Abstract
The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). Reindeer grazing was found to be extensive in southern Lapland and had limited effects on plant community composition and seedling germination. However, reindeer presence was found to influence plant functional traits, particularly in the subalpine birch forest. Tall herbs were lower and had lower SLA when reindeer were present, while small herbs showed an opposite pattern. The contrasting effects on the two herb groups are probably explained by a competitive release for small herbs when the tall herbs are suppressed by reindeer. Rodents had the largest relative impact on plant community composition in southern Lapland and this is consistent with the study from Finnmark, where rodents heavily affected dwarf shrubs on predator-free islands. With no predators present, vole densities increased profoundly and almost depleted some dwarf shrub species. These results support the idea that small mammals in arctic and alpine tundra are controlled by predators (i.e. top-down). However, a decrease in the nutritional quality in a sedge after defoliation gives support for the idea that small mammals are regulated by plant quality (i.e. bottom-up). In Beringia, small and large herbivores differed in the relation to plant community composition, since large herbivores were related to species richness and small herbivores were related to plant abundance. Plant functional traits were related only to large herbivores and standing crop of vascular plants.
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Claims 10
Claim · model-written summary
Reindeer grazing in southern Lapland had limited effects on plant community composition and seedling germination.
- Taxon
- plante0
- Interactor
- Reindeer
Rangifer taranduse0herbivore - Outcome
- plant community composition and seedling germinatione0
- Setting
- southern Laplande0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reindeer grazing was found to be extensive in southern Lapland and had limited effects on plant community composition and seedling germination.”
Claim · model-written summary
Tall herbs were shorter and had lower specific leaf area where reindeer were present.
- Taxon
- Tall herbse0
- Interactor
- reindeerRangifer taranduse0herbivore
- Outcome
- SLAe0
- Direction
- lowere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Tall herbs were lower and had lower SLA when reindeer were present”
Claim · model-written summary
Small herbs showed the opposite trait pattern where reindeer were present.
- Taxon
- small herbse0
- Interactor
- reindeerRangifer taranduse1herbivore
- Outcome
- opposite patterne0
- Direction
- oppositee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while small herbs showed an opposite pattern.”
e1“Tall herbs were lower and had lower SLA when reindeer were present”
Claim · model-written summary
Rodents had the largest relative effect on plant community composition in southern Lapland.
Verbatim
e0“Rodents had the largest relative impact on plant community composition in southern Lapland”
Claim · model-written summary
On predator-free islands in Finnmark, rodents heavily affected dwarf shrubs.
Verbatim
e0“Finnmark, where rodents heavily affected dwarf shrubs on predator-free islands”
Claim · model-written summary
With predators absent, voles increased profoundly and nearly depleted some dwarf shrub species.
Verbatim
e0“With no predators present, vole densities increased profoundly and almost depleted some dwarf shrub species.”
Claim · model-written summary
Defoliation reduced a sedge’s nutritional quality.
Not reportedComparator
Verbatim
e0“a decrease in the nutritional quality in a sedge after defoliation”
Claim · model-written summary
In Beringia, large herbivores were related to plant species richness.
- Taxon
- vascular plantsTracheophytae0
- Interactor
- large herbivorese1herbivore
- Outcome
- species richnesse1
Not reportedDirection
Verbatim
e0“Plant functional traits were related only to large herbivores and standing crop of vascular plants.”
e1“large herbivores were related to species richness”
Claim · model-written summary
In Beringia, small herbivores were related to plant abundance.
Not reportedDirection
Verbatim
e0“small herbivores were related to plant abundance”
Claim · model-written summary
Plant functional traits were related only to large herbivores and vascular plant standing crop.
- Taxon
- vascular plantsTracheophytae0
- Interactor
- large herbivorese0herbivore
- Outcome
- Plant functional traitse0
Not reportedDirection
Verbatim
e0“Plant functional traits were related only to large herbivores and standing crop of vascular plants.”