Document Detail

Use of thermal imaging to determine leaf conductance along a canopy gradient in European beech (Fagus sylvatica).
MedLine Citation:
PMID:  22427372     Owner:  NLM     Status:  Publisher    
Using an infrared camera, we measured the leaf temperature across different canopy positions of a 23-m-tall deciduous forest tree (Fagus sylvatica L.) including typical sun and shade leaves as well as intermediate leaf forms, which differed significantly in specific leaf area (SLA). We calculated a temperature index (I(G)) and a crop water stress index (CWSI) using the surface temperatures of wet and dry reference leaves. Additional indices were computed using air temperature plus 5 °C (I(G) + 5, CWSI + 5) as dry references. The minimum temperature of the wet leaf and the maximum temperature of the dry leaf proved to be most suitable as reference values. We correlated the temperature indices with leaf area-related conductance to water vapor (g(L)) using porometry at the leaf level and using xylem sap flow at the branch level. At the leaf and at the branch level, I(G) and CWSI were equally well suited as proxies of g(L), whereas the relationships of I(G) + 5 and CWSI + 5 with g(L) were only weak or even insignificant. At the leaf level, the correlations of I(G) and CWSI with g(L) were significant in all parts of the crown. The slopes of g(L) vs. I(G) and CWSI did not differ significantly among the crown parts; this indicates that they were not influenced by SLA or irradiance. At the branch level, close correlations (r > 0.8) were found between temperature indices and g(L) across the crown. These results demonstrate that satisfactory relationships between temperature indices and g(L) can be established in tall trees even in those canopy parts that are exposed to relatively low levels of irradiance and exhibit relatively low values of g(L).
Stefan Reinert; Rebekka Bögelein; Frank M Thomas
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-3-15
Journal Detail:
Title:  Tree physiology     Volume:  -     ISSN:  1758-4469     ISO Abbreviation:  -     Publication Date:  2012 Mar 
Date Detail:
Created Date:  2012-3-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100955338     Medline TA:  Tree Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
University of Trier, Geobotany, Behringstraße 21, 54296 Trier, Germany.
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