Tree stem diameter variations and transpiration in Scots pine: an analysis using a dynamic sap flow model

Perämäki, Martti; Nikinmaa, Eero; Sevanto, Sanna; Ilvesniemi, Hannu; Siivola, Erkki; Hari, Pertti; Vesala, Timo

doi:10.1093/treephys/21.12-13.889

Cited by 124 publications

(109 citation statements)

References 34 publications

Supporting

Mentioning

103

Contrasting

Order By: Relevance

“…9) are within the range of xylem or stem diameter changes that were observed for young European beech and Norway spruce (Pinus abies L.) trees (Steppe and Lemeur 2007;Perämäki et al 2001). This agreement results from the fact that based on the parameterisation of the xylem water retention curve obtained from the experimental curve of Oertli (1993), we get a value for the elastic modulus E which is similar to values found by Steppe and Lemeur (2007) and Perämäki et al (2001). However, this value might have been underestimated, since we assume that changes of xylem water potential correspond only to changes in the xylem water content neglecting related changes in water contents of phloem, cambium and heartwood.…”

Section: Discussionsupporting

confidence: 57%

“…Similar to the soil water flow model, which is based on the continuum approach as described by the Richards' equation, also the plant water flow is described by this porous media equation following Bohrer et al (2005). This description is in contrast to more discrete approaches that consider the plant as built up of storage compartments and describe the water flow by water exchange processes between these compartments (Perämäki et al 2001;Steppe and Lemeur 2007). But, besides the advantages of a continuous mathematical formulation representing mass conservation (Früh and Kurth 1999), due to the similarity between the porous media approaches to describe water flow in the soil and the xylem, it seems also to be conceptually easier to derive a consistent model of hydro-dynamics of soil-plant systems based on the continuum approach.…”

Section: Discussionmentioning

confidence: 99%

“…Assuming that tension changes the volume of water conducting sapwood only (Perämäki et al 2001) and neglecting corresponding changes in phloem water content, which are considered to be comparatively small, then, in combination with the xylem water retention curve, the xylem water content θ x,a at air entry can be derived using the relation between xylem matric potential and relative volume change of the xylem element (Steppe and Lemeur 2007) expressed by…”

Section: Hydraulic Characteristics Of the Xylemmentioning

confidence: 99%

See 2 more Smart Citations

A one-dimensional model of water flow in soil-plant systems based on plant architecture

et al. 2010

View full text Add to dashboard Cite

The estimation of root water uptake and water flow in plants is crucial to quantify transpiration and hence the water exchange between land surface and atmosphere. In particular the soil water extraction by plant roots which provides the water supply of plants is a highly dynamic and non-linear process interacting with soil transport processes that are mainly determined by the natural soil variability at different scales. To better consider this root-soil interaction we extended and further developed a finite element tree hydrodynamics model based on the one-dimensional (1D) porous media equation. This is achieved by including in addition to the explicit three- dimensional (3D) architectural representation of the tree crown a corresponding 3D characterisation of the root system. This 1D xylem water flow model was then coupled to a soil water flow model derived also from the 1D porous media equation. We apply the new model to conduct sensitivity analysis of root water uptake and transpiration dynamics and compare the results to simulation results obtained by using a 3D model of soil water flow and root water uptake. Based on data from lysimeter experiments with young European beech trees (Fagus silvatica L.) is shown, that the model is able to correctly describe transpiration and soil water flow. In conclusion, compared to a fully 3D model the 1D porous media approach provides a computationally efficient alternative, able to reproduce the main mechanisms of plant hydro-dynamics including root water uptake from soil.

show abstract

Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Hydraulic Characteristics Of the Xylemmentioning

confidence: 99%

See 1 more Smart Citation

A one-dimensional model of water flow in soil-plant systems based on plant architecture

et al. 2010

View full text Add to dashboard Cite

show abstract

“…By incorporating Eq. (2) with Hooke's Law, radial water exchange can observe the dimensional changes within the innerbark (Perämäki et al 2001). This novel modelling approach to understanding bark hydraulics in both vertical and horizontal dimensions has made it accessible to observe sugar transport, radial water exchange and radial growth dynamics.…”

Section: Quantifying Bark Hydraulicsmentioning

confidence: 99%

“…This model approach applies Hooke's Law, which indicates that water-induced dimensional changes in the xylem reflect changes in xylem water potential (Perämäki et al 2001). Consequently, the inner-bark would follow xylem water-related changes, as the radial exchange in water between the two tissues tend towards an equilibrium (Hölttä et al 2009).…”

Section: Modelling the Estimated Growth Signal Derived From Radial Stmentioning

confidence: 99%

Dynamic variations in bark hydraulics – understanding whole tree processes and its linkage to bark hydraulic function and structure

Chan

2016

Diss. For.

View full text Add to dashboard Cite

A mature tree stem generally consists of a column of wood that is composed of a series of annual incremental layers and enclosed in a covering of bark. The dynamic variations of the bark are complex due to its structure and function: the thick outer-bark acts as a protective barrier against the abiotic and biotic environment; while the phloem is where sugar transport occurs. Much of the bark variation is due to the transport of sugars and its related processes. The driving force for sugar transport in the phloem is generated by the accumulation of sugars at source sites (e.g. leaves), which creates differences in gradients in turgor pressure along the stem. As a result, mass flow occurs -transporting sugars to sink regions that require it (e.g. stem and roots) for active growth, respiration and storage. The xylem pathway, which transports water in the opposite direction, is connected to the phloem in parallel along the entire length of the stem. The immediate connection between these two transport pathways suggests a functional linkage, as the phloem draws water from the xylem in order for mass flow to occur. The dynamic interactions between the xylem and phloem, and the processes occurring within the bark have great implications for whole tree physiology.The purpose of this thesis is to study the dynamic processes that occur within the bark and its interaction with other internal tree processes and the external environment. This is accomplished by first understanding the bark hydraulic architecture and its linkage to the environment, followed by its linkage to various tree processes. These linkages have not been thoroughly quantified, especially on an intra-annual (e.g. daily) scale. The study of bark hydraulic dynamics is of great interest because it is a relatively new topic with great potential. The changes of the bark in response to the environment may play a large part as a regulator to other tree processes.The thesis consists of four papers, of which one is a modelling paper and three are experimental (field and laboratory) studies. The model estimates growth by using dendrometer measurements as inputs for the model. Growth is estimated by separating the water-related influences from measured inner-bark, revealing a growth signal -proxy for cambial stem growth. Using this growth signal, a correlation study to microclimate variables is examined in one paper; and to assumed growth respiration in a second paper. The remaining two papers explore the seasonality of photosynthesis and respiration, and bark stem dynamics during the winter recovery period in the spring.As a conclusion of this thesis, these four papers show how inextricably linked, the individual tree processes are to the changes within the bark, due to the tight coupling with sap flow-related changes of the xylem. The culmination of this thesis opens new opportunities to further understand the dynamics of bark hydraulics and ecophysiological processes by implementing field measurements and state-of-the-art modelling.Keywords: xylem, phloe...

show abstract

Active microwave observations of diurnal and seasonal variations of canopy water content across the humid African tropical forests

Konings

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

A higher frequency of severe droughts under warmer temperatures is expected to lead to large impacts on global water and carbon fluxes and on vegetation cover—including possible widespread mortality. Monitoring the hydraulic state of vegetation as represented by the canopy water content will allow rapid assessment of vegetation water stress. Here we show the potential of active microwave backscatter observations at Ku band for monitoring the diurnal and seasonal variations of top‐of‐canopy water content. We focus on the humid tropical forests of Central Africa and examine spatiotemporal variations of radar backscatter from QuikSCAT (2001–2009) and RapidScat (2014–2016). Diurnal variations in RapidScat backscatter demonstrate the occurrence of widespread midday stomatal closure in this region. Increases in backscatter during the dry seasons in humid forests could be explained by both dry season leaf flushing (as supported by canopy structure) and vapor pressure deficit‐driven increases in evapotranspiration rates.

show abstract

Tree stem diameter variations and transpiration in Scots pine: an analysis using a dynamic sap flow model

Cited by 124 publications

References 34 publications

A one-dimensional model of water flow in soil-plant systems based on plant architecture

A one-dimensional model of water flow in soil-plant systems based on plant architecture

Dynamic variations in bark hydraulics – understanding whole tree processes and its linkage to bark hydraulic function and structure

Active microwave observations of diurnal and seasonal variations of canopy water content across the humid African tropical forests

Contact Info

Product

Resources

About