Data from: Widespread plant species temporal variation along environmental and microclimate gradients in Norwegian mountains

The effect of climate change on mountain vegetation is influenced by environmental factors and site effects. To monitor the effect of climate change we therefore need to understand species sensitivity to microclimate and environmental gradients. The objective of this study is to study widespread plant species temporal and spatial variation along environmental and microclimate gradients in Norwegian mountains along a coast-inland gradient. Occurrence and abundance of plant species were surveyed in 110 study plots in four mountains at two points in time, seven years apart. Of the 222 plant species registered, Salix herbacea, Phyllodoce caerulea, Carex bigelowii, Juncus trifidus, Vaccinium myrtillus, Avenella flexuosa, and Empetrum nigrum were widespread across all mountains. These species responded differently to environmental and microclimate gradients, and abundance data was more sensitive than occurrence data. During the short time span we observed some indications of response which might support the assumption that boreal species outcompete alpine species in the forest transition zone, but our data does not indicate this effect at higher altitudes. Monitoring of climate change in mountains need to include plots along environmental and microclimate gradients as well as abundance of a set of wide-spread plant species that represent both regional and local environmental and climate gradients. However, when monitoring perennial plant species, the necessity of long-time monitoring projects is high because such species develop slowly over several decades.