Data/hora: 09/06/2024 05:21:18

Provedor de dados: 	17	
País: 	United Kingdom	
Título: 	Why plants lose their inhibitions in the Arctic: functional traits, phylogenetics and respiration in the light	
Autores: 	Nicholas Mirotchnick; Owen Atkin; Marc Cadotte; Matthew Turnbull; Kevin Griffin.	
Data: 	2010-12-09	
Ano: 	2010	
Palavras-chave: 	Ecology; Evolutionary Biology.	
Resumo: 	Background/Questions/Methods:&amp;#xd;&amp;#xa;Arctic vegetation represents a significant portion of the world&amp;#x2019;s&amp;#xd;&amp;#xa;global carbon stocks and is particularly sensitive to global climate&amp;#xd;&amp;#xa;change. Net plant carbon exchange depends on both photosynthesis and&amp;#xd;&amp;#xa;respiration, the latter of which is poorly understood in arctic&amp;#xd;&amp;#xa;ecosystems and yet is highly sensitive to global environmental change.&amp;#xd;&amp;#xa; Mitochondrial respiration can confound measurements of photosynthesis&amp;#xd;&amp;#xa;and thus is often isolated by measuring it in the dark.  We also know,&amp;#xd;&amp;#xa;however, that respiration can be inhibited by light, which complicates&amp;#xd;&amp;#xa;extrapolations from measurements in darkness.  Furthermore, the extent&amp;#xd;&amp;#xa;of this inhibition may be unique in arctic ecosystems as a result of&amp;#xd;&amp;#xa;the constant daylight they receive during growing seasons.&amp;#xd;&amp;#xa;&amp;#xd;&amp;#xa;We applied the Kok method to a survey of forty of the most common&amp;#xd;&amp;#xa;tundra plants found in communities surrounding the Toolik Lake Long&amp;#xd;&amp;#xa;Term Ecological Research Site in Alaska&amp;#x2019;s North Slope.  The Kok method&amp;#xd;&amp;#xa;segregates rates of respiration in the dark and those in the light by&amp;#xd;&amp;#xa;applying incrementally decreasing light levels to leaves.  Using this&amp;#xd;&amp;#xa;approach, we were able to compare these different rates and determine&amp;#xd;&amp;#xa;the extent of light inhibition across a variety of species, functional&amp;#xd;&amp;#xa;groups and habitat types.&amp;#xd;&amp;#xa;&amp;#xd;&amp;#xa;Results/Conclusions:&amp;#xd;&amp;#xa;Respiration is less inhibited by light in the Arctic than it is&amp;#xd;&amp;#xa;expected to be based on observations from lower latitudes. We measured&amp;#xd;&amp;#xa;several functional traits in order to identify the mechanisms plants&amp;#xd;&amp;#xa;have used to acclimatize to constant daylight. Carbohydrate content,&amp;#xd;&amp;#xa;photosynthetic capacity (Amax) and specific leaf area (SLA) were&amp;#xd;&amp;#xa;significant predictors of levels of inhibition.  There did not appear&amp;#xd;&amp;#xa;to be a significant effect of functional group membership on&amp;#xd;&amp;#xa;inhibition.  We detected considerable intraspecific variation in trait&amp;#xd;&amp;#xa;values and levels of inhibition and thus species identity did not&amp;#xd;&amp;#xa;explain variation in inhibition.  Preliminary tests for effects of&amp;#xd;&amp;#xa;evolutionary history on levels of inhibition indicate that inhibition&amp;#xd;&amp;#xa;may be lower in plants that have diversified at higher latitudes.&amp;#xd;&amp;#xa;These results underline the importance of accounting for respiration&amp;#xd;&amp;#xa;in the light in arctic carbon models.  Arctic carbon stocks may be&amp;#xd;&amp;#xa;significantly lower than previously thought since current estimates&amp;#xd;&amp;#xa;don&amp;#x2019;t include respiration in the light.	
Tipo: 	Presentation	
Identificador: 	http://precedings.nature.com/documents/5375/version/1

oai:nature.com:10.1038/npre.2010.5375.1

http://dx.doi.org/10.1038/npre.2010.5375.1	
Fonte: 	Nature Precedings	
Fonte: 	Creative Commons Attribution 3.0 License