Wetlands Buffer Zones

The Town of Tuftonboro enjoys many beautiful natural resources, among them wetlands. There are many types in town: lakes, ponds, marshes, beaver ponds, brooks and rivers to name a few.

Wetlands are sometimes covered with a shallow layer of water (think of the Great Meadow) but can also be dry for part of a year (vernal pools, for example). Wetlands can be identified by observing plant and soil type:

Plants: These are wetland indicator species and border species. These are specialized plants that have adapted through time to grow in a unique environment. Two examples of wetland plants are the cinnamon fern (Osmunda cinnamomea) and cattails (Typha latifolia). Witch Hazel (Hamamelis virginiana) is a good example of a border species, a plant that typically grows just outside of the wetland. 

Soils: Wetland soils are frequently saturated with water. This produces an anaerobic state (low oxygen). This combination of saturation and lack of oxygen causes chemical changes that affect the color of the soil, making it much darker.

Before zoning ordinances were in place many wetlands were used as dumps, drained for agricultural use and filled in for industrial and residential uses.

We are realizing now that wetlands have many important uses such as habitat for wildlife (Have you ever stopped to listen to the chorus frogs, or spring peepers, on Sodom Road?), erosion and flood control, trapping of sediment, recharging the water supply, breeding and feeding areas for larger wildlife, as well as providing recreational opportunities and scenic vistas.

Wetlands are extremely valuable in our ecosystem but the wetlands are only as good as the buffer zones around them. Buffer zones are the vegetative filters of undeveloped land between the wet area and the surrounding upland area. The vegetation is native and will ensure wildlife food and cover and helps to prevent the introduction of invasive species.

Development significantly changes the quantity and quality of wetlands. The more impermeable surfaces present after development, the less rainwater is able to infiltrate the soil. Rainwater that before was able to soak into the ground now runs off of roofs, driveways and roads at an increased rate and volume. This increases erosion and sedimentation and often carries contaminants such as fertilizers, pesticides, road salts and other chemicals into the wetland.  When natural buffer zones are not present between developed areas and wetlands the rain run off will carry exposed soil particles to the wet area. This increase in sedimentation fills in the wet areas. The sediment also destroys spawning grounds for fish. Sheet flow of surface water through buffer zones acts as a natural filter, trapping a majority of the sedimentation and contaminants from the development before they reach the wetlands. Whenever possible, during the planning stage of development, consideration should be given to limiting channelization of the surface water in favor of allowing it to sheet flow across vegetated areas. This filters the sediments and contaminants prior to entering the wetland areas.

With natural buffer zones in place the run off hits the hydric soil of the wetlands and this acts as a sponge by soaking up and storing the excess water. As the water level in lakes and rivers decreases the wetlands release the water at a gradual rate and acts as a flood control. The natural vegetation found in a buffer zone will absorb some of the rain water and will slow down the run off. The plants slow the flow of the water and allows sediment to settle in the buffer zone before in enters streams and lakes. After the polluted water passes through a wetland it becomes cleaner.  Some plants are adapted to use these extra nutrients and can trap them before they enter lakes and streams. This filtering process improves the quality of the water for both humans and wildlife.

Like most of us wildlife tends to need more than just one habitat in order to survive. The gray tree frog (Hyla versicolor) is an interesting example in that it needs water for part of its life cycle but then travels some distance to find other required living conditions. This except is taken from www.nhptv.org/Natureworks/graytreefrog.htm.

 “The gray tree frog is about two inches long. It is green, gray or brown in color. It can be a solid color or it can have blotches on its back. The gray tree frog can change its color in seconds. It tends to become darker when it is cold or dark. Its coloring helps it blend in with tree bark!  It has a white underside and lots of warts. It has large, sticky toe pads that help it cling to tree bark and other surfaces. It has bright yellow to orange skin under its thighs. The gray tree frog lives in moist, deciduous woodlands and swamps near water. It is also found in pine barrens. The gray tree frog finds its food in the trees and shrubs. It eats moths, tree crickets, ants, flies, grasshoppers and beetles. It is very acrobatic and will often jump from branch to branch to catch its prey. Breeding season runs from April to August. Males will gather in trees and bushes next to breeding ponds and swamps and begin calling. The male will aggressively defend its territory from intruders. The female selects a mate based on its call. She lays her eggs on the surface of shallow water in ponds or swamps. She may also lay her eggs in standing water, in tire ruts, vernal pools or even swimming pools. The eggs are attached to vegetation to keep them from floating away. The female lays as many as 2000 eggs in groups of 10-40. The tadpoles hatch in four or five days and will change into froglets in about two months. The gray tree frog is nocturnal. It spends the day resting in trees and shrubs. At night it crawls among the branches and leaves looking for food. It usually only comes out of the trees and bushes during breeding season. To survive the cold it hibernates under leaves, bark or rocks on the forest floor. It actually freezes in the winter! The green tree frog produces large amounts of glycerol. The glycerol is changed to glucose and then it is circulated through the frog's cells. The glucose acts like kind of antifreeze and prevents ice crystals from forming in the cells. If ice crystals formed in the cells, they would rip the cells apart and kill the frog. The rest of the water and blood in the frog’s body then freezes and its heartbeat and breathing stop! When the temperature warms up, the tree frog "thaws out" and returns to the trees!” 

This amphibian is just one excellent reason why we need to create and preserve buffer zones around our wetlands.  Without varied habitat this frog as well as other amphibians, reptiles, birds, insects and larger wildlife will not be able to complete their life cycles.

Protecting wetlands and maintaining buffer zones contribute to the rural character of our state and to the health of New Hampshire’s citizens and wildlife. It is a goal of the Conservation Commission to preserve as much biodiversity as possible and to maintain healthy watersheds and aquifers. To do this the Conservation Commission recommends a buffer zone around all wetlands while maintaining 50% natural vegetation within the zone.

Sources used:

Learning on the Wing-Wetlands, the Vital Link www.fws.gov/r5mnwr/lotw/wetlands.html

Habitat-Sensitive Site Design and Development Practices… www.des.state.nh.us/factsheets/id/id-4.htm

Willow Brook Watershed Project Warner, NH

Innovative Land Use Planning Techniques: A Handbook for Sustainable Development prepared by NHDES, The regional Environmental Planning Program etc

Milford Planning Board: Zoning Ordinance-2003 http://milfordnh.info/planning/zoning.htm

A Field Guide to Common Riparian Plants of New Hampshire. Published by NH DES Volunteer River Assessment Program. October 2006