A Treatise on Ecological Stability, Non-Weediness, and Complexity as the Rule Rather than the Exception

A Treatise on Ecological Stability, Non-Weediness, and Complexity as the Rule
Rather than the Exception

written by Justin Thomas

I believe a problem exists today in the interpretation of historical vegetation dynamics, especially as they relate to remnant grassland and woodland communities in the Midwest, east, and midsouth. The problem is that when one interprets the existence and persistence of grassland communities in this region as having resulted from historic forms of ecological “disturbance”, and then one applies one’s concept of that “disturbance,” the system often does not respond by moving closer to the perceived ideal condition (note: by “disturbance” I mean anything that induces chaos, weeds, and simplification). Instead, it becomes more chaotic, weedy, and simple, as opposed to more ordered, non-weedy, and complex.

When this happens, one must either question one’s interpretation of historical conditions or one’s concept of historical processes. Clearly, at least one is wrong. Modern “management,” almost always lacking in enough organismal knowledge to accurately judge the response of systems to “management,” have begun to interpret these simplified, weedy, and beaten responses as the natural state (note: I put managers and management in quotations because I think they are artificial constructs. The real human “managers” were exterminated long ago and contemporary attempts to manage are often based on weak assumptions that do not manifest). This often comes at the confusion or horror of those that DO have an organismal understanding of systems. In short, I don’t see any way the species assemblages that we use to define stable, non-weedy, complex systems could have coalesced under the intensities, frequencies, and seasonalities of the “disturbance” management that is applied in most circumstances today. Put another way, there is no reason to doubt the stable, non-weedy, and complex reality of historical systems in light of the induction of chaos, weeds, and ecological simplicity that modern “management” induces. The “canary in the coalmine” species, as well as many of the matrix species of what we know are historical reference states, do not persist at the current levels of “disturbance” inducing management. Thus, it is unlikely that they evolved under or were maintained by “disturbance” inducing management. The concepts of what maintained these systems, rather than the interpretation of historical conditions, must therefore be wrong.

A stable, non-weedy, complex woodland maintained without fire. 

Given this narrative, one is forced to seek a better understanding of historical conditions. So, under the assumption that the majority of the landscape was stable, non-weedy, and complex, what do stable, non-weedy, complex systems tell us?     

1. Stable, non-weedy, complex systems are resilient to change unless disturbed. For example, Eastern Red Cedar does not colonize grasslands unless the grasslands are damaged. All evidence suggests that before EuroAmericans, fire was infrequent, primarily of anthropogenic ignition, almost exclusively in the dormant season, and of moderate to low intensity. When we deviate from this, systems respond with chaos, weeds, and simplification. See Stambaugh’s “Wave of Fire” hypothesis for examples of landscape scale deviations from normal. Once you “disturb” stable, non-weedy, complex systems, as early settlers did on landscape scales, the autocatalytic drivers of ecological function are disrupted (see points number two and three below). This fuels rapid ecological change via chaos, weeds, and simplification. Eastern Red Cedar doesn’t move into systems. It is already there as seed. Waiting. It germinates in response to "disturbance" (see point number four).

A stable, non-weedy, complex prairie on left. The opposite on right. The difference is the right has been spring burned. The left not. 

2. Stable, non-weedy, complex systems are autocatalytic. They are driven by millennia of variation selection pressures (of which natural selection is but one). The species that assembled into these systems have deep evolutionary connectivity with each other that is heavily mediated by soil microorganisms. Autocatalytic systems are like a rapidly spinning top that over time has maintained its speed by maximizing ecological efficiency and streamlining poly-dynamic processes. The top itself is stable, though it may wander across the table (herein lies the dynamism of stability, in that the table could be interpreted as Mayr’s fitness landscape applied to communities). “Disturbance” inducing management negatively effects the spinning top’s ability to maintain itself. It makes it wobble. It slows it down. The more it slows, or has been slowed by negative legacy effects, the more likely it is to wobble, and eventually topple, if it cannot recover. Historically, in a landscape ruled by autocatalysis, ecological “disturbances” would certainly have happened, but they would have been buffered at temporal and spatial scales that do not exist today. This is why “heterogeneous management” and "disturbance" inducing management is potentially dangerous in most modern contexts. At a bare minimum these effects must be considered and monitored. Functionally, they never are.

This used to be an open shortleaf pine woodland. Then it was thinned and burned. Now it is a weedy woody thicket. 

3. Stable, non-weedy, complex systems are nutrient poor. At least in terms of nutrient availability. Stable, non-weedy, complex systems, as per number two, are not only maximizing energy efficiency, they are also maximizing nutrient efficiency. When you disrupt energy and/or nutrient efficiency you get chaos, weeds, and simplification (see Tilman’s Niche Dimension Hypothesis). The most botanically amazing and ecologically significant sites I know of all have low productivity. Even northern Missouri, Iowa, and Illinois where the soils are some of the most nutrient rich in the world, Big Bluestem gets merely chest high, while on CRP land right next door it is three meters tall. The difference is in ecological autocatalysis. Degraded sites are nutrient "hot". Stable, non-weedy, complex sites are nutrient "cool". This difference in productivity is a likely, but unconsidered, dynamic to declines in grassland bird populations, including Bobwhite Quail and the Greater Prairie Chicken. It isn't about grazing! Furthermore, nutrient dynamics in a “woodland” with 20-100 year old even-aged trees, are vastly different than nutrient dynamics in woodlands with 200-400 year old age-stratified trees. They are different at every scale – temporal, spatial, light, nutrient, microbial, biomass, etc. Prescribing a sudden “thinning” in a 70 year-old even-age forest releases nutrients via mortality, in addition to adding light energy, in a way that is wholly unnatural. Often, the result is chaos, weeds, and simplification. Burning in spring induces mortality that releases nutrients that result in chaos, weeds, and simplification (again, Tilman’s NDH). Mortality induced by intense grazing releases nutrients that result in chaos, weeds, and simplification. In essence, number three is really another type of autocatalysis.

Left is the ungrazed portion of glade that has soil and is stable, non-weedy, and complex. Right is a nearly soil-less, grazing-impacted glade. Guess where the cedars and sericea invade. 

4. Stable, non-weedy, complex organism were the rule, not the exception. In the Midwestern flora roughly 85 percent of the native species are non-weeds (determined by C-values being equal or less than three). 95 percent have a C-value of two or higher. This is a flora composed of stable, non-weedy, complex organisms. Not weeds. Not disturbiphiles. Just enough weediness to serve a functional role in a landscape where primary succession was unheard of and secondary succession a rare and low-octane event. Interestingly, we call native weeds "scab plants" for their analogous role. Platelets, the simple, nucleus free, red blood cells that form scabs, also occur at about 10 percent in the blood. More or less would be detrimental to the body. Add in the fact that these weedy species have seeds that bank for years, decades, and/or centuries and you see that they were evolved to the aleatoric – the random and rare events in nature. They were not the norm. The seeds of non-weedy species do not last in soil. Their ephemeralness strongly correlates with how sensitive they are to "disturbance". Also, since plants are the primary producers and as such define how all other organisms evolve, our rich conservative fauna mirrors this sensitivity. The fact that we have specialist animals (especially invertebrates) that do not persist in weedy habitats also suggest an element of overall persistent stability, non-weediness, and complexity.  

 A weedy hell-scape of a once stable and complex state designated natural area. Grazing for grassland game birds is not compatible with ecological function or persistence, if this is what it does. 

5. Climate drives biome-scale dynamics. Grasslands are climate driven. Transeau’s Prairie Peninsula was a response to climate, not fire and grazing. The end result, grasslands and woodlands, can and have been maintained against climate tension with fire, but I think we underestimate the influence of the massive droughts of the past 400 years as playing a major role in this. Once established and stable, native peoples burned grassland and woodland habitats to maintain their specialist flora and fauna. The did not do it to promote weedy generalist species. Burning crazy hot and outside the dormant season degrades the desirable and necessary character of landscapes. They also didn’t burn nearly as often as modern managers tout. This is all backed up by paleodendrochronologies, which are often misquoted.  

A stable, non-weedy, complex transition zone between glade edge and chert woodland. Maintained with infrequent, low-intensity fully dormant season fire. 

When these points are tied together, it paints a picture of a landscape that was stable, complex, and persistent by its own antiquity. These communities were stable because they were niche-maximized, nutrient slow, and energy efficient (autocatalytic). Only after these intensely efficient nutrient and energy cycles are shattered do systems change - and they change quickly. This is how you lose stable grasslands and woodlands. Not from fire suppression. Not from grazing suppression. These are auxillary phenomena. Sure, there were grazers and wildfires that made "disturbance" impacts, but they were tempered by space and time. There are dolomite glades in Missouri that have never been burned or grazed (in modern history), that are still open prairie-scapes. I’ve been on wonderful prairie remnants in Missouri, Iowa, Kansas, and Ohio that are not burned or grazed. They are stable. I’ve been in wonderful woodlands throughout the Midwest and midsouth that are phenomenal without fire or grazing and that show every indication of having been that way for time immemorial. They are stable, non-weedy, and complex because of their autocatalytic dynamism. They are rare because the landscape has been blitzed so comprehensively. This fact should make us look harder for living examples rather than default our shifting base-line to the degraded landscapes we see day in and day out. I’ve seen amazingly complex places sent spiraling into chaos from misapplied fire and grazing. I’ve also seen their grandeur maintained by low intensity dormant season fire and innocent degrees of grazing. In these cases, the spinning top is not slowed or sent wobbling. Its autocatalytic integrity is maintained. That is the only goal! 

A stabilizing, non-weedy, complexifying mesic woodland developing in the absence of grazing or fire. 

This leaves one conclusion: that “disturbance” inducing management is an inaccurate philosophy and an indefensible stance. The primary lesson from Missouri’s 35 years of prescribed fire revival, the earliest in the region, is that we have overshot the target. The benefits of fire were oversold because it was a hard sell and because no one knew the real effects. I’m afraid that that overselling, lack of complete understanding, and stubbornness to not concede despite the evidence, is destroying the few examples of reference community dynamism that we have. It is also sending most places that aren't as intact on random disturbance walks in directions that do not represent the healthiest aspects of their evolutionary histories. Grazing is doing the same thing. Rich, ecological complex, bountifully bedecked and buzzing communities are NOT weedy. Anything that makes them even slightly more so is unconscionable.