Maintaining hedges
Two years ago I blogged about regular maintenance and included a brief discussion of how often hedges on farms and on the edge of roads should be trimmed. I had taken this example from some guidance in a leaflet from our Devon County Council.
Earlier this year, I found a further objective in the list of conflicting objectives that appeared then. This is one which can be expressed as a constraint. (Treating objectives as constraints is one of the tools of multi-criteria decision-making.) Some hedgerow trees produce their flowers and fruit on second-year growth of the plant. So if the hedge is trimmed once a year, then the plants never produce blossom or fruit, which is a disservice to wildlife. So such hedges should not be pruned more often than every two years, but three year cycles are obviously possible. So, to help wildlife, there is a constraint if the hedge contains such species.
The same source of information also commented on the need to vary the method of cutting hedges back; if mechanical flails are the only tools used, then the young growth on the hedge is cut back more drastically than the established growth, and the base of the hedge can be opened as the hedge trees grow taller without fresh shoots at the base.
So this is a supplement to the earlier blog, a reminder (to me as well) that extra information for an O.R. study can be found and be used, even after many years!
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| Contrasting hedges on the two sides of the road |
Earlier this year, I found a further objective in the list of conflicting objectives that appeared then. This is one which can be expressed as a constraint. (Treating objectives as constraints is one of the tools of multi-criteria decision-making.) Some hedgerow trees produce their flowers and fruit on second-year growth of the plant. So if the hedge is trimmed once a year, then the plants never produce blossom or fruit, which is a disservice to wildlife. So such hedges should not be pruned more often than every two years, but three year cycles are obviously possible. So, to help wildlife, there is a constraint if the hedge contains such species.
The same source of information also commented on the need to vary the method of cutting hedges back; if mechanical flails are the only tools used, then the young growth on the hedge is cut back more drastically than the established growth, and the base of the hedge can be opened as the hedge trees grow taller without fresh shoots at the base.
So this is a supplement to the earlier blog, a reminder (to me as well) that extra information for an O.R. study can be found and be used, even after many years!
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