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Dynamics of non-structural carbohydrates in three Mediterranean woody species following long-term experimental drought.

Rosas T, Galiano L, Ogaya R, Peñuelas J, Martínez-Vilalta J - Front Plant Sci (2013)

Bottom Line: In the long-term drought experiment we found significant depletion in concentrations of total NSC in treatment plots only in the lignotuber of A. unedo.At the same time, A. unedo was the only species showing a significant reduction in BAI under the drought treatment during the 14 years of the experiment.However, we found a clear association between the concentrations of NSC and defoliation in Q. ilex individuals sampled outside the experimental plots, with lower total concentrations of NSC and lower proportion of starch in defoliated individuals.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recerca Ecològica i Aplicacions Forestals (CREAF) Cerdanyola del Vallès, Spain ; Departament de Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona Cerdanyola del Vallès, Spain.

ABSTRACT
Stored non-structural carbohydrates (NSC) have been proposed as a key determinant of drought resistance in plants. However, the evidence for this role is controversial, as it comes mostly from observational, short-term studies. Here, we take advantage of a long-term experimental throughfall reduction to elucidate the response of NSC to increased drought 14 years after the beginning of the treatment in three Mediterranean resprouter trees (Quercus ilex L., Arbutus unedo L. and Phillyrea latifolia L.). In addition, we selected 20 Q. ilex individuals outside the experimental plots to directly assess the relationship between defoliation and NSC at the individual level. We measured the seasonal course of NSC concentrations in leaves, branches and lignotuber in late winter, late spring, summer, and autumn 2012. Total concentrations of NSC were highest in the lignotuber for all species. In the long-term drought experiment we found significant depletion in concentrations of total NSC in treatment plots only in the lignotuber of A. unedo. At the same time, A. unedo was the only species showing a significant reduction in BAI under the drought treatment during the 14 years of the experiment. By contrast, Q. ilex just reduced stem growth only during the first 4 years of treatment and P. latifolia remained unaffected over the whole study period. However, we found a clear association between the concentrations of NSC and defoliation in Q. ilex individuals sampled outside the experimental plots, with lower total concentrations of NSC and lower proportion of starch in defoliated individuals. Taken together, our results suggest that stabilizing processes, probably at the stand level, may have been operating in the long-term to mitigate any impact of drought on NSC levels, and highlight the necessity to incorporate long-term experimental studies of plant responses to drought.

No MeSH data available.


Environmental variables during the period of study. (A) Daily temperature in 2012 and monthly average temperature during the years 1999–2012, (B) daily accumulated precipitation in 2012 and monthly accumulated precipitation during the years 1999–2012 and (C) seasonal patterns of midday leaf water potentials during 2012. Bars represent standard error (n = 3 plot averages).
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Figure 1: Environmental variables during the period of study. (A) Daily temperature in 2012 and monthly average temperature during the years 1999–2012, (B) daily accumulated precipitation in 2012 and monthly accumulated precipitation during the years 1999–2012 and (C) seasonal patterns of midday leaf water potentials during 2012. Bars represent standard error (n = 3 plot averages).

Mentions: The study was carried out in a holm oak (Quercus ilex L.) forest in the Prades Mountains, NE Spain, located on the south-facing upper slopes of the Torners valley (41°21′ N, 1°2′ E; 990 m asl). The climate is Mediterranean, with a mean annual rainfall of 609 mm and a mean annual temperature of 12.2°C (climate data for the period 1999–2012 from an automatic meteorological station installed at the site) (Figures 1A,B). Summer drought is pronounced, with 65.3 mm of rain on average from mid-June to mid-September. The soil is a Dystric Cambisol over Paleozoic schist, ranging between 35 and 90 cm in depth. Bedrock outcrops are frequent and the terrain slope is around 25%. The holm oak forest is dominated by Q. ilex L., P. latifolia L. and A. unedo L. There are other evergreen species well adapted to dry conditions (Erica arborea L., Juniperus oxycedrus L., Cistus albidus L.) and occasional individuals of deciduous species (Sorbus torminalis (L.) Crantz, Acer monspessulanum L.)


Dynamics of non-structural carbohydrates in three Mediterranean woody species following long-term experimental drought.

Rosas T, Galiano L, Ogaya R, Peñuelas J, Martínez-Vilalta J - Front Plant Sci (2013)

Environmental variables during the period of study. (A) Daily temperature in 2012 and monthly average temperature during the years 1999–2012, (B) daily accumulated precipitation in 2012 and monthly accumulated precipitation during the years 1999–2012 and (C) seasonal patterns of midday leaf water potentials during 2012. Bars represent standard error (n = 3 plot averages).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3795346&req=5

Figure 1: Environmental variables during the period of study. (A) Daily temperature in 2012 and monthly average temperature during the years 1999–2012, (B) daily accumulated precipitation in 2012 and monthly accumulated precipitation during the years 1999–2012 and (C) seasonal patterns of midday leaf water potentials during 2012. Bars represent standard error (n = 3 plot averages).
Mentions: The study was carried out in a holm oak (Quercus ilex L.) forest in the Prades Mountains, NE Spain, located on the south-facing upper slopes of the Torners valley (41°21′ N, 1°2′ E; 990 m asl). The climate is Mediterranean, with a mean annual rainfall of 609 mm and a mean annual temperature of 12.2°C (climate data for the period 1999–2012 from an automatic meteorological station installed at the site) (Figures 1A,B). Summer drought is pronounced, with 65.3 mm of rain on average from mid-June to mid-September. The soil is a Dystric Cambisol over Paleozoic schist, ranging between 35 and 90 cm in depth. Bedrock outcrops are frequent and the terrain slope is around 25%. The holm oak forest is dominated by Q. ilex L., P. latifolia L. and A. unedo L. There are other evergreen species well adapted to dry conditions (Erica arborea L., Juniperus oxycedrus L., Cistus albidus L.) and occasional individuals of deciduous species (Sorbus torminalis (L.) Crantz, Acer monspessulanum L.)

Bottom Line: In the long-term drought experiment we found significant depletion in concentrations of total NSC in treatment plots only in the lignotuber of A. unedo.At the same time, A. unedo was the only species showing a significant reduction in BAI under the drought treatment during the 14 years of the experiment.However, we found a clear association between the concentrations of NSC and defoliation in Q. ilex individuals sampled outside the experimental plots, with lower total concentrations of NSC and lower proportion of starch in defoliated individuals.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recerca Ecològica i Aplicacions Forestals (CREAF) Cerdanyola del Vallès, Spain ; Departament de Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona Cerdanyola del Vallès, Spain.

ABSTRACT
Stored non-structural carbohydrates (NSC) have been proposed as a key determinant of drought resistance in plants. However, the evidence for this role is controversial, as it comes mostly from observational, short-term studies. Here, we take advantage of a long-term experimental throughfall reduction to elucidate the response of NSC to increased drought 14 years after the beginning of the treatment in three Mediterranean resprouter trees (Quercus ilex L., Arbutus unedo L. and Phillyrea latifolia L.). In addition, we selected 20 Q. ilex individuals outside the experimental plots to directly assess the relationship between defoliation and NSC at the individual level. We measured the seasonal course of NSC concentrations in leaves, branches and lignotuber in late winter, late spring, summer, and autumn 2012. Total concentrations of NSC were highest in the lignotuber for all species. In the long-term drought experiment we found significant depletion in concentrations of total NSC in treatment plots only in the lignotuber of A. unedo. At the same time, A. unedo was the only species showing a significant reduction in BAI under the drought treatment during the 14 years of the experiment. By contrast, Q. ilex just reduced stem growth only during the first 4 years of treatment and P. latifolia remained unaffected over the whole study period. However, we found a clear association between the concentrations of NSC and defoliation in Q. ilex individuals sampled outside the experimental plots, with lower total concentrations of NSC and lower proportion of starch in defoliated individuals. Taken together, our results suggest that stabilizing processes, probably at the stand level, may have been operating in the long-term to mitigate any impact of drought on NSC levels, and highlight the necessity to incorporate long-term experimental studies of plant responses to drought.

No MeSH data available.