Alpine soil islands plant and soil microbial community composition, 2024.

High alpine ecosystems are particularly sensitive to climate-driven change, with vegetation expansion increasingly observed in historically barren soils. In late August and early September 2024, we revisited 50 previously established vegetation plots in Green Lakes Valley (Niwot Ridge LTER) to evaluate patterns of plant colonization and community change over time. Using legacy vegetation data from 2008 and 2015, we assessed changes in plant cover and composition in relation to microtopography and prior plant occurrence. Concurrently, we collected soil samples for 16S and 18S rRNA gene sequencing to characterize bacterial, archaeal, and eukaryotic microbial communities associated with these plots. Vegetation was resampled using spatially referenced 1-meter radius surveys, estimating species incidence and cover and documenting moss, lichen, sedge, and grass diversity. Together, these above- and belowground data provide insight into how priority effects, fine-scale environmental variation, and plant–microbe interactions influence alpine community dynamics, and may inform predictive models of ecosystem responses to ongoing climatic shifts.