scholarly journals Sap Flow in Aleppo Pine in Greece in Relation to Sapwood Radial Gradient, Temporal and Climatic Variability

Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 2
Author(s):  
Evangelia Korakaki ◽  
Mariangela N. Fotelli
Keyword(s):  
Sap Flow ◽  
Eastern Mediterranean ◽  
Climatic Variability ◽  
Radial Profile ◽  
Climatic Conditions ◽  
Aleppo Pine ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Radial Gradient ◽  
Seasonal Basis

Research Highlights: The radial gradient of sap flux density (Js) and the effects of climatic factors on sap flow of Aleppo pine were assessed at different time scales in an eastern Mediterranean ecosystem to improve our understanding of the species water balance. Background and Objectives: Aleppo pine’s sap flow radial profile and responses to environmental parameters in the eastern Mediterranean were, to our best knowledge, originating to date from more arid planted forests. Information from natural forests in this region was lacking. Our objectives were to (a) determine the species’ radial variability in Js on a diurnal and seasonal basis and under different climatic conditions, (b) scale up to tree sap flow taking into account the radial profile of Js and (c) determine the responses of Aleppo pine’s sap flow over the year to climatic variability. Materials and Methods: Js was monitored in Aleppo pine in a natural forest in northern Greece with Granier’s method using sensors at three sapwood depths (21, 51, and 81 mm) during two periods differing in climatic conditions, particularly in soil water availability. Results: Js was the highest at 21 mm sapwood depth, and it declined with increasing depth. A steeper gradient of Js in deep sapwood was observed under drier conditions. The same patterns of radial variability in Js were maintained throughout the year, but the contribution of inner sapwood to sap flow was the highest in autumn when the lower seasonal Js was recorded in both study periods. Not taking into account the radial gradient of Js in the studied Aleppo pine would result in a c. 20.2–27.7 % overestimation of total sap flow on a sapwood basis (Qs), irrespective of climatic conditions. On a diurnal and seasonal basis, VPD was the strongest determinant of sap flux density, while at a larger temporal scale, the effect of soil water content was evident. At SWC > 20% sap flow responded positively to increasing solar radiation and VPD, indicating the decisive role of water availability in the studied region. Moreover, in drier days with VPD > 0.7 KPa, SWC controlled the variation of sap flow. Conclusions: There is a considerable radial variability in Js of the studied Aleppo pine and a considerable fluctuation of sap flow with environmental dynamics that should be taken into account when addressing the species water balance.

Spatial variability of xylem sap flow in mature beech (Fagus sylvatica) and its diurnal dynamics in relation to microclimate

Botany ◽  
2008 ◽  
Vol 86 (12) ◽  
pp. 1440-1448 ◽  
Author(s):  
An Saveyn ◽  
Kathy Steppe ◽  
Raoul Lemeur
Keyword(s):  
Fagus Sylvatica ◽  
Sap Flow ◽  
Xylem Sap ◽  
Radial Profile ◽  
Vapour Pressure Deficit ◽  
Climatic Conditions ◽  
General Function ◽  
Sap Flux Density ◽  
Sapwood Area ◽  
Diurnal Variability

The spatial and diurnal variability of sap flow in a mature beech tree ( Fagus sylvatica L.) was investigated on days with different climatic conditions (sunny, cloudy, rainy), during the summer. Sap flux density (v) was measured with six heat field deformation probes placed around the stem circumference. Each probe measured v at six sapwood depths. Daily v exhibited clear radial variation, and the shape of the radial profile of v differed substantially among circumferential positions. At some positions, daily v decreased monotonically towards the stem centre, whereas at others it showed an almost monotonic increase. Hence, the conducting sapwood area of the beech was highly asymmetrical. At all positions, conducting sapwood reached beyond the deepest sampled sapwood depth, precluding correct estimations of total sap flow. The radial profile of v also differed among measuring days. A general trend was that the inner sapwood contributed relatively more to total sap flow under better weather conditions. Besides variations among days, the shape of the radial profile of v also showed within-day variations. The contribution of the inner sapwood to total sap flow increased in the afternoon, with increasing vapour pressure deficit and photosynthetic active radiation. Because of large circumferential and temporal variability, no general function for the radial profile of v could be developed.

scholarly journals Assessing variation in the radial profile of sap flux density in Pinus species and its effect on daily water use

2004 ◽  
Vol 24 (3) ◽  
pp. 241-249 ◽  
Author(s):  
C. R. Ford ◽  
M. A. McGuire ◽  
R. J. Mitchell ◽  
R. O. Teskey
Keyword(s):  
Flux Density ◽  
Water Use ◽  
Radial Profile ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Pinus Species ◽  
Daily Water

A Direct Method for Estimating the Average Sap Flux Density Using a Modified Granier Measuring System

1997 ◽  
Vol 24 (5) ◽  
pp. 701 ◽  
Author(s):  
Ping Lu
Keyword(s):  
Flux Density ◽  
Sap Flow ◽  
Direct Method ◽  
Estimation Error ◽  
Original Method ◽  
Measuring System ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Average Value ◽  
Modified Method

The Granier sap flow measuring system that normally uses one analogue input channel of a datalogger for each sensor was modified to enable one channel to measure the average value of signals from two or more sensors. The sap flux density calculated from this average value of signals was very close (difference < 6.0%) to the arithmetic mean of the sap flux densities measured separately by means of individual sensors (using two or more input channels). The dynamics of the sap flux density measured by the modified method were similar to those measured by the original method. On a per-channel basis, the modified method reduced the ‘estimation error’ of sap flux density by 4–14-fold compared to the original method. By using the modified Granier system, the error in sap flow measurement that is usually associated with limited sampling can be substantially reduced without the need for extra dataloggers, the greatest item of expense.

The importance of conduction versus convection in heat pulse sap flow methods

2020 ◽  
Vol 40 (5) ◽  
pp. 683-694
Author(s):  
Michael A Forster
Keyword(s):  
Flux Density ◽  
Sap Flow ◽  
Peclet Number ◽  
Velocity Measurement ◽  
Measurement Range ◽  
Heat Pulse ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Péclet Number ◽  
Fast Methods

Abstract Heat pulse methods are a popular approach for estimating sap flow and transpiration. Yet, many methods are unable to resolve the entire heat velocity measurement range observable in plants. Specifically, the Heat Ratio (HRM) and Tmax heat pulse methods can only resolve slow and fast velocities, respectively. The Dual Method Approach (DMA) combines optimal data from HRM and Tmax to output the entire range of heat velocity. However, the transition between slow and fast methods in the DMA currently does not have a theoretical solution. A re-consideration of the conduction/convection equation demonstrated that the HRM equation is equivalent to the Péclet equation which is the ratio of conduction to convection. This study tested the hypothesis that the transition between slow and fast methods occurs when conduction/convection, or the Péclet number, equals one, and the DMA would be improved via the inclusion of this transition value. Sap flux density was estimated via the HRM, Tmax and DMA methods and compared with gravimetric sap flux density measured via a water pressure system on 113 stems from 15 woody angiosperm species. When the Péclet number ≤ 1, the HRM yielded accurate results and the Tmax was out of range. When the Péclet number &gt; 1, the HRM reached a maximum heat velocity at approximately 15 cm hr −1 and was no longer accurate, whereas the Tmax yielded accurate results. The DMA was able to output accurate data for the entire measurement range observed in this study. The linear regression analysis with gravimetric sap flux showed an r2 of 0.541 for HRM, 0.879 for Tmax and 0.940 for DMA. With the inclusion of the Péclet equation, the DMA resolved the entire heat velocity measurement range observed across 15 taxonomically diverse woody species. Consequently, the HRM and Tmax are redundant sap flow methods and have been superseded by the DMA.

The ecophysiological and growth responses of Aleppo pine (Pinushalepensis) to controlled heating applied to the base of the trunk

1996 ◽  
Vol 26 (8) ◽  
pp. 1366-1374 ◽  
Author(s):  
Michel Ducrey ◽  
Fabrice Duhoux ◽  
Roland Huc ◽  
Eric Rigolot
Keyword(s):  
Stomatal Conductance ◽  
Water Potential ◽  
Flux Density ◽  
Electrical Resistance ◽  
Aleppo Pine ◽  
Sap Flux ◽  
Growth Responses ◽  
Tree Physiology ◽  
Sap Flux Density ◽  
Trunk Diameter

Controlled, localized heating was applied to the trunks of young Aleppo pines (Pinushalepensis Mill.) during the winter. Three levels of burning were applied to the circumference of the trunks (zero, partial, or total), and the effects on tree physiology and growth were monitored during the 7 months following heating. Effects of the heat treatment on tree physiology were assessed by measuring predawn water potential, sap flux density, microvariations in trunk diameter, electrical resistance of the cambium, and gas exchanges from the needles (photosynthesis and stomatal conductance). Morphological response measurements included height and radial growth of the trees and morphological characteristics of the needles. The amount of chlorotic foliage was also measured. Aleppo pine was highly resistant to trunk injury, surviving when 80% of the trunk circumference was destroyed by fire. The behaviour of partially burnt pines was not significantly different from that of controls, for all variables studied. Trees whose trunks were totally burnt died from 1 to 5 months after treatment. Sap flux density of totally burnt trees was already significantly lower than that of other trees in the first week following the treatment. A decrease in net photosynthesis and stomatal conductance in the still surviving totally burnt trees was also recorded during the first measurements made in July. Treatment differences in predawn water potential, microvariations in trunk diameter, and electrical resistance of the cambium only appeared a few days before death of the totally burnt trees.

scholarly journals Tree Water Dynamics in a Semi-Arid, Pinus brutia Forest

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1039 ◽  
Author(s):  
Marinos Eliades ◽  
Adriana Bruggeman ◽  
Hakan Djuma ◽  
Maciek Lubczynski
Keyword(s):  
Soil Moisture ◽  
Sap Flow ◽  
Water Dynamics ◽  
Hydraulic Redistribution ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Pinus Brutia ◽  
Soil Moisture Sensors ◽  
Air Temperatures ◽  
Semi Arid

This study aims to examine interactions between tree characteristics, sap flow, and environmental variables in an open Pinus brutia (Ten.) forest with shallow soil. We examined radial and azimuthal variations of sap flux density (Jp), and also investigated the occurrence of hydraulic redistribution mechanisms, quantified nocturnal tree transpiration, and analyzed the total water use of P. brutia trees during a three-year period. Sap flow and soil moisture sensors were installed onto and around eight trees, situated in the foothills of the Troodos Mountains, Cyprus. Radial observations showed a linear decrease of sap flux densities with increasing sapwood depth. Azimuthal differences were found to be statistically insignificant. Reverse sap flow was observed during low vapor pressure deficit (VPD) and negative air temperatures. Nocturnal sap flow was about 18% of the total sap flow. Rainfall was 507 mm in 2015, 359 mm in 2016, and 220 mm in 2017. Transpiration was 53%, 30%, and 75%, respectively, of the rainfall in those years, and was affected by the distribution of the rainfall. The trees showed an immediate response to rainfall events, but also exploited the fractured bedrock. The transpiration and soil moisture levels over the three hydrologically contrasting years showed that P. brutia is well-adapted to semi-arid Mediterranean conditions.

A direct method for estimating the average sap flux density using a modified Granier measuring system.

2001 ◽  
Vol 28 (1) ◽  
pp. 85 ◽  
Author(s):  
Ping Lu
Keyword(s):  
Flux Density ◽  
Sap Flow ◽  
Direct Method ◽  
Estimation Error ◽  
Original Method ◽  
Measuring System ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Average Value ◽  
Modified Method

The Granier sap flow measuring system that normally uses one analogue input channel of a datalogger for each sensor was modified to enable one channel to measure the average value of signals from two or more sensors. The sap flux density calculated from this average value of signals was very close (difference < 6.0%) to the arithmetic mean of the sap flux densities measured separately by means of individual sensors (using two or more input channels). The dynamics of the sap flux density measured by the modified method were similar to those measured by the original method. On a per-channel basis, the modified method reduced the ‘estimation error’ of sap flux density by 4–14-fold compared to the original method. By using the modified Granier system, the error in sap flow measurement that is usually associated with limited sampling can be substantially reduced without the need for extra dataloggers, the greatest item of expense.

scholarly journals Sap Flow Dynamics and Responses to Grazing and Seasonal Changes in Soil Moisture for Acacia Ancistroclada and Comberatum Molle in a Kenyan Savanna

2020 ◽  
Author(s):  
Joseph Ondier ◽  
Dennis Otieno ◽  
Daniel Okach ◽  
John Onyango
Keyword(s):  
Soil Moisture ◽  
Vapor Pressure ◽  
Flux Density ◽  
Sap Flow ◽  
Seasonal Changes ◽  
Vapor Pressure Deficit ◽  
Livestock Grazing ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Rainfall Patterns

Abstract The Kenyan savanna, which is dominated by Acacia ancistroclada and Comberatum molle, has experienced notable changes in rainfall patterns and increased livestock grazing. A significant decrease in trees spread from 5 % to less than 1 % has been documented for the ecosystem and could be linked to the increased livestock grazing and changes in rainfall patterns, however, scientific evidence is lacking. We utilized sap flow to analyze the hydraulic responses of the prevailing trees to livestock grazing and seasonal changes in soil moisture. Environmental factors including precipitation, air temperature, soil moisture at - 0.3 m, and vapor pressure deficit were simultaneously measured. The results showed that the diurnal variation in sap flux density exhibited a single peak curve at around midday and correlated strongly with vapor pressure deficit and air temperature. Sap flux density was higher in the grazed (27.47 ± 8.65 g m-2s-1) than the fenced plots (20.17 ± 7.27 g m-2s-1). In all the plots, sap flux density followed seasonality in rainfall patterns, increasing and decreasing in wet and dry seasons respectively. The higher crown projected area was responsible for higher sap flow in the grazed plots. The diurnal variation in sap flux density showed that sap flow was coupled to the atmosphere with relatively low boundary layer resistance and the seasonal variation in sap flow was controlled by stomatal regulation. These findings point to the possibility that the dominant tree species in Lambwe are isohydric species. However, additional measurements need to be conducted on the eligibility of the species to confirm the conclusion.

scholarly journals Radial variations in xylem sap flux in a temperate red pine plantation forest

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Alanna V. Bodo ◽  
M. Altaf Arain
Keyword(s):  
Flux Density ◽  
Water Use ◽  
Sap Flow ◽  
Xylem Sap ◽  
Red Pine ◽  
Sap Flux ◽  
Plantation Forest ◽  
Sap Flux Density ◽  
Flow Measurements ◽  
Sapwood Area

Abstract Background Scaling sap flux measurements to whole-tree water use or stand-level transpiration is often done using measurements conducted at a single point in the sapwood of the tree and has the potential to cause significant errors. Previous studies have shown that much of this uncertainty is related to (i) measurement of sapwood area and (ii) variations in sap flow at different depths within the tree sapwood. Results This study measured sap flux density at three depth intervals in the sapwood of 88-year-old red pine (Pinus resinosa) trees to more accurately estimate water-use at the tree- and stand-level in a plantation forest near Lake Erie in Southern Ontario, Canada. Results showed that most of the water transport (65%) occurred in the outermost sapwood, while only 26% and 9% of water was transported in the middle and innermost depths of sapwood, respectively. Conclusions These results suggest that failing to consider radial variations in sap flux density within trees can lead to an overestimation of transpiration by as much as 81%, which may cause large uncertainties in water budgets at the ecosystem and catchment scale. This study will help to improve our understanding of water use dynamics and reduce uncertainties in sap flow measurements in the temperate pine forest ecosystems in the Great Lakes region and help in protecting these forests in the face of climate change.

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