Significance of XXXX exposure for inter-annual differences in primary metabolites of old-growth beech (Fagus sylvatica L.) and Norway spruce (Picea abies L.) trees in a mixed forest stand.

@entity3363 @entity1472 @entity2041 @entity1787
The influence of long-term free-air @entity1787 fumigation and canopy position on leaf contents of total @entity2041 , its redox state, non-structural proteins (NSP), soluble @entity1472 compounds, and total soluble @entity3363 in old-growth beech (FAGUS SYLVATICA) and spruce (PICEA ABIES) trees were determined over a period of five years. @entity1787 fumigation had weak effects on the analysed metabolites of both tree species and significant changes in the contents of total @entity2041 , NSP, and soluble @entity3363 were observed only selectively. Beech leaves were affected by crown position to a higher extent than spruce needles and exhibited lower contents of total @entity2041 and NSP and total soluble @entity3363 , but enhanced contents of oxidised @entity2041 and @entity1472 compounds in the shade compared to the sun crown. Contents of total soluble @entity3363 generally were decreased in shade compared to sun needles of spruce trees. Interspecific differences between beech and spruce were more distinct in the sun compared to the shade crown. Contents of total @entity2041 were increased whilst contents of @entity1472 compounds and total soluble @entity3363 were lower in spruce needles compared to beech leaves. The metabolites determined showed individual patterns in the course of the five measurement years. Contents of total @entity2041 and its redox state correlated with air temperature and global radiation, indicating an important role for the antioxidant at low temperatures. Correlations of @entity2041 with instantaneous @entity1787 concentrations seem to be a secondary effect. Differences in proteins and/or @entity1472 compounds in the inter-annual course are assumed to be a consequence of alterations in specific N uptake rates.
