Thirteen Years of Rare Plant Population Changes in the Adirondack Alpine

New York's Adirondack alpine zone harbors many rare vascular plants threatened by climate change, atmospheric deposition, and damage from recreational use. Here, we report on the results of population monitoring at 6-year intervals of 15 alpine areas. We sampled 366, 360, and 369 randomly placed plots in 2006-2007, 2013, and 2018-2019, respectively. Ten species were found in at least 5% of the plots, with Trichophorum cespitosum (Deer's Hair Club Sedge; 60% of plots) and Huperzia appressa (Mountain Firmoss; 42%) most frequent. Of these 10 species, 5 showed significant increases in density over time and 3 had no significant change in density. The 5 species showing increases also had densities positively correlated with metrics of current or former physical disturbance, such as exposure to western slopes and proximity to hiking trails. These data suggest many rare alpine plants are maintaining population levels; environmental heterogeneity and hiker education in the alpine zone may be contributing to this pattern.