title: Herbivory and nutrient limitation protect warming tundra from lowland species' invasion and diversity loss.
abstract: Herbivory and nutrient limitation can increase the resistance of temperature-limited systems to invasions under climate warming. We imported seeds of lowland species to tundra under factorial treatments of warming, fertilization, herbivore exclusion and biomass removal. We show that warming alone had little impact on lowland species, while exclusion of native herbivores and relaxation of nutrient limitation greatly benefitted them. In contrast, warming alone benefitted resident tundra species and increased species richness; however, these were canceled by negative effects of herbivore exclusion and fertilization. Dominance of lowland species was associated with low cover of tundra species and resulted in decreased species richness. Our results highlight the critical role of biotic and abiotic filters unrelated to temperature in protecting tundra under warmer climate. While scarcity of soil nutrients and native herbivores act as important agents of resistance to invasions by lowland species, they concurrently promote overall species coexistence. However, when these biotic and abiotic resistances are relaxed, invasion of lowland species can lead to decreased abundance of resident tundra species and diminished diversity.
authors.affiliation: Department of Ecology, University of Oulu, P.O. Box 3000, FI-90014, Oulu, Finland.|Department of Physiological Diversity, Helmholtz Center for Environmental Research-UFZ, Permoserstr. 15, 04318, Leipzig, Germany.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103, Leipzig, Germany.
authors.forename: Anu
authors.initials: A
authors.lastname: Eskelinen
authors.affiliation: Department of Ecology and Environmental Sciences, Umeå University, SE-90187, Umeå, Sweden.|Plant Biology and Nature Management, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels, Belgium.
authors.forename: Elina
authors.initials: E
authors.lastname: Kaarlejärvi
authors.affiliation: Department of Ecology and Environmental Sciences, Umeå University, SE-90187, Umeå, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Olofsson
mesh_terms: D044822:Biodiversity; D018533:Biomass; D005502:Food; D057232:Global Warming; D060434:Herbivory; D012987:Soil / Q000737:chemistry; D065929:Tundra
chemical_list: D012987:Soil
keywords: abiotic resistance; biotic resistance; colimitation; community-weighted mean traits; establishment limitation; grazing; multiple interacting global changes; range shift