Inter-annual variation in the effect of snow on plants and their interactions with herbivores.
(English)Manuscript (preprint) (Other academic)
Plant traits and patterns of herbivory are influenced by environmental conditions and annual variability in climatic parameters is thus of great importance for plant-herbivore interactions in arctic ecosystems. Although many environmental manipulations are carried out as long-term experiments, the direct effect on plants and herbivores is often described for one year only. Snow manipulation experiments have often demonstrated a positive relationship between snow cover and plant nitrogen concentration, and studies have suggested that the higher nitrogen concentration in plants from snow-rich sites results in increased plant quality as food for herbivores. However, recent experiments indicate that the effect of snow on plants and herbivores may vary between years. In a five-year study in northern Sweden, where we used snow fences to manipulate the snow accumulation in winter, we found opposing effects of increased snow cover on plant carbon and nitrogen concentrations between years and in contrast to earlier findings, the effect of snow-lie on plant nitrogen concentration was predominantly negative. The effect of snow on the level of leaf damage by invertebrate herbivores remained predominantly positive. We found no conclusive evidence for any single factor causing the inter-annual variation in the effect of snow-lie manipulation on plant chemical traits and level of herbivory. However, our results indicate that interactions with summer and winter temperatures might be important. These findings highlight the importance of long-term studies when trying to understand vegetation responses and plant-herbivore interactions in a changing climate, and advocate that longer time series and more accurate measurements of both environmental and plant characteristics are needed in order to find the mechanisms causing the inter-annual variation in the effect of increased snow cover.
IdentifiersURN: urn:nbn:se:umu:diva-30411OAI: oai:DiVA.org:umu-30411DiVA: diva2:282795