umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Increased snow cover causes a shift towards negative neighbor interactions in tundra plant communities.
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
School of Biological and Biomedicinal Sciences, Institute of Ecosystem Science, University of Durham, Durham DH1 3LE, UK.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Gradients of increasing environmental harshness are associated with a shift from negative to positive interactions between plants. In alpine ecosystems, the severity of the environment generally increases with altitude and positive interactions between neighboring plants dominate at higher altitudes, while negative interactions dominate at lower altitudes. Similar shifts occur along local topographic gradients, where positive interactions predominate on exposed ridges, while negative interactions are more common in protected habitats. In a recent experiment, it was found that earlier snow-melt caused a shift towards more positive interactions between neighboring plants. This result suggests that differences in the duration of snow cover are responsible for differences in interactions between plants within such habitats. We examined this hypothesis by investigating the effect of longer-lasting snow cover on the intensity and direction of interactions between plants along an environmental gradient from exposed ridges with little natural snow cover to more sheltered fens and heathlands. We recorded a shift from positive interactions with neighbors on exposed ridges to negative interactions with neighbors in heathlands and fens. In accordance with previous studies, the increased snow cover resulted in more negative netinteractions between plants, but the effect was similar in all habitats. Other factors such as nutrient availability, soil humidity or wind exposure might explain these differences between habitats with respect to plant–plant interactions. These results improve our understanding of how abiotic conditions shape species interactions and thus add to our ability to predict how interactions between plants, and thus the composition of plant communities, will change in response to climate change.

National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:umu:diva-30413OAI: oai:DiVA.org:umu-30413DiVA: diva2:282797
Note
Submitted manuscript.Available from: 2009-12-22 Created: 2009-12-21 Last updated: 2009-12-22Bibliographically approved
In thesis
1. The Effect of Snow on Plants and Their Interactions with Herbivores.
Open this publication in new window or tab >>The Effect of Snow on Plants and Their Interactions with Herbivores.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The ongoing climate changes are predicted to accelerate fast in arctic regions with increases in both temperatures and precipitation. Although the duration of snow cover is generally expected to decrease in the future, snow depth may paradoxically increase in those areas where a large amount of the elevated precipitation will fall as snow. The annual distribution and duration of snow are important features in arctic ecosystems, influencing plant traits and species interactions in various ways. In this thesis, I investigated the effect of snow on plants and their interactions with herbivores by experimentally increasing the snow cover by snow fences in three different habitats along an environmental gradient in Abisko, northern Sweden.

I found that the snow cover mattered for plant quality as food for herbivores and herbivore performance. An enhanced and prolonged snow cover increased the level of insect herbivory on dwarf birch leaves under field conditions. Autumnal moth larvae feeding on leaves that had experienced increased snow-lie grew faster and pupated earlier than larvae fed with leaves from control plots. These findings indicated that plants from snow-rich plots produced higher-quality food for herbivores. My studies showed that differences in snow-lie explained parts of the within-year spatial and seasonal variation in plant chemistry and patterns of herbivory in this arctic landscape. The relationship between leaf nitrogen concentration and plant phenology was consistent between treatments and habitats, indicating that snow per se, via a delayed phenology, was controlling the nitrogen concentration. The relationship between leaf age and level of herbivory was positive in the beginning of the growing season, but negative in the end of the growing season, indicating an increasing importance of plant palatability and a decreasing importance of exposure time in determining the level of herbivory throughout the growing season. The concentrations of phenolics varied among habitats, treatments and sampling occasions, suggesting that these plants were able to retain a mosaic of secondary chemical quality despite altered snow conditions. Furthermore, the nutrient limiting plant growth, according to N:P ratio thresholds, appeared to shift from nitrogen to phosphorus along the topographic gradient from snow-poor ridges to more snow-rich heathlands and fens. Snow addition had, however, no significant effect on other nutrient concentrations than nitrogen and no significant effect on the leaf N:P ratio, indicating that differences in snow cover could not explain the variation in plant nutrient concentrations among habitats. In a five-year study, I found opposing inter-annual effects of increased snow on plant chemistry. In contrast to earlier results, the effect of snow-lie on plant nitrogen concentration was predominantly negative. However, the effect of increased snow cover on the level of herbivory remained predominantly positive. The strong within-year relationship between snow-melt date (via plant phenology) and plant nitrogen concentration and level of herbivory could not predict inter-annual variation in the effect of snow manipulation. I did not find any conclusive evidence for a single factor causing the inter-annual opposing effect of snow addition, but the results indicated that interactions with summer and winter temperatures might be important.

In conclusion, this thesis showed that climate-induced changes in snow conditions will have strong effects on plant traits and plant-herbivore interactions. However, alterations in snow cover do not influence all plant traits and the effect may vary in time and space.

Place, publisher, year, edition, pages
Umeå: Print&Media, 2010. 59 p.
Keyword
Snow, arctic ecosystem, plant-herbivore interactions, phenology, nitrogen, phenolics, experimental manipulation, natural gradient, inter-annual variability
National Category
Biological Sciences
Identifiers
urn:nbn:se:umu:diva-30444 (URN)978-91-7264-923-1 (ISBN)
Public defence
2010-01-22, Lilla Hörsalen (KB3A9), KBC-huset, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2009-12-29 Created: 2009-12-22 Last updated: 2009-12-29Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Olofsson, Johan
By organisation
Ecology and Environmental Science
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 18 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf