Habitat management: see Swengels' papers
gochfeld at eohsi.rutgers.edu
Thu Jan 24 15:20:18 EST 2002
I think that John's points and criticisms of the Swengel paper are
mostly correct. I don't think that undermines their interesting approach
to a large data set. My wife, Joanna Burger, and I certainly support
the importance of burning in pine barrens and in fact Joanna is writing
a book on the subject, which will repeat (for virtually every pine
barrens she has studied) the same point on the importance of fire and
the devastating role of fire suppression. Readers may get tired of the
redundancy after the eighth time.
So I would consider myself a burning advocate and a strong critic of
fire suppression (at least in the habitats I'm familiar with).
I realize that John's criticism comes from a much longer history with
the authors and issues of habitat management, that transcends the single
paper I mentioned, and I accept his greater experience on that issue.
However, I don't agree entirely with John's criticism, since the Swengel
study shows inconsistent responses which vary from place to place. I
appreciate John's insights into some of the limitations (which by the
way plague virtually all large scale "epidemiologic" studies of risk
factors). My first lecture in our epi course is on bias and
confounders. I think, however, that the over-riding theme of the
studies is that what works in one place doesn't necessarily work in
But the paper I cited was about butterflies. It did not purport to be
about all taxa.
Moreover, I strongly support John's point that what works for one taxon
(butterflies) might be harmful to others (and vice versa). We see the
converse, for example, in the long-standing conservation tradition of
protecting forests and ignoring grasslands (until New Jersey's grassland
bird community was on the brink of disappearing).
I have additional comments interspersed in John's message in CAPITAL
> I suggest that you look at "real" conservation biology literature before you
> hype the Swengel's work too much. The research in question suffers from
> many problems - like
I THINK THAT THIS CAVEAT CAN BE LEVELLED AT MANY (?MOST) ECOLOGICAL
STUDIES. THE QUESTION IS THE EXTENT TO WHICH THE BIASES UNDERMINE THE
> 1), ignoring the bottle neck effect of fire suppression of habitat size
> (they use today's remnant size and ignore the fact that most of their study
> sites went through major reductions in size (usually 75% reductions in
> available habitat due to woody encroachment) - so a 200 acre reserve today
> may have had about 50 acres of prairie habitat before the site was managed
> (fire and chainsaws usually - this was a major criticism of the attack on
> Iowa prairies in NABA recently):
I'M SURE THIS IS A TRUE AND VALID CRITICISM, BUT UNLESS THERE ARE
COMPARABLE DATA FROM THE PRE-BOTTLENECK PERIOD, I DON'T SEE HOW ONE
COULD EASILY GET AROUND THIS PROBLEM. WE HAVE TO WORK WITH WHAT DATA WE
HAVE. FOR EXAMPLE, THE 4TH OF JULY COUNTS (DESPITE METHODOLOGIC
LIMITATIONS AND CRITICISMS) PROVIDE SUBSTANTIAL DATA. BUT SINCE THEY
DID NOT EXIST PRIOR TO THE WIDESCALE USE OF PESTICIDES IN THE 1950'S,
THEY CAN'T BE ADDUCED TO ADDRESS PESTICIDE EFFECT QUESTIONS FOR THAT
> 2), ignoring all concepts of island biogeography and species equilibrium
THEIR STUDY CERTAINLY IGNORED ISLAND BIOGEOGRAPHY. AND IT IS TRUE THAT
ISLAND EXTINCTIONS CAN CERTAINLY OPERATE OVER A PERIOD OF A FEW YEARS.
HOWEVER, THAT IS THE BEAUTY OF A VERY LARGE DATA SET. SOME EVENTS CANCEL
OUT. ALSO THEY IGNORED IMMIGRATION AND RECOLONIZATION AS WELL. AT LEAST
AS I READ IT. IN ANY EVENT THERE STUDY WAS A REGRESSION STUDY WHICH HAS
ITS OWN SERIES OF LIMITATIONS, BUT AS A PERSON WHO DOES A LOT OF
REGRESSION STUDIES, I THINK THERE ARE VALID INTERPRETATIONS THAT CAN BE
> 3) equating large populations with the concept of increased viability (most
> conservation biologists are more concerned with minimum dynamic areas needed
> to support populations and ecological redundancy at landscape scales
I THINK THAT THE DATA IN THE PAPER I MENTIONED FOCUSED ON NUMBERS AND
SUPPORT THE CONCLUSION THAT WHAT FAVORS HIGHER NUMBERS IN ONE PLACE
DOESN'T IN ANOTHER.
> and most grievously 4) the focus on management of a single taxonomic group.
> The "hay prairies" touted as the perfect answer to butterfly management are
> extremely well known for the screwed up nature of the botanical community (a
> recent review of federally endangered Mead's milkweed indicates that these
> populations haven't set seed for a couple of decades in Missouri Hay
I AGREE WITH THIS LIMITATION, EXCEPT THAT THIS PAPER WAS ABOUT
BUTTERFLIES. I REALIZE THAT JOHN PROBABLY KNOWS A LOT MORE ABOUT THE
"POLITICAL" APPLICATIONS THAT THE AUTHORS MAY BE INVOLVED IN, BUT THAT
LIES BEYOND THE PAPER MENTIONED, WHICH LEADS TO THE CONCLUSION THAT NO
SINGLE METHOD IS UNIFORMLY BEST.
> The Swengles and other "anti-burning" butterfly types are roundly ignored
> by the conservation community for several reasons:
> 1: there is a vast literature on the role of fire in these ecosystems and
> the role it plays in maintain dynamic and species rich communities - look at
> your own Pine Barrens and the role that fire suppression has played in the
> loss of legumes and other forbs from the herbaceous community (the result of
> nitrogen enrichment due to lack of fires). At the Lep Soc Meeting a few
> years back I heard - and I quote" There is no science behind the ecology of
> fire". Wow, as long as you ignore fifty or so botanical journals - you
> could be right.
JOHN IS, OF COURSE, CORRECT THAT THERE IS A SUBSTANTIAL LITERATURE ON
FIRE ECOLOGY, WITH A LOT OF INTEREST ON THE EFFECT OF DIFFERENT
INTERVALS BETWEEN FIRE ON THE BUILD UP OF LITTER AND THE HEAT OF
SUBSEQUENT FIRES. IN OUR PINE BARRENS, THE MAIN ROLE OF FIRE
SUPPRESSION SEEMS TO BE TO INCREASE THE INTERVAL LONG ENOUGH SO THAT
WHEN A FIRE DOES EVENTUALLY BREAK OUT, IT IS A REAL KILLER.
INDEED, AS I RECALL, THE SWENGEL PAPER FOUND THAT FIRE WAS POSITIVELY
ASSOCIATED WITH HIGHER NUMBER OF BUTTERFLIES THAN IDLING.
BUT, I HAVE TO MENTION THAT OUR DEER POPULATION HAS ALSO DONE A NUMBER
(WHAT EVER THAT MEANS) ON OUR FOREST UNDERSTORY IN THE PINES (WHERE THEY
TEND TO BE SCRAWNY ANYWAY) AND THROUGHOUT THE STATE (AND BEYOND).
> 2: no-one in the conservation community believes that fire should be used
> with abandon. THIS IMPLIES THAT IN DISCUSSIONS OUTSIDE THE PAPER MENTIONED, THE ANTI-FIRE FOLK HAVE CREATED THE STRAWPERSON OF FIRE USED WITH ABANDON. Long before the Swengels, you had Ron Panzer pointing this
> out for invertebrates, grassland bird folks pointing out the problems with
> habitat structure, and herp folks talking about high mortality rates. The
> presentation of their arguments as "them versus the pyro-botanists" has only
> created the a lack of good will between land managers responsible for ALL
> biodiversity on a site and the Swengels who obviously don't give a royal
> damn about anything but butterflies and birds.
I HAVEN'T SEEN THOSE ARGUMENTS SO WAS UNAWARE OF THE AUTHORS' POLITICAL
VIEWS. IT PUTS A PERSPECTIVE ON WHAT I CONVEYED EARLIER, BUT DOES IT
UNDERMINE THE DATA? I DIDN'T READ THE PAPER AS VEHEMENTLY ANTI FIRE.
BUT SOME SCIENTISTS ARE DOGMATIC IN THEIR VIEWS (I HOPE THIS DOESN'T
ALSO, LIKE IT OR NOT, BIRDS AND BUTTERFLIES ARE VISIBLE ICONS OF
BIODIVERSITY, EVEN THOUGH THE SOIL NEMATODE AND MYCORHIZA COMMUNITY MAY
ULTIMATELY BE MORE IMPORTANT.
The Swengles and their
> groupies have literally created and maintained a false dichotomy between the
> two camps - and anyone who has every seen Ann scorned in public understands
> why the typical busy person doesn't want to deal with them. I HAVEN'T
> characterization of the two groups is that one camp views fire as an
> essential tool that has to be used with caution while the other camp is
> vehemently anti fire - most conservation biologists don't see room for
> compromise - myself included)
I'M NOT CLEAR ON THIS LAST POINT.
> 3: No-one is interested in prescriptive single taxa management
> recommendations in the conservation community at this point in time - its
> that simple. With the vast literature available on ecosystem dynamics,
> minimum dynamic area concepts, ecotonal flux and succession, the Swengles
> are pushing a "static management regime" to maintain a single target group.
> Life and ecosystems are too complex to even try and digest the flat earth
> approach to conservation biology.
I AGREE WITH THIS PRINCIPLE, AND FROM MY PARTICIPATION IN NEW JERSEY'S
LANDSCAPE PROJECT, I CAN VALIDATE THAT THIS IS AT LEAST PARTLY TRUE.
BUT THERE IS STILL A LOT OF SINGLE TAXON (EVEN SINGLE SPECIES) IN THE
CONSERVATION BIOLOGY LITERATURE.
> I have to admit that I have my own personal reasons for ignoring this work.
> I reviewed several of these manuscripts in earlier forms for various
> journals. I always sign my reviews and these manuscripts were all rejected.
> Now I see these same papers kicking about (with problems glossed over - like
> the fact that pollard transects for S. idalia were used in Wisconsin and
> counts from the hood of the car using binoculars were used in Missouri - and
> then the data statistically compared) and I AM LISTED IN THE ACKNOWLEDGMENTS
> AS HAVING REVIEWED (AND AGREE WITH) THESE PAPERS -Despite the fact that none
> of my comments were addressed. This is clearly a breach of ethical
> behavior - implying that I endorse the paper that I in fact trashed.
I CAN CERTAINLY EMPATHIZE WITH JOHN'S DISGRUNTLEMENT IN THIS REGARD. BUT
IT HAPPENS ALL THE TIME. WHY IS IT THAT WHEN YOU OR I AS A REFEREE
SUPPORT A PAPER FOR PUBLICATION AND EVEN OFFER VALUABLE ADVICE AND
ADDITIONAL REFERENCES, THE AUTHORS ACCEPT THE ADVICE BUT DON'T
ACKNOWLEDGE YOU, WHILE WHEN YOU DISAGREE YOU GET ACKNOWLEDGED. THERE'S
AN IRONY THERE FOR SURE.
> And I think that this sort-of encapsulates the entire attitude of the
> Swengles - fast, loose, and oblivious.
> (Look for a real paper on this issue in the next issue of cons biol - w/
> real experimental design, controls etc - novel but kinda like science as it
> is practiced in the rest of the world).
WE SHOULD ALL BE LOOKING AND PERHAPS JOHN CAN CIRCULATE IT TO THE LIST
AS A COUNTERPOINT.
> John A. Shuey
> Director of Conservation Science
> Indiana Office of The Nature Conservancy
> 1505 N Delaware Street, Indianapolis, IN 46202
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