Snowinduced changes in dwarf birch chemistry incr

Authors: Mikaela Torp Johan Olofsson Johanna Witzell Robert Baxter

Publish Date: 2009/11/06

Volume: 33, Issue: 5, Pages: 693-702

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Abstract

Changes in snow cover might influence arctic ecosystems to the same extent as increased temperatures Although the duration of snow cover is generally expected to decrease in the future as a result of global warming the amounts of snow might increase in arctic areas where much of the elevated precipitation will fall as snow We examined the effects of an increased snow cover as a result of a snow fence treatment on soil nitrogen mineralization plant phenology plant chemistry nitrogen and potential defense compounds the level of invertebrate herbivory and performance of invertebrate herbivores in an arctic ecosystem using dwarf birch Betula nana and the autumnal moth Epirrita autumnata as study organisms An enhanced and prolonged snow cover increased the level of herbivory on dwarf birch leaves Larvae feeding on plants that had experienced enhanced snow cover grew faster and pupated earlier than larvae fed with plant material from control plots indicating that plants from enhanced snowlie plots produce higherquality food to herbivores The increased larval growth rate was strongly correlated with higher leaf nitrogen concentration in plants subjected to snow manipulation and also to certain phenolic acids Snow manipulation did not change net nitrogen mineralization rates in the soil or total carbon concentration in leaves but it altered the withinseason fluctuating pattern of leaf phenolic compounds This study demonstrates a positive relationship between increased snow cover and level of herbivory on deciduous shrubs thus proposing a negative feedback on the climateinduced dwarf shrub expansion in arctic areasWe thank Hans Cornelissen and two anonymous reviewers for useful comments on the manuscript Kristoffer Sivertsson for his devoted work in the field and Clara Laguna Defoir and Rakel Berglund for their help with the chemical analyses The Abisko Scientific Research Station provided accommodation laboratory facilities and funding during the periods of field work The study was supported by grants from the Centre for Environmental Research in Umeå CMF and The Swedish Research Council for Environment Agricultural Sciences and Spatial planning to JO and NER/A/S/2001/00460 from the Natural Environment Research Council United Kingdom to RB The experiments comply with the current laws of the country in which they were performed

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