Environmental Engineering Reference
In-Depth Information
2005
2080
1500
1500
62
62
1000
500
1000
500
57
57
0 0
0 0
52
52
50
50
100
100
47
47
150
150
200
200
42
42
Fig. 9.6 Results of simulation runs for the dragonfly Gomphus vulgatissimus based on an
extended Leslie model with temperature and day-length as environmental variables. On the x -
axis time is shown, geographical latitude is on the y-axis and the simulated number of adult
dragonflies on the z -axis. The results are show along the gradient from 42 Nto62 N for current
climatic conditions (2005) and for the year 2080 according to the IPCC scenarios. The model
shows a northward extension of the species together with a faster development (Braune et al. 2008)
development. The model predicts that from 2020 a 2-year life cycle will predomi-
nate in wide parts of the current range of the species, whereas the 3-year life cycles
shift further northwards. The 4-year life cycle in the north became negligible in
2020 and disappeared even in the northernmost parts in 2050.
Common to all simulations was a shift towards a slightly later emergence from
south to north induced by the decrease of day-length with more northern latitudes.
Naturally, the beginning of emergence (which is reproduced by the model) ranged
from April to June between southern and northern populations. In the zones of
cohort overlap the model predicts a longer flight season in the future or even a
bimodal phenology, with a large peak in spring and a smaller peak in late summer.
The model also predicted a slight northwards shift of the distribution range by
at most 1.25 in 2080. Such northward shift for G. vulgatissimus has already been
recorded. It adds up to 104 km from 1960-1970 to 1985-1995 (Hickling et al. 2005).
Summarizing the model revealed three main climate change effects: first, the
distribution of voltinism patterns is affected with a general trend towards a spread of
shorter generation times in the northward direction. Second, emergence is accelerated
in southern latitudes. The pattern of earlier emergence does not shift northwards. This
may be due to the additional photoperiodic control in the model. Third, the tempera-
ture scenarios provided by the IPCC led to a northward extension of the species.
However, competition with related species, prey availability, droughts and other
factors may cause other reactions of the population that are not yet covered by the
model. Nevertheless it appears that population models based on Leslie matrices can
be powerful tools to forecast effects of climate change on voltinism patterns and
distribution range of species. Combining several single-species models can help
to analyze the consequences of climate change on community and ecosystem levels,
e.g. a temporal decoupling (“mismatch”) of up to now synchronized processes such
as temporal coincidence of predators and the appropriate prey populations.
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