Natural Cycle Disruption

Sprawl disrupts ecological processes and natural cycles of wildlife and plants. This discussion of sprawl—and its accompanying issues of habitat fragmentation, construction of roads and other impervious surfaces, introduction of invasive species and pollution—clearly illustrates how much ecosystems have been fundamentally changed. The paving over of wetlands, grasslands, forests and other sensitive areas have resulted in many poorly functioning ecosystems, bereft of important natural processes. Indicators of this ecosystem decline are evident in poor water and air quality and in declining species numbers.

Natural disturbances, such as fires, floods, windstorms, and landslides, contribute to ecosystem function and occur intermittently over long time periods. These changes have occurred for millions of years and have significantly shaped the evolution of many species. For example, many habitat types, such as prairie, oak savannas, and ponderosa pine forests depend upon fire to survive (Noss and Cooperrider 1994). The existence of some of these habitat types is in jeopardy because fire has been suppressed for decades to protect human populations that have encroached on forests and natural areas. When fires are suppressed woody fuel builds up, causing wildfires to be larger, more destructive, and more widespread than normal, like the wildfires in the western United States that have increased in recent years. Land-use planning in the developing West must take into account the nature of these fire-prone ecological systems to reduce the risk of wildfire damage without eliminating fire from the systems.

Another example of human actions altering natural disturbances is the prevention of natural flooding regimes to protect human populations located near riparian areas. The use of dams, berms, and other methods to control the water flow of rivers have eliminated historical periodic flooding cycles, preventing the regeneration of plant species dependent on floods and, therefore, drastically changing riparian plant communities (Noss and Cooperrider 1994).

Threats to Wildlife
More than one-third of wildlife species in the United States are considered in danger of extinction. The main threat to wildlife is habitat loss and fragmentation.
Invasive Species
Sprawl encourages the growth and expansion of invasive exotic species.
Impervious Surfaces
Sprawl increases the amount of impervious surfaces such as roads, parking lots, sidewalks, and rooftops.
Natural Cycle Disruption
The paving over of wetlands, grasslands, forests and other sensitive areas have resulted in many poorly functioning ecosystems.
Pollution
Sprawl extends pollution into areas where environmental quality may not yet have been severely compromised.