Limits...
Seasonal dynamics of mobile carbon supply in Quercus aquifolioides at the upper elevational limit.

Zhu WZ, Cao M, Wang SG, Xiao WF, Li MH - PLoS ONE (2012)

Bottom Line: During the growing season, plants grown at the elevational limit did not show lower NSC concentrations compared to plants at lower elevations, but during the winter season, storage tissues, especially roots, had significantly lower NSC concentrations in plants at the elevational limit compared to lower elevations.The present results suggest the significance of winter reserve in storage tissues, which may determine the winter survival and early-spring re-growth of Q. aquifolioides shrubs at high elevation, leading to the formation of the uppermost distribution limit.This result is consistent with a recent hypothesis for the alpine treeline formation.

View Article: PubMed Central - PubMed

Affiliation: Alpine Ecosystem Observation and Experiment Station of Gongga Mountain, Institute of Mountain Hazard and Environment, Chinese Academy of Sciences, Chengdu, China. wzzhu@imde.ac.cn

ABSTRACT
Many studies have tried to explain the physiological mechanisms of the alpine treeline phenomenon, but the debate on the alpine treeline formation remains controversial due to opposite results from different studies. The present study explored the carbon-physiology of an alpine shrub species (Quercus aquifolioides) grown at its upper elevational limit compared to lower elevations, to test whether the elevational limit of alpine shrubs (<3 m in height) are determined by carbon limitation or growth limitation. We studied the seasonal variations in non-structural carbohydrate (NSC) and its pool size in Q. aquifolioides grown at 3000 m, 3500 m, and at its elevational limit of 3950 m above sea level (a.s.l.) on Zheduo Mt., SW China. The tissue NSC concentrations along the elevational gradient varied significantly with season, reflecting the season-dependent carbon balance. The NSC levels in tissues were lowest at the beginning of the growing season, indicating that plants used the winter reserve storage for re-growth in the early spring. During the growing season, plants grown at the elevational limit did not show lower NSC concentrations compared to plants at lower elevations, but during the winter season, storage tissues, especially roots, had significantly lower NSC concentrations in plants at the elevational limit compared to lower elevations. The present results suggest the significance of winter reserve in storage tissues, which may determine the winter survival and early-spring re-growth of Q. aquifolioides shrubs at high elevation, leading to the formation of the uppermost distribution limit. This result is consistent with a recent hypothesis for the alpine treeline formation.

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Mean concentrations (calculated using pooled data across sampling dates; n = 6) of soluble sugars (dark gray), starch (white), and non-structural carbohydrates (NSC = soluble sugars+starch) in tissues of Quercus aquifolioides plants grown at 3000, 3500, and 3950 m a.s.l. on a SE-facing slope of Mt. Zheduo, Sichuan, SW China.Different letters indicate statistically significant differences (p<0.05) in NSC concentration among elevations. Standard error bars (+1SE) are given for NSC only.
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pone-0034213-g003: Mean concentrations (calculated using pooled data across sampling dates; n = 6) of soluble sugars (dark gray), starch (white), and non-structural carbohydrates (NSC = soluble sugars+starch) in tissues of Quercus aquifolioides plants grown at 3000, 3500, and 3950 m a.s.l. on a SE-facing slope of Mt. Zheduo, Sichuan, SW China.Different letters indicate statistically significant differences (p<0.05) in NSC concentration among elevations. Standard error bars (+1SE) are given for NSC only.

Mentions: The concentrations of soluble sugars significantly increased with increasing elevation in current-year leaves (P<0.001), previous-year leaves (P<0.001), current-year branches (P<0.001), 1-year-old branches (P<0.001), and previous-year branches (P<0.001) (Table 2, Fig. 3). Also, elevation significantly influenced the concentrations of starch in 1-year-old branches (P = 0.036), stem (P = 0.05), taproots (P = 0.002), coarse roots (P<0.001), medium roots (P<0.001), and fine roots (P = 0.038) (Table 2). The tissue NSC concentrations were found to be significantly affected by elevation for previous-year leaves (P = 0.04), current-year branches (P = 0.033), 1-year-old branches (P = 0.002), previous-year branches (P = 0.005), coarse roots (P<0.001), and medium roots (P = 0.023) (Table 2).


Seasonal dynamics of mobile carbon supply in Quercus aquifolioides at the upper elevational limit.

Zhu WZ, Cao M, Wang SG, Xiao WF, Li MH - PLoS ONE (2012)

Mean concentrations (calculated using pooled data across sampling dates; n = 6) of soluble sugars (dark gray), starch (white), and non-structural carbohydrates (NSC = soluble sugars+starch) in tissues of Quercus aquifolioides plants grown at 3000, 3500, and 3950 m a.s.l. on a SE-facing slope of Mt. Zheduo, Sichuan, SW China.Different letters indicate statistically significant differences (p<0.05) in NSC concentration among elevations. Standard error bars (+1SE) are given for NSC only.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316670&req=5

pone-0034213-g003: Mean concentrations (calculated using pooled data across sampling dates; n = 6) of soluble sugars (dark gray), starch (white), and non-structural carbohydrates (NSC = soluble sugars+starch) in tissues of Quercus aquifolioides plants grown at 3000, 3500, and 3950 m a.s.l. on a SE-facing slope of Mt. Zheduo, Sichuan, SW China.Different letters indicate statistically significant differences (p<0.05) in NSC concentration among elevations. Standard error bars (+1SE) are given for NSC only.
Mentions: The concentrations of soluble sugars significantly increased with increasing elevation in current-year leaves (P<0.001), previous-year leaves (P<0.001), current-year branches (P<0.001), 1-year-old branches (P<0.001), and previous-year branches (P<0.001) (Table 2, Fig. 3). Also, elevation significantly influenced the concentrations of starch in 1-year-old branches (P = 0.036), stem (P = 0.05), taproots (P = 0.002), coarse roots (P<0.001), medium roots (P<0.001), and fine roots (P = 0.038) (Table 2). The tissue NSC concentrations were found to be significantly affected by elevation for previous-year leaves (P = 0.04), current-year branches (P = 0.033), 1-year-old branches (P = 0.002), previous-year branches (P = 0.005), coarse roots (P<0.001), and medium roots (P = 0.023) (Table 2).

Bottom Line: During the growing season, plants grown at the elevational limit did not show lower NSC concentrations compared to plants at lower elevations, but during the winter season, storage tissues, especially roots, had significantly lower NSC concentrations in plants at the elevational limit compared to lower elevations.The present results suggest the significance of winter reserve in storage tissues, which may determine the winter survival and early-spring re-growth of Q. aquifolioides shrubs at high elevation, leading to the formation of the uppermost distribution limit.This result is consistent with a recent hypothesis for the alpine treeline formation.

View Article: PubMed Central - PubMed

Affiliation: Alpine Ecosystem Observation and Experiment Station of Gongga Mountain, Institute of Mountain Hazard and Environment, Chinese Academy of Sciences, Chengdu, China. wzzhu@imde.ac.cn

ABSTRACT
Many studies have tried to explain the physiological mechanisms of the alpine treeline phenomenon, but the debate on the alpine treeline formation remains controversial due to opposite results from different studies. The present study explored the carbon-physiology of an alpine shrub species (Quercus aquifolioides) grown at its upper elevational limit compared to lower elevations, to test whether the elevational limit of alpine shrubs (<3 m in height) are determined by carbon limitation or growth limitation. We studied the seasonal variations in non-structural carbohydrate (NSC) and its pool size in Q. aquifolioides grown at 3000 m, 3500 m, and at its elevational limit of 3950 m above sea level (a.s.l.) on Zheduo Mt., SW China. The tissue NSC concentrations along the elevational gradient varied significantly with season, reflecting the season-dependent carbon balance. The NSC levels in tissues were lowest at the beginning of the growing season, indicating that plants used the winter reserve storage for re-growth in the early spring. During the growing season, plants grown at the elevational limit did not show lower NSC concentrations compared to plants at lower elevations, but during the winter season, storage tissues, especially roots, had significantly lower NSC concentrations in plants at the elevational limit compared to lower elevations. The present results suggest the significance of winter reserve in storage tissues, which may determine the winter survival and early-spring re-growth of Q. aquifolioides shrubs at high elevation, leading to the formation of the uppermost distribution limit. This result is consistent with a recent hypothesis for the alpine treeline formation.

Show MeSH