Interspersed Denuded Zones (IDZs): their ecology and conservation significance

This morning I got a chance to kick around ideas about Interspersed Denuded Zones (IDZs) with the Wise Lab in University of Illinois Chicago.  You may not have heard the term IDZs before.  The fact is I coined the term along with Vassia Pavlogianis very recently for a piece in 3quarksdaily. com entitled “A Tiny DyingSuch As This”. 

I wager the following: right now you doubt their existence, a year from now you’ll acknowledge them and perhaps recognize an IDZ when you see it, in five years you will argue with those that dismiss their ecological significance, and in ten years time you’ll vaguely recall having coined the term!  You may even be attending the first international meeting on IDZs by 2022.

An IDZ is one of a number of patches of exposed soil in a habitat which more typically has a well developed and contiguous leaf litter layer.  An IDZ can occur naturally where, for a variety of reasons, leaf litter decomposed more rapidly than it is replaced through leaf fall.  Alternatively IDZ can develop in response to a variety of anthropogenic disturbances.  If a non-native species with highly decomposable leaf litter replaces species with more recalcitrant litter then an IDZ can develop.  Similarly modification of the decomposer community (e.g. introduction of non-native earthworms) can accelerate the breakdown of litter.  Other factors may contribute – nitrogen deposition, elevated temperature etc can result in the altered dynamics of soil organic matter.

The ecological significance of IDZs have not to my knowledge been investigated (that is, under any name) though Kristen Ross from UIC, a post-doc with Chicago Wilderness, tells me that there is now some interest in looking at biodiversity of invaded patches in Eastern deciduous forest where invasive species have radically altered the litter layer.  However, in cases where the litter completely disappears the consequences will be quite different.

In A Tiny Dying I was primarily interested in the conservation implications – my suspicion is that with the intermittent loss of litter the effective habitat size for litter dwellers disappears and the populations crash.  As a result there may be a lot of local extinction as a result.  If I am correct this may be one of the most significant conservation crises of our times.  This is because there a huge proportion of the diversity of organisms of most terrestrial systems living in the litter layer. 

I appreciated getting great input on this idea from all my colleagues at David Wise’s lab at UIC this morning. Basil Iannone, Cristian Martínez, Dan Milz (especially for the hover-board suggestion!), Kristen Ross, Matthew McCary, Monica Farfan, Robin Mores, and Susan Kirt Alterio.

The Sexiest Story Ever Told: The Evolution of Telling Tall Tales about Evolutionary Tall Tales

I’m finally getting around to reading Massismo Pigliucci and Jonathan Kaplan’s Making Sense ofEvolution – the Conceptual Foundation of Evolutionary Biology (University of Chicago Press, 2006).  A critical argument that they make in this book, it seems to me, is that the available techniques for testing adaptive hypotheses can either not be applied to humans or can be done so only with difficulty.  An important and fairly intuitive outcome of this is that we don’t have well founded evolutionary arguments for some fairly obvious human evolutionary trends: bipedalism, braininess, and relative hairlessness.

Instead of well tested insights about the evolution of key human characteristics we have a swarm of speculations, the problem with which is not that they are unconvincing but rather that they are all so seemingly plausible and we do not have a way of arbitrating them. 

So how, typically, are adaptive hypotheses tested?  Pigliucci and Kaplan (P+K) describe six techniques: phenotypic manipulation, transplant studies, laboratory explorations, optimization analyses, phylogenetic analyses and regression analyses.  The first three pose ethical problems – to put that famous Annie Dillard quote to new use: “We can leave the library then, go back to the creek lobotomized, and live on its banks as untroubled as any muskrat or reed. You first.”  Thus the equivalent of, say, filing a birds beak to test an adaptation (apparently such tests make it past the ethical boards!), might be to surgically chop a brain to test a hypothesis about the evolution of that massive protuberance, though it would be less seemly to do so.  In fact all sorts of clinching experiments may suggest themselves to test human evolutionary hypotheses, but few could be ethically undertaken.  P + K say that the other three approaches are possible but problematic since we often know little about the selective pressures surrounding human adaptations, and the clade to which the humans belong is relatively species poor.

The target of their critique is primarily evolutionary psychology (EP) the spunky younger cousin of sociobiology (SB) which came under stout attack from Stephen Jay Gould and Richard C. Lewontin (G+L) in their famously contentious “Spandrels” paper in 1979.  In short P+K are doing to EP what G+L did to SB!

I won’t say much more about it now other than to note that one’s response might be to stanch a temptation to hypothesize about the evolution of certain human traits – especially the evolution of mental characteristics where we seems to be on especially tricky ground.  This is indeed what they suggest for EP's future.  Focusing on less "sexy" traits, they say, "might prove to be more promising." (p153)

Alternatively one might just have at it.  Since we're in the position of being unable to test many of these ideas comprehensively we might entertain ourselves with increasingly implausible speculations knowing that they are no more nor less defensible that any others.  Indeed, the very tendency to speculate about human evolution may itself be an exquisite adaptation for befuddling and stymieing one’s intellectual competitors with tall tales.  S/he who is the greatest evolutionary fabulist and the least concerned with the exertion that accompanies hypothesis testing might be less prone to the life's depression inducing realities.  Or this trait may, of course, be a product of runaway sexual selection.  What could be sexier that a marvelous yarn about one’s origins? Are those humans who construct the splashiest evolutionary fables simple the peacocks with the prettiest ass feathers?

      

Making Nature Whole – A History of Environmental Restoration - STREAMING LIVE!

Making Nature Whole – A History of Environmental Restoration

By William Jordan III and George M. Lubick

WHEN: Wed 18th January 2012 at 6:30 pm CST (Environmental Science and Chemistry Building (McGowan South), 1110 West Belden Avenue, Chicago, IL 60614 ROOM 108)

Wednesday is the book launch of William R. Jordan III (co-director of DePaul University's Institute for Nature and Culture) and George M. Lubick's Making Nature Whole at 6:30 CST

Though we’d love to see you there is you are around, for those that can't make it we will be webcasting the event on our blog Environmental Critique <http://environmentalcritique.wordpress.com/> and, as long as all goes well with the technology gods, that video should remain online for you to watch at your leisure.

PROGRAM: Interdisciplinary reflections on the book by Tom Simpson (McHenry Co Conservation District), Anthony Paul Smith (DePaul University Institute for Nature and Culture), Paul Gobster, USDA (Forest Service), David Wise (UIC), Claire Butterfield (Faith in Place), and Gavin Van Horn (Center for Humans and Nature) and from the author William Jordan III.

A Tiny Dying Such as This – Is There an Ongoing Mini Mass Extinction of Soil Invertebrates in the Midwest?

My latest 3quarksdaily column

A short note in which I conjecture on a potentially vast local extinction event of Midwestern soil organisms especially of those inhabiting the leaf litter of woodlands.

In our evolutionary progression humans scrambled from the leafy treetops about half way down the length of the trunk.  We now live perched between treetop and root ball on that convenient platform we call the soil.  If physicists can give themselves vertiginous shivers by imagining those empty atomic spaces that constitute the seeming sturdiness of ordinary things then it is surprising that soil ecologists ever leave their homes knowing as they do how vastly crenulated, fissured, fractured and porous is the soil.

Ours is the exceptional ecological enterprise since more organisms live in the soil in those porous and interstitial lodgings than on the soil.  We are not directly equipped for flight, we rarely burrow, we are condemned to walk upon the dirt until at last we may complete our descent into the ground, toppling into that large furrow excavated for our remains.  A soil pore will have us after all.   

If we had been just a little smaller and had migrated just a little further down the length of that primordial tree we’d be living in one of the most biologically diverse and ecologically active compartments of the biosphere.  The upper ten centimeters or so of soil teems with living things.  The organisms living in Earth’s thin and hyperactive rind are phylogenetically diverse, trophically heterogeneous, functionally assorted, highly variable in size, dissimilar in longevity, variegated in morphology, behaviorally divergent, adapted to different soil horizons, disparately pigmented, but are united in their reliance on death.  Specifically, soil organisms are all similar in that they feed on detritus (i.e., dead organic matter).  As I discussed in a recent column, collectively the action of these organisms within detrital-based food webs results in the breakdown of dead organic matter and the mineralization of organic compounds that makes key nutrient available to the living. 

Examine your foot a moment.  If it is like mine when shod it measures roughly 30 cm in length (yes, a foot) by about 9 cm wide (your foot, of course, may not be quite so rectangular!).  A pair of feet such as these out for a stroll treads minimally upon the bodies as 270,000 protozoa, 135 mites, 3 springtails, and a one or more large earthworms with each footfall.  In places of high animal density the injury toll would be higher by several orders of magnitude.  If you were sallying along a woodland path in the temperate zone these crushed critters will be representative of about 30 distinct and species of which up to half may be previously undescribed by taxonomists.  Scaled up there can be as many as 200 species of soil insects and 1000 species of soil animals in total in every 1 m² of soil.

Read on at 3quarksdaily here