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Title: The effects of two contrasting canopy manipulations on the growth and water use of Prunus avium
Author: Dunn, J. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2006
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This work utilised two common methods of pruning individual urban trees: crown-reduction (partial shoot removal), which is commonly used to restrict the water use of trees through to be at risk within the context of subsidence, and crown-thinning (removal of whole side shoots or branches), which is more commonly used to reduce the shading effects of trees near buildings. These treatments were applied to individual, mature Prunus avium trees in an orchard in the South East of England. Despite rapid recovery of canopy LA within the crown-reduced trees, both treatments significantly reduced the water use of individual wild cherry trees during the first season following application, with crown-reduction having the greatest effect. Crown-thinning increased daily water use per unit LA, while crown-reduction decreased water use per unit when compared to that of the control trees. These differences in water use per unit LA and whole tree water use related well to the contrasting influence of the treatments on canopy architecture and rates of canopy regrowth. Boundary layer conductance (gb) and leaf irradiance were constantly lower within the crown-reduced trees and higher in the crown-thinned trees, when compared to control values. Differences in leaf level physiology were also observed as a result of canopy manipulation, with crown-reduced trees having the highest rates of assimilation (A) and stomatal conductance (gs) in the first year after manipulation. This difference was possibly the result of a smaller shoot:root ratio (S:R). These physiological differences resulted in the crown-reduced trees having a higher discrimination against the heavier 13C (Δ13C), traditionally implying low water use efficiency (WUE). However, measurements of the δ18O of leaf water and whole tree sap flux indicated that this treatment had a lower water use than either the crown-thinned or control trees.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available