Graph: Tradeoff between seed yield
and bee yield
Slide 3 of 17
Notes:
With these two assumptions about bee and plant populations, there is clearly
a tradeoff between bee yields and seed yields. Bee yields (purple line)
reach a peak when a relatively small bee population is introduced into the
field. As more bees are introduced, density dependent mortality causes the
bee offspring population to decline. The black line through the middle of
the graph indicates where the number of introduced bees equals the number of
offspring. Where the purple female offspring curve crosses the black line,
the introduced bee population results in a sustainable yield of offspring
bees. In this graph, the sustainable yield of bees is less than the maximum
bee yield, and seed yield (red line) is still increasing if more bees are
introduced into the field. Seed yields are maximized when a relatively large
number of bees are introduced into the field.
In summary, if there is density dependent bee mortality, then the optimum
introduced bee population for maximizing bee reproduction is lower than the
optimum bee population for maximizing seed yields.Download a copy of the Stella
II model to your computer:
With density dependent bee mortality
Without density dependent bee mortality
Download a demo
copy of Stella 6.0 from High Performance Systems.
The figure above, and the figure on slide 4 were made by running the model multiple times, each time
increasing the number of introduced bees. Results at the end of the run
were copied from the table in the model to an excel file. Download the
excel file.