In Southern Africa the indigenous land snails are more or less confirned to
small patches of indigenous forest/bush. These forests are an exception in
an otherwise grassy landscape. The landscape is grassy for two reasons, 1.
relatively low rain fall, and 2. seasonal fires. (Now that settled
agriculture has appeared on the scene number 2 has been interfered with, so
the grassland has in many instances been extensively altered by exotic trees
and shrubs.)
 
Curiously, the indigenous forest patches very rarely burn, even when the
hills about them are aflame. It is not clear to me whether the preference of
our molluscan  fauna for bush/forest derives from a preference for the
microclimate in these patches, or whether it relates also to protection from
intermittant fires.
 
 
 
 
---------------------------------------
Mike Cortie
Conch Soc , South Africa
 
phone RSA-11-709-4485
email [log in to unmask]
---------------------------------------
 
> -----Original Message-----
> From: Andrew K. Rindsberg [SMTP:[log in to unmask]]
> Sent: 13 May 1998 16:16
> To:   [log in to unmask]
> Subject:      Re: Landsnails and Fire
>
> Kevin Cummings asks about the effects of prescribed burns on landsnails. I
> have some background and speculation to add to this interesting topic.
>
> In the southeastern United States before 1492, the forests were frequently
> burned by native Americans in a controlled manner that was designed to
> reduce shrubs and to increase new, tender growth as forage for deer. Some
> of the forests were almost parklike as a result, and the early European
> settlers were able to drive their wagons through the forest in some
> places.
> Thus, the pre-1492 woodland was, to a considerable degree, controlled by
> prescribed burns. The trees that dominated these forests tended to have
> tall trunks with fire-resistant bark. What kinds of snails are best able
> to
> withstand fire? What physical or behavioral characteristics allow them to
> do this (e.g., burrowing, living in treetops, a tough operculum)? What
> season did the native Americans choose for burns?
>
> The work of forester Roland Harper, and of others, indicates that fire
> tends to restrict some kinds of trees to relatively wet areas: swamps,
> bottomlands, and steep gullies. Today, prescribed burns are less
> widespread, and flammable trees have become far more widespread, e.g., red
> cedar (Juniperus) and sweetgum (Liquidambar). What effect has the
> restriction of fire had on snail populations?
>
> It is easy to ask questions that cannot be answered without a great deal
> of
> fieldwork, but it is such an intriguing topic that I can't resist asking.
>
> Andrew K. Rindsberg
> Geological Survey of Alabama