Linking carbon supply to root cell-wall chemistry and mechanics at high altitudes in Abies georgei
Open Access
- 24 December 2010
- journal article
- research article
- Published by Oxford University Press (OUP) in Annals of Botany
- Vol. 107 (2), 311-320
- https://doi.org/10.1093/aob/mcq237
Abstract
The mobile carbon supply to different compartments of a tree is affected by climate, but its impact on cell-wall chemistry and mechanics remains unknown. To understand better the variability in root growth and biomechanics in mountain forests subjected to substrate mass movement, we investigated root chemical and mechanical properties of mature Abies georgei var. smithii (Smith fir) growing at different elevations on the Tibet–Qinghai Plateau. Thin and fine roots (0·1–4·0 mm in diameter) were sampled at three different elevations (3480, 3900 and 4330 m, the last corresponding to the treeline). Tensile resistance of roots of different diameter classes was measured along with holocellulose and non-structural carbon (NSC) content. The mean force necessary to break roots in tension decreased significantly with increasing altitude and was attributed to a decrease in holocellulose content. Holocellulose was significantly lower in roots at the treeline (29·5 ± 1·3 %) compared with those at 3480 m (39·1 ± 1·0 %). Roots also differed significantly in NSC, with 35·6 ± 4·1 mg g−1 dry mass of mean total soluble sugars in roots at 3480 m and 18·8 ± 2·1 mg g−1 dry mass in roots at the treeline. Root mechanical resistance, holocellulose and NSC content all decreased with increasing altitude. Holocellulose is made up principally of cellulose, the biosynthesis of which depends largely on NSC supply. Plants synthesize cellulose when conditions are optimal and NSC is not limiting. Thus, cellulose synthesis in the thin and fine roots measured in our study is probably not a priority in mature trees growing at very high altitudes, where climatic factors will be limiting for growth. Root NSC stocks at the treeline may be depleted through over-demand for carbon supply due to increased fine root production or winter root growth.Keywords
This publication has 50 references indexed in Scilit:
- Root reinforcement in plantations of Cryptomeria japonica D. Don: effect of tree age and stand structure on slope stabilityForest Ecology and Management, 2008
- Mobile carbohydrates in Himalayan treeline trees I. Evidence for carbon gain limitation but not for growth limitationTree Physiology, 2008
- Plant Growth Modelling and Applications: The Increasing Importance of Plant Architecture in Growth ModelsAnnals of Botany, 2007
- Large altitudinal increase in tree root/shoot ratio in tropical mountain forests of EcuadorBasic and Applied Ecology, 2007
- Does growing on a slope affect tree xylem structure and water relations?Tree Physiology, 2007
- End of season carbon supply status of woody species near the treeline in western ChinaBasic and Applied Ecology, 2006
- Fine root branch orders respond differentially to carbon source-sink manipulations in a longleaf pine forestOecologia, 2004
- Root Weights and Carbohydrate Reserves of Big SagebrushEcology, 1978
- Root Strength in SomePopulusandSalixClonesNew Zealand Journal of Botany, 1975
- Cone-in-Cone on Concretions from the Devonian of New YorkScience, 1928