For my last post of 2015, I leave you with these two images from a horse chestnut in Hampstead Heath that, most probably due to a land slide, has had half of its root system exposed. Without doubt one of the coolest things I have seen in recent times.
Month: December 2015
The intrigue of old trees
Stopping off for a quick break during work today, I parked under an oak that has always been of interest to me. Situated in the main car park for a large amenity park, not only is its mere existence intriguing (in many instances, such trees would likely have been removed), but its appearance sparks the imagination – amongst other qustions, what has this tree endured, and what ecological benefits does it provide?
As a matter of fact, this little critter could be seen fruiting within the tree itself during the summer.
Daedalea quercina upon a large oak log
Farmers may likely resort to placing large pieces of timber at the boundary of their land, in an attempt to stop vehicles driving onto their property and using it for either a temporary home (as travellers may do), or otherwise. Not only is such a tactic incredibly effective at halting vehicular trespass, but also more ecologically beneficial than constructing, for instance, a man-made fence.
On this oak log, we can see that Daedalea quercina (oak mazegill) has colonised and subsequently produced a sporophore. I first noticed this earlier in the year during an ‘inactive’ phase, though recently it has sprung into life again. I therefore took the opportunity to take some photos and a small sample, of which the results are below.
The oak mazegill, according to Mattheck et al. (2015), can be both parasitic and saprophytic, though I have only ever seen it act saprophytically. It induces a brown rot of the heartwood by preferentially degrading the cellulose, and is principally found on oak (though sweet chestnut may also be a host).
Japanese “it must be a kanzan” Cherries
Tounge-in-cheek title aside (we all know the columnar ones are Ama-no-gawa!), 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 sourced 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 exactly 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, make up 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.
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When we think of deadwood we often just think of standing deadwood, dead branches within living crowns, and debris on the woodland floor (be it entire fallen trees or fallen limbs and branches). However, many other forms of deadwood exist, of which submerged deadwood is one (and such deadwood has a significant ecological role). Many species of fish, freshwater invertebrates, and even bryophytes, will benefit from the presence of deadwood.
So next time you see a fallen tree within a pond, lake, stream, or river, consider the implications associated not only with the retention of the deadwood, but also the removal. Can some deadwood remain, if retaining it all is not feasible? Will site visitors (if there are any) be put at risk if deadwood is left? Can niche habitats be encouraged by retaining the deadwood? How will the deadwood impact upon the flow of water? All justified questions (of which there are many more to be asked not listed here), all of which will factor into the final decision.
Another visit to Pseudoinonotus dryadeus
You probably think I’m head-over-heels about this fungus, considering this is the third time I’m writing about Pseudoinonotus dryadeus in four days. To be honest, you’re not wrong! But who doesn’t get awestruck by wood-decay fungi?
I had the opportunity to re-visit a very large oak that – earlier in the year – I had noticed was colonised by this fungus. The below pictures were taken during August 2015 and early in the morning (around 9AM). Perhaps (in reference to the time of day) this is why the bracket was guttating, though I admit that my knowledge on guttation of fungi is severely limited (though this short article explains it quite nicely).
Today, during the afternoon, I took the below photos. Unlike the previous two posts on Pseudoinonotus dryadeus, this bracket was still very reminiscent of its former self, with very little algal growth atop and in a very early state of decomposition. I suspect the surroundings to the host oak will have played a role in this.
I think it’s always good to look at and learn to identify wood-decay fungi brackets in their ‘active’ form, as well as their decaying form. After all, if we come across a tree in winter and notice brackets around its base, an accurate diagnosis (or even just a provisional diagnosis) may be very important if access to the tree is limited, or if its condition is in serious question.
That’s all I have for Pseudoinonotus dryadeus at the moment – I promise. Now take a sigh of relief, have a drink, and enjoy the upcoming new year (and / or my blog posts before then)!
The wonder of veteran oaks
The appearance of a gnarled, twisting crown of a veteran oak is perhaps unrivaled. A romantic site, such old oaks have an almsot evocative presence for man. Thoughts of the sites the tree has seen (including the clearance of those around it!), weather events endured, and the stories it could tell if it could speak.
Existing before my lifetime and very likely still existing after, old trees are vanguards of history.
This oak I find particularly alluring. Its growth form is incredible, and its sheer presence was enough to make me force my girlfriend to stand by it to compare its size to that of a 5’7″ human being!
No doubt plenty more like this exist within the landscape, and this woodland alone had plenty of fantastic trees to offer. One huge Cedrus libani by the visitor centre almost stood as a sentinel, forever gazing over the thousands who grace its presence each year. This oak certainly has fewer visitors, given it is off of the beaten path, though that doesn’t make it any less special – perhaps even more so.
Saproxylic insects and ancient trees in wood pastures
The old wood 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).
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.
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Some recent book scores
Here are some books I have purchased recently. All but the Mycorrhizal Networks one were recommendations. I am currently reading through Mycelium Running and it’s a very well written book – I shall be sure to review it once I have finished reading it. It can be found online rather cheap, though I have linked to the author’s site below if you’d rather support the actual author.
Yet more Pseudoinonotus dryadeus on oak
So over the bank holiday weekend I shared some images of Pseudoinonotus dryadeus on an oak that stood at a woodland edge next to a golf course. Said oak exhibited all the classic signs of decay from this fungal species (significant root buttressing, in particular). Today, I was lucky to spot another example, complete with a developing hollow. Another Eiffel Tower in the making.