Late-stage canopy tree species with extremely low delta C-13 and high stomatal sensitivity to seasonal soil drought in the tropical rainforest of French Guiana

Citation
D. Bonal et al., Late-stage canopy tree species with extremely low delta C-13 and high stomatal sensitivity to seasonal soil drought in the tropical rainforest of French Guiana, PL CELL ENV, 23(5), 2000, pp. 445-459
Citations number
66
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences","Animal & Plant Sciences
Journal title
PLANT CELL AND ENVIRONMENT
ISSN journal
0140-7791 → ACNP
Volume
23
Issue
5
Year of publication
2000
Pages
445 - 459
Database
ISI
SICI code
0140-7791(200005)23:5<445:LCTSWE>2.0.ZU;2-2
Abstract
We assessed the daily time-courses of CO2 assimilation rate (A), leaf trans piration rate (E), stomatal conductance for water vapour (g(s)), leaf water potential (Psi(w)) and tree transpiration in a wet and a dry season for th ree late-stage canopy rainforest tree species in French Guiana differing in leaf carbon isotope composition (delta(13)C). Th, lower sunlit leaf delta( 13)C values found in Virola surinamensis (-29.9 parts per thousand) and in Diplotropis purpurea (-30.9 parts per thousand), two light-demanding specie s, as compared to Eperua falcata (-28.6 parts per thousand), a shade-semi-t olerant species, were clearly associated with higher maximum g(s) values of sunlit leaves in the two former species. These two species were also chara cterized by a high sensitivity of g(s), sap flow density (Ju) and canopy co nductance (g(c)) to seasonal soil drought, allowing maintenance of high mid day Psi(w) values in the dry season. The data for Diplotropis provided an o riginal picture of increasing midday Psi(w) with increasing soil drought. I n Virola, stomata were extremely sensitive to seasonal soil drought, leadin g to a dramatic decrease in leaf and tree transpiration in the dry season, whereas midday Psi(w) remained close to -0.3 MPa. The mechanisms underlying such an extremely high sensitivity of stomata to soil drought remain unkno wn, In Eperua, g(s) of sunlit leaves was nonresponsive to seasonal drought, whereas Ju and g(c) were lower in the dry season. This suggests a higher s tomatal sensitivity to seasonal drought in shaded leaves than in sunlit one s in this species.