The highest ranked Last Great Place honors one of America’s pioneering conservationists – the John Muir Wilderness in California’s Sierra Nevada ecoregion, followed by Big Bend National Park in the Chihuahuan Desert.
The top 25 ranked Last Great Places are shown in the table below.
The Last Great Places rank was determined on a 50-50 weighting of the overall percentile rank (among 3000 sites) and the ecoregion percentile rank (up to 60 sites per ecoregion). As a result, some overall highly ranked sites, such as Zion National Park (#2 ranked site in its ecoregion), are not on the top 25 list. Click here to review Methods.
Click here for the interactive Rankings spreadsheet. Sort and filter data to explore by ecoregions, ranks, types, or scores for each of the seven ranking factors.
Total Acres and Percent of Lower 48 States. The combined portfolio of 3000 sites, after all major portfolio overlaps were accounted for, was ~438,000,000 acres – representing approximately 22% of the ~1,997,000,000 acres of land and water in the lower 48 states.
Average Size. The average size of the 3000 sites across the three portfolios was approximately 193,000 acres, which was skewed upward by a few very large sites. The median size was approximately 59,000 acres. The largest site was the 8.6 million acre Northern Maine Forest Block IBA.
Ecoregional Representation. High-ranked sites were well distributed across the ecoregions. The top 100 sites included 33 ecoregions, the top 500 sites 60 ecoregions, and the top 1000 sites all 69 ecoregions. Among the top 100 sites, the ecoregions with the largest number of sites were all in the western United States.
Ecosystems Captured. The top 1000 sites in each of the portfolios capture over 95% of the 689 natural ecosystems in the lower 48 states, and multiple examples of the vast majority of ecosystems. Unsurprisingly, many of the ecosystems not captured are small localized systems with less than 1000 acres nationwide.
Portfolio Efficiency. The top 1000 PAs (including many national parks and wilderness areas) constituted the most efficient portfolio, with 95% of all ecosystems represented in just 104 million acres (~5% of conterminous U.S. area).
Overlapping Sites. There was substantial overlap among many of the sites in the three portfolios. For example, TNC’s Mt. Baxter site in the top 25 list above is located within the John Muir Wilderness. Also, the Frank Church – River of No Return Wilderness is included twice above, once as a PA and once as a TNC site. Different scores are due to different sizes or map configurations. America’s Last Great Places did not attempt to integrate or “resolve” the overlaps, as boundaries were rarely identical, but rather let each portfolio stand on its own accord.
Other Key Findings – Ranking Factors
Ecological Land Units (ELUs). Larger sites, unsurprisingly, tend to have greater variety of landforms, geology, climate regime and land cover; all of the top ten sites for ELU variety are over 1,000,000 acres. The variety of ELUs varies dramatically by ecoregion, from a high of 3857 in Lower New England / Northern Piedmont to only 118 in Tropical Florida.
Ecosystems. Site size is an important driver, but less so than with ELUs. Four sites have 65 or more different ecosystems. Ecosystem variety also differs by ecoregion, ranging from 26 to 121.
Rare and Imperiled Species Richness. Rare and imperiled species richness varies widely across the lower 48 states. The ecoregions with the most imperiled species are three orders of magnitude greater than the least-rich ecoregion. The top 10 sites for imperiled species richness are found in five ecoregions.
Human Modification. The top 10 sites for lowest human modification are found in six ecoregions, with three sites each in the Great Basin and the Sierra Nevada. The highest modification is found in the agricultural North Central Tillplain and the developed North Atlantic Coast.
Vegetation Condition. Two ecoregions have low mean overall ecological departure – the Wyoming Basins and the Black Hills. Four predominantly agricultural ecoregions have extremely high mean ecological departure.
Resilience. The ecoregions with the highest mean resilience scores were those with high geophysical relief (e.g., Black Hills, Sierra Nevada and Southern Blue Ridge. The lowest scores were in coastal/low-relief ecoregions (e.g., Florida Peninsula and Chesapeake Bay Lowlands. Site resilience was somewhat idiosyncratic and influenced by site boundaries as well as their inherent geophysical features.
Conservation Management. 283 of the 3000 sites had the lowest and best possible management score (GAP Status 1). These were predominantly Wilderness Areas, National Parks, National Wildlife Refuges, and a handful of IBAs and TNCs that overlapped federally protected areas.
Click here to download a Word document with detailed discussion of Results.