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Scots pine responses to drought investigated with eddy covariance and sap flow methods

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cris.virtual.author-orcid0000-0003-4070-6553
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cris.virtual.author-orcid0000-0001-5305-1045
cris.virtual.author-orcid0000-0002-1225-9170
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cris.virtualsource.author-orcidb7faa967-5967-4712-8dca-a56013492f1d
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cris.virtualsource.author-orcidaf3d5ff9-4724-46db-855d-91b429dae19a
cris.virtualsource.author-orcid454d47d0-3892-4b3a-a5c3-927100a1f1db
dc.abstract.enScots pine, as one of the dominant European tree species in the temperate zone, is experiencing intensified water deficits, especially in north-western and central Poland, where it suffers from frequent droughts and generally low precipitation. This work investigates drought impact on forest functioning, by analysing ecosystem transpiration under normal as well as dry conditions. Therefore, eddy covariance (EC) and sap flow measurements (using the thermal heat balance, THB, method) were combined to estimate transpiration (T) in two different-aged Scots pine (Pinus sylvestris) stands in north-western Poland: Mezyk (ME; 26 years old) and Tuczno (TU; 67 years old). Transpiration (T) estimates regarding EC measurements were derived from gross primary productivity (GPP) fluxes and vapour pressure deficit (VPD) dependence, considering their common relationship with stomatal activity. In 2019, the year following severe drought in Poland and Europe in general, total annual transpiration estimated based on sap flow measurements (TSF) was significantly lower than EC-derived transpiration (TEC) at both sites. The total ratio of TSF/TEC for the growing season (March–August) was 0.64 and 0.41 at ME and TU, respectively. We thus speculate that the understory, which was more abundant in TU than in ME, and which could only be observed by the EC system, may be responsible for the observed discrepancies. Bigger differences between TSF and TEC occurred under dry and wet conditions, while both were fairly similar under moderate conditions. The analysis of the relationships between TSF and soil water content (SWC) at depth of 10 cm revealed that there is a thresholds (SWC ~ 3.5%) at which TSF starts to decrease sharply, presumably due to stomatal closure. However, the decrease in GPP fluxes at the same time was less pronounced, indicating the impact of additional non-stomatal factor on water conductivity. We generally conclude that care should be taken if the conclusion of the occurrence of drought stress of some plants is derived from a bulk evapotranspiration flux, as it is commonly done with EC measurements averaging over the whole ecosystem. Our results also support the notion that non-stomatal water losses are an important element during extreme dry conditions, and that these may appear not only when stomata are already closed.
dc.affiliationWydział Inżynierii Środowiska i Inżynierii Mechanicznej
dc.affiliation.instituteKatedra Budownictwa i Geoinżynierii
dc.contributor.authorDukat, Paulina
dc.contributor.authorZiemblińska, Klaudia
dc.contributor.authorRäsänen, Matti
dc.contributor.authorVesala, Timo
dc.contributor.authorOlejnik, Janusz
dc.contributor.authorUrbaniak, Marek
dc.date.access2025-06-17
dc.date.accessioned2025-09-22T12:31:26Z
dc.date.available2025-09-22T12:31:26Z
dc.date.copyright2023-03-14
dc.date.issued2023
dc.description.abstract<jats:title>Abstract</jats:title><jats:p>Scots pine, as one of the dominant European tree species in the temperate zone, is experiencing intensified water deficits, especially in north-western and central Poland, where it suffers from frequent droughts and generally low precipitation. This work investigates drought impact on forest functioning, by analysing ecosystem transpiration under normal as well as dry conditions. Therefore, eddy covariance (EC) and sap flow measurements (using the thermal heat balance, THB, method) were combined to estimate transpiration (<jats:italic>T</jats:italic>) in two different-aged Scots pine (<jats:italic>Pinus sylvestris</jats:italic>) stands in north-western Poland: Mezyk (ME; 26 years old) and Tuczno (TU; 67 years old). Transpiration (<jats:italic>T</jats:italic>) estimates regarding EC measurements were derived from gross primary productivity (GPP) fluxes and vapour pressure deficit (VPD) dependence, considering their common relationship with stomatal activity. In 2019, the year following severe drought in Poland and Europe in general, total annual transpiration estimated based on sap flow measurements (<jats:italic>T</jats:italic><jats:sub>SF</jats:sub>) was significantly lower than EC-derived transpiration (<jats:italic>T</jats:italic><jats:sub>EC</jats:sub>) at both sites. The total ratio of <jats:italic>T</jats:italic><jats:sub>SF</jats:sub>/<jats:italic>T</jats:italic><jats:sub>EC</jats:sub> for the growing season (March–August) was 0.64 and 0.41 at ME and TU, respectively. We thus speculate that the understory, which was more abundant in TU than in ME, and which could only be observed by the EC system, may be responsible for the observed discrepancies. Bigger differences between <jats:italic>T</jats:italic><jats:sub>SF</jats:sub> and <jats:italic>T</jats:italic><jats:sub>EC</jats:sub> occurred under dry and wet conditions, while both were fairly similar under moderate conditions. The analysis of the relationships between <jats:italic>T</jats:italic><jats:sub>SF</jats:sub> and soil water content (SWC) at depth of 10 cm revealed that there is a thresholds (SWC ~ 3.5%) at which <jats:italic>T</jats:italic><jats:sub>SF</jats:sub> starts to decrease sharply, presumably due to stomatal closure. However, the decrease in GPP fluxes at the same time was less pronounced, indicating the impact of additional non-stomatal factor on water conductivity. We generally conclude that care should be taken if the conclusion of the occurrence of drought stress of some plants is derived from a bulk evapotranspiration flux, as it is commonly done with EC measurements averaging over the whole ecosystem. Our results also support the notion that non-stomatal water losses are an important element during extreme dry conditions, and that these may appear not only when stomata are already closed.</jats:p>
dc.description.accesstimeat_publication
dc.description.bibliographyil., bibliogr.
dc.description.financepublication_nocost
dc.description.financecost0,00
dc.description.if2,6
dc.description.number3
dc.description.points100
dc.description.versionfinal_published
dc.description.volume142
dc.identifier.doi10.1007/s10342-023-01549-w
dc.identifier.eissn1612-4677
dc.identifier.issn1612-4669
dc.identifier.urihttps://sciencerep.up.poznan.pl/handle/item/5034
dc.identifier.weblinkhttp://link.springer.com/article/10.1007/s10342-023-01549-w
dc.languageen
dc.relation.ispartofEuropean Journal of Forest Research
dc.relation.pagess. 671–690
dc.rightsCC-BY
dc.sciencecloudsend
dc.share.typeOTHER
dc.subject.enheat balance method
dc.subject.eneddy covariance
dc.subject.entranspiration
dc.subject.enscots pine
dc.subject.enwater balance
dc.subject.endrought stress
dc.subject.entemperate forest
dc.titleScots pine responses to drought investigated with eddy covariance and sap flow methods
dc.typeJournalArticle
dspace.entity.typePublication
oaire.citation.issue3
oaire.citation.volume142