222
~ Glill Based Mudelling
sumptions. Indeed, if storms and ice winters are deactivated in the model, the distribution pattern determined by both the topography (Fig. 8.4.1) and the assumptions of Fig. 8.4.2 emerge: Mytilus occurs on the top parts of the sandflat, Lanice
builds up high density patches at higher parts of the sandflat and low density
patches at lower parts (see, for example, Fig. 8.4.3b). But despite this more or less
obvious outcome of the model, the actual distribution pattern often differs considerably from this deterministic ideal due to the effect of disturbance events and the
interaction between the two species (succession, dispersal of Mytilus).
Fig. 8.4.4 shows time series of the overall abundance (in relative units) of
Mytilus and Lanice as well as the time series of the random events that shape the
2 years
CD
u 1.0
I:
..
"CI
I:
~ 0.5
«
21 years
33 years
,..,....:~~~'T"T",. ;......,~...---.-:-.--,--.--.-.---'-.-.-.,.....,,...., Storms
!-----.....-'----'--.---'---'---'--.-----,-f---l 1ce winters
Spatfalls
o
10
15
20
25
30
35
40
Years
Fig. 8.4.4 Exemplary results of TOPOGRID for the parameter values specified in the text. The
significance of the different grey scales is as in Fig. 8.4.3b. Arrows on top of the time series
indicate the years in which the spatial images are recorded
~ Glill Based Mudelling
sumptions. Indeed, if storms and ice winters are deactivated in the model, the distribution pattern determined by both the topography (Fig. 8.4.1) and the assumptions of Fig. 8.4.2 emerge: Mytilus occurs on the top parts of the sandflat, Lanice
builds up high density patches at higher parts of the sandflat and low density
patches at lower parts (see, for example, Fig. 8.4.3b). But despite this more or less
obvious outcome of the model, the actual distribution pattern often differs considerably from this deterministic ideal due to the effect of disturbance events and the
interaction between the two species (succession, dispersal of Mytilus).
Fig. 8.4.4 shows time series of the overall abundance (in relative units) of
Mytilus and Lanice as well as the time series of the random events that shape the
2 years
CD
u 1.0
I:
..
"CI
I:
~ 0.5
«
21 years
33 years
,..,....:~~~'T"T",. ;......,~...---.-:-.--,--.--.-.---'-.-.-.,.....,,...., Storms
!-----.....-'----'--.---'---'---'--.-----,-f---l 1ce winters
Spatfalls
o
10
15
20
25
30
35
40
Years
Fig. 8.4.4 Exemplary results of TOPOGRID for the parameter values specified in the text. The
significance of the different grey scales is as in Fig. 8.4.3b. Arrows on top of the time series
indicate the years in which the spatial images are recorded