Invasive Species

   The invasion of national parks by nonnative species ranks among the most significant causes of biodiversity loss in parks. Nonnative plants and animals introduced into a new ecosystem produce a variety of results. Some exotic species die out. Others, such as the apple tree, cause no major ecological problems. But yet others find the new environment hospitable and free of pests or predators, allowing them to compete aggressively with native species. Invading populations then expand rapidly, severing the supporting links in a once-functioning ecosystem.

Habitat Loss and Fragmentation

   Habitat destruction, fragmentation, and degradation continue at a rapid pace in the United States, mostly outside parks. Development fragments habitat, creating barriers to wildlife movement and complicating ecosystem management at the regional and landscape levels. Scientific evidence shows that no park ecosystem can remain healthy as an isolated refuge in a sea of development, yet parks—even large ones—are becoming surrounded.

Inadequate Park Boundaries

   One of the chief problems in protecting park biodiversity is the historical fact that the national parks were not originally created to protect ecosystems. When Yellowstone became the nation's first park in 1872, lawmakers simply drew lines on a map around some of the most spectacular mountain landscapes. If scientists and ecologists were to redraw those lines today, they would be sure to include more than high mountains. They would incorporate fertile lowlands and winter feeding grounds for bison, elk, and other creatures. 

   Many park boundaries were drawn for political or administrative reasons, failing to protect winter range or critical watersheds. Cutting-edge research in conservation biology emphasizes creation of new parks, expansion of existing parks, and creation of reserves of all kinds to protect biodiversity-rich areas and weave a network of connected, protected lands resilient for the long-term.

Global Warming

   Global warming, if unchecked, will bring devastating changes to ecosystems and wildlife even within protected lands like national parks. For example:

• an increase of 3 degrees centigrade in global average temperature, likely within the next century, could eliminate 7 to 11 percent of North America's vascular plant species (Cincotta and Engelman 2000). Unique coastal plants and fauna not adapted to salt water could be inundated and obliterated by rising sea levels. 

• Certain reptiles, including alligators, crocodiles, and turtles, are likely to decline because the gender of the developing embryos is determined by nest temperature. Eggs affected by global warming might all become the same sex, precluding reproduction in future generations. 

• Bird populations are likely to dwindle in many states as increased warmth destroys vital ecosystems faster than the ecosystems can shift north to cooler climes. Warming of streams could harm aquatic plants and animals that have narrow temperature tolerances. 

• Forests and grasslands may be damaged by changes in soil temperature and chemistry, affecting survival and reproduction in plant species. Grasses, trees, and other plants may die off as ambient temperatures increase.

Disruption of Natural Processes

   The health of park ecosystems depends on some of nature's most powerful recurring forces: free-flowing rivers, fire, erosion, and even major storms such as hurricanes. The ongoing human drive to dominate and harness nature, as well as the effects of historic patterns of human action that were based on incorrect information or lack of understanding, has meant the disruption of these forces in many places.

Funding Shortfalls

   The National Park Service lacks critical information about species, biological communities, ecosystems, and how best to manage the parks to conserve biodiversity. Recovery plans for some imperiled species are often incomplete and out-of-date, and, despite recent improvements, not one park has a complete inventory of its plant and animal species or a thorough monitoring system in place. Even though the Park Service is critically short of funds, the problem goes beyond a lack of money.