Modeling Environmental Factors : Response of Trees to Environmental Factors: General Principles :

1. Modeling Environmental Factors: • Response of Trees to Environmental Factors: • General Principles: • 1. Trees respond to AN environmental factor individually. • Response = f (one factor; for example temperature)

2. Modeling Environmental Factors: General Principles: • 2. Trees also respond “cumulatively” or simultaneously to other factors. • Response = f (one or more factors) • Environmental Effects are modeled individually and cumulatively • simultaneously

3. Modeling Environmental Factors: • Approaches to Modeling Environmental Effects: • 1. Minimum or “Most Limiting Factor” • Principle: Cumulative Environmental Effects is dictated by the “Most Limiting • Factor” • Model: • Growth = Goptimal * Min {f1, f2, …, fn}

4. Modeling Environmental Factors: Approaches to Modeling Environmental Effects: • Model: Growth = Goptimal * f1 + f2 + … + fn

5. Multiplicative approach: Approach used by JABOWA • Model: • Growth = Goptimal * {f1 * f2 * … *fn}

6. Factoring Environmental Effects D = D = (D * { f1 * f2 * … * fi} t t (t )opt (multiplicative assessment of cumulative effect) f1, f2, …, fi individually, denotes the tree’s response to one environmental factor fi  response functions  all scaled so that {0 < fi< 1}

7. Factoring Environmental Effects D = D = (D * { f1 * f2 * … * fi} t t (t )opt f1 * f2* … * fi tree responding to cumulative effect  interactive and synergistic effect  multiplicative interactions

8. D = D = f(intrinsic growth, environmental factors) D = {GD(1-DH/DmaxHmax)} * f(environ.) 274+3b2D-4b3D2 |__________| adjustment to optimal growth Factoring Environmental Effects

9. Factoring Environmental Effects f(environment) = fi(AL) *Qi *S(BAR) fi(AL) = the light response of the species S(BAR) = maximum basal area that the plot can support Qi = product of “response functions”

10. Factoring Environmental Effects Qi = product of “response functions” = Tfi * WiFi * WeFi * NFi Nfi  index of tree response to nitrogen ( 0 < Nfi< 1 ) Tfi  temperature response function (0 <Tfi< 1 ) WiFiwilt factor (index of drought cond.) ( 0 <WiFi< 1) WeFi  soil wetness factor ( 0 <WeFi < 1 )