Green infrastructure includes the connected natural systems and ecological processes that provide critical functions, such as habitat for wildlife, water storage and filtration, air quality, and healthful lifestyles.  The Conservation Fund defines green infrastructure as a “strategically managed network.”  What is meant by this is that habitats are linked and a systems approach is applied at the landscape scale. 

Now more than ever, we need to take a green infrastructure approach.  Evidence for declining resources abounds nationwide. Almost 2 million acres of farmland and half a million acres of private forest are developing each year, leading to loss of species, groundwater declines, climate change and lost recreation and open space. Loss of habitat not only degrades the quality of life and the environment, but it also has real economic consequences.  Parks, protected rivers, scenic lands, wildlife habitat, and recreational open space support a U.S. tourism industry valued at $502 billion annually. 

As we lose forests, we also lose our ability to have healthy and plentiful water.  According to the Trust for Public Land, studies have documented that the larger the forest cover in a watershed, the lower the cost to treat drinking water (2007).  Preserving and expanding our natural assets is thus also central to sound economic and heath policy. 

A simple way to think about what constitutes a green infrastructure approach is that  instead of considering a park, forest or wetland as individual sites, we consider how these resources are or could be tied together (travel for plants and animals, hydrology, etc.).  Taking a green infrastructure approach requires identifying and understanding natural systems and protecting those systems first, before development begins, as well as seeking to restore connections and habitats in already-developed landscapes. 

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Many species need intact areas that are not bisected by roads, power lines, or other divisions.  Often referred to as “hubs” or “cores,” or “patches” these intact zones are required by some species, such as the Louisiana water thrush, which prefers interior forest and requires clear, clean streams.  When habitats are fragmented, other species can invade these areas and compete with native species.  For example, brown headed cow birds invade fragmented areas and place their eggs in the nests of other birds, thus competing for food and resources.