Gulf of Maine Times

Shoreland buffers to protect wildlife
Waterfront setbacks commonly used to safeguard water quality can also help wildlife.

By Peter H. Taylor

It is widely known that shoreland buffers protect water quality of freshwater, estuarine and marine ecosystems. That is why many towns tightly regulate land development along the shoreline, specifying the setback from water’s edge to structures, number of trees that can be cut and other construction details.

The basic concept of the shoreland-water quality link is fairly straightforward. Water flowing downhill passes through the vegetated shoreland zone — both underground and across the soil surface—where natural processes may remove excess nutrients, sediments and other pollutants before the water enters the aquatic environment (see “Science Insights,” Gulf of Maine Times, Autumn 2002).

The shoreland-wildlife link is not as well understood, in part because the animals tend to be harder to observe and their behaviors less obvious than water flowing downhill toward a shore. Wildlife-related ecosystem linkages are also more complex, since the variety of animals involved is tremendous, and the processes are not necessarily one-directional like the flow of water pulled by gravity. Without these wildlife linkages, however, the shoreland or riparian ecosystem would not function the same, wildlife would suffer and ultimately even the shoreland’s ability to improve water quality might be affected.

One of the first steps toward protecting ecological roles of wildlife in riparian areas is to gain scientific understanding of them. In recent years, scientists have investigated many aspects of riparian wildlife and ecology in the Gulf of Maine region. From this research, it is increasingly apparent that the distinction separating “terrestrial” and “aquatic” ecosystems is blurry and in some ways meaningless. Just because the water’s edge looks like an ecosystem edge to us, doesn’t mean it is.

One example of wildlife-related linkages is that amphibians occupy both aquatic and terrestrial habitats. They play an integral role in the ecology and nutrient cycling both on land and in the water. Scientists have concluded that maintaining and restoring hardwood forest canopies is crucial to the persistence of amphibians around the Gulf of Maine. Since they migrate and use different areas during certain life stages, spotted salamanders, wood frogs, and wood turtles require a certain amount of forest area and connectivity of intact forest habitat. Conversely, from an aquatic perspective, some species such as spring salamanders live in small, ephemeral streams, which may not support fish, making protection of these headwater streams critical. For amphibians, the most responsible management strategy, according to some scientists, is to mimic the frequency and size of natural disturbances to the habitat.

Other animals require both aquatic and terrestrial habitats for feeding, breeding or other activities. For example, some fish spawn in seasonally flooded riparian forests, and loss of forest habitat with the appropriate topography next to a stream may jeopardize their survival. Similarly, some insects spend part of their life cycle underwater, and the other part as airborne inhabitants of the forest. They are a component of the food webs in both the aquatic and terrestrial worlds. Anything that affects the population of these insects on land might have ripple effects into the aquatic ecosystem and vice versa. It’s another reason why the notion of separate aquatic and terrestrial systems may be largely illusory.

Some species blur the aquatic-terrestrial boundary in ways that are more subtle but no less significant. For example, mammals like mink, beaver and river otter play an important role in nutrient exchange by foraging in aquatic habitats and defecating in terrestrial areas. This transfer of nutrients from water to land may be important in providing “fertilizer” for some forest plants.

The interchange continues when forest plants next to water bodies drop their leaves and twigs, providing a vital source of organic matter for the aquatic food web. Some of the matter falls directly into the water, while other bits may fall to the ground and be transported by rain or snowmelt. In recognition of this process, managers ought to consider that reductions in forest canopy may influence the stream-dwelling invertebrate community because of loss of energy entering the stream—which could in turn affect other fish and wildlife resources.

The protection of shoreland buffers can even benefit wildlife species that ordinarily do not need riparian habitat. In some places, shoreland buffers offer the only intact forest habitat in an otherwise heavily developed, farmed, or logged landscape. Consequently, the buffers act as vital travel corridors and refuges for creatures that could thrive far from the water’s edge, if only the habitat hadn’t been destroyed.

While scientists are still exploring the relationships among wildlife and riparian habitats around the Gulf of Maine, it is not too soon for some basic principles to be incorporated into shoreland regulations and management plans to help wildlife persist. Some initiatives by towns, states, provinces, federal agencies and private landowners around the Gulf of Maine are using the recent regional findings—along with information gleaned from elsewhere—to improve management of riparian areas and sustain the role of wildlife in these important ecosystems. The Science Translation Project of the Gulf of Maine Council is developing information resources to facilitate such efforts.

Peter Taylor (ptgomc@suscom-maine.net) is a science translator for the Gulf of Maine Council on the Marine Environment. For information about the Science Translation Project and its sponsors, visit www.gulfofmaine.org/science_translation..