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The Large Intact Blocks (LIB) dataset was calculated from the NatureServe Landscape Condition model as a way to identify large areas that were relatively intact or had low levels of anthropogenic impacts.Large Intact Blocks (LIBs) were derived directly from the landscape Condition scores similar to the methods used by the Washington Habitat Connectivity Working Group, as implemented in the Habitat Core Area tool (WHCWG 2010). The landscape was divided into 5 major ecodivison groups to account for major landscape Condition differences across the western United States (Great Plains, Rocky Mountains, Warm desert, Intermountain Basin, and Pacific Coast)
The Landscape Condition Quality Threshold (LCQT), or the minimum LC value that was considered to be high enough quality to be considered a core “block” or patch was identified for each sub region. The LCQT was determined using the footprint of the areas identified in the Protected Areas Database (PAD) that had a Gap status 1-3. The threshold value was the LC value that represented the top 80% of the LC values within the PAD.
The LC data was smoothed using a 1,000 ha moving window, then areas within each ecodivision were analyzed against their unique LCQT value and groups of pixels above that threshold and greater than the 1,000 ha minimum size threshold were identified as Large Intact Blocks (LIBs). Each LIB was then binned into three levels of importance, based on relative level of intactness in its ecodivision (3 quantiles based on mean LC value) and its total area (1,000 – 10,000 ha, 10,000 – 50,000 ha, and 50,000+ ha). LIBs with the highest third of mean LC values regardless of size were ranked as level 1. LIBs that were 10,00-50,000 ha in size that were not classified as Level 1 were classified as Level 3 importance. All remaining LIBs were classified as Level 2 importance.
This data layer is one of three that were produced to support the WGA Wildlife Council Landscape Integrity Working Group. The intent of these work products are to provide individual states with information on current landscape condition, significant large intact blocks and important connectivity zones mapped across the state and regional boundaries. These data may or may not be used by each state in the development of a state’s final crucial habitat map. States may choose to supplement or replace the work group data with other data sources that may be available only for their state (and neighboring states). The final crucial habitat maps are not expected to be published until fall of 2013, and data the states use of these data in creating their crucial habitat maps may change. As potential users of these data you are encouraged to talk with each state to further identify any additional concerns a state may have or updated data layers that are produced subsequent to the publication date of these layers.
For more information see LIB_methods.pdf and WGA Landscape Integrity Workgroup Recommendations, unpublished reports to WGA Wildlife Council State Technical Team dated 02/12/2013.