Quantitative information on population sizes is absent or sparse in this high elevation, non-commercial tree species. Utilizing the Research Natural Areas and Ancient Bristlecone Pine Forest acreages listed in 4b, a rough estimate of the size of individual subpopulations may range from 186 to 11,732 ha. Studies conducted in the mid-1980s concluded that subpopulations at Cedar Breaks (UT) and in the Egan Range were increasing, while the Wheeler Peak (NV) subpopulation was stable. In the White Mountains (CA) seedlings are establishing beyond the current upper elevational limits of mature trees, and no die-off is currently being observed at lower elevations, potentially indicating a continuing expansion of their range. Seedling establishment appears to be at a rate sufficient to replace current mortality.
Though generally restricted to high elevation mountain tops in the Great Basin, on isolated mountain ranges separated by xeric valleys, genetic diversity (He) is moderate to very high (0.134 to 0.327) particularly in Nevada, with little population differentiation (Fst or Gst ranging from 0.011 to 0.169) and low inbreeding coefficients (F ranging from 0.078 to 0.103). Populations in the White Mountains may be less genetically diverse than eastern populations, showing slightly lower than average genetic variation compared to most pine species.Great Basin Bristlecone Pine is well-known for slow growth rates and extreme longevity approaching 5,000 years. The Ancient Bristlecone Pine Forest contains trees as old as 4,600 years, as well as logs more than 4,000 years older and is a noted area for dendrochronology and paleoclimatic work relating to fossil timberlines. Another grove of ancient age is in Wheeler Peak Scenic Area, Humboldt-Toiyabe National Forest (NF), Nevada.