Forest loss has a cost


Depletion: Building pollution-fighting systems that wooded areas naturally provide is a bad deal for the Earth and budgets.

April 09, 2004|By Tom Horton | Tom Horton,SUN STAFF

IT'S OLD news that we have been steadily losing forests around the bay's metropolitan regions during recent decades.

Most probably think that it's regrettable, and many no doubt think it's a crying shame. But beyond lamentation, so what? What exactly does it mean when trees fall to development?

How about the costs to the public health and to water quality, and the public works budgets of $4.5 million a year during the last decade in the Jones Falls watershed of Baltimore City and Baltimore County?

How about $4.5 million annually in the Patapsco River headwaters in Howard and Carroll counties?

How about $3.2 million in the Eldersburg region of southern Carroll County, $1.5 million around Towson and $1.3 million a year around Salisbury on the Eastern Shore?

Those are serious numbers, and the budgets will grow if forests continue deteriorating as projected.

I got the above data easily and quickly by querying a software program called CITYgreen, developed by American Forests, a Washington-based, nonprofit conservation organization founded in 1875.

Here's how it works. CITYgreen can compare forest cover for most of the Chesapeake Bay's six-state watershed using satellite photography from 1992 and 2001.

For the 32,000 acres that drain into the Jones Falls, it reveals a loss of 2,000 forested acres.

Note that "loss" doesn't mean every single tree was cut -- but enough so that the critical, pollution-fighting functions of the forest were lost on those 2,000 acres.

Lost was the capacity of the Jones Falls forestland to absorb about 200,000 pounds annually of air pollution -- carbon monoxide, ozone, nitrogen, sulfur dioxides and particulate matter.

CITYgreen calculates the public health costs of this added pollution at about $500,000 a year.

The bigger ticket item is the added costs of managing storm water, or urban runoff -- a significant and growing source of pollution to the bay.

Rain that falls on forestland mostly soaks into ground water and emerges, filtered and clean, in streams and rivers feeding the bay.

When it falls on the developed landscapes that usually supplant forest, it quickly runs off, carrying metals, pesticides, bacteria, sediment and fertilizers to waterways.

The equivalent of 10 percent of the bay's volume can fall on the watershed in a single, 3.25-inch rain -- and a storm of that size hits the Chesapeake region about every two years.

"So how rain runs off the land, whether it is high-quality or polluted, is critical," says Gary Moll, a former Maryland state forester now with American Forests.

To mitigate the loss of forest-runoff control, it would have cost $3.8 million a year over the last decade to build traditional storm water detention ponds and other control devices along the Jones Falls, CITYgreen calculates.

One might argue that's an acceptable cost, simply part of the price of growth. But even if you buy that, it's badly flawed from a pollution standpoint.

That's because human-made storm water controls, although improving, especially in Maryland, don't come close to matching the forest in cleansing runoff and checking sediment.

Neither do they replicate the timing and volume of runoff from forestland, which is as critical to maintaining healthy streams as removing pollutants.

Finally, few jurisdictions have come to grips with the cost of maintaining and inspecting the tens of thousands of storm water ponds we are building to replace forests. One that has, Prince George's County, spends $6 million a year.

CITYgreen also calculates the loss of carbon storage from losing trees -- 84,000 tons in the Jones Falls during the last decade. This exacerbates global warming. No cost is assigned because government does not recognize it as a problem.

American Forests offers CITYgreen to local jurisdictions for $900. For more money, they can develop high-resolution forest data that literally shows individual trees.

This costs about $200,000 for a 640-square-mile region around Washington, D.C. The group has met with Maryland's U.S. senators to discuss a high-resolution forest analysis for the Baltimore metropolitan area.

The aim, Moll says, "is not to stop development. The hope is that when jurisdictions plan roads, development or other public works projects, they will know the real value of their forests and approach alterations to the landscape with a different view."

New federal regulations will require far broader use of storm water controls, but will give communities credit for maintaining and planting forests.

It's past time that the bay region began doing this and more. We don't protect what we don't value. And our economy's value system runs heavily to dollars and cents.

Nature's largely unsung services are far more vast than the forest's, ranging from pollination of crops to easing floods and droughts, decomposition of wastes and stabilization of climate. (Metro Atlanta grew 6 to 9 degrees hotter after clearing 65 percent of its forests in recent decades.)

For more information, contact American Forests at www. or 202-955- 4500.

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