Replication Data for: Long-term homogenization of Fennoscandian heathland and tundra vegetation is connected to the expansion of an allelopathic dwarf shrubdoi:10.18710/VYQFPKDataverseNO2025-08-111Maliniemi, Tuija; Kiilunen, Petteri; Bråthen, Kari Anne; Kapfer, Jutta; Bockelie Rosendal, Torunn; Grytnes, John-Arvid; Saccone, Patrick; Virtanen, Risto, 2025, "Replication Data for: Long-term homogenization of Fennoscandian heathland and tundra vegetation is connected to the expansion of an allelopathic dwarf shrub", https://doi.org/10.18710/VYQFPK, DataverseNO, V1Replication Data for: Long-term homogenization of Fennoscandian heathland and tundra vegetation is connected to the expansion of an allelopathic dwarf shrubdoi:10.18710/VYQFPKMaliniemi, TuijaKiilunen, PetteriBråthen, Kari AnneKapfer, JuttaBockelie Rosendal, TorunnGrytnes, John-ArvidSaccone, PatrickVirtanen, RistoTuija MaliniemiTuija MaliniemiPetteri KiilunenKari Anne BråthenJutta KapferTorunn Bockelie RosendalRisto VirtanenUniversity of OuluUiT The Arctic University of NorwayR statistical environment259072302749Finnish Cultural FoundationProfi6, 336449, Biodiverse AnthropocenesUniversity of Oulu262693, 730938DataverseNOUiT The Arctic University of NorwayMaliniemi, TuijaBråthen, Kari AnneMaliniemi, Tuija2025-08-01Earth and Environmental Sciencesbiodiversity changevegetation resurveyheathlandstundraEmpetrum nigrumcrowberrybiotic homogenisationThis dataset contain plant community data (including vascular plants, bryophytes and lichens) from 275 vegetation plots from northern Fennoscandia (northern Finland and northern Norway). Values for each species are percentage cover estimates from 2 x 2 meter plot. Each plot has been surveyed twice, i.e., species have old and new percentage cover from 1964-75 and from 2013-23. We analyzed temporal changes in community composition and diversity across the study area and in different biogeographic zones, continentality-humidity classes and habitat types. We found a strong homogenization trend across the study area, with plant communities becoming more similar in composition over the decades when all taxa were treated together. The observed homogenization was driven especially by the increased similarity of vascular plant and lichen communities and was largely independent of biogeographic zones or continentality-humidity gradient. Homogenization was particularly associated with the drastic encroachment of the evergreen dwarf shrub Empetrum nigrum in habitat types originally dominated by other species, and with the decrease in lichen cover. In general, our findings suggest that Fennoscandian heathland and tundra vegetation is transforming towards a more homogeneous evergreen dwarf shrub-dominated system, which may threaten ecosystem multifunctionality. Our results highlight the importance of exploring biodiversity among different metrics and growth forms to understand the overall changes in heathland and tundra biodiversity.1964197520132023FinlandNorway17316671survey dataData from the original survey were extracted from Haapasaari, M. 1988. The oligotrophic heath vegetation of northern Fennoscandia and its zonation. - In: Acta Botanica Fennica 135. Finnish Botanical Publishing Board.<a href="http://creativecommons.org/publicdomain/zero/1.0">CC0 1.0</a>A third survey round and monitoring is ongoing for this dataset (not included in this dataset or in the related publication). Please contact Point of Contact (Tuija Maliniemi) for more information and/or data.Maliniemi, T., Kiilunen, P., Bråthen, K.A., Kapfer, J., Bockelie Rosendal, T., Grytnes, J.-A., Saccone, P. & Virtanen, R. (2025). Long-term homogenization of Fennoscandian heathland and tundra vegetation is connected to the expansion of an allelopathic dwarf shrub. Ecography. https://doi.org/10.1002/ecog.0792110.1002/ecog.07921Maliniemi, T., Kiilunen, P., Bråthen, K.A., Kapfer, J., Bockelie Rosendal, T., Grytnes, J.-A., Saccone, P. & Virtanen, R. (2025). Long-term homogenization of Fennoscandian heathland and tundra vegetation is connected to the expansion of an allelopathic dwarf shrub. Ecography. https://doi.org/10.1002/ecog.0792100_Maliniemi_et_al_2025_Ecography_README.txttext/plainMaliniemi_et_al_2025_Ecography_data_for_Figure_3.csvtext/comma-separated-valuesMaliniemi_et_al_2025_Ecography_data_for_Figure_4.csvtext/comma-separated-valuesMaliniemi_et_al_2025_Ecography_main_data.csvtext/comma-separated-valuesMaliniemi_et_al_2025_Ecography_R_code.Rtype/x-r-syntax