Replication Data for: Greening conceals evergreening: can allelopathy undermine the resource base of a reindeer pastoralist system?

1. Ongoing Arctic greening can increase productivity and reindeer pasture quality in the tundra. However, greening may also entail proliferation of unpalatable species, with distinct consequences for pastoral socialo-ecological systems (SES). 2. We show extensive greening across 20 reindeer districts in northern Norway between 2003 and 2020. The allelopathic, evergreen dwarf-shrub crowberry biomass increased by 60%, contrasted by smaller increases of deciduous dwarf-shrubs and stagnating forb and graminoid biomass. 3. We found evidence, although uncertain, of a negative relationship between biomass and reindeer densities, but only among forbs, the least abundant plant group. 4. Our results challenge the management decision-making, which aims at sustainable pasture management, but which assumes stationary density-dependent relationships. Adaptive management criteria sensitive to changes in focal resource-consumer relationships could help to avoid mismanaging a SES in transition. 5. Large-scale shift towards increased allelopathy may undermine the resource base of a key Arctic herbivore and pastoral SES.