single tree's demise, and the same factors can affect different species in different ways.
By understanding how trees die, scientists hope to improve the accuracy of our climate forecasts: If they can include forest decline – and its implications for the world's carbon budget – in computer simulations of future climate, they'll be better able to predict the speed and strength of climate change worldwide.
Scientists also hope their studies will benefit living forests, and those of us who live among them. Plants have a remarkable variety of strategies for dealing with stress, and as the climate changes, some strategies will be more successful than others. Knowing which species survive in which conditions will help managers decide if, how, and where to try to make forests more resilient.
These are grim questions, and they're yielding grim forecasts. But ecologist Craig Allen points out that the researchers' motivations are anything but. "What underlies this is the love of life," he says. "Trees are one of the most glorious expressions of that on this planet."© High Country News