Abiotic environmental change, local species extinctions and colonization of new species often co-occur. Whether species colonization is driven by changes in abiotic conditions or reduced biotic resistance will affect community functional composition and ecosystem management. We use a grassland experiment to disentangle effects of climate warming and community diversity on plant species colonization. Community diversity had dramatic impacts on the biomass, richness and traits of plant colonists. Three times as many species colonized the monocultures than the high diversity 17 species communities (~30 vs. 10 species), and colonists collectively produced 10 times as much biomass in the monocultures than the high diversity communities (~30 vs. 3 g/m2). Colonists with resource-acquisitive strategies (high specific leaf area, light seeds, short heights) accrued more biomass in low diversity communities, whereas species with conservative strategies accrued most biomass in high diversity communities. Communities with higher biomass of resident C4 grasses were more resistant to colonization by legume, nonlegume forb and C3 grass colonists, but not by C4 grass colonists. Compared with effects of diversity, 6 years of 3°C-above-ambient temperatures had little impact on plant colonization. Warmed subplots had ~3 fewer colonist species than ambient subplots and selected for heavier seeded colonists. They also showed diversity-dependent changes in biomass of C3 grass colonists, which decreased under low diversity and increased under high diversity. Our findings suggest that species colonization is more strongly affected by biotic resistance from residents than 3°C of climate warming. If these results were extended to invasive species management, preserving community diversity should help limit plant invasion, even under climate warming.
Bibliographical noteFunding Information:
We thank Troy Mielke for coordinating research at Cedar Creek, Cedar Creek interns for help with data collection and two anonymous reviewers for comments that helped improve the paper. We acknowledge funding from the Australian Research Council (DE120102221) and the ARC Centre of Excellence for Environmental Decisions (to J.A.C.), and the US National Science Foundation Long-Term Ecological Research Program, including DEB-0620652 and DEB-1234162. Cedar Creek Ecosystem Science Reserve and the University of Minnesota provided further support.
© 2020 John Wiley & Sons Ltd
- Cedar Creek Ecosystem Science Reserve
- biotic resistance
- climate change
- community diversity
- experimental warming
- functional traits
- global environmental change
- long-term grassland experiment
- plant species colonization
- species invasion