The vegetation in the Arctic is changing, and tundra ecosystems in the southern limit of the Arctic become greener and gradually give way to boreal ecosystems. This change affects local populations, wildlife, energy exchange processes between environmental compartments, and the carbon cycle. To understand the progression and the implications of this vegetation transition, satellite measurements and surface models can be employed, but in situ observational data are required for validation. This data collection presents such data from two nearby sites in the forest-tundra ecotone in the Tasiapik valley near Umiujaq in northern Quebec, Canada. One site is on a mixture of lichen and shrub tundra and the data set there comprises 9 years of meteorological, soil and snow data as well as 3 years of eddy covariance data. The other site, 850 m away, features vegetation consisting mostly of tall shrubs and black spruce. There, 6 years of meteorological, soil and snow data are available. In addition to the data from the automated stations, profiles of snow density and specific surface area were collected during field campaigns.