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Wright CL, West JB, de Lima ALA, Souza ES, Medeiros M, Wilcox BP. Contrasting water-use strategies revealed by species-specific transpiration dynamics in the Caatinga dry forest. Tree Physiol 2024; 44:tpad137. [PMID: 37935389 DOI: 10.1093/treephys/tpad137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 11/01/2023] [Indexed: 11/09/2023]
Abstract
In forest ecosystems, transpiration (T) patterns are important for quantifying water and carbon fluxes and are major factors in predicting ecosystem change. Seasonal changes in rainfall and soil water content can alter the sensitivity of sap flux density to daily variations in vapor pressure deficit (VPD). This sensitivity is species-specific and is thought to be related to hydraulic strategies. The aim of this work is to better understand how the sap flux density of species with low versus high wood density differ in their sensitivity to VPD and soil water content and how potentially opposing water-use strategies influence T dynamics, and ultimately, correlations to evapotranspiration (ET). We use hysteresis area analysis to quantify the sensitivity of species-specific sap flux density to changes in the VPD, breakpoint-based models to determine the soil water content threshold instigating a T response and multiscalar wavelet coherency to correlate T to ET. We found that low wood density Commiphora leptophloeos (Mart.) Gillett had a more dynamic T pattern, a greater sensitivity to VPD at high soil water content, required a higher soil water content threshold for this sensitivity to be apparent, and had a significant coherency correlation with ET at daily to monthly timescales. This behavior is consistent with a drought avoidance strategy. High wood density Cenostigma pyramidale (Tul.) E. Gagnon & G. P. Lewis, conversely, had a more stable T pattern, responded to VPD across a range of soil water content, tolerated a lower soil water content threshold to T, and had a significant coherency correlation with ET at weekly timescales. This behavior is consistent with a drought-tolerant strategy. We build on previous research to show that these species have contrasting water-use strategies that should be considered in large-scale modeling efforts.
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Affiliation(s)
- Cynthia L Wright
- Southern Research Station, USDA Forest Service, 4700 Old Kingston Pike, Knoxville, TN 37919, USA
- Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panama City, Panama
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37830, USA
- Ecology and Conservation Biology, Texas A&M University, 534 John Kimbrough Blvd, College Station, TX 77843, USA
| | - Jason B West
- Ecology and Conservation Biology, Texas A&M University, 534 John Kimbrough Blvd, College Station, TX 77843, USA
| | - André L A de Lima
- Universidade Federal Rural de Pernambuco, Unidade Acadêmica de Serra Talhada, Av. Gregório Ferraz Nogueira, S/n, Bairro: José Tomé de Souza Ramos, Caixa Postal 063, CEP: 56.909-535, Serra Talhada, Pernambuco, Brazil
| | - Eduardo S Souza
- Universidade Federal Rural de Pernambuco, Unidade Acadêmica de Serra Talhada, Av. Gregório Ferraz Nogueira, S/n, Bairro: José Tomé de Souza Ramos, Caixa Postal 063, CEP: 56.909-535, Serra Talhada, Pernambuco, Brazil
| | - Maria Medeiros
- Universidade Federal Rural de Pernambuco, Unidade Acadêmica de Serra Talhada, Av. Gregório Ferraz Nogueira, S/n, Bairro: José Tomé de Souza Ramos, Caixa Postal 063, CEP: 56.909-535, Serra Talhada, Pernambuco, Brazil
- Federal University of Pernambuco, Department of Botany, Avenida Professor Moraes Rego, s/n, Cidade Universitária, CEP: 50670-901, Recife, Pernambuco, Brazil
| | - Bradford P Wilcox
- Ecology and Conservation Biology, Texas A&M University, 534 John Kimbrough Blvd, College Station, TX 77843, USA
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Wright CL, de Lima ALA, de Souza ES, West JB, Wilcox BP. Plant functional types broadly describe water use strategies in the Caatinga, a seasonally dry tropical forest in northeast Brazil. Ecol Evol 2021; 11:11808-11825. [PMID: 34522343 PMCID: PMC8427645 DOI: 10.1002/ece3.7949] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 11/11/2022] Open
Abstract
In seasonally dry tropical forests, plant functional type can be classified as deciduous low wood density, deciduous high wood density, or evergreen high wood density species. While deciduousness is often associated with drought-avoidance and low wood density is often associated with tissue water storage, the degree to which these functional types may correspond to diverging and unique water use strategies has not been extensively tested.We examined (a) tolerance to water stress, measured by predawn and mid-day leaf water potential; (b) water use efficiency, measured via foliar δ13C; and (c) access to soil water, measured via stem water δ18O.We found that deciduous low wood density species maintain high leaf water potential and low water use efficiency. Deciduous high wood density species have lower leaf water potential and variable water use efficiency. Both groups rely on shallow soil water. Evergreen high wood density species have low leaf water potential, higher water use efficiency, and access alternative water sources. These findings indicate that deciduous low wood density species are drought avoiders, with a specialized strategy for storing root and stem water. Deciduous high wood density species are moderately drought tolerant, and evergreen high wood density species are the most drought tolerant group.Synthesis. Our results broadly support the plant functional type framework as a way to understand water use strategies, but also highlight species-level differences.
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Affiliation(s)
- Cynthia L. Wright
- Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTNUSA
- Ecology and Conservation BiologyTexas A&M UniversityCollege StationTXUSA
| | - André L. A. de Lima
- Universidade Federal Rural de Pernambuco/Unidade Acadêmica de Serra Talhada (UFRPE/UAST)Serra TalhadaBrasil
| | - Eduardo S. de Souza
- Universidade Federal Rural de Pernambuco/Unidade Acadêmica de Serra Talhada (UFRPE/UAST)Serra TalhadaBrasil
| | - Jason B. West
- Ecology and Conservation BiologyTexas A&M UniversityCollege StationTXUSA
| | - Bradford P. Wilcox
- Ecology and Conservation BiologyTexas A&M UniversityCollege StationTXUSA
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