NJAS Opinion: November, 2003

Troy Ettel, Director of Conservation and Stewardship

The picturesque landscapes giving the “Garden State” its nickname are critically threatened. Over 50 acres are lost to development daily in New Jersey, a state ranked only 46th in total landmass. Despite having one of the nation’s best-funded land acquisition programs, Green Acres, New Jersey still struggles with the reality that developers continue building on sensitive lands.

If current population and development trends continue, New Jersey’s state forests, parks, and related preserves will provide the final refuges for the state’s remaining biota. Will they adequately meet that challenge? We cannot allow natural habitats to degrade to the point where species disappear from them. Yet, unfortunately, they already have.

With development threats removed, the question is, “Now what are we doing, that even ‘protected’ land is not protected?” The answer, for all but a few well-managed natural areas, is nothing. That is the problem. New Jersey lacks a cohesive, integrated vision of land stewardship that will address water quality protection and the habitat needs of threatened and endangered species on public lands.

Loss of Ecosystem Forces

The idea that Nature is incapable of sustaining itself without intervention by humans is troubling. The unfortunate reality is that human civilization has deprived many natural systems of their ability to self-regulate. Fire suppression, river damming and channelization, ditching, diking, and draining wetlands have suppressed restorative ecosystem processes like flood and fire. Today, levies and dams prevent frequent, small-scale floods, while making less frequent, massive floods more catastrophic. Likewise, fire suppression prevents frequent, low-intensity fires while allowing accumulation of fuel loads leading to more massive blazes. Floods and fires of this extent are rare in nature. Rather, they are a product of human-induced habitat changes.

In addition to changes driven by fire and water, historically, some wildlife species effected landscape-scale habitat modifications. The magnitudes of habitat changes induced by passenger pigeon roosts (covering up to 100 square miles), bison runs (pounded by thousands of hooves), or trees felled by nature’s clearcutter, the beaver (at pre-settlement densities) are unknown. In part because of their abundance and skill at habitat modification, these species interfered most with settlement. Their populations were widely extirpated or reduced, disrupting their roles as ecosystem architects. Like fire and flood, the habitat disturbances instituted by these animals have mostly disappeared from the landscape.

As forces that shape ecosystems fade away, plant and animal species dependent upon habitat regeneration also disappear. As habitat diminishes in extent, remnant patches become increasingly fragmented and isolated from each other. Of the ecosystems experiencing declines greater than 98% in eastern North America, 5% are grasslands, shrublands, and barrens and another 24% are shrub communities. These habitats are early successional, meaning that in the absence of periodic disturbance, i.e. fire, they will succeed into forested habitat. That is not too good if you are a northern pine snake, Henslow’s sparrow, or frosted elfin butterfly, all of which are threatened or endangered in New Jersey and dependent on grasslands or barrens. In fact 28.6% of all birds listed as threatened, endangered, or special concern in New Jersey are dependent on early successional habitats. Even if large acreages were purchased exclusively for these species, they would still disappear, along with their habitats, without active management. Acquisition alone is clearly not enough for them.

Alien Assailants

Besides the elimination of natural perturbations and keystone species, human actions have had other negative consequences on natural habitats in the eastern United States (U.S.). Human introductions of exotic plants and animals are severely threatening native species. Over 42% of plants and animals listed under the Endangered Species Act are threatened by predation from or competition with exotic species. Exotic species do over $138 billion of damage in the U.S. each year. History offers many heartbreaking examples demonstrating why these problems cannot be ignored.

The eastern forests of North America have been devastated by exotic insects and diseases. The American chestnut was formerly the most dominant tree and most important producer of hard mast in the eastern U.S. Today, the species is functionally extinct in the wild, the victim of an exotic fungus, and exists only as sprouts from the roots of dead trees. Others have met similar fates, or else continue to struggle. American elm succumbed to Dutch elm disease, Frazier and balsam fir to the balsam wooly adelgid, eastern and Carolina hemlocks are under attack from hemlock wooly adelgid, eastern flowering dogwood is being attacked by anthracnose, and beech bark disease is destroying American beech. These nonnative diseases and insects were all accidentally introduced to North America by humans. Both active management and adequate funding are needed to apply known treatments for some of these pathogens and to continue research for the development of effective controls. A passive response to exotic, plant diseases is a sad obituary for natural ecosystems. 

In addition to exotic insects and disease, nonnative plants are causing tremendous ecosystem damage throughout the eastern U.S. Introduced into a new continent where competitors and natural predators are nonexistent, exotic plants can quickly displace native vegetation and takeover ecosystems. Some of the worst-case scenarios include purple loosestrife which is spreading at a rate of 444 square miles per year, altering the structure of wetlands it invades, causing over $45 million in damage annually. Another highly invasive species in New Jersey that has escaped into natural areas is a popular ornamental shrub, Japanese barberry. Barberry’s popularity as a landscaping shrub comes from its ability to form dense, nearly impenetrable hedges. This trait gives the shrub a competitive advantage in forested environments, allowing it to outcompete native shrubs, herbaceous plants, and tree seedlings. Other invasive plants causing tremendous amounts of damage to native ecosystems in New Jersey include Japanese stiltgrass, Japanese honeysuckle, Asian bittersweet, princess tree, and multiflora rose. These species crowd and overtake native plants that have difficulty competing with the aggressive interlopers.

Eating Ecosystems to Death

White-tailed deer are key accomplices to the success of invasive plants. Although they are important components of natural ecosystems in New Jersey, deer quickly devastate other native wildlife and plants when they exceed the densities their habitat can support. Throughout central New Jersey, deer densities have exceeded this limit (see “Ghost Forest” this issue). Impacts of elevated deer densities can be measured in losses of native plants and other wildlife. Ground- and shrub-nesting birds such as Kentucky warbler, worm-eating warbler, and wood thrush are particularly susceptible to overbrowsing by deer and typically suffer population declines or total extirpation in areas where deer are superabundant.

Further exacerbating the problem, many native plants are favored as browse by deer over exotic plants. Denuding areas of native vegetation allows exotic plants to rapidly colonize and capture sites. The impact can reach far beyond the midstory and understory vegetation in forested situations. When trees die or fall during storms, new tree seedlings are immediately consumed by deer before they can exploit the newly created gap. As a result, some forested ecosystems in New Jersey are slowly dying and converting to habitats dominated by exotic plants.

Costs of Inaction

Human civilization has permanently altered ecosystems in New Jersey and threatens the future integrity of natural areas. Without sound stewardship, native plant communities on New Jersey public lands and populations of animals associated with them will collapse under the pressure of elevated deer densities and exotic plant, insect, and disease invasions. New Jersey Audubon Society (NJAS) joins other conservation organizations in supporting the development and implementation of comprehensive stewardship plans on public lands throughout the state to create and maintain native habitats for New Jersey’s plants and animals. NJAS further recognizes the harm that a passive response to stewardship issues will cause, and supports a proactive approach to developing solutions.