SAXATILE PLANTS AND SAXICOLE MICROBES

[Stone Rider]

SAXATILE PLANTS AND SAXICOLE MICROBES
When you read old literature dealing with rock gardening you can not get information how is a saxatile (rock dwelling plant) alpine able to get nutrients out of the rock. Duncan Lowe describes in his useful book about Cushion Plants (1995) two kinds of roots- the ´delving´ type and the ´searching´ type together with the fact that cushion forming plants generate a root system up to four times greater in extent than the growth above ground. From some (practical) reasons he did not write about the complex of happenings inside a crack; what is the real way how to get the essential food out of the rock.

  Later I read about microbial weathering sandstones of German cathedrals and about bacteria deteriorating concrete bridges in the places with humidity higher than 65%. Marble sculptures were always very sweet for bacteria, so may be for this reason all Cretan marbles (namely statues) were painted. I read about nitrate fixing bacteria in soil and bacteria producing strong organic acid to dissolve rocks and I had a wish that some scientists can do deep research in the deepness of a natural crevice to know what is really happening there including information about measuring condensation of water in an artificial crevices. I was sure about cooperation between plants and the microbes in soil and about the fact that in an artificial crevice is less of stress for helpful microflora (microbes).



Daphne petraea photo Milan Halada
Broken cliff showing root system of Daphne petraea
Daphne petraea 2photo Milan Halada
Daphne petraea in limestone cliff

[Stone Rider]

 I wrote in the “The Crevice Gardens and its Plants” (Alpine Garden Society Guide) following idea: “Water vapour in warm humid air, present in a crevice, produces moisture by condensation in the inner cooler rock surface. This kind of moisture, available in the form of a microscopic film, is probably constant in deeper crevices. Dead fine roots in a crevice are recycled by bacteria into humic acids and nitrate, which can be used by the plant. Any excess nitrate is probably used by infinitely small microbes, which need it to produce other acids to break dawn the rock surfaces. The symbiotic cooperation between the microbes and the plant creates a stable mineral environment in crevices”.

Rhodothamnus chamaecistus-1
Primula albenensis
Primula auricula photo Milan Halada
Primula grignensis Mt. Grigna Septentrionale

[Stone Rider]

  Last week I found in Internet substantial information: BBC Earth News –19 August 2009 issued article “How cacti become ´rock busters´”. This is an extract of very perfect 4 years long research in Baja California Sur. For the readers who do not have time to study all new details of the research, I copy basic information of BBC: “We were working in the desert when we observed that many individual cacti grew in sheer rock. They looked good and green at the habitats where usually plants do not grow. The enigma is that plants need minerals and nitrogen to survive. But neither are available in rock, which binds in minerals and contains no accessible nitrogen. The only explanation we could think of is involvement of microorganisms assisting the plant to grow, fixing nitrogen and dissolving mineral. We looked for them and found them.”
 Dr Yoav Bashan and US-based colleagues Dr Esther Puente and Dr Ching Li have discovered that cardon cactus Pachycereus pringlei (good individual can be 15 m tall with a weight 25 tons) growing in the volcanic region of the Baja California Sur mountain range harbour bacteria, that are capable of dissolving rock. These bacteria are not only live on the surface of the plant’s roots but also within cells that make up the root itself, the scientists report in the journal Environmental and Experimental Botany. Further tests revealed the endophytic bacteria also grow on the cactus fruit and from there are transferred into seeds and that these bacteria can weather rock, dissolving particles into smaller sizes.
  We believe that we have found new symbiosis between bacteria and plants; the cactus is a carbon provider for the bacteria and the bacteria indirectly provide the minerals and nitrogen for the plants. The bacteria and plant work in concert. The bacteria dissolve the rock, allowing the cactus seed to take purchase. The roots than drill into the weathered rock fracturing it further. Further tests revealed that without bacteria cacti couldn’t survive.
All the details including photos from a special microscope are available in two papers published at www.bashanfoundation.org . The title of the original paper is “Microbial Populations and Activities in the Rhizoplane of Rock-Weathering Desert plants”

Mt. Heart, Wyoming _0992
KELSEYA AT HEART
KELSEYA UNIFLORA IN FULL SUN
KELSEYA UNIFLORA Mt. Heart

[Stone Rider]

LITHOSOL ZONE IN SAGEBRUSH COUNTRY

 I know American deserts from hot car and mountain semi deserts from close observation of decorative plants during half of dozen expeditions. Plants from semi deserts grow in thin substrate called lithosol. Lithosol literally means rock-soil. Most soils develop in areas underlain by basalt, a dark volcanic rock. Soil deposition is insignificant. Yet, because of the undesirable environmental conditions, rather than in spite of them, the lithosol provide some of the most spectacular arrays of spring flowers to be found in the sagebrush steppe. Most lithosol species grow close to the ground and resemble the cushion plants of the arctic and alpine tundra.  I have now no doubt that what was happening in the basalts of Mexico is everywhere here with plants living in the lithosol zone. Rock dissolving microbes are here in the rhizosphere of Eriogonum, Phlox and Penstemon, making life of the plants possible, only having some different Latin names of bacterium or fungi.
  In some places of my garden I use just mineral soil (the product of dissolved dolerite stone) and all Eriogonums (and their endophytic bacteria) like it. The fact, that rock dissolving bacteria do not survive in competition of the colonies of richer soil specific bacteria is seen here, where I lost some E. caespitosum in the richer garden soil.
Here is explanation why the old growing technique of Dionysias in practically sterile mineral substrates is in good function in the same way as growing plants in holes of tufa stones (planting in silver sand or tufa fine grit).


PETROPHYTUM WYOMING-1
SHOSHONEA PULVINATA
Pellaea glabella
Eriogonum soredium, Frisco
Juniperus osteosperma, Utah-2
Penstemon sp. Sheldon Refuge-1
Pinus longaeva, cones-2
Pinus longaeva, White Mts.-1
Sheldon Refugio, Nevada 7266

[Stone Rider]

So, from the reasons written above is quite perfect method to grow plants from lithosol zones (Golden West, Balcan Peninsula and Turkey) in the relatively sterile sand beds covered with a crevice rockwork and with no soil which can content bad fungi and hostile bacteria. We help our plants to develop strong colonies of symbiotic bacterias in their rhizosphere if we keep the right type of hygiene.



see also:
http://www.srgc.org.uk/smf/index.php?topic=4656.0



Dionysia zschummelii, G. Tjeerdsma
Eritrichium nanum photo Jirka Novák

[Lesley Cox]

What an incredibly interesting subject this is, and what useful information, especially to one just about to start filling and planting some new troughs, with built up crevices. I don't fully understand all you have written Zdenek, but will re-read it all several times and hope to absorb more. Thanks for starting this thread and I hope many more Forumists with geological minds will contribute.

As always, the photographs are wonderful and I am sure now that I'll plant one of my two Daphne petraea plants in the crevices. Many thanks.

[maggiepie]

I agree with Lesley, this is such an interesting thread with wonderful photos.

[cohan]

i agree, very interesting, and very useful information (not to mention the photos, which i think, may prompt at least one change in my alplains order!)..
now, to find the right materials at the right price to implement some of those ideas...

thanks for this, zz

[Luc Gilgemyn]

Fascinating stuff ZZ !!!
Very interesting indeed !
Another 5 star thread that deserves a sticky, Maggi ! 

[jomowi]

Don't forget that many plants themselves should be able to extract nutrients from rock.  There are a variety of compounds secreted by roots.  Some of these help to maintain the rhyzosphere microbes.  Others with varying degrees of success will be able to  mobilise minerals.  For example a common plant acid, citric acid, is quite good at mobilising iron, similarly metal ions such as calcium attached to acetate (again which can be of plant origin) will usually penetrate membranes quite easily as an uncharged complex thereby entering the plant.  I doubt if the microbial population alone is responsible for keeping plants supplied with nutrients, in rock or indeed any other situation.  Likewise both parties help in preventing the toxic effects of excess (or out of balance) minerals released when the rock is solublised.

Brian Wilson
Aberdeen

[krisderaeymaeker]

I like  this subject ,always be fascinated by cracks and crevices ...
Thanks to Zdenek for his explanation .
Just few other examples ,this is Cyclamen persicum in Cyprus.

[ian mcenery]

ZZ Fascinating subject.

It is true that one should try to learn something new every day. What clever things plants really are !!!

[maggiepie]

(not to mention the photos, which i think, may prompt at least one change in my alplains order!)..
thanks for this, zz

Cohan, which ones are you thinking of ordering?

[Lesley Cox]

Those are very telling photographs Kris. I doubt if the wind carried cyclamen seeds to such a place. Surely they were carried there by ants or other insects.

We don't think of bulbs much, as crevice plants but there must be many in various situations, which makes me consider what I have among my own bulbs that may be happy in a crevice garden or trough.

[cohan]

(not to mention the photos, which i think, may prompt at least one change in my alplains order!)..
thanks for this, zz

Cohan, which ones are you thinking of ordering?

oh, a whole bunch of things...lol--i still need to reduce the number further, though i have been working on it a while... eriogonum, some little odd things in apiaceae, scrophulariaceae, portulacaceae, asteraceae, cacti, etc etc.
the one that was potentially affected by this thread was Petrophyton, which i hadnt seen a really good image of before; i'm just not sure yet, since i dont know if i will get a suitable spot built yet this year..

kris--those cyclamens are as wonderful as the place they are growing!