Wednesday, July 27, 2016

SearchResearch Challenge (7/27/16): Mind the gap!

The biggest surprises... 

... are sometimes the ones you don't see at first.  They're the kind of little things that slowly creep into your consciousness and make you wonder... why is it that this is so??  

Long-time readers will remember the one of the harder Challenges of the past ("How much death at the roadside?") when we tried to figure out why there are gaps in the plant cover next to many roads in California. We discovered in that Challenge that the state Dept. of Transportation (CalTrans) regularly sprays herbicide on the edge of the road to prevent weeds from taking over the road.  

This week we have another "gap in the weeds" Challenge.  

Not long ago, I went for a run up on Black Mountain, one of the local peaks in the Santa Cruz mountain range.  If you look carefully on the right side, you can see the typical summer-time wave of fog coming in from the Pacific Ocean.  On typical summer evenings, that fog (aka "Karl") comes in from the sea to cover San Francisco.  Luckily, Black Mountain is usually high enough that the fog comes around, not over, the peak.  

Selfie of me running in the early morning at the peak of Black Mountain

It was on this run that I noticed something that was pretty small, but very odd.  Here are 3 pictures I took on that run of a strange phenomenon.  (Remember that you can click on the images to see larger versions.)  

What struck me about each of these pictures is that there's a noticable gap between the green plant and the grassland next to it.  Oddly, this doesn't happen ALL the time, but it does happen a lot.  

The plants here are chamise (Adenostoma fasciculatum), but I'm pretty sure I saw gaps like this around coyote brush (Baccharis pilularis) in the same area.  

This strange plant-free boundary around most (but not all!) of the plants on Black Mountain led me to this week's Challenge:  

1.  What causes the odd, plant-free gap around the plants in these photos?  

If it helps (and it might, or might not), these photos were taken on August 13, 2013, at 37.3195203,-122.1630756  Which looks like this in the Google Earth photo:  

Looking carefully at this clump of chamise and coyote brush, you'll see this kind of gap all around these plants.  (The light color perimeter is where you can see the soil 

What's going on here?  I looked very carefully, and this gap at the periphery aren't trails of people or deer.  (You can see deer trails weaving between the clusters of bushes, especially to the west of the drop pin.)  

So... What's causing this?  Any ideas?  Let's do some of that SearchResearch and figure it out! 

Once you've figured it out, be sure to let us know HOW you figured it out.  What sources did you refer to?  And best of all, how did you know to search for that?  We all want to learn from your crazy SearchResearch skills!  

Search on!  


  1. what/how I found on the fly – see bolded section:
    Coyotebrush is a shade-intolerant species. Along with other small-seeded coastal sage shrubs, it colonizes actively eroding or alluviating areas such as dunes and gravel bars. Exposed mineral soil gives coyotebrush an advantage over perennial grasses and chaparral shrubs [36]. Coyotebrush's successional status varies with habitat type [68]. In California grasslands, it is a late seral species that invades and increases in the absence of fire or grazing [30,56,68]. The rate of invasion is generally positively correlated with the amount of spring rainfall, because wet springs maximize early root growth. Coyote bush invasion of grasslands is of structural importance because it facilitates the establishment of other coastal sage species. Shrub cover subsequently increases numbers of rabbits and small mammals (and birds too) that reduce herbaceous vegetation and favor shrub development [25,54]. Thus, well-established coyotebrush stands generally have depauperate understories [30]. Coyotebrush is a common dominant in coastal sage scrub, but because seedling growth is poor in shade, coyotebrush does not regenerate under a closed shrub canopy [68]. Coast live oak, California bay, or other shade tolerant species replace coastal sage scrub and other coyotebrush-dominated areas, particularly when fire and grazing are excluded "

    the 'invasion of the grass snatches' or the grassland cycles… used the plant type you mentioned to search for info and found a plausible explanation with it's invasive nature and the cycle of
    open grasslands — [soil around coyote brush]. Would think the small mammal & bird habitat/usage would be a strong factor too…

    secondary pioneer species
    coyote bush

    "Plant strategy type/successional stage (stress-tolerator, competitor, weedy/colonizer, seral, late successional)
    Coyote bush is a shade-intolerant species. Along with other small-seeded coastal sage shrubs, it colonizes actively eroding or alluviating areas such as dunes and gravel bars. Exposed mineral soil gives coyote bush an advantage over perennial grasses and chaparral shrubs. Coyote bush's successional status varies with habitat type. In California grasslands, it is a late seral species that invades and increases in the absence of fire or grazing. Coyote bush is a common dominant in coastal sage scrub, but because seedling growth is poor in shade, coyote bush does not regenerate under a closed shrub canopy. "

    in WA

    any of this kind of 'ground truth?' fecal pellet

    2nd brush pic ⋰・∵∷

    1. Karl brought a smile… "All that is sunny does not glitter, not all those in the fog are lost." so sayth Karl…
      K & D on the GGB sorta-selfie
      enjoyed the Karl mention
      who knew he had thumbs?
      foggy mystery

      Cali Chaparral
      on fb – "In California we call 'em tarantula hawks... in Wisconsin, katydid killers!"

      "It furnishes a large quantity
      of low to medium quality browse for both livestock and big game.
      Chamise is a staple deer food (by volume) throughout much of California.
      Deer use is often year-round, particularly in northern
      California , but is most concentrated during the summer and fall.
      Limited livestock use occurs, primarily during the
      spring and summer. Chamise in mature chaparral is seldom
      browsed because stands are too dense for livestock or big game species
      to penetrate, making the current growth largely inaccessible"

    2. Karl's cousin, Kaleb, in Vegas, courtesy of Cali wildfires…

  2. I found this question interesting since I also live in California, and once you mentioned that there was a dead area around bushes, I knew exactly what you were talking about and had a sort of “huh…?” moment.

    I started with a few searches on dead areas around bushes, but just came back with articles about gardening, mulch, and herbicide, so I decided to look into the coyote bush more specifically since it was mentioned in the challenge. I came across an article ( that mentioned the term “depauperate understories”, which sounded interesting.
    After trying to define the term, then doing a general search I had limited success since most articles referred to forests, which was the wrong type of environment for the information I was seeking. After changing my search to “depauperate understories chaparral”, I was able to find this paper on the USGS site ( In the introduction, it explains

    “One noteworthy characteristic of chaparral is the depauperate herbaceous vegetation under the canopy. This lack of herbs occurs even in relatively open stands and, when chapparal is juxtaposed with herbaceous vegetation such as grassland, this near lack of herbaceous vegetation often extends into a zone 1-2m around the shrub boundary. In contrast, there is an abundant and diverse herbaceous flora in the first spring after a wildfire (Horton and Krabel 1955,Sweeney 1956, Keeley et al. 1981).……...One explanation for this phenomenon that has received wide attention is the theory that shrubs produce chemicals that are leached out of the foliage and allopathically inhibit the germination of herb seeds (Muller 1968). When fire removes the shrub canopy, the seeds are released from the inhibitory effects of the allelopathic chemicals.”


  3. I first searched: "plants that can't coexist" [1:19 PM]
    I selected Incompatible Plants:20 plants & What they can't grow with
    From there I learned the word allelopathy, did a quick search for the definition and confirmed that it meant what I thought.
    I combined allelopathy and chamise [1:23 PM] and selected an article entitle Adenostoma fasciculatam after reading the blurbs, and the article confirmed a theory:

    Short-lived shrubs and herbaceous cover are largely lacking from
    undisturbed stands of chamise chaparral [116]. Chamise probably
    produces allelopathic toxins which inhibit germination and growth of
    other species [16,17]. During summer drought, chamise leaves accumulate
    water-soluble phenolics as a result of normal metabolic activity; fog
    drip and rain transport the toxins into the soil [43,83]. Competition
    for light may also be a factor controlling seed germination beneath
    mature stands [67,69].

    1. Jeff, 'allelopathy' was a good find, congrats… finding & having the right search lingo is helpful… seems that might be a factor in the bare soil gap
      Terrestrial Vegetation of California, pages 190-94 used[Allelopathy coyote brush]
      Allelopathy: How Plants Suppress Other Plants
      "Allelopathy: The essential oil from California sagebrush contains 5 toxic terpenes. It has been suggested that the release of terpenes by California sagebrush contributes to the relative lack of vegetation under and adjacent to the shrub [82,121,213]. During the 1st rains of December, the leaf drip from California sagebrush is toxic. The rain leaches toxins from the leaves and litter that is absorbed by the soil, adding to toxins previously deposited by volatilization during the dry season [116]."
      'volatilization' is another term
      naturally occurring herbicide

    2. Great finding jodimillard and Jeff and Remmij. I didn't thought the words selected for you. I thought this was due to some animal or another factor but not because plant. It is very interesting and once again, new for me. Thanks for giving us more knowledge, Dr. Russell.

      After reading posts made:

      [list of allelopathic plants]

      The plant that was established first - tree or turf - has the advantage...The study conjectured that a combination of competition and allelopathy accounted for this result. Mentios Volatilization as Remmij mentioned and also Leaching and Exudation.

      [allelopathic "coyote brush" | "chamise"]

      Allelopathy In Plants: What Plants Suppress Other Plants Curios thing, in the link I posted before comes this new word but is only mentioned for Eucalyptus and Laurel

      Chamise probably produces allelopathic toxins Other pages of this site has been mentioned.

      Allelopathic Effects of Adenostoma fasciculatum, "Chamise", in the California Chaparral Still need to read on detail

      In search of allelopathy: an eco-historical view of the investigation of chemical inhibition in California coastal
      sage scrub and chamise chaparral
      Also looks interesting, but need to read it.

      Remmij, your photo as always fantastic! And the link with the glossary super helpful. Other ones, need to read with more detail.


  4. Just punched in the names. I had a hunch about the first plant chamise which proved correct. I think.
    Allelopathogens And Herbaceous Growth
    Chamise stands generally contain little herbaceous growth, compared to nearby grasslands or woodlands. Normal metabolism results in an accumulation of a water-soluble toxin, or allelopathogen, on the surface of chamise leaves at the top of the plant. Seven to ten years after a fire, allelopathogens created by chamise are dissolved and carried to the soil, where they suppress the growth of other plants. With each rain, new amounts of the toxin are added to the soil. The toxin does not kill directly, but instead suppresses root growth to the point where a slight drought would cause the annual plant to die. The toxin is concentrated in the upper one to three centimeters of soil. Mild heating or exposure to rain and sun can decrease the effectiveness of the toxin. Chamise seeds are inhibited by the toxin, which occurs at its highest levels during the germination period. For this reason, seeds are generally not found in mature chamise stands, but are common after fires.

    Same process for coyotebrush turned out very differently. The clear spaces are perhaps an artifact of the very tiny seeds and seedlings not finding enough moisture and being out competed by grasses with larger carbohydrate storage
    coyotebrush is excluded or reduced by competition from grasses and other species that have larger seeds with more carbohydrate storage

    Yet another nifty Challenge.

    Jon tU

  5. Good day, Dr. Russell and everyone.

    [gaps around chamise plant]

    Chamise: Fire and animals

    Chamise – a key chaparral plant

    [black mountain august fire 2013] [black mountain fire 2013]

    Nothing that can help us. And, I think fire is not the reason for those gaps.

    ["coyote brush" Chamise plant gap] and ["coyote brush" Chamise gap between plants]

    Defensible Space Also talks about EUCALYPTUS, for example.

    Still nothing helpful to solve Challenge. Tried others but zero results. Be back with more

  6. As a botanist, I would initially search:
    [allelopathy <"plant name">]

    However, there are many in-field reckonings that are published as facts ...
    ... a botanist mentions 'this is probably allelopathy' and a scribe publishes it as fact.
    As such, I would use the botanical name and use Google Scholar.

    There are laboratory and field tests to help prove an allelopathy hypothesis.
    If it was important, I would track down original research and read the methodology.

    Alternatives to allelopathy:
    Nutrient depletion - do these shrubs successfully extract a scarce nutrient and bind it in their tissue.
    Intensive grazing - a small critter seeks refuge under or near these bushes and grazes intensely.
    Intensive traffic - a small critter has pounded a track around bushes.

  7. Replies
    1. Hi Remmij! Thanks for the name link!

      I was thinking about what Dr. Russell said: "Oddly, this doesn't happen ALL the time, but it does happen a lot." so tried this

      [why allelopathy doesn't always work]

      Experimenting with Allelopathy

      Marine Allelopathy

      ‘secondary metabolites’ – that is they’re not directly involved in the plant’s growth and reproduction

      But so far nothing else. Also, found term is from 1937 (Wikipedia) and in Spanish is Alelopatía. Also tried to visit [international allelopathy society] but link doesn't work anymore and that is why I searched for it.

      WELCOME TO THE WORLD OF ALLELOPATHY and What is the International Allelopathy Society or IAS?

      With [allelopathy explained] found the answer in the video!

      Allelopathy plants distribute in uniform way. Video mentions there are 3 ways of distribution. And also mentions is common in areas with not so much water

      On other topic, Dr. Russell, Remmij and peers, is there a way to know the urls that we linked without hovering the mouse over them? I mean when we create a live url, Ctr-f only finds the link text but not the url. I ask because sometimes I post some links that others have found, so I wish I could find a way to check that quickly and not repeat many.

    2. I don't know of a way to do this (control-F for the contents of the URL), but there well could be a Chrome extension to do something like this. It wouldn't be that are to write (and I'd call it something like "Look Inside," suggesting that it would do a text find *inside* of a link).

    3. Thanks Dr. Russell! Have excellent day

    4. Sorry for new post. I tried to find searching before posting but couldn't find anything helpful, until Dr. Russell posted "and I'd call it something like "Look Inside,"..." After some queries tried [how to control f hyperlink] "View Source" and then Ctrl-F Not exactly perfect, beautiful as just Ctrl-F, but works. Thanks again, Dr. Russell!

    5. creeping consciousness/skipping unconsciousness >> Janus surprise… meanwhile, in cat news… Yo estoy mirando a ti, Ramón (was searching for a paper free of domestic political rambling…)
      Pallas's cat/Manul cats (a former sRs subject)
      Amur leopard
      Bucky cat, comic relief

      Ramón, regarding the URL question - don't know of an easy way either - the approach Fred uses with "One Tab" makes things easier to trace, but has its drawbacks too…
      found this article - a bit dated and doesn't offer much that you don't already know - hovering the cursor so the URL shows in the status bar (varies some depending on browser)
      and the ability to copy link URLs and paste them into a list:
      "how do you quickly and safely grab the URL without opening anything? Easy. Just right-click the link to bring up a context menu, then click Copy shortcut (in Internet Explorer), Copy Link Location (in Firefox), or Copy Link Address (in Chrome). "
      used [identify url in live link without clicking]
      but that doesn't really help identify a YouTube video title/content or shortened URLs — maybe Dan is right about the existence of an extension or add-on??
      the hover may be the best current option… sifting redundancy is a search trait/skill/albatross… =•\
      fwiw: like Michael Michelmore's reasoned analysis of the soil ring conundrum… wonder if Dan notices variances that are time of year related?
      the scoop on poop — more than I needed to know…

    6. Hello Remmij! Thanks for the links, so much appreciated. I hope the leopard is fine and the Pallas Cat is awesome!

      The links to check for URL also very helpful and new for me. And the link of the scoop made me remember this Challenge What kind of animal? I remember I saw another one about animal tracks but I can't find it.

      And here is the link to the Second Pallas Challenge for those who missed it and for re-reading. That also links to the first one. Great memory, Remmij. A nice way to re-track and refresh my learning.

    7. …speaking of cats… Feel the Grump… a mind gap…
      the evolution of B&G

    8. Karl⇄Carl… a red herring, but tasty.
      "The person behind the fog account, who answered questions via email and requested anonymity (to the point of not even revealing a gender), says some inspiration for what eventually became Karl came from the fake BP public relations account that sprang up after the oil spill in the Gulf of Mexico in June 2010. "It was the first parody account I followed and thought the idea was brilliant and that I could do something like it," writes Karl's puppet-master. "I love the idea of blending fact and fiction and not knowing where one stops and the other begins." The final inspiration came after a bout of foggy weather. "Friends were whining about the most recent fogpocalypse and I was loving it. ... I've always thought of the fog as mysterious and romantic and looked forward to its arrival. Since everyone was complaining, I started thinking, 'I wish the fog had a chance to defend itself,' and that's when I created the Twitter account.""
      a Karl haunt
      see Laura Kruser
      Karl once had a 'fro
      "The biggest surprises... ... are sometimes the ones you don't see at first. They're the kind of little things that slowly creep into your consciousness and make you wonder...
      why is it that this is so?? "

      another example - words/reality/images:
      absurd… the gap ring between creativity, faux reality and the internet

    9. Exactly correct. I was thinking about the London Tube when I gave this Challenge that title. How many other people recognized the London reference??

    10. This comment has been removed by the author.

  8. One further aspect of interest may be the environment which suggests that is a contributing factor to these types of plants/shrubs. Here's a starting point to this discussion.
    It suggests " abundance of serpentine and related rocks is responsible for its significant botanical features." Interesting read.