Comparisons of delta13C of photosynthetic products and ecosystem respiratory CO2 and their responses to seasonal climate variability

This study investigated the relationship between delta13C of ecosystem components, soluble plant carbohydrates and the isotopic signature of ecosystem respired CO2 (delta13CR) during seasonal changes in soil and atmospheric moisture in a beech (Fagus sylvatica L.) forest in the central Apennine mountains, Italy. Decrease in soil moisture and increase in air vapour pressure deficit during summer correlated with substantial increase in delta13C of leaf and phloem sap soluble sugars. Increases in delta13C of ecosystem respired CO2 were linearly related to increases in phloem sugar delta13C (r2=0.99, P