Sustainable Sites Credit 5.1: Site Development Protect or Restore Habitat

According to LEED 2009 Reference Guide for New Construction and Major Renovations,

For Greenfield Sites, limit all site disturbance to the following parameters:
1. 40 feet (12 meters) beyond the building perimeter and parking garages;
2. 10 feet (3 meters) beyond surface walkways, patios, surface parking and utilities less than 12 inches (30 centimeters) in diameter;
3. 15 feet (4.5 meters) beyond primary roadway curbs and main utility branch trenches;
4. 25 feet (8 meters) beyond constructed areas with permeable surfaces (such as pervious paving areas, stormwater detention facilities and playing fields) that require additional staging areas to limit compaction in the constructed area.

and for Previously Developed Areas or Graded Sites,
Restore or protect a minimum of 50% of the site (excluding the building footprint) or 20% of the total site area (including building footprint), whichever is greater, with native or adapted vegetation2. Projects earning SS Credit 2: Development Density and Community Connectivity may include vegetated roof surface in this calculation if the plants are native or adapted, provide habitat, and promote biodiversity.
Projects with limited landscape opportunities may also donate offsite land in perpetuity, equal to 60% of the previously developed area (including the building footprint), to a land trust within the same EPA Level III Ecoregion identified for the project site. The land trust must adhere to the Land Trust Alliance ‘Land Trust Standards and Practices’ 2004 Revision.

Hope this helps.