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| Squamulea subsoluta |
Lichens are well known for their bright colors, fungus-autotroph symbiosis, and ecosystemic value.
Despite their importance, information on "natural" lichen cultivation appears quite sparse. In laboratory dishes, lichen fungi often behave abnormally by failing to capture algae and forming fluffy networks resembling bread mold instead; resynthesis of behaviorally normal specimens has proven difficult. On the other hand, many websites intended for a general audience give poor advice ("lichens cannot last long in harsh sunlight" is easily refuted by the xerophytic yellow Squamulea on my old diving board!), and I have never seen anyone blog about their lichen gardens.
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| Candelaria pacifica(?) |
The "heat islands" hypothesis
Although many species are well known as microhabitat specialists which quickly vanish from even slightly polluted areas, synanthropic lichens do exist. These are naturally more well suited to being captive specimens, since synanthropes are usually adaptable and highly generalistic. I was quite pleased to accidentally encounter the following research paper while half-heartedly foraging in a bibliography:
A simple outdoor culturing system for the foliose macrolichens Xanthoria parietina (L.) Th. Fr. and Parmelia sulcata Taylor
This strongly suggested that most synanthropic lichens could be easily grown as long as they did not succumb to brick poisoning or overwatering-induced rot. Unfortunately, I soon realized that synanthropic lichens seemed not very abundant here in southern California despite many non-poisonous surfaces being available. I became even more confused after a recent trip to the European rainforest, since their cities were covered in thick yellow and minty green coats of assorted species sitting happily next to small cigarette heaps.
My suspicions about CA semidesert aridity being responsible were somewhat confirmed by an old lichenological bulletin I found after further fruitless searches; most notably, it stated that several microhabitat specialists here grow like weeds in soggy New Zealand!
CALS Bulletin, Summer 2003 (see first article, "urban lichens" section)
Naturally, this suggests a hypothesis: can improving hydration to local synanthropic lichens increase their abundance and biodiversity? I have started watering the pathetic dot and flake colonies in my yard [Update: I am no longer watering them], being careful to:
water only when shade appears, because they lower their defenses during photosynthesis
keep watered specimens wet for extended periods of time, because rapidly going in and out of dormancy harms photosynthetic efficiency
not keep them permanently wet, because dry periods are still important for many species (it facilitates normal morphological development and presumably discourages rot)
So far things have not been going well for them, because I get too excited whenever a cloud covers the sun; often it passes by quickly and I end up inducing fungal sunburn. The captive and wild local vertebrates are also occasionally contaminating most of the clusters with fecal dusts, which may prove useful as fertilizer but are very hazardous (they should dissipate quickly enough for me to not stop visiting the clusters, but I do not dare to bring any specimens indoors).
On a more pleasant note, today I have found more support for my hypothesis.
Collema experiences a massive growth boost when under unnaturally frequent hydration, although it is still slow:
Rapid ex situ culture of N-fixing soil lichens and biocrusts is enhanced by complementarity
Although many species are well known as microhabitat specialists which quickly vanish from even slightly polluted areas, synanthropic lichens do exist. These are naturally more well suited to being captive specimens, since synanthropes are usually adaptable and highly generalistic. I was quite pleased to accidentally encounter the following research paper while half-heartedly foraging in a bibliography:
A simple outdoor culturing system for the foliose macrolichens Xanthoria parietina (L.) Th. Fr. and Parmelia sulcata Taylor
This strongly suggested that most synanthropic lichens could be easily grown as long as they did not succumb to brick poisoning or overwatering-induced rot. Unfortunately, I soon realized that synanthropic lichens seemed not very abundant here in southern California despite many non-poisonous surfaces being available. I became even more confused after a recent trip to the European rainforest, since their cities were covered in thick yellow and minty green coats of assorted species sitting happily next to small cigarette heaps.
My suspicions about CA semidesert aridity being responsible were somewhat confirmed by an old lichenological bulletin I found after further fruitless searches; most notably, it stated that several microhabitat specialists here grow like weeds in soggy New Zealand!
CALS Bulletin, Summer 2003 (see first article, "urban lichens" section)
Naturally, this suggests a hypothesis: can improving hydration to local synanthropic lichens increase their abundance and biodiversity? I have started watering the pathetic dot and flake colonies in my yard [Update: I am no longer watering them], being careful to:
water only when shade appears, because they lower their defenses during photosynthesis
keep watered specimens wet for extended periods of time, because rapidly going in and out of dormancy harms photosynthetic efficiency
not keep them permanently wet, because dry periods are still important for many species (it facilitates normal morphological development and presumably discourages rot)
So far things have not been going well for them, because I get too excited whenever a cloud covers the sun; often it passes by quickly and I end up inducing fungal sunburn. The captive and wild local vertebrates are also occasionally contaminating most of the clusters with fecal dusts, which may prove useful as fertilizer but are very hazardous (they should dissipate quickly enough for me to not stop visiting the clusters, but I do not dare to bring any specimens indoors).
On a more pleasant note, today I have found more support for my hypothesis.
Collema experiences a massive growth boost when under unnaturally frequent hydration, although it is still slow:
Rapid ex situ culture of N-fixing soil lichens and biocrusts is enhanced by complementarity
in Mediterranean climates (like southern CA), lack of hydration caused by city-induced temperature increase can indeed be a population growth limiter more important than pollution:
