American Society of Landscape Architects / Professional Practice / 2015 

Green Infrastructure:  Forests and Nature Reserves

       Forests and nature reserves -- which can include beaches and wetlands, prairies and meadows, and even desert landscapes -- have long been recognized as places for social interaction, psychological renewal, recreation, and education. In recent decades, scientists have also learned more about how natural areas provide ecosystem services such as carbon sequestration, air and water purification, and large-scale nutrient cycling for entire regions. Preserving and restoring natural areas is a remedy for long-term regional, urban, and suburban challenges, such as climate change, pollution, and loss of productive agricultural lands. Governments, organizations, and communities must continue to invest in forests and nature reserves, protecting nature in the process.

       A number of states and local governments have taken steps to raise much-needed revenue to create, expand, and preserve these important systems. Revenue bonds, transfer of development rights, and partnerships with the private sector or non-profit organizations are just a few of the methods used to create resources for natural conservation areas.

       Policy makers should also consider increased multiple-use trails, rails-to-trails, both "wild and scenic" and recreational river and greenways programs, which all provide educational opportunities that enable people to learn about the value of forests and reserves.

       As urbanization continues, it's critical for communities to work regionally to coordinate planning and design for maintaining forests and reserves. Green infrastructure of special natural, scenic, and cultural significance should be protected and preserved. In rural areas, existing parks should be rehabilitated to protect vanishing landscapes.

Forest and nature reserve benefits include:  

Water Management  

          Watersheds with more forest cover have been shown to have higher groundwater recharge, lower stormwater runoff, and lower levels of nutrients and sediment in streams than areas dominated by urban and agricultural uses. A U.S. Geological survey study of nutrients in undeveloped watersheds (mostly forested) found that forests “produced the best water quality in the country.”

     -   Forests delay water through greater interception in their multi-layered leaf canopy.

     -   Forests have sturdy, long-lived roots that help to anchor soil against erosion. Deep roots also promote greater evapotranspiration (drawing water from soil and releasing it as water vapor into the atmosphere) and thus create soil water deficits, allowing forest soils to absorb more water during storm events (think dry sponge versus wet, saturated sponge).

     -   The forest litter layer further promotes infiltration of water into the soil, slows water flow above-ground, and decreases erosion.

     -   Sub-surface water flow minimizes pollutant and sediment contamination of waterways, and gives ample opportunity for plants and microbes to take up nutrients.

     -   A large-scale watershed study analyzing 16 river mixed-use basins in the Northeast found that nitrogen loading downstream decreased as percentage of forest land increased.

     -   Forest canopy in the Pacific Northwest was also found to minimize the impact of rain-on-snow storm events, as evergreen conifers intercepted rain precipitation. Reduced windspeeds and more consistent air temperatures due to forest canopy also resulted in slower snowmelt and more gradual run-off rates. (1)

Economic

     -   Sanitation District #1 in northern Kentucky (covering 220 square miles) developed an integrated watershed-based plan providing cost savings of up to $800 million. Its green infrastructure projects will reduce annual combined sewer overflow (CSO) burden by 12.2 million gallons. (2)

     -   Seven U.S. cities with excellent water quality (resulting from protecting regional forest systems) have saved from $500,000 to $6 billion in avoided water treatment infrastructure costs (2)

Air Pollution

     -   According to a study quantifying ecosystem services resulting from Portland, Oregon’s green infrastructure practices in 2009, public acquisition of natural areas reduced particulate matter less than 10 micrometers in diameter (PM-10) by 23.3 lbs per acre per year. (3)

Property Value

     -   One study found home values within 800-1,000 feet of parks increased in property value by 14 percent. Property values increased by 3-13 percent near forests with restored streams. (3)

Role of the Landscape Architect

       Since Frederick Law Olmsted, who founded the profession of landscape architecture, landscape architects have created regional plans, which lay out areas for development and other areas for the protection and preservation of natural areas. These plans enable growth to happen elsewhere, making forest and nature reserve protection real for the long-term. 

       At the planning level, landscape architects work with communities and scientists to analyze existing green spaces and determine the most important areas for conservation and recreation and propose areas for reforestation and a restoration.

       Landscape architects create master plans for parks, trail networks, wildlife habitats, recreation and gathering spaces; and draft design details from road systems on down to visitor centers, transportation systems, and interpretive art and signage.

Sources:

        (1). “Natural Infrastructure: Investing in Forested Landscapes for Source Water Protection in the United States,” World Resources Institute   

       (2).“Banking on Green: A Look at How Green Infrastructure Can Save Municipalities Money and Provide Economic Benefits Community-wide,” ASLA

       (3). “Portland’s Green Infrastructure: Quantifying theHealth, Energy, and Community Livability Benefits,” Environmental Services, City of Portland