Sapflow measurements in forest stands: methods and uncertainties

Köstner, Barbara; Granier, André; Čermák, Jan

doi:10.1051/forest:19980102

Cited by 219 publications

(176 citation statements)

References 30 publications

Supporting

Mentioning

149

Contrasting

Unclassified

Order By: Relevance

“…Similar transpiration rates were found in studies on stands of Pinus sylvestris [25] and Picea abies [27]. Comparisons between the two systems installed in the same trees were made on Quercus petraea [20] and Picea abies [26]. No significant difference was reported between the two systems.…”

Section: Introductionsupporting

confidence: 59%

“…This implies that the difference in response had to do with the flow rate and not with sensor malfunction due to temperature or humidity. Most other studies report good agreement between the two systems, but the range of studied trees and range of sapflow densities in those other studies was rather limited [20,26]. Measured sapflow density was rarely higher than 30 g m -2 s -1 in most earlier studies on Scots pine and Norway spruce, whereas in this study, sapflow density reached 60 g m -2 s -1 .…”

Section: Comparison Of the Two Systemscontrasting

confidence: 45%

“…In these studies, and many others, tree transpiration is commonly measured by the sapflow technique. This is a technique which has become very popular as an elegant tool for measuring tree water uptake [26,45,50]. Assessment of the performance and accuracy of such methods is important in assuring the quality of knowledge gained from such studies.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of heat balance and heat dissipation methods for sapflow measurements in pine and spruce

2001

View full text Add to dashboard Cite

-The tissue heat-balance method (Cÿ ermák) and the heat-dissipation method (Granier) were compared in three Scots pines and two Norway spruces in a forest in central Sweden. The Granier system measured up to 50% lower sapflow than the Cÿ ermák system at high flow rates. New coefficients for the Granier system were estimated, based on sapflow density from the Cÿ ermák measurements. Without compensation, natural temperature gradients may cause large errors in measurements made by the Granier system. By using a horizontal reference sensor, no compensation was necessary. It was also shown that radial flow patterns must be considered when calculating total tree sapflow. Transpiration of two adjacent stands, one measured by the Granier method and the other by the Cÿ ermák method, showed good agreement internally and with total evaporation measured by the eddy-correlation method. THB / HD / sap-flow / transpiration / Picea abies / Pinus sylvestrisRésumé -Évaluation des méthodes des équilibres thermiques et de dissipation thermique concernant la mesure de flux de sève pour le pin et l'épicéa. La méthode des équilibres thermiques (Cÿ ermák), et la méthode de dissipation thermique (Granier) ont été comparées pour trois Pins sylvestres et deux épicéas dans une forêt du centre de la Suède. Le système Granier a donné des valeurs de flux de sève jusqu'à 50 % plus faible que le système Cÿ ermák pour les flux élevés. De nouveaux coefficients basés sur les mesures de densité de flux obtenues avec le système Cÿ ermák ont été estimés pour le système Granier. Le système Granier sans compensation pour les gradients naturels de température dans le tronc peut présenter de larges erreurs, mais si un capteur de référence horizontal est utilisé, les compensations ne sont pas nécessaires. Il a aussi été démontré que les variations radiales de flux doivent être prises en compte lors des calculs de flux de sève pour l'arbre entier. Les transpirations de deux couverts adjacents, l'un mesuré avec la méthode Granier, et l'autre avec la méthode Cÿ ermák, sont en accord entre elles et avec l'évaporation totale mesurée par la méthode des corrélations turbulentes. THB / HD / flux de sève / transpiration / Picea abies / Pinus sylvestris

show abstract

Section: Introductionsupporting

confidence: 59%

Section: Comparison Of the Two Systemscontrasting

confidence: 45%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of heat balance and heat dissipation methods for sapflow measurements in pine and spruce

2001

View full text Add to dashboard Cite

show abstract

“…Two methods for measuring xylem sapflow were employed to measure tree transpiration: thermal flowmeters constructed according to Granier [16,17] and the steady-state, null-balance method of Cermák and co-workers [10,28,30] [28,29] Nevertheless, many observations are required and sampling should be carried out over long periods [39]. Figure 1 shows the distribution of observed shoot water vapor conductance values for P. sylvestris as related to temperature (figure 1a), air saturation deficit (figure 1b), and photosynthetically active photon flux density (PPFD; figure 1c, d).…”

mentioning

confidence: 99%

Environmental and endogenous controls on leaf- and stand-level water conductance in a Scots pine plantation

et al. 1998

Self Cite

View full text Add to dashboard Cite

“…Granier et al, 1996b;Köstner et al, 1998) and the azimuthal variations in u in the trunk, especially when growing in open canopy space like an orchard (Lu et al, 2000), must be determined. These variations of u can be measured by inserting a number of Granier sensors at the same height into a single tree.…”

Section: Introductionmentioning

confidence: 99%

Effet de la longueur de la portée des sondes de dissipation thermique de type Granier sur des mesures de densité de flux de sève

Iida

Tanaka

2010

Ann. For. Sci.

View full text Add to dashboard Cite

Abstract• Granier-type thermal dissipation sensors measure sap flux density (u) by using the temperature difference between the heater and the reference probe. To detect u correctly, heat must not be transferred to the reference probe by thermal conduction. The distance across which heat can be transferred by conduction is important for the span length of a sensor and spacing of a number of sensors.• To validate span lengths and spacing of sensors, we used numerical simulations to calculate the potential distance across which heat can be transferred by conduction. We compared measurements with an original and a modified sensor for a Japanese red pine (Pinus densiflora) from December 2004 to May 2005. The span length of the original and the modified sensor is 15 and 4 cm, respectively.• Numerical simulations showed that span length and spacing of Granier sensors should be more than 10 cm for trees in which u ceases for a few hours before the predawn period. The modified sensor underestimated u by 18-46% in winter (December-March) because its reference temperature was increased by heat transferred by conduction. The modified sensor measured u correctly in warm seasons, and only underestimated the annual amount of transpiration by 6%. Mots-clés :technique de dissipation thermique / altération du capteur / conduction thermique / sous-estimation de la densité de flux de sève Résumé -Effet de la longueur de la portée des sondes de dissipation thermique de type Granier sur des mesures de densité de flux de sève.• Les capteurs de dissipation thermique de type Granier mesurent la densité du flux de sève (u) en utilisant la différence de température entre le radiateur et la sonde de référence. Pour détecter u correctement, la chaleur ne doit pas être transférée à la sonde de référence par conduction thermique. La distance à travers laquelle la chaleur peut être transférée par conduction est importante pour la longueur de la portée d'un capteur et l'espacement de nombreux capteurs.• Pour valider les longueurs des portées et l'espacement des capteurs, nous avons utilisé des simulations numériques pour calculer la distance potentielle à travers laquelle la chaleur peut être transférée par conduction. • Des simulations numériques ont montré que la longueur de la portée et l'espacement des capteurs Granier devraient être supérieurs à 10 cm pour les arbres dans lesquels u cesse pendant quelques heures avant la période précédant l'aube. Le capteur modifié sous-estime u de 18 à 46 % en hiver (Décembre-Mars), car sa température de référence a été augmentée par la chaleur transférée par conduction. Le capteur modifié mesurée u correctement pendant les saisons chaudes, et seulement sous-estime la transpiration annuelle totale de 6 %.

show abstract

Sapflow measurements in forest stands: methods and uncertainties

Abstract: Abstract-This paper discusses the respective advantages and disadvantages of three sapflow techniques used for measuring tree transpiration in forests: heat pulse velocity, tissue heat balance (Cermák-Type), and radial flowmeter (Granier-Type)

Cited by 219 publications

References 30 publications

Evaluation of heat balance and heat dissipation methods for sapflow measurements in pine and spruce

Evaluation of heat balance and heat dissipation methods for sapflow measurements in pine and spruce

Environmental and endogenous controls on leaf- and stand-level water conductance in a Scots pine plantation

Effet de la longueur de la portée des sondes de dissipation thermique de type Granier sur des mesures de densité de flux de sève

Contact Info

Product

Resources

About