Heat balance measurements—to quantify sap flow in thin stems only?

Herzog, Karl Martin; Thum, Roland; Zweifel, Roman; Häsler, R.

doi:10.1016/s0168-1923(96)02355-6

Cited by 21 publications

(14 citation statements)

References 27 publications

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“…Since the measurements were initially not realistic, they were adjusted by reference to the gauge SGB 25 for stem heat balance (Dynamax Inc., Houston, TX, USA;Sakuratani 1984). Parameters for this adjustment were derived in situ by comparing the two techniques in the upper half of the crown (Herzog et al 1997). Flow meters were placed 3.3 m and 15.6 m above ground (base and midcrown) on the north stem and 2.3 m above ground (base) on the south stem (Fig.…”

Section: Tree and Site Descriptionmentioning

confidence: 99%

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Patterns and mechanisms of transpiration in a large subalpine Norway spruce (Picea abies (L.) Karst.)

Herzog

Thum

Kronfus

et al. 1998

Ecological Research

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In situ water relations of a large subalpine Norway spruce (Picea abies) were analyzed by simultaneous measurements of sap flow at different crown positions. In the diurnal scale, transpiration varied greatly, both spatially and temporally. Over longer periods, however, different parts of the crown transpired in fairly constant proportions. The average estimated transpiration was about 3.5 times greater in the upper than in the lower half and decreased 1.6‐fold from south to north. Water intercepted from rain, fog and dew buffered and significantly decreased the transpiration. The effect was strongest in those parts which were least coupled to the free atmosphere. The top of the crown seemed to experience a regular shortage of water shortly after starting transpiration, when it was forced to switch from internal reserves to sources in the soil. Further, lower branches then started transpiring, which may have led them to compete for the water. An enhanced nocturnal sap flow during warm and dry winds (Foehn) indicated that the tree also transpired at night. Shaded twigs had more capacity to intercept water externally than twigs in the sun. The significance of the crown structure for interaction with water in both liquid and vapour phases is discussed.

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Section: Tree and Site Descriptionmentioning

confidence: 99%

“…Depending on the thermal conductance of the surroundings, the heat in the stem dissipates quickly, especially under conditions with low sap flow (cf. Gerdes et al 1994; Gutierrez et al 1994; Herzog et al 1997). Therefore, the techniques for such measurements are subject to continuous improvements (Swanson 1994).…”

Section: Introductionmentioning

confidence: 99%

Patterns and mechanisms of transpiration in a large subalpine Norway spruce (Picea abies (L.) Karst.)

Herzog

Thum

Kronfus

et al. 1998

Ecological Research

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“…Stems of four S. caroliniana trees in each measurement zone (Figure 1) were instrumented to measure transpiration utilizing the stem heat balance (SHB) method (Smith and Allen, 1996). The SHB method has been proven to be accurate compared with gravimetric methods (Heilman and Ham, 1990;Akilan et al, 1994;Baker and Bavel, 1987) and is often preferred to other heat balance methods when measuring flow rates in smaller stem diameters of angiosperms (<120 mm) (Herzog et al, 1997;Hall et al, 1998). Flexible sapflow gauges (Dynamax Sapflow, Dynamax, Houston, TX, USA) and logger (Dynamax Flow 4 DL W sapflow logger) were installed to obtain stem flow rates as mass flux of water per hour.…”

Section: S Caroliniana Rooting and Transpirationmentioning

confidence: 99%

The Ecohydrology of a pioneer wetland species and a drastically altered landscape

2011

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Vegetation plays a central role in forming and maintaining an ecosystem's physical conditions, which in turn strongly influence vegetation function. These bidirectional feedbacks may be particularly evident during an ecosystem succession following large‐scale disturbances. Clay settling areas (CSAs) are large elevated impoundments that receive clay slurry as a by‐product of phosphate mining in Florida. As CSAs mature, a limited seed source arrests ecological succession, resulting in the dominance of Salix caroliniana, which is likely further supported by altered abiotic conditions. The dominance of this wetland pioneer species and its interactions with soil and hydrology may largely determine the future ecosystem state. To identify how interactions between groundwater levels, soil water availability, and vegetation response regulate the succession of CSA ecosystems, we measured groundwater levels, vertical soil moisture profiles, soil water potentials, and root biomass allocation and transpiration of S. caroliniana at two sites. Fine soil texture in the CSAs resulted in capillary fringe heights greater than 1 m, which maintained soil moisture near saturation well above the water table. Rooting depths over 1 m in the clay soils provided sufficient water availability, which, along with high residual phosphorus concentrations, explained the dominance and high transpiration rates of S. caroliniana across CSAs. Capillary rise‐induced water availability created wetland soil conditions far upgradient from inundated areas, underscoring the role of soil texture in determining wetland extent. The strong coupling between water table and S. caroliniana transpiration, however, suggests that beyond soil development, this pioneer phreatophyte may also drive succession through systematic dewatering. Copyright © 2011 John Wiley & Sons, Ltd.

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“…No entanto, à medida que o diâmetro aumenta, dificuldades associadas ao isolamento térmico do sistema de medição e contato da fonte de aquecimento com o caule promovem erros na determinação dos componentes radial e axial do balanço de energia, principalmente durante períodos de baixa transpiração (HERZOG et al, 1997;TREJO-CHANDIA et al, 1997;MARIN et al, 2008). Assim, para plantas com diâmetros maiores, esta técnica tem sido substituída pelo método da dissipação de calor ou pulso de calor, com a introdução da fonte de aquecimento no caule, apesar de ser uma solução invasiva para o processo de medição (COELHO et al, 2012;DELGADO-ROJAS et al, 2007).…”

Section: Introductionunclassified

Determinação do fluxo de seiva na cana-de-açúcar pelo método do balanço de energia caulinar

Boehringer¹,

Zolnier²,

Ribeiro³

et al. 2013

Eng. Agríc.

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RESUMO:Medições do fluxo de seiva são importantes não somente no campo da agrometeorologia, mas também em estudos de natureza fisiológica para identificação de doenças vasculares e pesquisas destinadas à quantificação do movimento de água no sistema solo-planta--atmosfera. Este trabalho foi realizado com o objetivo de avaliar o desempenho do método do balanço de energia, a partir da inserção de um minirresistor no centro do colmo de plantas de cana--de-açúcar, visando à determinação do fluxo de seiva sob condições ambientais distintas, utilizando--se de medições gravimétricas como padrão comparativo. O experimento foi conduzido em uma casa de vegetação não climatizada, localizada na área experimental da Universidade Federal de Viçosa, Viçosa -MG. Com base no erro médio de estimativa (MBE), verificou-se que o método do balanço de energia apresentou desempenho satisfatório para a determinação da transpiração da cana-de-açúcar, tanto em condições de céu nublado como parcialmente nublado, tendo subestimado os valores gravimétricos em apenas 3,0 e 6,5 g planta -1 h -1 , respectivamente. Em termos percentuais, esses valores correspondem a 4 e 5% da transpiração máxima da cana-de-açúcar. PALAVRAS-CHAVE:transpiração, Saccharum officinarum, eficiência do uso de água, disponibilidade hídrica, irrigação. SUGARCANE SAP FLOW DETERMINATION BY THE ENERGY BALANCE METHODABSTRACT: Sap flow measurements are important not only in the agrometeorology field, but also in studies of physiological nature to identify vascular diseases and researches concerned with quantification of water movement in soil-plant-atmosphere system. This study was carried out to evaluate the performance of the energy balance method, implemented by insertion of a miniresistor in the stem center of sugarcane plants, in order to determine the sap flow under distinct environment conditions, utilizing gravimetric measurements as comparative standard. The experiment was conducted in a non-environment controlled greenhouse, located at the Federal University of Viçosa, Viçosa-MG. Based on the mean bias error (MBE), it was verified that the energy balance method presented satisfactory results to determine sugarcane transpiration, both in cloudy and partly cloudy sky conditions, underestimating gravimetric values by only 3.0 and 6.5 g plant -1 h -1 , respectively. In percentage terms, these values correspond to 4 and 5% of the maximum sugarcane transpiration.

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Heat balance measurements—to quantify sap flow in thin stems only?

Cited by 21 publications

References 27 publications

Patterns and mechanisms of transpiration in a large subalpine Norway spruce (Picea abies (L.) Karst.)

Patterns and mechanisms of transpiration in a large subalpine Norway spruce (Picea abies (L.) Karst.)

The Ecohydrology of a pioneer wetland species and a drastically altered landscape

Determinação do fluxo de seiva na cana-de-açúcar pelo método do balanço de energia caulinar

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