Effects of elevated pO_3 on carbon cycle between above andbelowground organs of trees

作     者：LIU Xi-ping Rennenberg Heinz Matyssek Rainer 

作者机构：College of Life Sciences Northwest Sci-Tech University of Agriculture and Forestry Yangling 712100 China Institute of Forest Botany and Tree Physiology University Freiburg D-79110 Freiburg Germany Department of Ecopogy/Ecophysiology of Plants Technical University Munich D-85354 Freising Germany 

出 版 物：《Journal of Environmental Sciences》 (环境科学学报（英文版）)

年 卷 期：2006年第18卷第5期

页      面：932-936页

核心收录：

学科分类：0830[工学-环境科学与工程（可授工学、理学、农学学位）] 07[理学] 070602[理学-大气物理学与大气环境] 09[农学] 0903[农学-农业资源与环境] 0706[理学-大气科学] 0713[理学-生态学] 

基　　金：The Deutsche Forschungsgemeinschaft (DFG  SFB 607  part project A2/B5) 

主　　题：beech carbon cycle elevated pO3 phloem spruce xylem 

摘      要：Translocation of carbohydrate from leaves to roots via phloem and reallocation from roots to leaves via xylem regulate the allocation of carbon （C） between above and belowground organs of trees. To quantitatively analyze effects of elevated ozone concentrations pO3 on the internal cycle of C, juvenile beech and spruce were grown in phytotrons and exposed to ambient and elevated pO3 （i.e. twice-ambient O3 levels, restricted to 〈 150 ppb） for two growing seasons. The translocation of C in the phloem and xylem was quantitatively studied by investigating the phloem/xylem-loading of sugars, the differentiation of stem conductive tissue and the hourly water flow through the stem. Results in the present study shown, elevated pO3 significantly decreased C translocation from shoot to roots in beech by reducing both sugar concentration in the phloem and conductive phloem area. Elevated pO3 also significantly decreased C reallocation from the roots to the shoot in beech by reducing both of sugar concentration in the xylem and transpiration rate. The adverse effects of elevated pO3 on C translocation in the phloem and xylem, however, were small in spruce. Contrasting to beech, spruce is less sensitive to elevated pO3, regarding to phloem differentiation and sugar concentrations in the phloem and xylem.