Early successional stages
Kondla, Norbert FOR:EX
Norbert.Kondla at gems3.gov.bc.ca
Thu Jan 17 11:26:30 EST 2002
Some additional natural disturbance agents in my part of the world that
'recycle'/open up that nasty old tree canopy and create butterfly habitat
are: pine beetles which sometimes reach epidemic proportions over large
areas; small patch openings are regularily created by Armillaria root rot
and this has a most salubrious effect in contributing habitat diversity to
an otherwise monotonous coniferous forest; snow avalanching is very common
here and maintains early succesional habitats (many of these are well known
for their spring feeding value to Grizzly Bear but remain unstudied re.
butterfly use. On a microscale, ground squirrel digging and bear digging
create substrate for the Polygonum host plant of Lycaena nivalis. Lots of
fascinating stuff going on out there. I recall somebody suggested that there
should be more study of model tropical systems. Worthy as that is; I cannot
see how that will be of much or any use to people that have to make land use
and resource management decisions in other completely different ecosystems.
From: Michael Gochfeld [mailto:gochfeld at eohsi.rutgers.edu]
Sent: Monday, January 14, 2002 6:12 PM
To: Kondla, Norbert FOR:EX
Cc: 'fnkwp at aurora.alaska.edu'; leps-l at lists.yale.edu; 'altabugs'
Subject: Early successional stages
As Norbert points out many leps or their host plants seem to be
of early successional stages and thrive where forest has been disturbed.
not necessarily that butterflies ask themselves where is the nearest borrow
but that the revegetation of borrow pits is sometimes (not always)
Historically, forests suffered from fire that created openings on a more or
frequent cycle. Fire suppression practices are a form of negative habitat
modification. Nature Conservancy, to its credit, has recently realized that
it's not only forest tracts that are worth preserving.
"Kondla, Norbert FOR:EX" wrote:
> Thanks to Ken for sharing these interesting examples of unplanned
> enhancement for butterflies. There are plenty more examples from around
> globe and I would be interested in more exmaples that others wish to share
> with the rest of us lepsters. Just one Yukon example that I observed in
> 1999. A roadside strip that had been bladed in the past and had developed
> completely unnatural very dense growth of Penstemon sp. This allowed the
> resident Euphydryas anicia helvia population to explode to amazing level.
> BC example has to do with an endangered species (ssp actually): Apodemia
> mormo is red listed in BC and the largest population owes its existence to
> the fact that a natural slope was reshaped by railroad construction many
> years ago. The resulting soil conditions allowed the Eriogonum niveum
> to expand and multiply into a denser than normal stand. In turn this has
> allowed the Apodemia population to expand several orders of magnitude
> those under natural conditions. Old airstrips and even areas near new
> airstrips, borrow pits from road construction etc are great spots for
> butterflies and have been seen to result in unnatural densities of things
> like Pieris marginalis, Euchloe, Parnassius, Oeneis chryxus etc. The
> is creation and/or maintenance of early seral habitats and proliferation
> the host plants of these butterflies. If we tried to "protect" everything
> would instead be doing horrendous damage to those species who are crowded
> out by natural succession and which need disturbance to survive. The
> do not care at all if a stand of Arabis is growing on a natural
> or if it is there because a human on a bulldozer bared some soil. All
> apparent environmental damage is not damage to all organisms; it simply
> provides a different environment which is then often used by different
> species. There is no waste in nature; everything gets used by something.
> -----Original Message-----
> From: Kenelm Philip [mailto:fnkwp at aurora.alaska.edu]
> Sent: Monday, January 14, 2002 1:55 PM
> To: leps-l at lists.yale.edu
> Subject: Environmental enhancement?
> In the light of the current thread about environmental degradation
> and its severe impact on butterflies, I thought it might be of interest
> to bring up a couple of (minor) counter-examples in Alaska.
> 1) The roadside along the Haines Highway north of Haines, Alaska, is now
> lined with dandelions. According to the natives, these were unknown along
> the river valley in the old days. Judging by what I saw in May 1994, the
> roadside dandelions are acting as an excellent concentrating mechanism for
> the local butterflies, especially _Anthocharis sara_.
> 2) The gravel pad under the Aleska oil pipeline has, in some areas, become
> a good collecting site for certain species of butterflies. I first noticed
> this in 1979, near Galbraith Lake--the pipeline pad had a concentration of
> _Oeneis bore_ (which was widely distributed over the adjacent tussock
> tundra). In 1991, at a Dalton Highway site with the odd name of 'Oil Spill
> Hill', the pipeline gravel pad had been taken over with both grasses and
> legumes. The legumes had concentrated several species of _Colias_ that
> were more sparsely distributed over the Sagavanirktok River floodplain,
> and the grasses supported a dense population of _Oeneis bore_ and _O.
> excubitor_ (= _O. alpina_).
> This last summer I had the opportunity to check Oil Spill Hill
> for a second time. The legumes were no longer there, so there were no
> _Colias_--but the grasses were doing fine, and there were very high con-
> centrations of _Oeneis bore_ and _O. excubitor_. _O. excubitor_ was having
> a good summer (unlike many other butterfly species in 2001) on the North
> Slope, but at no other site did we find such a dense population as under
> the pipeline at Oil Spill Hill.
> 3) A number of small airstrips in eastern Alaska have produced good crops
> of legumes. These have not subsequently vanished, like the ones at Oil
> Spill Hill--possibly because the strips are regularly mowed. These strips
> have dense populations of _Colias krauthii kluanensis_ (or _C. christina
> kluanensis_ according to some), and also support other _Colias_ species.
> Note: I am not trying to defend environmental degradation! I have
> seen its effects, even up here. However, every once in a while something
> good occurs, at least from the viewpoint of lepidopterists.
> Ken Philip
> fnkwp at uaf.edu
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