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Simple degree-days model of temperature influence on development of plants and invertebrates

Thu, 23/08/2012 - 17:17 — jonathanm
ModelId: 
DegreeDays1
SimileVersion: 
4.0

The development rate of plants and invertebrate animals often depends on amount of heat received while the ambient temperature is between minimum and maximum thresholds.

The number of degree-days is a commonly used statistic related to the development of plants and invertebrates. Degree-days, DD, is given by:
 

DD = ∫ Tt.dt

  • T is temperature in degrees Celsius (could be Fahrenheit)
  • t is time in days.

degree-days is then oC days or oF days.

Equations: 

Compartment DegreeDays : Degree days

Initial value = 0
Rate of change = + dDt on dt
Comments:
Also called temperature sum or less accurately "heat sum".

Flow dDt on dt : Rate of accumation of degree-days (degC)
dDt on dt = max(T_m-T_thresh,0)
Where:
T_m=../Environment/T_m

Variable Sdevelopment : State of development
Sdevelopment = min(DegreeDays/DDreq,1)
Comments:
Value = 0 to 1

Equations in Environment

Variable T_m : Mean daily temperature

 

 

Results: 


Weblinks: 

 University of California Integrated Pest Management Program [1] [1] http://www.ipm.ucdavis.edu/WEATHER/ddconcepts.html

Model tags: 
Basic System Dynamics
Insects
Pests
Degree-days
Develoment
physiological
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