Resurrecting the In-Stream Side of Riparian Forests

With all the trees you folks are planting around here,” the old farmer said as he watched staff members from the Stroud Water Research Center place yet another row of flags along a meadow creek on a clear fall morning, “pretty soon this whole area will be woods. You know,” he went on, “when our forefathers first set foot on this ground, there wasn’t a tree anywhere around here. ” So began a conversation with a man who had no idea that the land his family had farmed for generations in “Penn’s Woods” had once been completely forested. This is less surprising than it may at first appear because within a century after the first Europeans had settled, virtually every tree in southeastern Pennsylvania (PA) had been felled. Some of the first to go were those in riparian forests, which were cut for firewood and building material, for agricultural land and access to fresh water. The streams and rivers became the flowing commons of the New World, providing drinking water and waste disposal, hydropower and irrigation, food, transportation, and hygiene – all free of charge. As settlers marched westward across the continent, chopping down riparian forests, planting crops up to the river’s edge, and letting their livestock contaminate creeks, they wrote a tragedy of those commons (Hardin 1968), for which the nation continues to pay. Even as the world increasingly acknowledges the vital things trees do for people and their environment, the destruction continues. During the 15-year period from 1985 to 2000, for example, the Delaware Valley region of southeastern Pennsylvania and southern New Jersey lost 12,655 ha or 1.5 percent of its heavy forest canopy, representing an annual loss of at least 1.5 million m3 of stormwater retention, 750,000 kg of air pollution abatement, and 643 million kg of stored carbon (American Forests 2003). Perhaps nowhere has the destruction of America’s forests been more devastating than along its streams – and particularly its small streams – which are the source of most of the nation’s fresh water. In fact, a recent study found 19 percent of the total length of small streams in the U.S. to be in poor condition due to “severely simplified riparian vegetation” (U.S. Environmental Protection Agency 2006). Note our use of the phrase “riparian forests” rather than “riparian buffers. ” In the last two decades, many policy makers have come to recognize the need to create a physical space – or buffer – to protect their freshwater sources from the harmful effects of human activity. Such policies have been supported by a significant body of scientific research demonstrating that buffers act as barriers to keep sediment and other pollutants from running off the land and into the stream (see reviews by U.S. Environmental Protection Agency 1995, Lowrance et al. 1997, Bentrup et al. 2005, Mayer et al. 2005). As a result, riparian buffers have become best management practice in most U.S. landscapes. While the recognition of the importance of such buffers has been a valuable addition, both to the scientific literature and to public policy debates, it has also had a little-noted but marked negative effect. The emphasis on the role of the buffer as a barrier, shielding a stream from harmful human activities, caused people to overlook the substantial benefits that riparian forests provide to the health and integrity of the stream itself. In this essay, we explore the important role riparian forests play in protecting our streams and rivers in a number of ways: