May 2017

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Bumper year for Festuca versuta, a vulnerable species

It has been dry for about a month, seed from cool season seed might ripen earlier than last year.  One of the things we look for to indicate seed ripeness is that the stem below the inflorescence is no longer green, but has cured to a straw color, so because it is dry, that may happen sooner than in a wet year.  We have already been harvesting Texas Grama, and may be able to start harvesting Bluebonnets, other forbs, Ozarkgrass, Little Barley, Melica, Texas Cupgrass, and Carolina Canarygrass by the end of the month.  Texas Cupgrass and Texas Grama are warm season species, but produce seed in both the spring and fall, and the rest listed are all cool season species.

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A small elk herd lives in south Austin.

The really special seed harvest potential this spring is from Texas Fescue.  This cool season savannah species seems to occur mainly in dappled shade on the edge of oak mottes and partially wooded upland drainages.  Our understanding of this species may be limited by scant evidence because it has been grazed nearly out of existence in most of its range.  On at least one site, it is thriving in full sun.  Does this indicate it’s habitat range is wider than we thought?  Or is it just expanding in response to a few years worth of favorable conditions?  Rainfall over the past few years (starting in 2013) has been strongly bimodal, or concentrated in spring and fall (as is true of historic rainfall patterns for central Texas but not during the period between about 1980 and 2010), so the fescue could have benefited from that… or the wet August of last year.  Or it could be increasing in response to management.  All of the sites where it appears to be increasing have been treated with prescribed fire in the past 10 years, have had either thinning (brush cutting) treatments or burns in the last 4 years (during this bimodal rainfall resumption), and have not been grazed in almost 20 years.  Whatever the reason is, the stuff appears to be going bonkers.  It actually showed up on a site where we routinely monitor seed ripeness, and adjacent to a restoration project site on a blown-out stock dam that we are cultivating as an enriched-diversity seed sourcing area.

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Some of the Texas Fescue seed will be ripe soon.

In Daniel Kahneman’s book Thinking, Fast and Slow, he describes how ideas with more detail appeal to our story-making minds more so than those with less.  However, with every additional detail, the story becomes less probable.  The most general statement one could make, something like, “you know something is happening, but you don’t know what it is,” is also the most probable.  The probability that you know something is happening but you don’t know what it is is about 100%.  As the story becomes less general, it becomes more compelling, and narrative.  For example, the story that “due to a few trends starting with the removal of domestic livestock, followed by management practices such as prescribed burning and thinning that increase light  at the ground surface, and a resumption of bimodal rainfall that is characteristic of grassland habitats in North America, the rare Texas Fescue (Festuca versuta), is increasing in abundance,”  is one we can all feel good about, and might be totally true.  Every detail in that story that describes how and why a vulnerable species is thriving makes it more believable.  Paradoxically, each of these details is also a filter that makes the story less probable, especially the detail that assigns causation.  To say, “we took the cows off, which may or may not be connected to an increase by Texas fescue,” is a forgettable story that is technically more probable (because it includes both “may” and may not”) and thus more rational.

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I’m excited about the Fescue.

This tension between probability and plausibility is particularly consequential for the fate of the environment as determined by democratic societies.  The scientific method tests hypotheses (the plausibility of narrative) by mathematically calculating probability. No matter the outcome, as soon as science enters the conversation, the narrative becomes less compelling.  The first step in the scientific process is to call everything into question, and the ultimate fruition of science is to create a story that is duller than the one we started with (by admitting uncertainty, and narrowing the scope of the narrative).  Certain political forces exploit the discord between the cause-seeking, story-making human mind and the rational caveats of accurate information, so what starts with some corporate sham like climate denialism spirals into a flat rejection of rationality.  People casually dismiss theories that are supported by a broad scientific consensus (whole disciplines, countless hours devoted by some of the brightest and most diligent minds on earth) in exchange for some lame story that is peppered with memorable details and irrelevant truisms that could not withstand even the slightest honest scrutiny.

I find some refuge from this trouble in the story that habitat restoration, and any method that draws an ecological system somehow closer to its historic range, is compatible with and supportive of a thriving earth.  Within the context of this broader story, we can create tests and define probabilities (and maybe not quite isolate causality) but still continue with a sense of purpose.  That is the compelling narrative that brings me back to the ever-changing present moment of the land. I believe this story to be capable of withstanding formal scrutiny, but I also take it to be self-evident. Some would question it, and have done so, to the conclusion that the historic range is already too far out of reach, and where that is true, we may need to find a more expansive definition of our target…  like something compatible with the historic range (see what I did there?).  But I have found that if we stay close to the story of habitat restoration, it will guide and support our work, and the land will respond in kind.  I take this Fescue as a word of encouragement, despite that all I really know about it is that something is happening, but I don’t know what it is.

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KR Bluestem has a decumbent growth form.

In my last post, I promised photos of exotic invasive species that would help ID them before seed is ripe (short circuiting the trap whereby we can’t manage plants until we can ID them, and we often can’t ID them without flowering parts, which may include seed and exacerbate the problem).  For more on that topic, see a recent talk I gave to the a local chapter of Master Naturalists:

2017 Restoration Techniques

Or if you really want to dig in, there is a book for that:

Grasses of the Hill Country: Vegetative Key

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