The Structure and Dynamics of Agricultural Landscapes as Drivers of Biodiversity - Landscape Ecology for Sustainable Environment and Culture - page 288

14.3.2.2 Using Models to Predict the Influence of Management
Successions and Crop Rotations on Biodiversity

In landscapes where too many habitat patches are simultaneously disturbed each
year, the limited habitat complementation/supplementation processes might result
in a population decrease or even extinction in the long term (Vasseur et al. in
press ). We used an existing spatially-explicit model to simulate the yearly and
pluri-annual dynamics of populations of the Meadow brown (Maniola jurtina)
under different scenarios of habitat disturbance extent (i.e. percent cover of
grasslands mown in a 1 km 2 landscape) (Aviron et al. 2007 ). Simulations were run
on the landscape unit where empirical data on the effect of mowing on butterfly
movements were available, in order to validate the model's predictions. Our results
show that when habitat suppression through mowing occurs during the activity
period of butterflies (in summer), butterfly populations get rapidly extinct if a large
amount of grassland habitats (80 %) is simultaneously disturbed each year
(Fig. 14.5 ). On the contrary, the synchronous disturbance of a lower amount of
grasslands (20 %) each year allows population persistence and increase over the
years, probably due to higher possibilities of habitat complementation/supple-
mentation for butterflies (Fig. 14.5 ). Thus, the long-term persistence of butterfly

(a)

20% grassland mown 80% grassland mown

Unmown
grasslands
Mown
grasslands

Othertypes of
land-covers

200m

(b)

200

No mowing

150

20% grasslands
mown

100

80% grasslands
mown

50

0

0 2 4 5 8 10

Time (years)

Fig. 14.5 Scenarios of butterfly habitat disturbance (20 and 80 % of grasslands mown each year)
(a) and predicted evolution of total butterfly abundances over 10 years for the two scenarios of
habitat disturbance and in absence of mowing (b) (derived from Aviron et al. 2007 )