Document Detail

Variable temperature effects of Open Top Chambers at polar and alpine sites explained by irradiance and snow depth.
MedLine Citation:
PMID:  23504721     Owner:  NLM     Status:  In-Data-Review    
Environmental manipulation studies are integral to determining biological consequences of climate warming. Open Top Chambers (OTCs) have been widely used to assess summer warming effects on terrestrial biota, with their effects during other seasons normally being given less attention even though chambers are often deployed year-round. In addition, their effects on temperature extremes and freeze-thaw events are poorly documented. To provide robust documentation of the microclimatic influences of OTCs throughout the year, we analysed temperature data from 20 studies distributed across polar and alpine regions. The effects of OTCs on mean temperature showed a large range (-0.9 to 2.1 °C) throughout the year, but did not differ significantly between studies. Increases in mean monthly and diurnal temperature were strongly related (R(2)  = 0.70) with irradiance, indicating that PAR can be used to predict the mean warming effect of OTCs. Deeper snow trapped in OTCs also induced higher temperatures at soil/vegetation level. OTC-induced changes in the frequency of freeze-thaw events included an increase in autumn and decreases in spring and summer. Frequency of high-temperature events in OTCs increased in spring, summer and autumn compared with non-manipulated control plots. Frequency of low-temperature events was reduced by deeper snow accumulation and higher mean temperatures. The strong interactions identified between aspects of ambient environmental conditions and effects of OTCs suggest that a detailed knowledge of snow depth, temperature and irradiance levels enables us to predict how OTCs will modify the microclimate at a particular site and season. Such predictive power allows a better mechanistic understanding of observed biotic response to experimental warming studies and for more informed design of future experiments. However, a need remains to quantify OTC effects on water availability and wind speed (affecting, for example, drying rates and water stress) in combination with microclimate measurements at organism level.
Stef Bokhorst; Ad Huiskes; Rien Aerts; Peter Convey; Elisabeth J Cooper; Linda Dalen; Brigitta Erschbamer; Jón Gudmundsson; Annika Hofgaard; Robert D Hollister; Jill Johnstone; Ingibjörg S Jónsdóttir; Marc Lebouvier; Bart Van de Vijver; Carl-Henrik Wahren; Ellen Dorrepaal
Publication Detail:
Type:  Journal Article     Date:  2012-10-18
Journal Detail:
Title:  Global change biology     Volume:  19     ISSN:  1354-1013     ISO Abbreviation:  Glob Chang Biol     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-03-18     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9888746     Medline TA:  Glob Chang Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  64-74     Citation Subset:  IM    
Copyright Information:
© 2012 Blackwell Publishing Ltd.
Department of Forest Ecology and Management, Swedish University of Agricultural sciences, Umeå, 901 83, Sweden.
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