Kveldssanger

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Aye, doing the lvl 4

Half way through pretty much, and doing it with Treelife. Until this week, work was easily manageble (doing after work) as there was at least a three week window. This time, there's a two week window, and I am having to rush it a little. Darren Blunt is my tutor.

I am not doing it, but I was told by someone that it was 'easier' than the Lvl 4 as you had more time to do it. If that means anything...

09/02/16. Fact #148. As the climate changes, the phenology of constituent tree species will also change. For example, bud burst may be earlier or later, as may fruit production, leaf fall, and so on. Therefore, in Japan, where spring is marked by the blossoming of the cherry trees, phenological changes may have a marked impact upon how festivals associated with the spring blossom are organised. Thus, the purpose of this study was to determine whether residents of Japan recognise the association between the changing climate and the timing of cherry blossom, with particular focus on those involved with arranging the blossom festivals and those businesses who benefit from them. Three sites were the focus of this study – two in rural areas (Kakunodate and Komoro), and one in an urban location (Nakano-ku). Collectively, the tree sites attract an estimated 1,500,000 visitors per year, during April and May (1,000,000 of which go to Kakunodate). The authors held personal interviews with the organisers of these three festivals (including staff and local government employees), and the managers of businesses who greatly benefit from the festivals taking place (food shops, in particular). During the interviews, questions were asked such as how the individual viewed climate change, what they considered to be impacting upon the changing climate, and how they felt the changing climate would affect the blossom festivals. In total, 28 questions were asked to each organiser and the average time taken to complete the interview was 40 minutes, whilst 12 questions were asked to bussiness owners and the average time taken was 10 minutes. The blossom festival in Kakunodate attracts around 1,000,000 visitors during April and May, every year. Here we can see a fantastic cherry-lined river. Just beneath the trees we can see a walkway full with visitors. Source: Japan Times. Of the organisers interviewed, 92% of them said they felt climate change (global warming) was indeed occurring – the rest were unsure. In relation to festival-specific impacts, how organisers felt about a festival potentially missing the blossoming period (due to climate change) was highly varied (see below images), with organisers at Kakunodate being very concerned, and organisers at the other two locations not being overly concerned (if at all). The argument made the the organisers of the latter two was that people would still turn up to the festivals, perhaps because it’s a cultural thing that may exist independently from the blossoming itself. However, many managers of bussinesses were concerned over the festival’s timing. Those concerned stated that people may not frequent their shops if the festival missed the blossoming period. Despite this, some managers were relaxed about the issue, and felt they would not lose out on custom. A few of the concerned organisers as Kakunodate, in response to the potentially changing blossoming period, said they would absolutely change the festival date to fit with the time of the blossom – this is not surprising. However, most of the organisers of all three festival sites stated they would only consider changing the festival time to fit with the blossom. The organisers of the two sites that were less worried about the festival timing not coinciding with the time of blossoming more notably held this attitude, though these two sites did have far fewer organisers involved (as they are smaller events). The responses by the individuals questioned to: ‘‘What if the festival missed the blossoms?” ‘‘How can you and the festival / store cope with the change in flower timing?” was the question asked in this instance. With regards to shop managers, many were not prepared to change as a result of the changing phenology of cherry trees. Businesses would operate as usual. However, as most managers interviewed were based at Kakunodate, this result may be somewhat skewed. Certain managers were prepared to plant cherry trees that blossom later, however – this would ensure that any change in phenology of the cherry trees did not fully divorce the festival from the blossoming period. In terms of what individuals thought they could do to reduce their impact upon the changing climate, most suggested they could not use their cars so much, reduce on the amount of waste they produce, and so on. However, two individuals stated that they felt they were impotent, and there was a limit to what an individual can do. From this study, we can see that the response individual stakeholders have to how climate change will impact upon blossoming times varies. In Kakunodate, where the festival is huge (attracting 1,000,000 visitors each year), organisers and shop managers were clearly more worried about the festival missing the blossoming period, when compared to the other two areas. This really is not something that is all too surprising, as the potential economic loss will be much greater (and for a rural economy, where other means of income may be less abundant). Furthermore, the fact that individuals also stated that they recognised climate change was occurring because of the changing blossom times, means that a culturally-important event such as this can be used to educate Japanese residents about how climate change can impact upon the ecological world. A group of blossoming cherries in Nakano, Tokyo. This festival attracts around 250,000 visitors per year. Source: Weepingredorger. Certainly, it would be interesting to see larger-scale studies undertaken across Japan, with focus also on those who visit the festivals. There is a huge risk of organisers and businesses owners being markedly biased in their response, with their concerns over the economic impact climate change may have upon their ability to operate at a profit clouding wider judgement and heavily influencing opinion. In addition, the study is automatically narrowed a great extent by removing a huge potential pool of data (visitors to the festivals), so the results should not necessarily be treated as highly indicative of the thoughts of the wider Japanese demographic (though the authors do recognise this). Even so, an interesting study that certainly makes you think, and is a wonderful foundation to build from in terms of research. It’s great to see such a topic being studied. Source: Sakurai, R., Jacobson, S.K., Kobori, H., Primack, R., Oka, K., Komatsu, N., & Machida, R. (2011) Culture and climate change: Japanese cherry blossom festivals and stakeholders’ knowledge and attitudes about global climate change. Biological Conservation. 144 (1). p654-658.

Please, someone do this!

Loads of images: Ganoderma at the base. Loads of white rot throughout the stem. Crack opened up the whole tree in the end!

Felled that afternoon! Photos to follow...

The below post is something I am sharing from an assignment I wrote recently. It is long, though I hope it is of use to some of you. All sources are at the end, and I strongly suggest the books I have referenced you buy – they’re all absolutely fantastic books. Particular kudos goes to Dujesiefken & Liese’s ‘The CODIT Principle’, which is hands-down brilliant. 08/02/16. Fact #147. The compartmentalisation process can be split into four sections, under the banner of two governing parts. The four stages are: (1) wounding, (2) response of the tree to compartmentalise the injury and possible infection, (3) the succession of micro-organisms that seek to actively or passively combat the tree’s natural defence mechanisms, and (4) development of subsequent wood discolouration and decay. The two governing parts are: (1) events that occur within the wood at the time of wounding, and (2) events that occur afterwards (Shigo, 1991). However, there are many aspects that we likely yet do not properly understand, or even understand at all. It is also necessary to recognise that, by default, trees are hugely compartmented (Karban, 2015; Shigo, 1986). Wood is split up by growth rings and radial rays into small sections, single cells are internally compartmented into many different functional units and are themselves segmented into groups by radial and terminal parenchyma, and branches are not conductively attached to the trunk tissue from above. Certain species will also form heartwood, which further compartmentalises the tree. Compartmentalisation is nothing new to a tree, therefore. There is nonetheless a difference – natural growth form leads to high levels of ‘compartmentation’, whilst ‘compartmentalisation’ is a concept that relates to resisting decay exclusively (Shigo, 1986). The overall concept of phenotypic response to infection is determined by not only genetics (Santamour, 1979; Santamour, 1984a; Santamour, 1984b; Shigo, 1986; Shigo, 1991), though also energy levels (Shigo, 1986; Shigo, 1991; Wargo, 1972; Wargo, 1976; Wargo, 1977). Where energy reserves are high, the compartmentalisation of decay will be more effective than if energy levels are low. When a tree that has poor energy reserves is infected, the pathogen will thus have an easier means of establishment internally, further reducing already-depleted reserves. Therefore, CODIT mechanisms, whilst dictated by genetic qualities primarily, are heavily influenced by the energy available to the tree. Without needed energy reserves, not even a mighty oak may be able to compartmentalise effectively. It should also be noted that phenology plays a role in successful defence (Shigo, 1991). All trees have their weak points, and therefore at times the response to wounding will inherently be less favourable, given the traits of the tree. Such a weakness may be exacerbated if the period of acute weakness aligns with the period of maximum strength of the infecting pathogen. In essence, compartmentalisation is a truly dynamic process. Reaction zones are constantly shifting in response to pathogenic activity (sometimes on multiple fronts from multiple wounds). This favours everything involved within the process, as a state of immobility in nature means death. Despite this, the tree always has the upper hand, as the pathogen that wins the battle to begin infecting its host may (1) not be the pathogen that is best-suited to attack the specific host tree, and / or (2) the pathogen does not know what it can expect in terms of resistance by the tree – the tree’s defence system responds to pathogen presence, in a sort of unexpected counter-attacking measure that the pathogen cannot (accurately) anticipate (Shigo, 1986). With all this in mind, we can now explore the effectiveness of the physiological responses a tree will go through following wounding. Physiological changes As previously ascertained, the CODIT model is segmented into the reaction zone (walls I-III), and the barrier zone (wall IV). Whilst all four walls resist the spread of dysfunction, they are not all as effective as one another. In fact, the relative strength of each wall increases from I through to IV. Wall I, which resists vertical spread of dysfunction from the wound site, is not a biological feature. It is nonetheless under strong genetic control. It provides the weakest of all the wall defences, but this makes the most sense when one recognises that a tree requires vascular connectivity and function for all of its life processes – if too many vascular elements are plugged, other problems may arise (Shigo et al., 1977). Additionally, any vertical spread of infection is largely without significant risk, as the new growth rings formed in the years following will ensure the tree retains an element of vascular functionality (Shigo, 1986). Where this wall is particularly weak, extensive vertical columns of discolouration and decay will likely manifest (Shigo, 1991). Tyloses, which are balloon-like structures, form from the parenchyma cells that border the vascular tissues, and thus facilitate with the plugging of conductive vessels within angiosperms. The pits, which border the vessels, ensure vascular functionality is retained by promoting the localised lateral movement of water around the plugged vessels (Watson, 2006). This adaption ensures the tree can still operate with relative efficiency. Further, depending on the abundance of parenchyma cells around the vessels, the effectiveness of wall I may be very weak or rather robust. Quercus spp. do, for instance, have parenchyma cells that surround all large vessels in the earlywood, whereas other species may only see parenchyma cells surround a portion of the vessels – Ulmus spp. are but one genus with this characteristic, as their earlywood vessels are so massive and latewood vessels are so densely clustered together that parenchyma cells cannot envelop the entire vascular network. However, the vessel structure of elm means that wood is essentially more air than it is wood, which also acts as a defensive mechanism against pathogen invasion (Shigo, 1986). Tyloses (T) entirely plugging a vessel within a wounded Quercus sp. (Dujesiefken & Liese, 2015). In particular species, the tyloses are also suberised – Prunus avium, Quercus rubra, and Ulmus americana are just three examples (Biggs, 1987). Such suberisation will aid with the ability of wall I to resist pathogenic spread in a vertical manner, though this does not cause the wall to rank above others in terms of efficacy. The second wall, which resists inward spread of dysfunction, is also not a biological feature and is, too, under strong genetic control. This wall is stronger than the first wall, and is strengthened post-wounding by tyloses and suberin within parenchyma cells (Shigo et al., 1977). Wall II is able to be ‘defeated’ by pathogens relatively easily, however – particularly in diffuse-porous woods, where latewood cells are not as densely clustered. The propensity of the wall being breached, therefore, ultimately relates to the thickness of the terminal parenchyma band within the previous year’s latewood – Ulmus spp. will suffer, as their terminal parenchyma are very thinly spread (Shigo, 1986). Where this wall is breached, a deep decay column will form (Shigo, 1991). Radial parenchyma (P), terminal parenchyma (white arrows), and vessels (V) of Acer rubrum under the microscope. (Shigo, 1986). Wall III, which constitutes the existing radial rays within the wood structure, much like wall II, is strengthened post-wounding. This wall provides a better likelihood of protection against decay than the first and second walls respectively, mainly because (at least in broadleaves; not so much on conifers) the radial parenchyma sheets are very thick (many single sheets of parenchyma cells very close together) (Shigo, 1986; Shigo et al., 1977; Thomas, 2000). The fact that no ray will come into contact with another ray is a further safeguarding measure (Dujesiefken & Liese, 2015), as this nullifies the risk of a fungal pathogen using rays as vectors for internal establishment. An increased abundance of radial parenchyma sheets will also impact beneficially upon efficacy of this wall. Where this wall fails, decay will spread inwards and laterally. Where it is successful, decay will be ‘channelled’ between the two successful rays. Depending on the success of wall II however, the decay may still propagate deep into the wood structure (Shigo, 1986; Shigo, 1991). The barrier zone, or wall IV, differs from the reaction zone walls I-III, in the sense that the resultant structure is anatomically different, and separates infected wood from the healthy wood laid down following wounding. Formed from living parenchyma tissues within the cambium that existed at the time of wounding, the barrier zone is initially heavily lignified, though over time suberin accumulates within the new cells’ walls and provides these cells with an impermeable property, preventing propagation of the pathogen into the ‘new wood’ (Biggs, 1985; Biggs, 1986; Shigo, 1986). As already elucidated to, the rate of suberin accumulation and its overall abundance will impact upon success of the wall. The form that the barrier zone adopts is influenced by wound severity, the time of wounding, the species of invading pathogen(s), and the host-specific traits. Some species will form very strong barrier zones and weak reaction zones, whilst other species may be inversely-specialised (Shigo, 1991). The densely-arranged barrier zone (B), separating the discoloured wood below from the woundwood above (Dujesiefken & Liese, 2015). Decay rarely spans out into the new vascular tissues laid down following wounding, as the barrier zone is comprised of short parenchyma cells. Further, as the new wood of the barrier zone is hydraulically and structurally ‘sound’, it is free of dysfunction and therefore highly resistant to decaying organisms (Lonsdale, 1999; Shigo, 1991); that is, unless, another wound occurs in the new barrier zone tissues, at which point the process begins again. At times, this new wound can be self-inflicted, as the barrier zone is prone to splitting under loading conditions. This is caused by the propensity for the rolling woundwood ribs to not properly adjoin – the rolling ribs may, at times, turn inward, creating radial ‘shakes’ that act as internal cracks (Shigo, 1986). An incompletely closed wound may also provide an excellent environment for fungal pathogens, and it is possible that pathogenic micro-organisms influence the direction of growth of new vascular cambium (Blanchette & Biggs, 1992). The barrier zone also doesn’t actually aid with structural stabilisation very well – its role is to retain the tree’s functional integrity, and not so much its structural integrity (Shigo et al., 1977). Alternatively, the barrier zone can be broken by insect borers. In fact, insects are rather common in trees where wounding has occurred, as the decaying wood within is an ideal substrate for larvae. Such tunnelling by the insect therefore penetrates through barriers, and the tree cannot do anything but look to further wall-off itself (Shigo, 1986), which makes it progressively harder to repeat the same processes as there is less energy available for storage and thus for use. Interestingly, despite the barrier zone’s resistance to the spread of dysfunction into new wood, certain species of fungi, such as Inonotus hispidus, can penetrate the barrier zone (Lonsdale, 1999; Thomas, 2000). Furthermore, the wounding site is most beneficial to fungal growth when woundwood has almost occluded the wound, though once closed, fungal infection of the site will usually stop (unless oxygen is supplied from elsewhere) (Shigo, 1986). Ultimately however, even when walls I-III fail, wall IV is usually steadfast in its defence. Further comments regarding physiological changes The reaction zone (walls I-III) is, in the best cases, able to fully restrict fungal infection further into the wood after wounding, though the success of the reaction zone is largely related to carbohydrate availability in adjacent tissues, in addition to ample water so to combat against the transpirational loss triggered by the death of the exposed wound area’s xylem tissues. Such water stress in particular can cause wood to dry out further away from the wounding site, therefore improving the conditions for successful fungal establishment (Lonsdale, 1999). One can therefore stipulate that the health of the tree prior to wounding plays a significant role in the ability for the tree to resist the fungal attack. It should be noted here that seasonal changes in carbohydrate reserves, and the accompanying changes in wood moisture content, have been shown to alter successful invasion rates of fungi such as Chondrostereum purpureum (Schwarze & Baum, 2000). Furthermore, the reaction zone is not structurally homogeneous and does not therefore form a continuously-similar morphological barrier to the ingress of air and / or fungal attack (Schwarze & Baum, 2000). The research by Schwarze & Baum (2000) also demonstrates that, where reaction zones should migrate alongside the internal progression of fungal pathogens (or other dysfunction), various fungal species (such as Ganoderma adspersum, Inonotus hispidus, and Kretzschmaria deusta) are able to extend into functional sapwood some way beyond the reaction zone, whilst not stimulating the simultaneous migration of the reaction zone. Instead, a new reaction zone forms later at the new colonization front and, much like its predecessor, there is no guarantee this reaction zone won’t befall the same fate. Starch grains (arrows) inside tissues, adjacent to vessels, within the sapwood system (Dujesiefken & Liese, 2015). However, one must recognise that trees may have hundreds – if not thousands – of decayed and discoloured patches amongst their structure. By-and-large, the compartmentalisation process is successful, and most injuries are small (from small insect bore holes, dead twigs, etc), though it only takes one instance of failure (usually with more serious wounds) for dysfunction of any kind to wreak havoc on the tree’s system. This risk also increases over time, after each instance of compartmentalisation, as the locked-away resources and storage parenchyma cells cannot be accessed or used any longer (Shigo, 1986). Furthermore, the chemically-strengthened reaction zone around a wound is, in addition to being loaded with suberin and parenchyma cells, laden with phenolic compounds that act as a toxin to most pathogens present. These phenols are toxic not only to invading micro-organisms, but also to the tree itself (Shigo et al., 1977). Despite this, substantial degradation of phenolic compounds by Ganoderma adspersum and Ganoderma resinaceum has been observed in a range of broadleaved species (Schwarze & Baum, 2000). Therefore, phenols are not necessarily an absolutely sure-fire combatant against fungal pathogenicity. In essence however, the tree segments part of its structure to act as the sacrificial lamb. Of course, the tree most usually survives because, alongside the fortification provided by the reaction zone it is also generating new, healthy wood from the cambium, though it should be noted that a tree cannot fully compartmentalise all of its structure as in doing so it will die (Shigo, 1991) – there comes a point where compartmentalisation simply cannot occur any further, as the loss in accessible parenchyma cells for energy storage reaches a critical point where life processes cannot be sustained. Diverting attention again towards the barrier zone, it is necessary to recognise that the production of callus tissue, the subsequent cellular differentiation within the vascular cambium of the callus, and the eventual closure of the wound (which usually results in fully functional vascular connectivity), occurs following wounds inflicted only up to the depth of the xylem – heartwood, or inactive wood, void of parenchyma cells that can morphologically differentiate into necessary tissues, is unable to respond to wounding in the same manner that sapwood can (Neely, 1988b; Shigo, 1986). The amount and rate of callus production following wounding will of course vary between and within species, the size of the wound, the location of the wound on the tree, and the local environmental conditions (light availability, rainfall patterns, and so on). For example, the higher on the stem an injury is located, the faster the wound is closed. Further, young and small trees overgrow wounds more effectively when compared to older or thicker trees (Neely, 1988a; Schneuwly-Bollschweiler & Schneuwly, 2012). After significant wounding, trees might even produce additional sapwood and also stall heartwood formation, in order to bolster parenchyma cell abundance within the wounded region (or even throughout the entire circumference) (Shigo, 1991). Additionally, radial growth increases following wounding have been observed where drill bits were drilled nearly all of the way through the tree, though did not touch the cambium on the opposite side to the entry point. Curiously, the results of the drill tests indicate that the cambium tissue reacts even when not touched (or directly associated with the problem), and receives signals via the symplastic components of the overall structure (Shigo, 1986) – this crucial vascular connectivity further adds context to the reason why wall I is the weakest of the four walls. Moving away from the four walls on an exclusive basis and broadening the horizons of resistance to dysfunction as a whole, there are many other observable physiological mechanisms that a tree goes through following wounding. One significant aspect of resisting pathogens, whilst previously described in brief, is suberin accumulation. Suberin accumulation is an important process within the cell walls of new tissues that have formed after wounding, but before the internal spread of the pathogen is resisted to any marked degree. It does also occur within the lamella on the inner wall of a cell, which is already present at the time of wounding, though this lamella differentiates into a ligno-suberized layer following any such wounding (Biggs & Miles, 1988). The rate at which an infected site can accumulate suberin is directly related to the resistance to pathogen spread, as established. Therefore, trees that can flush the wound site with suberin stand a better chance of resisting infection (Biggs & Miles, 1985). However, suberin accumulation typically works in conjunction with, in angiosperms, the tyloses’ ‘plugging’ of conductive vessels. Suberin, on an exclusive basis, is not normally able to form homogeneous resistance (Biggs, 1987). Furthermore, suberin and its relation to the barrier zone (it is present as a lining of the cells present within the barrier zone) is very much evident, and its abundance will therefore have direct relevance to the success of the barrier zone (Shigo et al., 1977; Shigo, 1986). Suberin is ultimately what provides the fourth wall with its microbial resistance; many – but not all – fungal species cannot break down suberin (Biggs, 1987). Additionally, the accumulation of suberin (and lignin) within the boundary zone is reliant upon temperature, with 0°C being the threshold (Biggs, 1986). For wounds to completely lignify and suberise therefore, it may take many hundreds of ‘degree days’, and thus the rate of ligno-suberisation absolutely impacts upon the resistance of the barrier zone to infection. Wounds will also decrease in infection potential over time as they lignify and suberise (Watson, 2006), with a more rapid process, which is related to preferred temperatures (that will vary between species), aiding with a more swift decline in infection potential (Biggs, 1986). It is critical to note, however, that suberin is only produced by living cells (Deflorio et al., 2008), and therefore if a wound extends into the heartwood then suberin cannot play a role in particular areas of the wound (those spanning outside of the sapwood region). However, heartwood can ‘compartmentalise’. Where it is wounded, a boundary is formed of enzymes that react with oxygen or in response to the presence of chemical secretions by micro-organisms (Shigo, 1986; Shigo, 1991). Such chemical alteration of the heartwood ensures that fungal pathogens do not have free-reign of the heartwood. Interestingly, heartwood that has very high concentrations of extractives is generally found to be within the longest-lived trees (Shigo, 1986) – heartwood therefore is critical in the overall compartmentalisation process, without question. Pathogens will eventually break down the extractive-rich heartwood, however. The process is simply much slower. At this point, it is worth noting that tree species with false heartwood (including Acer spp., Fagus spp., Fraxinus spp.) do not form their ‘heartwood’ (that is simply a discoloured central column) regularly, but instead form such discoloured wood following branch death. The discoloured wood serves the same purpose as heartwood does, by-and-large. Discolouration in false heartwood species is initially a light pink to orange, with the wood only darkening upon infection (Shigo, 1986). In some species, such as Acer spp. and Betula spp., injuries made in very late winter or early spring may ooze or drip sap for some days to weeks afterwards (Shigo, 1986). This is a normal response and aids with creating undesirable (anaerobic) conditions at the wounding site for micro-organisms. Conifers do the same with traumatic resin ducts (canals). As the sap clogs the vessels, oxygen availability progressively decreases. Because wood-decay fungi are aerobes, they cannot function where the sap has clogged the region. Further, the pressure flow is outward, not inward (Dujesiefken & Liese, 2015; Shigo, 1986; Shigo, 1991). Sources: Biggs, A. (1985) Suberized boundary zones and the chronology of wound response in tree bark. Phytopathology. 75 (11). p1191-1195. Biggs, A. (1986) Prediction of lignin and suberin deposition in boundary zone tissue of wounded tree bark using accumulated degree days. Journal of the American Society for Horticultural Science. 111 (5). p757-760. Biggs, A. (1987) Occurrence and location of suberin in wound reaction zones in xylem of 17 tree species. Phytopathology. 77 (5). p718-725. Biggs, A. & Miles, N. (1985) Suberin deposition as a measure of wound response in peach bark. HortScience. 20 (5). p903-905. Biggs, A. & Miles, N. (1988) Association of suberin formation in uninoculated wounds with susceptibility to Leucostoma cincta and L. persoonii in various peach cultivars. Phytopathology. 78 (8). p1070-1074. Blanchette, R. & Biggs, A. (1992) Defence mechanisms of woody plants against fungi. Hong Kong: Springer. Deflorio, G., Johnson, C., Fink, S., & Schwarze, F.. (2008) Decay development in living sapwood of coniferous and deciduous trees inoculated with six wood decay fungi. Forest Ecology and Management. 255 (7). p2373-2383. Dujesiefken, D. & Liese, W. (2015) The CODIT Principle: Implications for Best Practices. USA: International Society of Arboriculture. Karban, R. (2015) Plant Sensing & Communication. USA: University of Chicago Press. Lonsdale, D. (1999) Principles of Tree Hazard Assessment and Management (Research for Amenity Trees 7). London: HMSO. Neely, D. (1988a) Tree wound closure. Journal of Arboriculture. 14 (6). p148-152. Neely, D. (1988b) Wound closure rates on trees. Journal of Arboriculture. 14 (10). p250-254. Santamour, F. (1979) Inheritance of wound compartmentalization in soft maples. Journal of Arboriculture. 5 (10). p220-225. Santamour, F. (1984a) Early selection for wound compartmentalization potential in woody plants. Journal of Environmental Horticulture. 2 (4). p126-128. Santamour, F. (1984b) Wound Compartmentalization in Cultivars of Acer, Gleditsia, and Other Genera. Journal of Environmental Horticulture. 2 (4). p123-125. Schneuwly-Bollschweiler, M. & Schneuwly, D. (2012) How fast do European conifers overgrow wounds inflicted by rockfall?. Tree Physiology. 32 (8). p968-975. Schwarze, F. & Baum, S. (2000) Mechanisms of reaction zone penetration by decay fungi in wood of beech (Fagus sylvatica). New Phytologist. 146 (1). p129-140. Shigo, A. (1986) A New Tree Biology. USA: Shigo and Trees Associates. Shigo, A. (1991) Modern Arboriculture. USA: Shigo and Trees Associates. Shigo, A., Marx, H., & Carroll, D. (1977) Compartmentalization of decay in trees. USDA Forest Service Agricultural Information Bulletin 405. Thomas, P. (2000) Trees: Their Natural History. UK: Cambridge University Press. Wargo, P. (1972) Defoliation-induced chemical changes in sugar maple roots stimulate growth of Armillaria mellea. Phytopathology. 62 (11). p1278-1283. Wargo, P. (1976) Variation of starch content among and within roots of red and white oak trees. Forest Science. 22 (4). p468-471. Wargo, P. (1977) Wound closure in sugar maple: adverse effects of defoliation. Canadian Journal of Forest Research. 7 (2). p410-414. Watson, B. (2006) Trees – Their Use, Management, Cultivation, and Biology. India: The Crowood Press.

Here's an old hawthorn that, unfortunately (due to a lot of bark inclusion and also some brown rot), has failed significantly down the main stem. I'll let the video do the talking. Play in full screen. Short one (including me talking a little): https://vid.me/J2Lu Longer one (different video taken jsut after without me talking): https://vid.me/5dBh Cool eh! Not for the tree... Also has what looks like a small (but rather orange) Ganoderma at the base.

Doing the Lvl 4 at the moment. I can attest to it being a fair amount of work, though it's entirely manageable (I don't have kids, mind). Never done the climber route myself - went from uni to being a tree officer, so it's not always 'best' to undertake the 'rite of passage' thing that seems to be so very common. Find something you like? Go for it.

I should have specified scale - apologies! Perhaps a mystery, it will remain.

Not sure; shall check. The pores are on the upper surface. It was, apparently, a long and wide 'mat' of fungus atop the branch, around 1cm deep. Rather squidgy texture. Going through Jordan's book it could be a good few species, though never seen this before so really haven't got a clue.

You'd like to think so, that's for certain! An article by Jeremy Barrell in the recent Arb Mag was quite interesting though, and covered that somewhat.

This was found on Guernsey (not by myself). On a living holm oak branch (on the top side). A polypore of sorts (?), but not sure what. Cheers.

07/02/16. Fact #146. Trees provide a huge number of ecosystem services, ranging from the amenity value they provide to the ecology they support through their mere existence. In a setting where there is no target zone, a tree can be allowed to simply persist in any sort of state without there being the risk of injury or damage to property, though where the tree resides within a busy environment this is not the case. Therefore, a particular conflict arises between retaining viable and niche decaying (or hollow) habitat in an old tree and reducing the risk associated with the retention of such a tree. In this study, the authors assess how balancing such conflicting demands impacts upon saproxylic beetles including the endangered Osmoderma eremita. The study area for this project was a large area (159ha) of parkland in the city of Rome, Italy. The parkland is characterised by areas of woodlands and scattered mature trees, with a species composition that features exotic cedars, pines, and cypress, though is dominated by old Quercus ilex (holm oak). These holm oaks were the focus of this research, and 1,247 individuals were surveyed in the areas of the park that were designated for Visual Tree Assessment surveys by the park’s managers (presumably because these oaks were seen to be of greatest potential risk to the public). The gardens of Villa Borghese. Source: Wikimedia Commons. Alongside the VTA, (initially) all holm oaks were surveyed for saproxylic beetles (every fourth day) between 14:00 and 19:00 from 19th July to 28th August. This involved exploring all hollows up to 5m above ground level. After a period of time, only those oaks with more significant decay were surveyed. Further, from 1st September to 30th September, between 09:00 and 18:00, the holm oaks were surveyed three times for beetle larvae and frass. In all, ten species of saproxylic beetle were identified from 66 of the 1,247 holm oaks. However, 41% of the beetle population was found within the holm oaks considered to be at highest risk of falling (category D3 – see table below), with some species being found exclusively in such trees. For Osmoderma eremita, four D3 trees were host to the species, and the remaining seven host trees were deemed less likely to fail. The number of beetles found, of different species, in the holm oaks surveyed. D3 relates to the holm oaks at highest risk of falling, and the data shows how much of the population of beetles exists within these trees. In relation to the properties of the trees that contained the beetles, it was found that host holm oaks had an average DBH of 71.5cm, height of 16m, and spacing (relative to other trees) of 13m (these are big trees!). 63% of the hollows within such oaks, which were home to saproxylic beetles, had a fair amount of mould, and many of the cavities were moderate in size (an average of 18cm in width – only a few cavities of 50cm width were found to have beetles), and the decaying wood within was situated some way from the opening of the hollow. Of these hollows, many had a north-eastern or south-eastern orientation, were no higher than 2m from ground level, and were free from bird nests. Holm oaks with damage to the root collar were also found to be most likely to be host to more species of beetle (higher species richness), most probably because of the greater amount of internal hollowing and decay close to the base of the tree (where the largest hollows can form). The authors suggest that, in order to preserve viable habitat for Osmoderma eremita, there is a need to retain living and large holm oaks that are close together (no more than 100m apart, but ideally far less), that have a lot of internal wood mould, and have nest-free cavities situated on NE and SE sides of the tree – this ensures there is high humidity but also a relatively cool internal temperature, and a lack of predators in the form of nesting birds. Therefore, the removal of such hazardous (category D3) oaks found to be host to the species is damaging in the sense that the beetle’s habitat is fragmented and also largely removed, meaning remaining beetle populations may become isolated (even when found only a few hundred metres from other suitable holm oaks) and the carrying capacity of a landscape is reduced. An overhead shot of some of the park. We can see how dense the tree cover is. Source: Personal Drones. Concerningly, because 41% of holm oaks host to saproxylic beetles were considered to be of high risk to members of the public (because of their poor condition), there is an evident conflict of interest associated with management of many trees that are ecologically critical for rare and threatened insects. In fact, large trees home to beetles including Osmoderma eremita were already on a felling schedule, which is catastrophic for the saproxylic species’ longevity on the site. In place of felling, it is suggested that old trees are retained via the installation of supporting structures that reduce the risk of large limbs falling, or such hazardous limbs have some of the more unnecessary side-branches removed to reduce mechanical loading. However, if limbs must be removed, they should be left on the ground beneath the tree, and the cuts made should mimic a natural fracture created under over-loading conditions. This begs the question – are park managers, who are responsible for many mature and veteran trees, aware of their ecological benefits, and are they prepared to extra spend money on retaining such trees for their habitat whilst also satisfying the need to reduce the risk to visitors (and do they even have the expertise to request this)? Because many of the holm oaks found to be host to saproxylic beetles were already on a felling list, it suggests that park managers (at least in this instance) were more than prepared to accept the loss of habitat in the pursuit of public safety (did they even know about the beetles being there?). How willing would park managers be to change their stance, and strike more of a balance between the two conflicting aspects of tree management? Source: Carpaneto, G.M., Mazziotta, A., Coletti, G., Luiselli, L. and Audisio, P., 2010. Conflict between insect conservation and public safety: the case study of a saproxylic beetle (Osmoderma eremita) in urban parks. Journal of Insect Conservation. 14 (5). p555-565.

If it's an old ash and it is to be damned, then just monolith it. Great deadwood habitat. Also opens up the ash to colonisation by other fungi, which can have positive effects for fungivores (species of insect, notably on Inonotus hispidus).

Hold fire. At least sound it first. No absolute need for a reduction, necessarily.

Gotcha. Makes sense now. Pardon the misinterpretation.

That logic cannot apply here. I cannot project my stance on a situation onto others and expect them to also adopt it, regardless of circumstance (this includes whether you are an employer or employee). If you are an employer and pull stunts that see you desregard the needs of others in testing times, expect to lose respect by your peers and perhaps lose good staff as well.

If I had a genuine emergency and needed to get a lift back and it was refused for whatever reason, I wouldn't be happy at all. I think, assuming it was a genuine emergency and there was only one vehicle, there should be no second thoughts as to dropping everything. Retaining the respect of peers and colleagues is most important, as you have to work together at the end of it all. Not dropping everything could come across as "yeah, well we get you have an emergency, but tough".

I can always trust to learn from you both when you make a post. Good posts, guys!

That's glorious!

05/02/15. Fact #145. As trees transpire, they cool their surrounds. In urban areas, where the heat island effect may at times be quite significant, such transpirational activity is necessary for reducing both day-time and night-time temperatures. However, transpiration is not constant, and trees therefore may provide different ‘levels’ of cooling at different parts of the day. Efficacy may in fact be weather-related, or even impacted by the permeability of the ground surrounding the tree’s rooting system – this is because such factors influence how much water is available to the tree. In turn, transpiration rates are affected, which has a knock-on effect of impacting upon ambient temperatures. In this study, the authors investigate seven of the most common urban tree species (Acer platanoides, Aesculus hippocastanum, Betula pendula, Fagus sylvatica, Prunus serrulata, Quercus robur, and Tilia europaea) in Gothernburg, and ascertain their benefits with regards to cooling via transpiration. From (most of) the study trees (which were ‘avenues’ or groups of a single species), the authors measured stomatal conductance, transpiration rates, and photosynthetic rates both during the day- (solar noon) and night-time (1-4 hours after sunset) on warm summer days; one day where no clouds were present, and one where clouds were moderately present. Certain tree species, including Acer platanoides, only had their measurements taken on one day. The reason for some tree species only having one reading was because of their locations (the map below highlights all locations across the city), and because the equipment used to take the readings was malfunctioning. Data relating to leaf area, solar radiation, and energy loss (heat) beneath the tree canopies was also collected, amongst other things (the table below the map shows some of the collected data relating to the trees surveyed). A map showing the locations of all the tree species. Tilia europaea (A-C), Quercus robur (D), Betula pendula (E), Acer platanoides (F), Aesculus hippocastanum (G), Fagus sylvatica (H), and Prunus serulata (I). Some of the information that was gathered by the authors relating to tree properties. In addition to the tree data captured, meteorological data was also taken from the sites. Air temperatures, relative humidity levels, atmospheric pressure, recent rainfall, and so on, were captured, and the article itself contains a very large table outlining the weather conditions at each site. Results The authors found that day-time stomatal conductance of leaves was two-times greater in sun leaves than in shade leaves. The greatest differences between stomatal conductances during day and night were observed in Quercus robur and Prunus serrulata along streets and in Tilia europaea within parkland, whilst the lowest difference was observed in Aesculus hippocastanum and Tilia europaea along streets. Transpiration rates were also found to be higher in sun leaves; on average, three-times higher. However, there was marked variation between species, with street-based Quercus robur and Betula pendula sun leaves having the greatest transpiration rates of the entire study on the sunny, warm, dry day. In addition, park-based Tilia europaea sun leaves were found to transpire at almost twice the rate of its street tree counterparts. Not only this, but individuals growing on streets with wide lawns transpired at higher rates than ones growing on narrow lawns. Transpiration may therefore be location-specific, even when assessing the same species. Such transpirational differences were not found within shade leaves. Despite the above, and induced by the falling solar radiation levels and air temperatures, the transpiration rates of all individuals begun to drop 2-3 hours before sunset. However, transpiration did persist following sunset (at a rate of up to 20% of daytime rates) – for at least four hours (transpiration may have persisted after, though the data collection stopped 4 hours after sunset). Such night-time rates were also different between species, with Prunus serrulata transpiring at a much greater rate than Betula pendula. The other species all sat within the range these two species established, though day-time transpiration rates were somewhat correlated to night-time transpiration rates – as in, trees that transpired more during the day also did so at night. Both stomatal conductance and transpiration rates were also shown to be markedly impacted by recent rainfall episodes – particularly over the 5-30 days prior to the data collection. Where there had been less rainfall, stomatal conductance and transpiration was reduced. However, impermeable surface to permeable surface ratios in the immediate surrounds to the study trees was also determined to be a strongly-influencing factor, in terms of how much of the rainfall actually was made available to the trees. Trees that sat in parks or along wide street verges had higher stomatal conductance rates than those on narrow verges – particularly in sun leaves. Across all species, Quercus robur and Prunus serrulata had higher transpiration rates compared to the other tree species, at similar levels of ground permeability. Such foliar activity led to between 9-64% of incoming short-wave solar radiation being ‘reflected’ back as latent heat energy (associated with transpirational cooling). The lower end of the spectrum was occupied by Tilia europaea residing within narrow-verged and heavy-traffic streets, whilst Quercus robur occupied the upper echelons. Such latent heat ‘reflection’ lead to the reduction in heat energy beneath the tree canopies, and the data collected at each site is shown below. However, it was found that day-time cooling effects were somewhat – or fully – negated by the ‘mixing’ of air in the vicinity of the trees (the air during the day was more volatile, perhaps induced by higher temperatures), meaning that transpirational cooling was actually more effective later during the daylight hours and soon after sunset. A comparison between species and the day and night. What does this data mean? In essence, it can be asserted that both the species of a tree, and its location, will influence upon the cooling effects associated with its presence. For cooling effects to be most significant, not only should species selection be carefully undertaken, but urban trees should be provided with the necessary levels of moisture required to sustain ‘healthy’ operations (irrigation may be necessary, in periods of drought – even for larger trees), and surrounding surfaces should be permeable in nature (and if not, irrigation should be strongly considered). For the best cooling effects, trees should be situated within parks. However, as the benefits of tree cooling are most desired in streets where there is a greater accumulation of heat energy, it may have to be accepted that constituent trees will not operate to maximum beneficial capacity – though not utilising trees should not even be considered, as all trees provide some benefit. It may indeed be a case of selecting species that are more effective at cooling the street localities, though also tolerate urban conditions and will not cause damage or other adverse impact in their environment (for small streets with narrow verges, Prunus serrulata may be a good choice of tree – assuming its roots do not cause damage to the pavements). Because this study suggested that transpirational cooling during the day might not be overly significant (or even non-existent), and as such a conclusion is in-line with other studies, there must be a degree of acceptance that trees are not miracle-workers. Of course, the shading (shadowing) trees provide will lower ambient temperatures (at which point, larger and denser-canopy trees will be preferable), though it is during the later parts of the day (and the early night hours – at a point, transpiration no longer impacts upon cooling during the night) when trees will cool the air, through transpiration, most significantly. This is still nonetheless highly important, as the removal of heat during the evening (and even during the night) can be of marked benefit to residents – not only is it difficult to sleep when it is warm (and costly to cool a property), but increased temperatures have also been attributed to increased restlessness and crime. An urban scene within Gothernburg, filled with large trees. During the middle of the day, it may perhaps only be their shading that reduces ambient temperatures, though as the evening draws in their foliar transpiration will have a positive effect on air temperatures. Imagine, for a minute, if these trees weren’t here – how uncomfortably hot (and bright!) might it be? Source: Skyscrapercity. Source: Konarska, J., Uddling, J., Holmer, B., Lutz, M., Lindberg, F., Pleijel, H., & Thorsson, S. (2016) Transpiration of urban trees and its cooling effect in a high latitude city. International Journal of Biometeorology. 60 (1). p159-172.

Few days off, I think. Let you guys catch up.