(Arboricultural-styled) 'Fact of the Day'

[Kveldssanger]

Read the whole journal article. Learned a lot on that one. I posted this over on my blog as well, and back referenced to a few bits and bobs.

[daltontrees]

Read the whole journal article. Learned a lot on that one. I posted this over on my blog as well, and back referenced to a few bits and bobs.

 

Perhaps Stamets read it too and jumped to an unscientific conclusion that you took as fact.

 

Nunc melius cognoscere causas

[Kveldssanger]

Perhaps (though I am not referring to the S. crispa article as I am yet to read that). Until I reach a state of omniscience, I shall be just as human as the rest of us.

[Kveldssanger]

OK, I am reading through this Sparassis crispa article and have the following observations to make (chronologically):

 

 

- In the abstract, the authors write: "Both compounds [scI and ScII] were found in the decayed wood of trees, where their presence was diagnostic of S. crispa infection." This suggests that, if we take what the authors say literally, S. crispa has caused these antifungal compounds to be present within the decayed wood.

 

 

- In 1923, sparassol (methyl-2-hydroxy-4-methoxy-6-methylbenzoate) was identified by Falck as an antifungal compound that suppressed the growth of competing fungi, enabling Sparassis crispa to grow without other fungi 'contaminating' its 'territory'. This was ascertained in vitro.

 

 

- When Sparassis crispa was grown in vitro with other fungi, the following observations could be made: "Growth of H. annosum was almost completely suppressed, and that of Inonotus dryadeus and Rigidoporus ulmarius markedly inhibited. Mutual growth inhibition was evident with Armillaria gallica, A. mellea, A . ostoyae and Stereurn sanguinolentum. With A. tabescens, Coriolus versicolor, Hyphlophoma fasciculare, Phaeolus schweinitzii and Rhizina undulata, no gross inhibition was observed prior to contact, although P. schweinitzii exhibited a strong incompatibility response along the interaction interface." From this, we can allege that, in relation to Armillaria spp., the study suggests they both suppress one-another.

 

 

- The compunds ScI and ScII persist at a ratio of between 3.8-4.1 in cultures of Sparassis crispa, and over a period of 8 weeks they were observed to markedly increase in abundance. From this, we can posit that Sparassis crispa will synthesise these compounds as it grows at relatively steady rates.

 

 

- The authors list sparassol, ScI, and ScII, as "orsellinic acid derivatives". This suggests that they are borne from (definitions include: "originating from"; and synonyms include: "imitative, unoriginal, copied") orsellinic acid. Their chemical properties must therefore be at least predominantly similar. Therefore, relating back to Stamets' words (which we all agree that 'parasitises' is the wrong choice of word) and Jules' comments, Jules is indeed correct in asserting that sparassol is not identical to orsellinic acid.

 

 

- "It is likely that a major part of the antifungal activity that Falck (1923) observed [which he penned was down to sparassol] preventing the contamination of old cultures was attributable to ScI and ScII, rather than to sparassol." We can deduce from this that scientific advancements have lead to older work becoming slightly obsolete, though still relevant from contextual purposes.

 

 

- The authors confirm that orsellinic acid is produced by Armillaria spp.

 

 

- More proof is required before it can be stated with absolute confidence that Sparassis crispa suppresses the growth of fungi such as H. annosum via the synthesising of ScI and ScII: "the data available are insufficient for proof."

 

 

- The authors conclude by saying: "The present study has demonstrated that ScI and ScII occur naturally in wood decayed by S. crispa, at concentrations sufficient to impair the growth of other fungi. It seems possible, therefore, that these compounds may contribute to the suppression of potential competitors, hence allowing S. crispa to persist for an extended period."

 

...and: "Detection by HPLC of ScI and ScIl in extracts of conifer wood (which in some cases had been exposed to environmental weathering) decayed by S. crispa but not in wood decayed by other brown rot fungi, notably P. schweinitzii" was found. These conclusions are self-explanatory, though I cannot identify where Jules has read that ScI and ScII are present in wood inherently.

 

Therefore, Jules' comment: "What I thought most interesting of all is that ScI and ScII are present naturally in woods, poresumably as antifungal defences, but that S. crispa can tolerate these better than its competitors can, giving it almost exclusive access to colonised (but still living) woody hosts" is without reference. ScI and ScII are not present in wood naturally, if we are to go by this article (and what I interpreted their words as). They are present only in wood decayed by Sparassis crispa.

 

 

- Jules' comment: "Rather than being parasitism it is out-competition" is something I agree with, though we're arguing with symantecs here. I completely agree that Stamets used the wrong word when he chose to say S. crispa parasitises Armillaria.

[daltontrees]

...and: "Detection by HPLC of ScI and ScIl in extracts of conifer wood (which in some cases had been exposed to environmental weathering) decayed by S. crispa but not in wood decayed by other brown rot fungi, notably P. schweinitzii" was found. These conclusions are self-explanatory, though I cannot identify where Jules has read that ScI and ScII are present in wood inherently.

 

Therefore, Jules' comment: "What I thought most interesting of all is that ScI and ScII are present naturally in woods, poresumably as antifungal defences, but that S. crispa can tolerate these better than its competitors can, giving it almost exclusive access to colonised (but still living) woody hosts" is without reference. ScI and ScII are not present in wood naturally, if we are to go by this article (and what I interpreted their words as). They are present only in wood decayed by Sparassis crispa.

 

Not entirely without reference, and I am relieved to see that I didn't make it up, although I my be interpreting 'occur naturally' wrongly as meaning something different from 'are present'. Viz. -

 

"The present study has demonstrated that ScI and ScII occur naturally in wood decayed by S. crispa, at concentrations sufficient to impair the growth of other fungi. It seems possible, therefore, that these compounds may contribute to the suppression of potential competitors, hence allowing S. crispa to persist for an extended period."

 

Looking again at the article 'Methods' I can't see that a control analysis of undecayed wood was undertaken, and the article doesn't therefore settle the matter of whether ScI/II occurs naturally in undecayed wood. I think it is reasonably settled that trees produce antifungal substances preventatively and/or reactively, but we can't say (at least, based on this article) whether Sc is one of them.

Edited December 29, 2015 by daltontrees

[Kveldssanger]

I can accept that.

[Kveldssanger]

29/12/15. Fact #111.

 

The old pastures of the UK that were once (or still are) grazed by livestock are home to many of our ancient trees. These ancient trees may be particularly crucial for saproxylic (deadwood) insects, which rely upon their host trees having adequate space to reach their maximum sizes. Because pastures were (or are) routinely grazed, regeneration from seed was (or is) very limited – this has lead to many ancient trees within such pastures being exposed, and having very full crowns (very much the opposite to what we see in closed canopy situations). As saproxylic species require expanses of heartwood and large lateral limbs that have died yet remain attached to the trunk, the conditions generated by grazing are ideal – trees become very broad in girth (to support the heavy crowns) and form wide crowns with large lateral limbs (to maximise photosynthetic capability).

 

Many saproxylic insects also require significant amounts of light, with particular species of longhorn beetle needing large fallen branches to be exposed to plenty of light in order for there to be a viable habitat. Of course, the exact light conditions required will vary between species of insect (some moths will very much pursue shaded hosts), though the incubation effect of the wood from sun-exposed trees (the wood will be warmer) will usually mean that breeding is more frequent and mortality rates of larvae are lower. However, the exact required balance of sun-exposure and shade is not currently known.

 

The benefits of grazing to saproxylic insects do not end just with the tree, however. Because many saproxylic insects require nectar as a food source, there is a necessary access to tall and white flowering herbaceous species such as hogweed. Whilst such plant species are found in pastures, they would not be found under closed canopy conditions. Other flowering plant species, which are usually to be considered trees (namely hawthorn and elder), also act as a critical nectar source. Again, these species are infrequently found within woodlands, and if they are then it would commonly be at a woodland edge or clearing (hawthorn will not flower under dense shade).

 

Sources:

 

Alexander, K. (2013) Ancient trees, grazing landscapes and the conservation of deadwood and wood decay invertebrates. In Rotherham, I. (ed.) Trees, Forested Landscapes and Grazing Animals – A European Perspective on Woodlands and Grazed Treescapes. UK: Earthscan.

 

Siitonen, J. & Ranius, T. (2015) The Importance of Veteran Trees for Saproxylic Insects. In Kirby, K. & Watkins, C. (eds.) Europe's Changing Woods and Forests - From Wildwood to Managed Landscapes. UK: CABI.

[Kveldssanger]

30/12/15. Fact #112.

 

There's a rich history to the Japanese cherries. In fact, there are books exclusively focussed on them, and one of them is the source for this day's post.

 

Ultimately, Japanese cherries can be found within the forests of their homeland, as well as in cultivation (where many hundreds of cultivars exist). Talking specifically about the cultivated cherries, some may be only one individual strong - the author here alleges that such cultivars hardly deserve to be called as such. Others, such as Prunus x subhirtella, are well-known and abundant, and have a clear standing within the classification system.

 

Perhaps confusion over exact which Japanese cherries are which is because the 'classification system' is not really one. As many cultivars now used were historically found only in gardens within Japan, and known as sato-zakura (meaning "village-cherries"), there is no 'formal' means of classification for these cultivars. This problem is exacerbated by the fact that documentation of Japanese cherries in the English language is not abundant (or at least wasn't at the time this book was written). Two common forms of sato-zakura are, of course, 'Kanzan' and 'Ama-no-gawa'.

 

So what are the parents of all these cultivars? Simple... (sort of)! The author does a good job here, if I am honest, and suggests that the three forms of Prunus serrulata (var. spontanea, var. speciosa, and var. pubescens), as well as Prunus apetala, and Prunus pseudo-cerasus, are suggested as the main parental range. The situation really isn't aided, however, by the fact that the sato-zakura 'system' lacks any discernible breeding history. Despite this, it is considered that most semi-double flowered forms have Prunus serrulata var. speciosa as a parent.

 

The Flower Association of Japan, in 1982, did manage to collate the hundreds of cultivars into one publication, and ended up describing roughly 200 cultivars. A book entitled Nihon no Sakura, soon after (in 1993) and authored by T. Kawasaki, attempted to classify around 350 different cultivars into family 'trees', and to this day has only been published in Japanese. However, these publications did not seek to remedy the endless abyss of confusion regarding identification in the West.

 

This post has probably cleared up none of the confusion, and probably instead added to the anxiety we all experience when looking at a Japanese cherry cultivar. I guess that's all part of the fun...

 

Source: Kuitert, W. & Peterse, A. (1999) Japanese Flowering Cherries. Hong Kong: Timber Press.

Edited December 30, 2015 by Kveldssanger

[Steve Bullman]

Views are mounting up mate

[Kveldssanger]

Aye! It's good. I really enjoy exploring all my books and sources I find online, and there are some good discussions following some more 'sciency' facts. Jules' comments with the Sparassis crispa one were much appreciated, for example. Always good to learn new things, and I try to keep it enjoyable for readers.

 

I always maintain, if anyone has any cool stuff to share here too, they can!