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Shizuoka University (2014)

ISOTOPIC (Δ14C,δ13C) AND ANATOMICAL STUDY ON RADIAL INCREMENT LAYERS OF A TYPICAL SHRUB (HALOXYLON AMMODENDRON) FROM THE GURBANTÜNGGÜT DESERT, NORTHWESTERN CHINA

LI, Junfeng

Titre : ISOTOPIC (Δ14C,δ13C) AND ANATOMICAL STUDY ON RADIAL INCREMENT LAYERS OF A TYPICAL SHRUB (HALOXYLON AMMODENDRON) FROM THE GURBANTÜNGGÜT DESERT, NORTHWESTERN CHINA

Auteur : LI, Junfeng

Université de soutenance : Shizuoka University

Grade : Doctoral Thesis 2014

Résumé
Dryland degradation-desertification has become a serious international environmental issue. The Haloxylon species is xero-halophytic C4 desert shrub which exhibiting excellent drought resistance and salt tolerance, and is major dominant species widely distributed in Central Asia arid areas and plays an important role for maintaining the desert ecosystem. It is known that Haloxylon has successive cambia and its stem can form multiple radial increment layers through successive cambia (RISC layers) in one growing season. Its age is not clear because the annual growth boundary cannot be confirmed by dendrochronological approach. It is difficult to clearly distinguish RISC layers from seasonal annual rings, because the RISC layers possess similar morphological character comparing with seasonal annual rings through megascopic cross sectional observations. Two Haloxylon ammodendron (H.ammodendron) specimens (S1 and S2) were collected from the Gurbantünggüt Desert in Northwestern China. The objective of present study is to clarify the radial growth rate and attempt to illuminate the mechanism that multiple RISC layers of H.ammodendron are formed in one growing season. This thesis focuses on the radiocarbon dating, the stable carbon isotopic (δ 13C) and anatomical analysis of H.ammodendron, with the goals of (1) clarifying the annual radial growth rate of the RISC layer ; (2) demonstrating the main effect factor of RISC layers formation in H. ammodendron stems ; and (3) attempting to illuminate the mechanism of the seasonal multiple RISC layers formation.

Research methods are including : (1) α-cellulose extracting ; (2) α-cellulose combustion ; (3) the CO2 purifying : (4) graphitization ; (5) the δ 13C measurement ; (6) the 14C measurement ; (7) the radiocarbon dating (F14C) ; (8) the microstructural features observation.

Mots clés Haloxylon ammodendron ; Radial increment layer through successive cambia (RISC layer) ; Radiocarbon dating ; Stable carbon isotope (δ 13C) ; Wood anatomical analysis ; Dendrochronological research ; Gurbantünggüt Desert.

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Page publiée le 15 octobre 2016, mise à jour le 20 avril 2020