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Silvicultural systems Peter Savill (University of Oxford)

Silvicultural systems Peter Savill (University of Oxford). Department of Agriculture University of Reading 1 February 2000. Silvicultural systems are:.

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Silvicultural systems Peter Savill (University of Oxford)

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  1. Silvicultural systemsPeter Savill(University of Oxford) Department of Agriculture University of Reading 1 February 2000

  2. Silvicultural systems are: The processes by which the crops that constitute a forest are tended, removed and replaced by new crops, resulting in the production of woods of a distinctive form. Name of a system is based on: • number of age classes (e.g. even-aged, uneven-aged), or • regeneration method (e.g. shelterwood, selection)

  3. A silvicultural system involves: • method of regeneration (e.g. coppice, planting, natural regeneration, direct seeding) • form of the crop produced (e.g. “regular” or “irregular”) • arrangement of the crops over the forest (a form of “normality” usually aimed at)

  4. 70 year old, clear felled A sustainable 70 year-rotation in a 700 ha even-aged forest Area not contributing to production Area being thinned on a cycle

  5. Annual planting or felling areas

  6. Forecast production from British forests

  7. Intensive versus extensive forestryFeatures Intensive forests Age distribution Even aged Rotation Short (45-60 years) Species composition Pure, exotic, clonal Management Cheap Establishment In open, by planting Scale of operations Large, concentrated Production 15-30 m3ha-1yr Conservation value Low

  8. Intensive versus extensive forestryFeatures Extensive forests Age distribution 0 to rotation Rotation Long (150-200 years) Species composition Many, indigenous Management Expensive Establishment Under canopy, natural regeneration Scale of operations Small, scattered Production 3-4 m3ha-1yr Conservation value High

  9. Classification of silvicultural systems 1.coppice systems 2.high forest systems a) regeneration over whole forest which is uneven-agedpolycyclic or selection systems b) regeneration concentrated in one part of forest at any one time i) old crop removed in several fellings over yearsshelterwood systems ii) old crop removed by a single fellingmonocyclic or clear felling system

  10. Intensive versus extensive systems Intensive (monocyclic) systems coppice coppice with standards clear felling (shelterwood) Extensive (polycyclic) systems selection group systems

  11. Application of coppice systems • Where small dimensioned material is required (fuel wood Salixand Populus, pulp Eucalyptus) • Generally only with broadleaved trees • Where some forms of nature conservation are important • Formerly for basket willows, farm and household implements, etc

  12. A sustainable 70 year-rotation in a 700 ha even-aged forest

  13. Selection system

  14. Size distributions in tropical rain forest

  15. Number of trees per hectare at different ages in an even-aged stand Douglas fir, yield class 24

  16. Application of selection systems • On steep sites for protection against soil erosion and avalanches • Where landscape continuity is required (urban forests) • Where wood production and profit are not major motives • Mainly appropriate for shade bearers (beech and silver firs)

  17. Uniform shelterwood system

  18. Application of shelterwood systems • Usually on rather similar sites to clear felling—where soil deterioration is not a serious risk • In environments where species grown produce viable seed regularly (oak and beech in parts of Europe, sycamore and ash in UK, Dipterocarps in SE Asia)

  19. Clear felling system:a typical plantation life history for spruce (oak) Year Obtain seed -3 Raise plants -2 Prepare ground -0.5 Planting 0 Tending 4-15 (0-20) Thinning 20-45 (30-100) Clear felling 55 (120) Replantingsecond rotation

  20. Application of clear felling system • On sites where forest clearance will not cause erosion or other problems • Where profit is a major motive for planting • With light-demanding species that have evolved in monocultures (often pines, spruces, eucalypts)

  21. Group system

  22. Choice of system depends on: Regeneration ecology of trees Site, topography, soil Wildlife Pests and diseases Fire Climatic risks Size, age, vigour of existing stand Introduction of new genotypes Financial constraints

  23. maximum M.A.I. Patterns of volume increment for an even-aged stand = Yield Class

  24. Mean annual increment curves for different species

  25. Mean annual increment curves for a single species

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