• Growth and yield modeling has a long history in forestry.
• Methods of measuring the growth of uneven-aged forest stands have evolved from those developed in France and Switzerland during the last century.
• Uneven-aged growth and yield modeling has progressedrapidly since the first models were pioneered by Moser andHall (1969)
• Projects tree growth usually as a function of present size andstand level variables (age, site index, BA/ha)
• Models assume that spatially all spp. and sizes of trees areuniformly distributed throughout the stand
• Not necessary to know individual tree locations
• Growth and Yield models which use individual trees as the basic unit have been developed for mixed species, uneven aged as well as pure even aged stands
  An example is FOREST, a computer model published by Ek and Monserud (1974) for simulating the growth and reproduction of even or uneven aged mixed species stands
  Usual input for FOREST, a distance dependent model, is set of tree coordinates and associated tree characteristics (e.g. ht, dia, age, clear bole length and species)
• In any year of simulation optional redirection routines may be called to allow for regeneration by seed and sprout production of the overstory
• Silvicultural treatments, including site alteration, cutting or pruning operations may be specified for implementation as stand develops
• Output of the model is the form of periodic stand tables with yield and mortality for various products

Common growth models

• Simple Linear yt= a+b(t)
• Linear transformation yt= at^b or log yt=(log a)+b(log t)
• Exponential models yt=ae^bt or log yt=(log a)+t (b log e)
• Polynominal models yt= a+bH+CH2+……

Hypothesis

1. ΔV = f (A, dh, N, v, BA, S) where ΔV = Volume increment, A = age, Dh= dominant ht., N= No. of stems/ha, v = volume/ha, BA= Basal area/ha, S= Site index
2. ΔD= f (RB,Hd,Td) where ΔD=dia. Increment, RB=Relative BA, Hd=Dom.ht, Td=Tree dominance