Plant & lichen species composition data for Saddle Nodal Plots, 1971 - ongoing.

To study long-term changes in alpine tundra plant communities, thirty permanently marked plots were surveyed in 1971. These same plots were surveyed at twenty, thirty, forty and fifty year intervals from the initial sampling date; in 1991, 2001, 2011, and 2021. Due to covid and other events, data for the 50-year time point was collected over three summers, from 2021-2023. Plots are one by ten meters, divided into ten subplot quadrats, and marked with rebar. The presence or absence of each vascular plant species was recorded per plot. The cover was recorded for each species that appeared in a one meter by ten centimeter strip at the base of each quadrat within each plot. The cover of non-vascular plants, soil, rocks, and lichens was also recorded within the strip in most sampling years. Lichen were also surveyed in 1971 and 2021.These data have been used to study the changes in vascular plant and lichen communities and cover across habitats following a moisture gradient on the saddle portion of Niwot Ridge; these habitats include dry fellfield, dry meadow, moist meadow, wet meadow, snow bank, and shrub tundra. While we have observed some changes in species richness and cover in the plots, overall the plant communities seem fairly stable over time. Lichen species richness has increased in some habitats, while some lichen species have been disappearing from others.