Crown structure of Eucalyptus globulus Labill. in a coppiced plantation

Pereira, J. S.; Araujo, Ciro Colodetti Vilar de; Borralho, N. M. G.

doi:10.1007/978-3-642-70868-8_35

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…A study of regenerating Eucalyptus maculata Hook. found the vertical distribution of leaf area was skewed to the top of individual tree crowns (Pook 1984), whereas in a coppiced plantation of Eucalyptus globulus Labill., the maximum amount of leaf area was found near the midpoint of the live crown (Pereira et al 1987).…”

Section: Introductionmentioning

confidence: 89%

Crown structure and leaf area index development in thinned and unthinned Eucalyptus nitens plantations

Medhurst

Beadle

2001

Tree Physiology

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The crown structure of Eucalyptus nitens (Deane & Maiden) Maiden 6 years after thinning, and the development of stand leaf area index both immediately and 6 years after thinning, were investigated. Thinning did not alter branch angle, branching density or the relationship between branch size and branch leaf area. However, larger branches were found in the lower crown of thinned trees and the increase in leaf area as a result of thinning occurred on the northern aspect of the crown. The vertical distribution of leaf area in unthinned trees was skewed toward the top of the crown and correlated with live crown ratio. The vertical distribution of leaf area in thinned trees tended to be less skewed and was unrelated to tree size or dominance. Leaf area index, as estimated from light interception measurements, increased at a constant rate soon after thinning regardless of residual stocking. In the longer term, residual stocking had a strong influence on leaf area increase per tree and was correlated with changes in crown length.

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Section: Introductionmentioning

confidence: 89%

Crown structure and leaf area index development in thinned and unthinned Eucalyptus nitens plantations

Medhurst

Beadle

2001

Tree Physiology

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“…Early morning photosynthesis may be particularly pronounced in eucalypt-dominated ecosystems because the characteristically pendulous (in some species up to 75 % of mature leaves typically hang at angles > 80 • from horizontal; Pereira et al, 1987), amphistomatous leaves evolved to maximise incident radiation at low sun angles. This shifts photosynthetic activity towards periods with lower vapour pressure deficit, reducing water losses (James and Bell, 1996).…”

Section: Effects Of Correction Methods On Diel and Annual Neementioning

confidence: 99%

Interactions between nocturnal turbulent flux, storage and advection at an “ideal” eucalypt woodland site

et al. 2017

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Abstract. While the eddy covariance technique has become an important technique for estimating long-term ecosystem carbon balance, under certain conditions the measured turbulent flux of CO 2 at a given height above an ecosystem does not represent the true surface flux. Profile systems have been deployed to measure periodic storage of CO 2 below the measurement height, but have not been widely adopted. This is most likely due to the additional expense and complexity and possibly also the perception, given that net storage over intervals exceeding 24 h is generally negligible, that these measurements are not particularly important. In this study, we used a 3-year record of net ecosystem exchange of CO 2 and simultaneous measurements of CO 2 storage to ascertain the relative contributions of turbulent CO 2 flux, storage, and advection (calculated as a residual quantity) to the nocturnal CO 2 balance and to quantify the effect of neglecting storage. The conditions at the site are in relative terms highly favourable for eddy covariance measurements, yet we found a substantial contribution (∼ 40 %) of advection to nocturnal turbulent flux underestimation. The most likely mechanism for advection is cooling-induced drainage flows, the effects of which were observed in the storage measurements. The remaining ∼ 60 % of flux underestimation was due to storage of CO 2 . We also showed that substantial underestimation of carbon uptake (approximately 80 gC m −2 a −1 , or 25 % of annual carbon uptake) arose when standard methods (u * filtering) of nocturnal flux correction were implemented in the absence of storage estimates. These biases were reduced to approximately 40-45 gC m −2 a −1 when the filter was applied over the entire diel period, but they were nonetheless large relative to quantifiable uncertainties in the data. Neglect of storage also distorted the relationships between the CO 2 exchange processes (respiration and photosynthesis) and their key controls (light and temperature respectively). We conclude that the addition of storage measurements to eddy covariance sites with all but the lowest measurement heights should be a high priority for the flux measurement community.

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“…Early-morning photosynthesis may be substantial in eucalypt-dominated ecosystems in which the characteristically pendulous (in some species up to 75% of mature leaves typically hang at angles > 80 degrees from horizontal; Pereira et al, 1987), amphistomatous leaves evolved to maximise incident radiation at low sun angles, which shifts photosynthetic activity towards periods with lower vapour pressure deficit (James and Bell, 1996). Mutual shading would partially counteract this effect at low sun angles, but this may have less effect in systems with sparse canopies such as the woodland in this study.…”

Section: Effects Of Correction Methods On Diurnal and Annual Carbon Bmentioning

confidence: 99%

Interactions between nocturnal turbulent flux, storage and advection at an ‘ideal’ eucalypt woodland site

McHugh¹,

Beringer²,

Cunningham³

et al. 2016

Preprint

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Abstract. While the eddy covariance technique has become an important technique for estimating long-term ecosystem carbon balance, under certain conditions the measured turbulent flux of carbon at a given height above an ecosystem does not represent the true surface flux. Profile systems have been deployed to measure periodic storage of carbon below the measurement height, but have not been widely adopted. This is most likely due to the additional expense and complexity, and possibly also the perception &#8211; given that net storage over intervals exceeding 24 hours is generally negligible &#8211; that these measurements are not particularly important. In this study, we used a three year record of net ecosystem exchange of carbon and simultaneous measurements of carbon storage to ascertain the relative contributions of turbulent carbon flux, storage and advection (calculated as a residual quantity) to the nocturnal carbon balance, and to quantify the effect of neglecting storage. The conditions at the site are in relative terms highly favourable for eddy covariance measurements, yet we found a substantial contribution (~&#8201;40&#8201;%) of advection to nocturnal turbulent flux underestimation. The most likely mechanism for advection is cooling-induced drainage flows, the effects of which were observed in the storage measurements. The remaining ~&#8201;60&#8201;% of flux underestimation was due to storage of carbon. We also showed that substantial underestimation of carbon uptake (approximately 80&#8201;gC&#8201;m&#8722;2&#8201;a&#8722;1, or 25&#8201;% of annual carbon uptake) arose when standard methods of nocturnal flux correction were implemented in the absence of storage estimates. These biases were much larger than quantifiable uncertainties in the data. Neglect of storage also distorted the relationships between the carbon exchange processes (respiration and photosynthesis) and their key controls (light and temperature, respectively). We conclude that addition of storage measurements to eddy covariance sites with all but the lowest measurement heights should be a high priority for the flux measurement community.

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Crown structure of Eucalyptus globulus Labill. in a coppiced plantation

Cited by 3 publications

References 7 publications

Crown structure and leaf area index development in thinned and unthinned Eucalyptus nitens plantations

Crown structure and leaf area index development in thinned and unthinned Eucalyptus nitens plantations

Interactions between nocturnal turbulent flux, storage and advection at an “ideal” eucalypt woodland site

Interactions between nocturnal turbulent flux, storage and advection at an ‘ideal’ eucalypt woodland site

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