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 (±1SE, n = 6, % d.m.) of nonstructural carbohydrates (left panels), soluble sugars (middle panels), and starch (right panels) in relation to sampling time for tissues of Quercus aquifoliodes shrubs grown at 3000 m, 3500 m, and 3950 m a.s.l. on the Mt. Zheduo, SW China.Symbols: • (red) = 3000 m a.s.l.; ▪ (yellow) = 3500 m a.s.l.; Δ (black) = 3950 m a.s.l.
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pone-0034213-g001: Mean concentrations (±1SE, n = 6, % d.m.) of nonstructural carbohydrates (left panels), soluble sugars (middle panels), and starch (right panels) in relation to sampling time for tissues of Quercus aquifoliodes shrubs grown at 3000 m, 3500 m, and 3950 m a.s.l. on the Mt. Zheduo, SW China.Symbols: • (red) = 3000 m a.s.l.; ▪ (yellow) = 3500 m a.s.l.; Δ (black) = 3950 m a.s.l.

Mentions: With an exception of NSC in stem wood, concentrations of soluble sugars, starch, and NSC in each tissue varied significantly with sampling dates (P<0.001 for sugars in all tissues; P<0.05 for starch and NSC in all tissues) (Table 2, Fig. 1). Only in two cases significant interactions of elevation×sampling date were found, i.e. for NSC in coarse roots (P = 0.011) and for soluble sugars in 1-year-old branches (P = 0.033) (Table 2). In all other cases, there were no elevations×sampling date interactions on concentrations of NSC, sugars, and starch in tissues (Table 2), indicating that the patterns of seasonal variations in NSC and its components within each tissue type were similar in oak plants grown at different elevations (Fig. 1).


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 (±1SE, n = 6, % d.m.) of nonstructural carbohydrates (left panels), soluble sugars (middle panels), and starch (right panels) in relation to sampling time for tissues of Quercus aquifoliodes shrubs grown at 3000 m, 3500 m, and 3950 m a.s.l. on the Mt. Zheduo, SW China.Symbols: • (red) = 3000 m a.s.l.; ▪ (yellow) = 3500 m a.s.l.; Δ (black) = 3950 m a.s.l.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0034213-g001: Mean concentrations (±1SE, n = 6, % d.m.) of nonstructural carbohydrates (left panels), soluble sugars (middle panels), and starch (right panels) in relation to sampling time for tissues of Quercus aquifoliodes shrubs grown at 3000 m, 3500 m, and 3950 m a.s.l. on the Mt. Zheduo, SW China.Symbols: • (red) = 3000 m a.s.l.; ▪ (yellow) = 3500 m a.s.l.; Δ (black) = 3950 m a.s.l.
Mentions: With an exception of NSC in stem wood, concentrations of soluble sugars, starch, and NSC in each tissue varied significantly with sampling dates (P<0.001 for sugars in all tissues; P<0.05 for starch and NSC in all tissues) (Table 2, Fig. 1). Only in two cases significant interactions of elevation×sampling date were found, i.e. for NSC in coarse roots (P = 0.011) and for soluble sugars in 1-year-old branches (P = 0.033) (Table 2). In all other cases, there were no elevations×sampling date interactions on concentrations of NSC, sugars, and starch in tissues (Table 2), indicating that the patterns of seasonal variations in NSC and its components within each tissue type were similar in oak plants grown at different elevations (Fig. 1).

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