Riparian Restoration
CHAPTER 3: HOW RECREATION IMPACTS AFFECT KEY CHARACTERISTICS OF RIPARIAN ECOSYSTEMS (CONTINUED)
Wildlife
Complex structure and function, species diversity, and age composition of riparian habitats are essential elements for sustaining healthy wildlife populations (McKee and others 1996). The presence of water and rich plant diversity encourages animal diversity. Less and/or weakened vegetation means less available vegetative matter (structure) for animals and microbes to use for food and shelter (Knight and Gutzwiller 1995). Wildlife also affects plant diversity because it pollinates plants and transports seed. See figure 47.
The presence of humans, their paraphernalia, and their machines affects the health of the riparian ecosystem and the welfare of wildlife. Knight and Cole cite four main ways that humans impact wildlife: (1) exploitation (hunting, trapping, collection), (2) disturbance (intentional or not; for example, wildlife viewing, hiking through an animal’s territory), (3) habitat modification, and (4) pollution (Knight and Gutzwiller 1995). See figure 48.
Figure 48—Partially hiding used toilet paper under a rock is
not only unsightly
and unsanitary; it could also attract and
sicken
wildlife. It may signify ignorance
about
proper waste
disposal procedures and overuse of an area.
“Long-term effects of repeated disturbances range from an increase in the population of one or more species tolerant of human activities to the extirpation of one or more populations” (Stanley 2000). These disturbances affect the diversity and dynamics of the ecosystem. Even seemingly innocuous activities such as picnicking and wildlife viewing can have longlasting effects on wildlife. Encounters increase the metabolism of animals, causing them to burn more calories and expend more energy (Stanley 2000).
Although the human impact on wildlife is not well researched, some data exists. For instance, wildlife viewing or photography can cause animals to change their normal behaviors. Steve Cain, senior wildlife biologist at Grand Teton National Park, notes that “encounters with humans increase stress on animals that are already struggling to survive. As the fight-or-flight instinct kicks in, some animals may flounder through deep, heavy snow to get away. Even if an animal sits still in an encounter with humans, its metabolism is probably racing and its energy stores are rapidly declining.
Biologists have quantified this effect using heart-rate monitors. By some estimates, an ungulate may expend a week’s worth of energy during a single encounter with a human” (Berwyn 2001). Other examples of data concerning human impact on wildlife are as follows:
- Winter recreation can be more detrimental
than warm-season recreation for wildlife because animals are weak and stressed
in the winter. Compacted snow is deadly for small mammals, such as voles.
For example, in meadows snow forms an insulating layer that keeps the ground
warm
enough for animals to survive the winter. When snow is compacted, it loses
its insulating value and causes the ground temperature to drop and the animals
to
die. Snowmobiles are particularly damaging to frozen shrubby vegetation,
which is brittle and snaps off when run over. (Cole as quoted in Alexander
and Fairbridge
1999). Winter recreation can cause loss of habitat and food.
- Klein (1993)
found that photographers exited their vehicles and moved closer to wildlife
more frequently
than other wildlife viewers, causing unforeseen problems such as one that
Klein (MacIvor and others 1990) points out: “Predators learn to follow the human scent
trails to
nest sites” where humans had ventured (Knight and Gutzwiller 1995).
- Yarmoloy and others (1988) noted that radio-collared mule deer altered their feeding and spatial-use patterns and showed a loss in reproductivity a year following harassment with all-terrain vehicles (ATVs) (Knight and Gutzwiller 1995).
Bears and their habitat are affected by human behaviors, such as recreational-use patterns and habits. Bears have learned to associate humans and camping with food. Rather than spend their time foraging, as nature would have it, they seek out improperly stored food caches for easy meals. As a result, nuisance bears may have to be killed or be relocated from their territories. They and other animals also are susceptible to human disease and can become ill from exposure to trash and food left behind by humans (Cole as quoted in Alexander and Fairbridge 1999). See figure 49.
Figure 49—This campfire is full of nonbiodegradable trash that
should
have been
packed out. It may be a hazard to wildlife.
Impact Matrix
See appendix A for a matrix that summarizes potential impacts of recreation facilities and activities to riparian forests.
E-mail: 