Subject: Butterfleis & Nature Conservation

From: [email-masked] (Hans-Ulrich Thomas)
Date: Wed, 08 Mar 1995 18:26:30 -0300

We hope that somebody can help with an advice or a pointer to the
literature, a person who might know etc with the following problem.

The problem concerns a nature conservation project about species diversity
in a particular environment in the Northeast of Switzerland. 

- How do butterflies cope with the fact that their habitat, small wetland
areas of about 200-300 m in diameter, is surrounded (now!) by dense pine
tree forest? The distance between two habitats is about 300-500 m. We fear
that the surrounding forest has an isolating effect therefore leading to a
reduction of species diversity.

- Does anybody know of European butterfly species (Rhopalocera, Diurna)
typical for wetlands, being cabable of maintaining a viable population
under the described conditions?

- How do individuals spread? Do they fly over the treetops or through the
forest of 200-300m?

- Is anything known about a species that locally disappeared because of an
isolating effect of surrounding forests?

- Or are other effects more important?

Thanks in advance for any help or suggestion

Hans

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From: [email-masked] (Pierre Zagatti)
Date: 9 Mar 1995 09:07:02 GMT

>- How do individuals spread? Do they fly over the treetops or through 
the

I think that the size of the parcel is not so important, many localized
species like Lycaena helle or Proclossiana eunomia can live for years
in quite narrow patches of their natural biotope. More important is
the change induced by the surrounding forest. A dense conifer forest may
induce modifications in light, temperature and humidity conditions that 
lead to modify the plant cohort of a sunny meadow. Some plant species
may appear and other disappear with major consequence on the survival
of specialized species.
Little is known on the ability of sedentary butterflies to colonize new 
areas over hundreds of meters. Apparently, some very specialized species
can live in autarcy while their biotope remains stable, whereas other
species need to be distributed over large areas with rather high 
population levels to survive.

Pierre Zagatti
[email-masked]

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From: [email-masked] (Meindert de Jong)
Date: 10 Mar 1995 10:02:27 GMT

>under the described conditions?
Dear Hans,

In The Netherlands Vacciniina optilete and Boloria aquilonaris occur on small
peatboggs. These boggs are always surrounded by dense forrest. On a few spots
the forest was removed, but strangely enough the butterflies disappeared.
We think that these species need the shelter. The populations are very 
isolated and we never found any evidence for dispersal. Nevertheless we
believe that there must be some contact between the populations.
A problem is that they seem to have colonized new sites (or we think so).
Since this area was always investigated very bad in the past, we don't know
this for sure.
Maculinea alcon is a species which has become quit rare in our country.
>From this species we know that it can maintain small population for a very
long time (on an area of 10x10 m for at least 30 years). This population had
no contact with any other population, since the nearest was at least 20 km
away.
I hope you can use this information.

Chris van Swaay
Dutch butterfly foundation