• Protect existing undeveloped forests and greenspaces from further development.
• Enhance the health, condition and function of existing tree and forest fragments to provide such things as air quality and temperature regulation, hydrologic function and habitat.
• Restore open lands and impervious areas through either planting or natural regeneration to regain original forest functions.

Understanding the Benefits of Urban Forest Cover

Trees and shrubs provide benefits, but location and forest conditions matter.

For example the protection of headwater streams, small streams found at the tops of headwaters, provides key water quality protection. These streams are the most sensitive to development because they are feed by a very small watershed area; therefore, any disturbances in these watersheds have a much greater impact than downstream waterways. In north Georgia these streams are often designated as trout streams and are the least protected. Riparian buffers and better storm water management can be used to protect the natural functions of these streams and reduce the expense of the loss of ecosystem services they provide. Identification of lands that provide greater benefits is the first step in any green infrastructure planning process.

Economic, environmental and community benefits of trees | Regional benefits of forest cover

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The economic, environmental, and community benefits of trees (modified from Cappiella, et al. 2005)

Scale	Category	Benefit
Watershed	Environmental	• Reduce storm water runoff • Improve regional air quality • Reduce stream channel erosion • Improve soil and water quality • Provide habitat for terrestrial and aquatic wildlife
	Economic	• Reduce summer air and water temperatures • Decrease heating and cooling costs • Reduce construction and maintenance costs (by decreasing costs related to clearing, grading, paving, mowing, and storm water management) • Increase property values • Positively influence consumer behavior
Parcel	Environmental	• Reduce urban heat island effect • Enhance function of storm water treatment practices
	Economic	• Increase livability • Improve health and well-being • Block UV radiation • Provide shade • Buffer wind and noise • Increase recreational opportunities • Provide esthetic value

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The regional benefits of forest cover (modified from Cappiella, et al. 2005)

Benefit	Description
Reduce storm water runoff and flooding	• Trees intercept rainfall in their canopy, reducing the amount of rain that reaches the ground. A portion of this intercepted rainwater evaporates from tree surfaces. This effect is greater in low rainfall events. • Trees take up water from the soil through their roots during transpiration, which increases soil water storage potential and lengthens the amount of time before rainfall becomes runoff. • Trees promote infiltration by attenuating runoff and by increasing soil drainage due to the creation of macropores by tree roots. The addition of organic matter (e.g. leaf litter) also increases the storage or water in the soil, further reducing runoff. • Reduced runoff from forested land reduces the frequency and volume of downstream flood events.
Improve regional air quality	• Trees absorb nitrogen dioxide, carbon monoxide, ozone, and particulate matter from the atmosphere. • Trees reduce air temperature which reduces formation of pollutants that are temperature dependent, such as ozone. • Trees indirectly improve air quality by cooling the air, storing carbon and reducing energy use, which reduces power plant emissions.
Reduced stream channel erosion	• Trees growing along a stream bank prevent erosion by stabilizing the soil with root systems and the addition of organic matter, and by substantially dispersing raindrop energy • Reduced runoff volume due to forest upstream can reduce downstream flood flows that erode the stream channel
Improve soil and water quality	• Trees prevent erosion of sediment by stabilizing soil with root systems and the addition of organic matter, and by substantially dispersing raindrop energy • Trees take up nutrients such as nitrogen from soil and groundwater • Forested areas can filter sediment and associated pollutants from runoff • Certain tree species break down pollutants commonly found in urban soils, groundwater, and runoff, such as metals, pesticides and solvents
Provide habitat for terrestrial and aquatic wildlife	• Forests (and even single trees) provide habitat for wildlife in the form of food supply, interior breeding areas, and migratory corridors • Streamside forests provide habitat in the form of leaf litter and large woody debris, for fish and other aquatic species • Forest litter, such as branches, leaves, fruits, and flowers, form the basis of the food web for stream organisms
Reduced summer air and water temperatures	• Riparian forests shade the stream and regulate summer air and water temperatures, which is critical for many aquatic species • Trees and forest shade impervious surfaces, reducing temperature of storm water runoff, which can ameliorate the thermal shocks normally transmitted to receiving water during storms. • Streamside forests provide habitat in the form of leaf litter and large woody debris, for fish and other aquatic species • Forest litter, such as branches, leaves, fruits, and flowers, form the basis of the food web for stream organisms

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