 |
| Titel |
Short-term dynamics and partitioning of newly assimilated carbon in the
foliage of adult beech and pine are driven by seasonal variations |
| VerfasserIn |
Dorine Desalme, Pierrick Priault, Dominique Gérant, Masako Dannoura, Pascale Maillard, Caroline Plain, Daniel Epron |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144783
|
| Publikation (Nr.) |
 EGU/EGU2017-8652.pdf |
|
|
|
|
|
| Zusammenfassung |
| Carbon (C) allocation is a key process determining C cycling in forest ecosystems.
However, the mechanisms underlying the annual patterns of C partitioning in trees,
influenced by tree phenology and environmental conditions, are not well identified
yet.
This study aimed to characterize the short-term dynamics and partitioning of newly
assimilated carbon in the foliage of adult European beeches (Fagus sylvatica) and
maritime pines (Pinus pinaster) across the seasons. We hypothesized that residence
times of recently assimilated C in C compounds should change according to the
seasons and that seasonal pattern should differ between deciduous and evergreen tree
species, since they have different phenology. 13CO2 pulse-labelling experiments
were performed in situ at different dates corresponding to different phenological
stages. In beech leaves and pine needles, C contents, isotopic compositions, and 13C
dynamics parameters were determined in total organic matter (bulk foliage), in
polar fraction (PF, including soluble sugars, amino acids, organic acids) and in
starch.
For both species and at each phenological stage, 13C amount in bulk foliage decreased
following a two-pool exponential model, highlighting the partitioning of newly assimilated C
between ‘mobile’ and ‘stable’ pools. The relative proportion of the stable pool
was maximal in beech leaves in May, when leaves were still growing and could
incorporate newly assimilated C in structural C compounds. Young pine needles were
still receiving C from previous-year needles in June (two months after budburst)
although they are already photosynthesizing, acting as a strong C sink. In summer,
short mean residence times of 13C (MRT) in foliage of both tree species reflected
the fast respiration and exportation of recent photosynthates to support the whole
tree C demand (e.g., supplying perennial organ growth). At the end of the growing
season, pre-senescing beech leaves were supplying 13C to perennial organs, whereas
overwintering pine needles accumulated labelled PF, probably to acclimate to colder winter
temperatures.
Results of this experiment revealed that the dynamics and the in-leaf partitioning of newly
assimilated C varied seasonally according to the phenology of the two species. In the future,
coupling 13C pulse labelling with compound-specific isotope analysis will be promising for
tracing the allocation of newly assimilated C to various physiological functions such as
growth, export, osmoregulation and defence in trees submitted to global changes. |
|
|
|
|
|
|