Normal forest – growing stock and increment


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Normal forest – growing stock and increment

  1. 1. Normal Forest – growing stock and increment Muhammed Iqbal A Dept. of Forest Management and Utilization College of Forestry 1
  2. 2. Definition“A Forest which, for a given site and givenobjects of management, is ideally constitutedas regards growing stock, age-classdistribution and increment , and from whichthe annual or periodic removal of produceequal to the increment can be continuedindefinitely without endangering future yields.A forest which by reason of normalcy in theseaspects serves as a standard of comparison forsustained yield management.” (Glossary) College of Forestry 2
  3. 3. Characteristics of Normality• Three main attributes of an ideal forest managed for sustained yields in perpetuity2.A normal series of age-classes or age- gradations3.A normal increment and4.A normal growing stock College of Forestry 3
  4. 4. Normal Age gradation• Trees of all ages from one year old to rotation age in appropriate quantity• When trees of certain age limits occur mixed together on the same area forms an age-class• In a very irregular forest there may neither be age-gradations nor age-classes; in such cases the sign of normality is the proper distribution of trees of all ages College of Forestry 4
  5. 5. Normal Increment• Maximum increment attainable by a given species and for a given rotation, per unit area on a given site• Abnormality may be due to faulty formation, faulty treatment, injurious external influences and also unequal distribution of age-classses College of Forestry 5
  6. 6. Normal Growing Stock• Volumes of stands in a forest with normal age classes and a normal increment• In practice this taken to be the volume indicated in Yield Tables for each classes• NGS doesn’t necessarily imply a normal forest• Example a forest of low density College of Forestry 6
  7. 7. An Ideal Standard• Normal forest is an Ideal model• Nothing as absolute normality• Concept is related to both rotation and system of management• To compare the existing condition of the forest and to get the maximum benefit• Necessary for proper appreciation of the principles of Yield Regulation College of Forestry 7
  8. 8. Abnormality1. Over stocking2. Under stocking3. NGS volume but abnormal distribution of age classes or age gradations4. Subnormal increment5. Normal Increment Volume in a abnormal forest College of Forestry 8
  9. 9. Silvicultural system on Normality• Normal Even aged Forest• Normal Un evenaged Forest College of Forestry 9
  10. 10. Normal Even aged Forest• The clear-felling system, in which all age gradations from one year to Rotation age are present, each occupying equi-extensive/equi- productive areas, in which the rotation-age coupe is felled and regenerated every year, offers the simplest example of a conventional Normal forest, capable of giving annual sustained yield College of Forestry 10
  11. 11. • Test of normality is the presence of all age- gradations/classes, occupying equi-extensive/ equi-productive areas, fully stocked and putting on normal increment . Strictly speaking, occupation of equal areas by class is not essential, but the proportion of different ages should be correct College of Forestry 11
  12. 12. Normal Un evenaged Forest• In an entierly uneven-aged forest worked under Selection System, trees of all ages (and sizes) are found mixed together on every unit of area, even as small as half an hectare• Large, mature trees are felled when they reach exploitable size or their increment falls below the acceptable level• Age and rotation are meaningless concepts College of Forestry 12
  13. 13. DE LIOCOURT’S LAW• F. DE LIOCOURT discovered that in a fully stocked Selection Forest, the number of stems falls off from one diameter class to the next in geometrical progression, which means that the percentage reduction in the stem number from one diameter class to the next is constant . College of Forestry 13
  14. 14. References• Forest Management by Ram Prakash, IBD, Dehradun.• Google College of Forestry 14
  15. 15. THANK YOU College of Forestry 15