Seasonal dynamics in the stable carbon isotope composition (δ13C) from non‐leafy branch, trunk and coarse root CO2 efflux of adult deciduous (Fagus sylvatica) and evergreen (Picea abies) trees

• Published in: Plant, cell and environment Vol. 34; no. 3; pp. 363 - 373
• Main Authors: KUPTZ, DANIEL, MATYSSEK, RAINER, GRAMS, THORSTEN E. E.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2011; Blackwell
• Subjects: Biological and medical sciences; branch, trunk and coarse root respiration; corticular and winter photosynthesis; Fagus sylvatica; Fundamental and applied biological sciences. Psychology; phenological change; phosphoenolpyruvate carboxylase (PEPc); Picea abies; respiratory carbon flux; sap flow, stable carbon isotope composition (δ13C); stable carbon isotope composition (δ; Gas emission; Sap; C; Carbon isotope discrimination; respiratory carbon flux; Carbon dioxide; Carbon Isotopes; trunk and coarse root respiration; phosphoenolpyruvate carboxylase (PEPc); Lyases; Isotopic composition; branch; Internal flow; Seasonal variation; Carboxy-lyases; Dicotyledones; Stable isotopes; Angiospermae; Softwood forest tree; Gymnospermae; sap flow; Hardwood forest tree; Phosphoenolpyruvate carboxylase; Branching; Carbon exchange rate; Root; Enzyme; Plant ecology; phenological change; Plant leaf; Fagaceae; corticular and winter photosynthesis; Carbon-carbon lyases; C-13; Phenology; Coniferales; Spermatophyta; Photosynthesis; Respiration; Picea abies; Fagus sylvatica
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2010.02246.x

ABSTRACT Respiration is a substantial driver of carbon (C) flux in forest ecosystems and stable C isotopes provide an excellent tool for its investigation. We studied seasonal dynamics in δ13C of CO2 efflux (δ13CE) from non‐leafy branches, upper and lower trunks and coarse roots of adult trees, comparing deciduous Fagus sylvatica (European beech) with evergreen Picea abies (Norway spruce). In both species, we observed strong and similar seasonal dynamics in the δ13CE of above‐ground plant components, whereas δ13CE of coarse roots was rather stable. During summer, δ13CE of trunks was about −28.2‰ (Beech) and −26.8‰ (Spruce). During winter dormancy, δ13CE increased by 5.6–9.1‰. The observed dynamics are likely related to a switch from growth to starch accumulation during fall and remobilization of starch, low TCA cycle activity and accumulation of malate by PEPc during winter. The seasonal δ13CE pattern of branches of Beech and upper trunks of Spruce was less variable, probably because these organs were additionally supplied by winter photosynthesis. In view of our results and pervious studies, we conclude that the pronounced increases in δ13CE of trunks during the winter results from interrupted access to recent photosynthates.