Photosynthetic response to green crown pruning in young plantation-grown Eucalyptus pilularis and E. cloeziana

Alcorn, Philip J.; Bauhus, Jürgen; Thomas, Damon; James, Ryde; Smith, Ben; Nicotra, Adrienne B.

doi:10.1016/j.foreco.2008.03.030

Cited by 27 publications

(20 citation statements)

References 64 publications

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“…cx 4 ) fitted to the response of log 10 (total polyphenol concentration) (log 10 [TP]) in mature leaves above 1.5 m to log 10 (proportion of productive canopy volume missing as a result of shoot browsing ?1) for C. apiculatum taller than 2 m at Nkuhlu, 28-30 January 2008 Table 4 Parameters of linear models (y = a ? bx) fitted to (a) the response of log 10 (phosphorus concentration) to log 10 (total proportion of productive canopy volume removed by shoot browsing ?1), and (b) the response of log 10 (total polyphenol concentration) to log 10 (total proportion of productive canopy volume removed by shoot browsing ?1) for G. flavescens at Nkuhlu, 28-30 January 2008 increasing browsing intensity accumulate C from current photosynthate or storage (Medhurst et al 2006;Alcorn et al 2008;Olesen et al 2008). The primary C source in G. flavescens is not likely to be storage because the root system is not large; plants are easily uprooted by elephants, revealing shallow roots.…”

Section: Resultsmentioning

confidence: 99%

Secondary metabolites and nutrients of woody plants in relation to browsing intensity in African savannas

Scogings

Hjältén

Skarpe³

2011

Oecologia

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Carbon-based secondary metabolites (CBSMs) are assumed to function as 26 defences that contribute to herbivore-avoidance strategies of woody plants. Severe 27 browsing has been reported to reduce concentrations of CBSMs and increase N 28 concentrations in individual plants, causing heavily browsed plants to be characterised 29 by N-rich/C-poor tissues. We hypothesised that concentrations of condensed tannins 30 (CT) and total polyphenols (TP) should decrease, or N increase, in relation to 31 increasing intensity of browsing, rendering severely browsed plants potentially more 32 palatable (increased N:CT) and less N-limited (increased N:P) than lightly browsed 33 ones. We sampled naturally browsed trees (taller than 2 m) of four abundant species 34 in southern Kruger National Park, South Africa. Species-specific relationships 35 between N:CT, CT, TP and P concentrations and increasing browsing intensity were 36 detected, but N and N:P were consistently invariable. We developed a conceptual 37 post-hoc model to explain diverse species-specific CBSM responses on the basis of 38 relative allocation of C to total C-based defence traits (e.g., spines/thorns, 39 tough/evergreen leaves, phenolic compounds). The model suggests that species with 40 low allocation of C to C-based defence traits become C-limited (potentially more 41 palatable) at higher browsing intensity than species with high allocation of C to C-42 based defences. The model also suggests that when N availability is high, plants 43 become C-limited at higher browsing intensity than when N availability is low. 44 45

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Section: Resultsmentioning

confidence: 99%

Secondary metabolites and nutrients of woody plants in relation to browsing intensity in African savannas

Scogings

Hjältén

Skarpe³

2011

Oecologia

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“…The middle portion of the crown has a higher photosynthetic rate than does the lower crown (Wong and Dunin 1987;Alcorn et al 2008b). Consequently, if pruning is too drastic and removes part of the middle crown, plant growth may be impaired because most assimilates are immediately allocated to support the rapid crown recovery at the expense of stem growth.…”

Section: Discussionmentioning

confidence: 99%

“…The reduction in the photosynthetic capacity may also be explained by basal crown shading because new foliage is promptly formed after pruning (Pinkard and Beadle 1998a). Alcorn et al (2008b) reported no photosynthetic rate increases between 6 and 13 months after pruning in Eucalyptus pilularis and Eucalyptus cloeziana probably because crown recovery had been completed before 6 months. The change in the root:foliage ratio may also explain the fast crown recovery after pruning.…”

Section: Treatmentsmentioning

confidence: 99%

Growth of pruned eucalypt clone in an agroforestry system in southeastern Brazil

Fontan

Reis

et al. 2011

Agroforest Syst

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“…Dark respiration at 25°C (mol·m −2 ·s −1 ) 0.3 to 3 Grassi et al 2002;Medlyn et al 2007;Alcorn et al 2008;Christina et al 2015; this study ␣ Quantum yield of electron transport (mol·mol −1 ) 0.2 to 0.4 Grassi et al 2002;Medlyn et al 2007;Christina et al 2015; this study Curvature parameter of the light response of photosynthesis (unitless) 0.2 to 1 Grassi et al 2002;Christina et al 2015 Marsden et al 2013;Christina et al 2015; this study…”

Section: Polynomial First-level Metamodelsmentioning

confidence: 98%

Sensitivity and uncertainty analysis of the carbon and water fluxes at the tree scale inEucalyptusplantations using a metamodeling approach

et al. 2016

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Understanding the consequences of changes in climatic and biological drivers on tree carbon and water fluxes is essential in forestry. Using a metamodeling approach, sensitivity and uncertainty analyses were carried out for a tree-scale model (MAESPA) to isolate the effects of climate, morphological and physiological traits, and intertree competition on the absorption of photosynthetically active radiation (APAR), gross primary production (GPP), transpiration (TR), light use efficiency (LUE), and water use efficiency (WUE) in clonal Eucalyptus plantations. The metamodel predicting daily TR was validated using one year of sap flow measurements and showed close agreement with the measurements (mean percentage error = 11%, n = 2155). Simulations showed that APAR, GPP, and TR were very sensitive to the tree morphology and to a competition index representing its local environment. LUE and WUE were, in addition, very sensitive to the natural variability of the physiological leaf and root parameters. A maximum percentage error of 10% in these parameters leads to 18%, 17%, 16%, 9%, and 18% uncertainty for APAR, GPP, TR, LUE, and WUE, respectively. The uncertainties in TR were highest for the smallest trees. This study highlighted the need to take account of the spatial and temporal variability of tree traits and environmental conditions for simulations at the tree scale.

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Photosynthetic response to green crown pruning in young plantation-grown Eucalyptus pilularis and E. cloeziana

Cited by 27 publications

References 64 publications

Secondary metabolites and nutrients of woody plants in relation to browsing intensity in African savannas

Secondary metabolites and nutrients of woody plants in relation to browsing intensity in African savannas

Growth of pruned eucalypt clone in an agroforestry system in southeastern Brazil

Sensitivity and uncertainty analysis of the carbon and water fluxes at the tree scale inEucalyptusplantations using a metamodeling approach

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