The Vermont Agency of Natural Resources
Forests and Forest Lands

Diverse and healthy plant and animal populations are essential components of healthy ecosystems. These include terrestrial ("upland") ecosystems such as hardwood and conifer forests, alpine tundra, and open fields, and aquatic ecosystems such as lakes, ponds, rivers, streams, and wetlands. In addition, Vermont’s wildlife heritage supports various activities for residents and visitors alike including wildlife watching, fishing, photography, and hunting.

Although we have varying levels of knowledge about the population and health status of Vermont’s plants and animals, one point is clear: all native species, including the tiniest or seemingly most obnoxious, are important components of properly functioning ecosystems. Consequently, the Department of Fish and Wildlife monitors the distribution, abundance, and health of the state’s plant and animal life.

THREATS TO VERMONT’S ECOSYSTEMS

There are a number of real and potential threats to the integrity of Vermont's ecosystems. At present, the Department is most concerned about land use practices which directly or indirectly impact critical habitats (e.g. deer winter range, fish spawning areas) and rare, threatened, or endangered species. Although little background data exist, the accumulation of toxic substances in plants and soils is a potential threat to wildlife and human health (e.g. cadmium in deer and moose livers). A third concern is the establishment and proliferation of "exotic" (i.e. non-native) plant and animal species which can significantly alter ecosystem functioning.

HABITAT ALTERATION

While gaps in historical data often make it difficult to directly assess the loss of habitat, evidence of ecosystem decline does exist. The "sandplain forest" of the Winooski River Valley was once a significant and vibrant ecosystem covering approximately 15,000 acres in the Burlington region. Development pressures over the past century have reduced the sandplain forest to its current level of less than 600 acres (Fig. 1).

In cases where direct evidence of habitat loss is lacking, species particularly sensitive to changes in habitat can act as indicators of ecosystem health. Three such indicators of habitat alteration in Vermont are black bears, forest birds, and freshwater mussels.

Black bears require large blocks of contiguous, relatively remote forest land. The Department is attempting to raise the black bear population from its current estimated 2,300 animals to 2,500 animals. Achievement of this goal depends upon the continued protection of critical sources of food, such as beech stands and wetland communities, and upon the availability of large blocks of forest with little impact from development. Annual bear harvest data will be used to assess progress toward this goal and range mapping will be used to monitor habitat availability.

Forest fragmentation can have negative impacts upon some songbirds and birds of prey. In Vermont, as the amount of forest land has increased in recent decades, populations of songbirds and birds of prey have generally remained stable or increased. According to the U.S. Fish and Wildlife Service Breeding Bird Survey data, Of the 34 songbirds and birds of prey which nest in Vermont forests, 10 species showed significant increases between 1966 and 1991, 23 species showed no significant population changes, and only one showed a significant decline.

Modification of stream and river flows and channel structure can result in severe impairment of the ability of certain species to reproduce. One group of species particularly sensitive to these types of habitat alterations are native freshwater mussels. Mussels move little during their lifetimes and do not easily adapt to sudden or rapid changes in their habitat. The favored habitat of mussels is often directly eliminated by construction projects or indirectly but often fatally altered through large increases in sediment build-up.

Vermont's waters can support a relatively high diversity of mussel species (17 species), but today most rivers have few species or support low numbers of mussels. In the early 1900s, the Connecticut River above Massachusetts supported at least 7 mussel species, including the presently endangered dwarf wedge mussel. This mussel, which historically occurred in many locations between the Connecticut Lakes and Massachusetts, is now located only in one 18-mile stretch of the river. Long-term monitoring of this mussel's population is currently underway.


POLLUTION

Pollution is a threat to both terrestrial and aquatic plants and animals. Development along waterways can add various pollutants and massive amounts of sediment. High amounts of phosphorus discharges can lead to rapid algae growth and subsequent decreases in water oxygen. Ammonia, nitrates, and chlorine in aquatic systems can kill aquatic organisms.

In the past decade there have been documented fish kills in the Dog, Willoughby, Johns, and Clyde Rivers. A 1989 chlorine spill to the Dog River killed an estimated 1,600 wild rainbow trout and up to 16,000 fish of other species along a 6/10 mile segment of the river. These events kill not only fish, but other aquatic life (e.g. insects) that are important parts of the food chain.

Certain toxic substances such as mercury and PCBs persist in the environment and accumulate in the flesh of fish. Fish consumption advisories (recommended limitations on the consumption of particular fish species) remain in effect for certain long-lived fish species in Lake Champlain and in one Vermont river (Fig. 2).

Persistent toxic chemicals are a threat not only to human health, but also to other animal species that eat aquatic organisms. Two birds of prey, the osprey and peregrine falcon, had disappeared from Vermont by the 1960s and 70s. Because of widespread pesticide use (e.g. DDT) which they picked up in their food, these species we're no longer able to produce viable eggs and their populations plummeted throughout the eastern U.S.

With bans on the use of these pesticides and some assistance in providing nest sites, Vermont's osprey and peregrine populations have rebounded. In I 994, nine nesting pairs of ospreys produced 23 young. In 1985, the first instance in more than 25 years of a wild peregrine nesting pair producing young was recorded in Vermont. In 1994, 11 breeding pairs produced 31 young falcons which survived to fledge (Fig. 3).


INTRODUCTION OF NON-NATIVE SPECIES

Introduction of non-native plants and animals has altered the structure of wetland, lake, and stream ecosystems. These species, facing no effective natural controls, out compete native species for habitat and food sources. Examples of non-native species affecting Vermont include sea lamprey, white perch, rudd fish, zebra mussel, and Eurasian watermilfoil.

Zebra mussels offer a recent example of the significant impacts and costs associated with the introduction of non-native species. Zebra mussels were first observed in Lake Champlain in 1993 near Benson, Vermont. As of September 1994, adult zebra mussels have been found in scattered locations throughout the lake and are expected to be well established lakewide within 1-3 years. Initial capital costs for the protection of public water intake pipes are estimated at $5-10 million; the ultimate costs to society and the environment are incalculable.

CHALLENGES

Negative impacts to fish and wildlife habitat and whole ecosystems should be evaluated, prevented, or mitigated. Steps toward achieving these goals should include: