In a Warming World, What Happens to the Trees?

In a Warming World, What Happens to the Trees?

Plant a tree

Across the American West, increasing heat and drought have killed a number of old-growth forests. These aren’t saplings, an inch or two in diameter, but trees which have established themselves and sent out roots systems up to 15 feet deep, with feeder roots spreading well beyond an average drip line of 8 to 10 feet on each side.

The fatality rate for these trees doubles every 17 to 29 years, according to Phillip J. van Mantgem of the U.S. Geological Survey’s (USGS’s) Western Ecological Research Center, the lead author behind the 2009 study, which culled data from 52 years of forest research beginning in 1955 and ending in 2007.

With this summer’s drought sweeping across the West, the damage is now even greater than Mantgem reported three years ago. His projections, that climate change will continue to reduce the numbers of trees in any given forest, so that future forests have only small trees less able to store carbon dioxide, or CO2, have outpaced themselves.

This CO2 storage, called carbon sequestration, is one of Nature’s ways of balancing the ingredients in earth’s atmosphere. In the future, though, these newer, less established forests may fall prey to sudden, cataclysmic demise.

As forests diminish, succumbing to bark beetles, white pine blister rust and a host of bacterial and fungal diseases, they provide less habitat for fish and wildlife and other ecosystem species. In human terms, these decimated, second growth forests mean more wildfires, like the ones that took vast swaths of forest in California, Colorado, Nevada, Oregon, Idaho and Washington.

Trees: we seldom think about them unless we are planting one in our backyards or digging one out to build – or build onto – our homes. Few of us, noting them as we drive to work or to the grocery store, realize that some of the most majestic specimens like oak, beech, black walnut and the once almost ubiquitous American Elm, are three or more times as old as we are. An oak can easily live to be 200 years old, as can an elm tree.

Trees do all kinds of friendly things. They not only sequester CO2, but shed their leaves before winter to protect plants closer to the ground which might be less adaptable to cold. In spite of this, many people rake their leaves and send them to the landfill.

Composted over winter by dark, cold and damp, dead leaves in the spring harbor all kinds of useful insects and provide a duff layer which keeps moisture in and heat out over the summer. Gardeners do basically the same things when they chop up their leaves in a shredder and dump them on a mulch pit.

Trees contribute to the production of paper products, disposable diapers, books, clothing, fences, furniture, houses, movie tickets, pencils, toothpaste and kitchen utensils. The most egregiously wasteful process is disposable diapers, which occupy about one percent of all U.S. landfills and end the lives of more than a billion trees a year, while taking 500 years to decompose.

Faced with a double onslaught of climate change and rising population, which means more people needing more paper, houses, disposable diapers and the like, it’s not a good time to be a tree.

As forests gradually erode or die en masse, environmental disasters multiply. Loss of forest alters local rainfall patterns, speeds up soil erosion (welcome to the 21st century Dust Bowl), and causes rivers to flood and find alternate routes – often right through people’s homes. These effects lead to loss of critical habitat.

It is sad to lose a forest. But it’s tragic to lose everything that goes into making a forest a place of wonder; things like bloodroot and ladyslipper and chipmunks and woodpeckers and deer and beaver and streams full of trout hovering in the shade of those same trees.

These are things I have seen and marveled at. Will my great-grandchildren be able to do the same?


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