Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees
Seasonal regulation of leaf water potential (ΨL) was studied in eight dominant woody savanna species growing in Brazilian savanna (Cerrado) sites that experience a 5-month dry season. Despite marked seasonal variation in precipitation and air saturation deficit (D), seasonal differences in midday mi...
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todo:paper_09311890_v19_n3_p296_Bucci2023-10-03T15:48:12Z Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees Bucci, S.J. Goldstein, G. Meinzer, F.C. Franco, A.C. Campanello, P. Scholz, F.G. Hydraulic conductance Nocturnal transpiration Plant-water relations Sap flow Savannas Biodiversity Hydraulic conductivity Physiology Plants (botany) Precipitation (meteorology) Soils Wetting Air saturation deficit architectural traits Cerrado tree species Isohydric behavior Nocturnal transpiration Seasonal regulation Stomatal conductance Woody savanna species Meteorology Biodiversity Meteorology Physiology Plants Precipitants Saturation Seasonal Variation Soil Seasonal regulation of leaf water potential (ΨL) was studied in eight dominant woody savanna species growing in Brazilian savanna (Cerrado) sites that experience a 5-month dry season. Despite marked seasonal variation in precipitation and air saturation deficit (D), seasonal differences in midday minimum ΨL were small in all of the study species. Water use and water status were regulated by a combination of plant physiological and architectural traits. Despite a nearly 3-fold increase in mean D between the wet and dry season, a sharp decline in stomatal conductance with increasing D constrained seasonal variation in minimum ΨL by limiting transpiration per unit leaf area (E). The leaf surface area per unit of sapwood area (LA/SA), a plant architectural index of potential constraints on water supply in relation to transpirational demand, was about 1.5-8 times greater in the wet season compared to the dry season for most of the species. The changes in LA/SA from the wet to the dry season resulted from a reduction in total leaf surface area per plant, which maintained or increased total leaf-specific hydraulic conductance (G t) during the dry season. The isohydric behavior of Cerrado tree species with respect to minimum ΨL throughout the year thus was the result of strong stomatal control of evaporative losses, a decrease in total leaf surface area per tree during the dry season, an increase in total leaf-specific hydraulic conductance, and a tight coordination between gas and liquid phase conductance. In contrast with the seasonal isohydric behavior of minimum ΨL, predawn ΨL in all species was substantially lower during the dry season compared to the wet season. During the dry season, predawn ΨL was more negative than bulk soil Ψ estimated by extrapolating plots of E versus ΨL to E=0. Predawn disequilibrium between plant and soil Ψ was attributable largely to nocturnal transpiration, which ranged from 15 to 22% of the daily total. High nocturnal water loss may also have prevented internal water storage compartments from being completely refilled at night before the onset of transpiration early in the day. © Springer-Verlag 2004. Fil:Bucci, S.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Goldstein, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Campanello, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Scholz, F.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_09311890_v19_n3_p296_Bucci |
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Universidad de Buenos Aires |
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I-28 |
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R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Hydraulic conductance Nocturnal transpiration Plant-water relations Sap flow Savannas Biodiversity Hydraulic conductivity Physiology Plants (botany) Precipitation (meteorology) Soils Wetting Air saturation deficit architectural traits Cerrado tree species Isohydric behavior Nocturnal transpiration Seasonal regulation Stomatal conductance Woody savanna species Meteorology Biodiversity Meteorology Physiology Plants Precipitants Saturation Seasonal Variation Soil |
| spellingShingle |
Hydraulic conductance Nocturnal transpiration Plant-water relations Sap flow Savannas Biodiversity Hydraulic conductivity Physiology Plants (botany) Precipitation (meteorology) Soils Wetting Air saturation deficit architectural traits Cerrado tree species Isohydric behavior Nocturnal transpiration Seasonal regulation Stomatal conductance Woody savanna species Meteorology Biodiversity Meteorology Physiology Plants Precipitants Saturation Seasonal Variation Soil Bucci, S.J. Goldstein, G. Meinzer, F.C. Franco, A.C. Campanello, P. Scholz, F.G. Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees |
| topic_facet |
Hydraulic conductance Nocturnal transpiration Plant-water relations Sap flow Savannas Biodiversity Hydraulic conductivity Physiology Plants (botany) Precipitation (meteorology) Soils Wetting Air saturation deficit architectural traits Cerrado tree species Isohydric behavior Nocturnal transpiration Seasonal regulation Stomatal conductance Woody savanna species Meteorology Biodiversity Meteorology Physiology Plants Precipitants Saturation Seasonal Variation Soil |
| description |
Seasonal regulation of leaf water potential (ΨL) was studied in eight dominant woody savanna species growing in Brazilian savanna (Cerrado) sites that experience a 5-month dry season. Despite marked seasonal variation in precipitation and air saturation deficit (D), seasonal differences in midday minimum ΨL were small in all of the study species. Water use and water status were regulated by a combination of plant physiological and architectural traits. Despite a nearly 3-fold increase in mean D between the wet and dry season, a sharp decline in stomatal conductance with increasing D constrained seasonal variation in minimum ΨL by limiting transpiration per unit leaf area (E). The leaf surface area per unit of sapwood area (LA/SA), a plant architectural index of potential constraints on water supply in relation to transpirational demand, was about 1.5-8 times greater in the wet season compared to the dry season for most of the species. The changes in LA/SA from the wet to the dry season resulted from a reduction in total leaf surface area per plant, which maintained or increased total leaf-specific hydraulic conductance (G t) during the dry season. The isohydric behavior of Cerrado tree species with respect to minimum ΨL throughout the year thus was the result of strong stomatal control of evaporative losses, a decrease in total leaf surface area per tree during the dry season, an increase in total leaf-specific hydraulic conductance, and a tight coordination between gas and liquid phase conductance. In contrast with the seasonal isohydric behavior of minimum ΨL, predawn ΨL in all species was substantially lower during the dry season compared to the wet season. During the dry season, predawn ΨL was more negative than bulk soil Ψ estimated by extrapolating plots of E versus ΨL to E=0. Predawn disequilibrium between plant and soil Ψ was attributable largely to nocturnal transpiration, which ranged from 15 to 22% of the daily total. High nocturnal water loss may also have prevented internal water storage compartments from being completely refilled at night before the onset of transpiration early in the day. © Springer-Verlag 2004. |
| format |
JOUR |
| author |
Bucci, S.J. Goldstein, G. Meinzer, F.C. Franco, A.C. Campanello, P. Scholz, F.G. |
| author_facet |
Bucci, S.J. Goldstein, G. Meinzer, F.C. Franco, A.C. Campanello, P. Scholz, F.G. |
| author_sort |
Bucci, S.J. |
| title |
Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees |
| title_short |
Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees |
| title_full |
Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees |
| title_fullStr |
Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees |
| title_full_unstemmed |
Mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in Neotropical savanna trees |
| title_sort |
mechanisms contributing to seasonal homeostasis of minimum leaf water potential and predawn disequilibrium between soil and plant water potential in neotropical savanna trees |
| url |
http://hdl.handle.net/20.500.12110/paper_09311890_v19_n3_p296_Bucci |
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