Kveldssanger

It's almost like Arbtalk's own COINTELPRO 'topic dilution' technique. I agree with Sean, and perhaps a few more mods would be an idea?

16/03/16. Fact #174. The use of an increment borer to obtain a core sample from a tree may be used for a variety of reasons, including tree ageing, determining past climatic conditions in which the tree has existed through, and ascertaining wood properties (generally associated with establishing internal decay). However, taking a core sample is not without its issues. For instance, around the wound site, the tree will form reaction zones in an attempt to compartmentalise the damage, and such damage may also breach existing reaction and barrier zones established from prior instances of wounding and internal spread of decay. Therefore, there is a theoretical risk of such cored trees suffering from the injury, and potentially having a reduced life expectancy / increased mortality rate because of an increased spread of internal decay. In order to test this theoretical assumption, the authors of this study commissioned a survey of unmanaged Picea abies (Norway spruce) stands in the Scatlè Forest, which lies within the Swiss Alps. In two small segments of this forested area, when the entire forest became protected under Swiss law in 1965, all of the trees were inventoried and many of the spruce (approximately 25%, amounting to 619 spruce) of over 8cm in diameter at breast height were cored. In 2011, the authors re-visited 22 of these trees, and paired them with 22 ‘control’ (un-cored) trees in similar micro-sites within the very near locale (basically, one could say they were paired with a close neighbour). At these study trees, they used sonic tomography (PiCUS Sonic) and electrical resistivity tomography (PiCUS Treetronic) to ascertain internal wood properties, and considered any trees to be decayed only if it had an evidently and extensively decayed heartwood region in both of the PiCUS tests. The tomograms below show, as an example, how the two PiCUS tests outlined trees with decay and trees without decay. The tomograms marked A and B are sonic tomograms (of the same spruce), whilst C and D are electrical resistance tomograms (of another spruce). The top two images are from a spruce considered largely free of decay, whilst the bottom two are considered to be of a spruce that is significantly decayed within the heartwood zone. Following these tests, the authors took samples from ten (five neighbouring pairs) of the trees (six with observable decay and four without observable decay, from the tomograms – the six decayed trees were not necessarily considered to be extensively decayed, however), to determine whether the two fungal heart rot pathogens Heterobasidion annosum and Armillaria sp. were present. These two fungal pathogens are viewed as significant agents of damage, within coniferous stands across Europe. These samples were taken at heights of 1m, the height of the tomograph measurements (around 45-90cm), and at the butt. In light of the data collected, it was found that only four of the 44 Norway spruce had heartwood decay, and just one of these four had been cored in 1965 (just over 9% of trees surveyed were thus deemed to be decayed). Curiously, this is lower than the accepted ‘background rate’ of decay within coniferous stands across Europe, which is considered to be between 15-80% (depending upon the study). The reason for this, it is suggested, is that because the stand is unmanaged, the damage to remaining trees associated with timber extraction has not occurred. This has therefore led to the trees not being wounded to such an extent as conifers in harvested stands would be wounded. Furthermore, because the cores were taken in 1965, it can be said that they are unlikely to have enabled for decay to extend into the region, as if they had increased the risk of decay, then more of the cored trees would have shown up as being decayed with the tomographic surveying. When recognising that Heterobasidion annosum can potentially extend in the stem by 30-40cm a year, and the cores were taken at 40-90cm up the stem in 1965, if there cores would have facilitated in heartwood decay then they would have done so already. From the ten trees cored for living samples of Heterobasidion annosum and Armillaria sp., it was found that 75% were colonised, discoloured, and in six cases observably decayed by either of the fungi. Generally, these decayed trees occupied a space in close proximity to one another, and of these trees, Heterobasidion annosum was observed to be a much more comment (seven trees) agent of decay than Armillaria sp. (one tree). The close proximity of decayed spruce to one another is perhaps not surprising, when one recognises that both fungi can colonise via active pathogenesis (root-to-root contact only, in the case of Heterobasidion annosum). Therefore, it is perhaps more likely that decay is not facilitated by increment coring, but instead root grafts between spruce trees. In addition, because Heterobasidion annosum has a life expectancy of around 40 years, after which it has a high mortality rate (per tree), it seems yet further unlikely that the cores taken in 1965 caused the decay and discolouration in the ten tested trees. It is far more likely, instead, that infection came (long) after, given that 75% of the ten tested trees had living mycelium found in the core samples taken. Not only this, but artificial core inoculation of trees with Heterobasidion annosum has a very low success rate, and therefore in this sense taking core samples is also very rarely going to induce decay by the fungus. To conclude, it can be asserted that increment coring spruce trees is not at all routinely going to induce decay by Heterobasidion annosum or Armillaria sp. Of course, other decay fungi may potentially utilise cores that are not studied here (Phaeolus schweinitzii, for example), and because the PiCUS is not as effective at discerning only slightly decayed wood, the 9% of trees deemed to have extensive heartwood decay (of which only one had been cored) may be a slightly conservative estimate. Further to this, because the sample size was only small, larger-scale studies may be needed to add weighting to the findings contained within this report. Nonetheless, it can hardly be stated that increment coring has massively adverse impacts to tree health, if the results here are anything to go by. Source: Wunder, J., Manusch, C., Queloz, V., Brang, P., Ringwald, V., & Bugmann, H. (2013) Does increment coring enhance tree decay? New insights from tomography assessments. Canadian Journal of Forest Research. 43 (8). p711-718.

If you're referring to my shots, then thank you.

Indeed. More phosphorus = less mycorrhizae (crudely-speaking).

Ask Glynn Percival. I hear he's enthusiastic! So from that quote we can ascertain that the golden stuff (not the golden stuff Gordon Brown sold) causes plasmolysis, thereby inducing water stress directly (and then compounded with indirect water stress via glazing over the soil). An interesting line of research yet to be explored it seems, and I'm sure there are plenty of dog owners out there who would be happy to help in allowing just their dogs to piddle up some lovely veteran oaks.

Brief mention here at the bottom of p3. Otherwise, finding any journal articles is proving difficult.

Hahah I love what I do and absolutely love learning more things. What's not to be enthused about!?

Indeed. I suppose they didn't consider it pertinent to the discussion, for whatever reason. I have no doubt Glynn knew about it, amd I'm sure he'll write a lot on it in the coming few years!

This was in 2014 (probably written a good few months before, maybe even in late 2013), so perhaps the threat was not as evident as it is now. The scope of this was just assessing these two, as even leaf blotch was cut out. No doubt the horse chestnut is being brutalised, and many other tree species as well. Rather depressing, to be honest.

Nice snaps there, mate!

15/03/16. Fact #173. In the UK, the introduced tree species horse chestnut (Aesculus hippocastanum) has been, over the centuries, a highly amenable tree. It has graced many important landscapes, features heavily as a mature population in many cities and their parks, and is a favourite amongst people of all ages for the conkers it drops and its stellar flowering display in spring. However, in recent times its amenity value in particular has been challenged, and namely by the various pests and pathogens obligated to the species: Cameraria ohridella (horse chestnut leaf miner), Guignardia aesculi (leaf blotch), and Pseudomonas syringae pv. aesculi (bleeding canker). Of course, such pests also impact upon the health of the tree. The repeated defoliations over successive years by the two leaf pests and pathogens, in addition to the bark lesions induced by Pseudomonas syringae pv. aesculi, will be progressively more taxing to the infected tree. Energy reserves may, therefore, eventually be entirely depleted, and the tree then ‘starves’ itself to death (if bark lesions haven’t girdled, and thus killed, the tree, by this point). At the same time, we must also remember that urban areas outside of parks may not be entirely suitable for the species (abiotic stressors), and therefore the trees may suffer as a result of human activity as well. An example of horse chestnut foliage being attacked by the leaf miner. Source: The Wild Diary. Because of this war of attrition the horse chestnut is suffering from, it is very much critical that we understand the drivers behind this evident multiple-pronged attack. In this case, we look at a study by Glynn Percival and Jonathan Banks, who investigated whether there is a relationship between Cameraria ohridella and Pseudomonas syringae pv. aesculi (Pae). Specifically, they sought to understand if the presence of the former heightened the severity of the latter, upon four year old horse chestnuts. Furthermore, they investigated whether secondary plant metabolites synthesised in response to Pae were impacted by a double-pronged attack courtesy of leaf miner. In order to ensure leaf blotch did not hamper the study, they treated all trees with a fungicide to prevent its manifestation. In terms of what they found, it was identified that a combination of leaf miner and bleeding canker increased lesion sizes of Pae by 42%. Because the size of a lesion is one of the current recognised means of ascertaining pathogenicity of Pae, this is significant, as it suggests that if a horse chestnut suffers as a result of more than one biotic stressor, its health is quite likely going to suffer far more. By a similar token, where the two biotic agents were attacking the same host tree, leaf chlorophyll content and chlorophyll fluorescence were impacted slightly more significantly than when only leaf miner was present. For chlorophyll content, hosts only host to leaf miner had a loss of 86.1% of their content, and this increased marginally to 86.3% when bleeding canker was present too. Chlorophyll fluorescence was similarly impacted, with an adverse change of 72.4% and 75.2%, respectively. Both suggest the host trees are not photosynthesising in an efficient manner, and therefore cannot produce the carbohydrates required to defend themselves against such attacks – they will likely, in time, need to draw upon their energy reserves. Conversely, when only bleeding canker was present and leaf miner presence was controlled via insecticide application, chlorophyll content decreased and chlorophyll fluorescence was adversely impacted by only 12.3% (not significant – unsurprising as Pae is not principally a leaf pathogen) and 31.7% (significant), respectively. Leaf miner is, in this case, clearly has a massive impact. Horse chestnut bleeding canker upon the main stem of an individual. Source: Beterebomen. Looking now towards the synthesis of defensive enzymes against infection, it was found that in trees where only bleeding canker was present that such enzymes were at a level significantly higher than control trees in the areas surrounding lesions. Specifically, β-1,3-glucanase, which breaks down specific parts of the cell wall within fungal cells, was observed to increase by 57.7%, whilst peroxidase, a metabolite that increases lignin production in the host tree, increased in presence by 51.6%. Conversely, when the host tree was also being attacked by leaf miner, these metabolites were found in the locality of lesion sites at far reduced levels of 15.4% and 17.7%, respectively. Therefore, it can easily be recognised that these secondary metabolites, crucial to the effectiveness of the tree’s defensive response to attack, are markedly suppressed by leaf miner, and thus the tree will be in a far worse position to defend itself. Combined with reduced photosynthetic potential, one can really begin to recognise how, in the natural world, 1+1 may not necessarily equal two but instead five (basically, the compound impacts are synergistic, instead of additive). Furthermore, as photosynthesis is important in enabling a tree to create such secondary metabolites, horse chestnuts can, if they are impacted by leaf miner and bleeding canker (and bear in mind this is excluding leaf blotch, which is also common in the UK), suffer from a negative feedback cycle by where there is a continuous decline in tree health up until a point of human intervention (a spiral of decline, if you will). Without question, it is also worth noting that this study was done on young trees grown under controlled conditions. Because young trees are usually more vigorous, if this study was to be done on old trees that were located out in the ‘real’ landscape, we could probably expect the effects to be jut as bad, if not worse. Thus, next time you see a horse chestnut that is being battered by leaf miner and bleeding canker, don’t let anybody tell you it’s largely an amenity problem – it’s not! It’s a health problem, that may very well eventually kill the tree outright, or let another pest or pathogen come in and finish the job. Combined with leaf blotch and abiotic stressors common in urban locations (pruning, ground compaction, pollution, drought, and so on), urban horse chestnuts in particular may very well be suffering very significantly. If we don’t do something, we can very well expect for horse chestnuts to gradually decline in terms of mature populations, and I very much expect this isn’t something that anybody wants. Source: Percival, G. & Banks, J. (2014) Studies of the interaction between horse chestnut leaf miner (Cameraria ohridella) and bacterial bleeding canker (Pseudomonas syringae pv. aesculi). Urban Forestry & Urban Greening. 13 (2). p403-409.

I'm going to hazard a guess that it's something to do with elemental composition of the sporophore, though I'll try and find out if I have time later on.

You're welcome! Pleased others find it equally as cool.

You should read Paul Stamets' book 'Mycelium Running'! You may very well like it. (seriously)

Cool aint it! Clearly at least somewhat decayed, to reach such a stage of visible colonisation. Quality habitat.

A really good site to see, when out walking in some woods nearby. Plenty of Trametes on the first section of stem wood, and then Daldinia concentrica extensively colonising the upper stem and crown area. Never seen so much fungi in one place! Lots of images below (over 30). Click on individual ones for larger images.

Indeed! Drop me a PM closer to the time if you want, so I know who to look out for.

Success! Perhaps get some hornbeam hedging in as well, or some Ilex? As for trees, if you have a decent-sized front garden then Ilex may serve well, as may some smaller maples (including our native field maple)?

Or, as I was told recently, £42,000 for fixing a roof. A bunch of absolute chancers 'pruned' a tree and just so 'happened' to note that a lady's roof was in an allegeded poor state of repair. Pah! OP, if it comes to it and you feel a little bad then just hand a little back, or offer to do a bit of work for free next time she asks you to do some work for her?

Aye!

12/03/16. Fact #172. Where there is human activity, there is usually noise. A particular type of human activity, which is that of vehicular travel, is a principle means of noise pollution, and wherever the highway supporting such vehicular travel may reside (in an urban, rural, or largely isolated area), there are adverse consequences to the noise pollution (for human health and ecosystem health). Therefore, it is important that we can understand what tree species are best-placed to buffer the most amount of noise, as particularly for urban locations it may influence how buffer planting schemes may be designed. Beyond the urban setting, recognising how the impacts of noise from a road will be dampened by constituent tree species is also important, as it may potentially influence exactly how such a site is managed. In the study that is the focus of this post, the authors investigated how deciduous and coniferous tree species influence noise levels at staggered distanced away from roads in the Sonbolrood forest, Iran. The forest is home to the coniferous tree species Cupressus sempervirens var. horiztalis, Juniperus spp., Taxus spp., Thuja orientalis, and the deciduous tree species Alnus spp., Fagus orientalis, and Platanus spp. For the purposes of this study, 25 plots containing predominantly coniferous species, and another 25 plots containing predominantly deciduous species, were identified, with each one measuring 20m x 50m. All plots were located adjacent to a road, and also had their total tree populations counted. At each plot location, in the adjacent roadway, a trumpet was sounded four times (with an approximate sound level of 100 decibels), and the decibel level was measured (at an elevation of 1.8m) at distances of 20m, 100m, and 300m (the latter two were to understand how noise is dampened over much greater distances) for each of the four sounds. Therefore, a total of 600 measurements were taken). In terms of what the authors found, they first recognised that the more trees present within a plot the greater the noise reduction. However, there were observed differences between the effectiveness of deciduous and coniferous stands in dampening such sound, with deciduous trees reducing sound more significantly at densities of up to 40 trees when compared to coniferous trees. However, once coniferous stands reached beyond 40 trees in the sample areas, they dampened sound more effectively than their deciduous counterparts (as shown by the two graphs below). This, the authors allege, is because the crowns of deciduous trees are generally broader and less regularly shaped, thereby meaning they dampen sound waves more readily (as they have more matter with which to buffer against the waves). Furthermore, though also applicable for some constituent coniferous species such as Thuja orientalis, the form of deciduous trees sees them adopt, in general, a lower H : D ratio (height:diameter), and such larger trunks have more mass with which to reflect or refract sound waves. Of course, because deciduous trees abscise their foliage during winter, they may potentially dampen noise less effectively than coniferous species when their foliage is absent. In this sense, a mixed stand may well be most optimal for noise buffering. Average sound reduction by coniferous trees (left) and deciduous trees (right), in relation to plot density. Interestingly, but probably unsurprisingly, there was also a near uniform decrease in the decibel level measured at all three distances away from the sound's origin, and this applies for both predominantly broadleaved and coniferous plots. Of course, for the two distances beyond the plots themselves, stand composition and density was not measured, though such a feat would have been wonderfully impressive at the 300m distance, in particular. Again, the two graphs below demonstrate this sound level reduction associated with tree density. How deciduous plots (top) and coniferous plots (below) dampened sound levels, at all three distances, away from the sound of the trumpet. In relation to the graph displaying sound level reductions in coniferous plots, it is actually interesting to note that the decibel measurements at 20m, 100m, and 300m were all relatively similar, and only when these plot stands had tree densities of over 26-29 individuals was there sufficient dampening of the trumpet's sound. With regards to broadleaved stands, the authors suggest that shade tolerant species including Fagus orientalis may, because they can persist in the lower canopy and form dense branching structures, effectively dampen sounds and thereby supplement, particularly in summer, the effectiveness of deciduous stands (or, if they exist underneath stands of conifers, those also). Drawing upon the results provided, we can begin to understand, albeit in a rather basic sense, exactly how trees can aid with noise level reductions. Admittedly, this study was undertaken in a forest, and it is almost impossible that an urban highway would be bordered by 100m+ of tree belt, but if focussing on the results from 20m it may perhaps be best to select deciduous species principally, though consider planting conifers within, at high densities. Beyond the scope of this study, but something worth considering too, is whether deciduous species that actively sprout from the base, such as Tilia spp., will aid with the dampening of sound yet further. Source: Nasiri, M., Fallah, A., & Nasiri, B. (2015) The effects of tree species on reduction of the rate of noise pollution at the edge of Hyrcanian forest roads. Environmental Engineering and Management Journal. 14 (5). p1021-1026.

Only on a Sunday! If this gets 8,703,168 likes on social media then I shall make this into a series that makes even Harry Potter look meagre. This is my reaction:

For the sake of me getting me eight hours sleep tonight, I shall run with that! Run out of my lifetime's supply of Horlicks, so I don't want to be having nightmares.

I think that's what you call a Fairy of Death. That skull in the centre is awfully disconcerting!

If fairies weren't real then yes! Hahah!