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  1. During the Carboniferous Period some 345-280m years ago, the continent of Pangaea began to drift northwards from its southern hemisphere origins, and also began to pivot 30 degrees to the west. Giant insects developed, amphibians evolved further and reptiles became more land-based. Plants were reproducing in an alternating manner of asexual and sexual methods across different generations (spores and seed respectively). Equisetum plants (includes Horsetails) became huge, forming Calamites in damp, swampy areas, and forming Cordaites (that had pollen sacs and ovules at branch tips - later forming the first conifers, such as ginkgos, during the Permian Period 280-225m years ago) in drier areas. Clubmosses grew to 30-45m in height. All of this development was fueled by the equatorial climate induced by the drift northwards of Pangaea, particularly at the northern-most end of the super-continent. Coal measures were thus formed very readily from such large plants in what now constitutes Northern Europe (given this segment of Pangaea was first to travel over the equator), once the sea began to engulf the swamps of massive clubmosses, semi-composting them and later compacting them down with silt and clay to form lignite, and eventually forming coal under continued compression events. It took 20m of rotted 'forest' biomass to produce a 1m-thick coal measure, so given many European coal measures are hundreds of metres thick, the length of time required to create such coal measures would have been hugely significant. This also adds significance to our eagerness to burn such stored coal, releasing carbon that has been locked away for hundreds of millions of years in mere decades. The southern area of Pangaea (Africa, Australia) contained smaller plants and thus smaller coal measures, only beginning to lay down larger coal measures (that never amounted to the extent of the earlier coal measures, as the steamy swamps that produced the huge clubmosses and subsequent coal measures no longer existed due to climate change) much later once the southern segment of Pangaea did reach the equator (during the Cretaceous and Tertiary Periods) when plants had evolved to develop roots and reproduce sexually via seed. Evolutionary-speaking, the development of reproduction via seed was critical to the survival of plants long-term, as germination could be delayed until conditions were desirable. Building on the above a little, though nonetheless as a tangent, Europe has so few tree species as tree populations could not retreat southwards as the ice sheets encroached into their territory, given the east-west running mountain ranges that are the Alps and Pyrenees, and the area that is now the Mediterranean Sea. Because of these blockading landscapes, tree diversity is rather low within Europe, when compared to the Americas and Asia. The UK's plant diversity is even more impoverished as when the ice sheets last retreated 12,000 years ago, the subsequent rising of sea levels bridged the gap to mainland Europe. Thus, only species that had colonised during the 6,000 years after the ice caps began to retreat are found today - any others that may have potentially once again reached these shores (I suspect sweet chestnut, plane, holm oak, etc, though definitely Norway maple and larch) were barred from doing given the mass of water in the way. Source: Davis, M. (2015) A Dendrologist's Handbook. UK: The Dendrologist.
  2. The traditional view of mycelial fungi is that the development cycle can be split into two stages: vegetative and reproductive. The former relates to the mycelial spread within the host and the latter the production of sexual or asexual structures that produce spores. However, a more contemporary approach to discerning the development cycle of fungi reveals four distinct stages: arrival, establishment, exploitation, and exit. Such development stages are considered to be triggered by the changing conditions of the substrate (such as drying, cell degradation, etc), as in meeting the changing conditions the fungus must adapt its own behaviour (dubbed 'functional modes') to successfully persist within the host. Curiously, a fungus can compartmentalise itself so that, at different stages of decay within the same host, it adopts a different functional mode. Each mode is briefly described below: (1) Arrival: two known mechanisms exist: arrival as propagules (airborne and seemingly only favourable when localised conditions are optimised at the arrival surface - good supply of nutrients, a good microclimate, and a lack of competitors), or arrival as migratory mycelium (contact of an infected host to a non-infected host, such as with H. annosum and A. mellea). (2) Establishment & exploitation: three principal concepts of this mode are understood: the fungus must successfully gain access to the host and begin to command available resources; the fungus must begin to successfully convert potential energy resources into actual energy sources, and; the fungus must successfully 'wall-off' an area to resist against competitors or the host tree itself, or in turn have a rapid exit strategy (panic fruiting on the wound surface or within the inside of the hollow(ing) host, for example). (3) Exit: in the rawest sense, exit can be achieved either through the formation of reproductive structures or by the outgrowth of mycelium (relating back to the arrival strategies). The efficacy and extent of the exit mode is dictated by two factors: the extent to which resources are re-allocated from the mycelial biomass within the wood structure to the biomass of external structures, and; the effect of the environment on the form these exit structures adopt. At a slight tangent, the r-K continuum further dictates exit strategy, with r-strategists (Deuteromycotina, Zygomycotina) taking a more rapid, economical stance to reproduction (not developing massive or durable exit structures), whilst K-strategists (Ascomycotina, Basidiomycotina) limit commitment of non-reproductive biomass, though also possess greater ability to develop exit structures that persist and are thus durable and do so at more 'fixed' stages. Within the continuum, certain species do however hold the ability to possess more than one mode of exit (such as with F. hepatica and L. sulphureus having the ability to develop either as a basidiospore on primary fruiting structures and as a conidiospore on auxiliary structures). Source: Rayner, A. & Boddy, L. (1988) Chapter 5: Development Cycles. In Fungal Decomposition of Wood: Its Biology and Ecology. UK: John Wiley & Sons.
  3. Severing roots out of purpose is hardly ever something that an arborist would find desirable, though it nonetheless occurs rather commonly where construction takes place and also where abatement of nuisance is practiced for terrestrial encroachment of a tree. Current research indicates that the severance of roots is, by-and-large, highly variable. In one instance, root severance may have very little adverse impact on tree stability, though in other cases may weaken a tree by over 20%. Roots that 'guy' a tree (exist uphill of the trunk) or reside on the outer (tension) side of a lean are ultimately far more crucial to the tree than the majority of the remaining root crown. Severing roots may not therefore simply be a case of "no more than 25% of the root crown can be lost", as context is key. If a guying / tension root is severed, the impact upon stability will be far more significant than if a compression root (or even multiple roots) is lost. Statistically (from a survey done on willow oak), when assessing strength loss due to buttress root severance at the base of the trunk, a loss of 50% of the buttress roots will reduce the mechanical required force to move the tree one degree by a third (33%). However, due to the oscillating nature of winds, such a loss in root mass will result in a much higher decline in strength, particularly for larger trees with more wind sail (or where root decay is evident). Interestingly, such a loss can at times be achieved simply by severing a single guying / tension root, which suggests that trenching may be of particularly significant adverse impact to trees in more exposed sites. Additionally, research indicates that severing roots closer than at a radius three-times the trunk diameter is not recommended, as tree stability declines significantly once this threshold is surpassed. Source: Smiley, E. (2009) Root pruning and stability of willow oak. In Watson, G., Costello, L., Scharenbroch, B., & Gilman, E. (eds.) The Landscape Below Ground III. USA: International Society of Arboriculture.
  4. The Midland Reafforesting Association was created in 1903 with the intention of undertaking afforestation projects (amounting to 14,000 acres) across the Black Country, England. Whilst in principle such projects were met with support by the government and other organisations, less than 1% of the target was planted so by 1925 the project was terminated and the Midland Reafforesting Association dissolved. Predominant drivers behind the failure of the project included the residents' acceptance of the industrialised and bleak landscapes as if they were the norm and status quo, the lack of necessary funding from bodies that verbally supported the efforts of the Midland Reafforesting Association (particularly as the subsoiling / ripping of poorer-quality sites being very expensive), 'technical difficulties' (species selection, poor site quality, etc), and the fact that one of the core motives for the afforestation project, that of such forest creation improving land value, was at the time not supported by crucial evidence in favour of such a claim. Unfortunately, and somewhat ironically, only one-sixth of the derelict 14,000 acres remained by 1953. Most had been built on due to demand for infrastructural services and homes for the rising population of the UK. The remaining derelict land, which would amount to around 2,400 acres, did funnily enough regenerate naturally, gradually 'greening' the residual areas left behind after continued construction. To top the whole thing off, The Black Country Urban Forestry Unit (BCUFU) that was formed in 1985 to continue the efforts of the project from 1903, which evolved into the National Urban Forestry Unit (NUFU) in 1995, also disbanded (prematurely) due to a lack of funding from central government. The project managed to plant 837 acres of woodland over six years with a £8.5m budget, before calling it a day. Not all is lost in failure however, as the lessons drawn from the demise of such an ambitious project paved the way for research into species selection for plantations, management of plantations, and planting techniques. Source: Webber, J. (2008) Greening the Black Country: The Work of the Midland Reafforesting Association in the Early Twentieth Century. Arboricultural Journal. 31 (1). p45-62.
  5. During the 18th and 19th centuries, coppice woodlands underwent an 'improvement' period, which involved either (1) selective removal of more undesirable species with artificial planting / propagation of more desirable species, and (2) conversion to high forest (perhaps even the former followed later by the latter). In reference to point (1), whilst many coppice woodlands only saw such improvement come in the form of gap-filling with Fraxinus excelsior and other desirable species, composition of other woods dramatically changed. For example, in the South-east Lowlands, certain coppice woodlands saw the introduction of Castanea sativa, Fraxinus excelsior, Corylus avellana, and Alnus glutinosa, whilst simultaneously seeing the removal of Acer campestre and, in somewhat of a paradox, Fraxinus excelsior, where the overriding objective of coppice was to harvest Corylus avellana poles. In the Western Uplands, Quercus petraea, and to a lesser extent Quercus robur, were selectively planted with the intention of subsequent harvesting for the leather tanning process and for charcoal to be sold into the metal industry, whilst Corylus avellana was selectively removed. In reference to point (2), the conversion of coppice to high forest was driven by local demands (or even general neglect). Where action was deliberate, Quercus spp. were principally planted, though Fagus sylvatica was also planted in abundance (notably in the Chilterns and the Cotswolds) as, after a period of undesirability (due to its poor coppicing ability), it could now flourish within the high forest, continuous cover-esque style management regimes. Ultimately however, Quercus spp. planting was more evenly-spread than Fagus sylvatica planting. Source: Peterken, G. (2015) Woodland History in the British Isles – An Interaction of Environmental and Cultural Forces. In Kirby, K. & Watkins, C. (eds.) Europe's Changing Woods and Forests: From Wildwood to Managed Landscapes. UK: CABI.
  6. As is clearly obvious already but merely to clarify, since changing jobs and working as a consultant I have very little spare time (when also considering I'm buying a house, have personal commitments and whatnot, plus hobbies to pursue). Therefore, this thread is no more, in terms of new content. I'm getting back some momentum into Arbtalk and shall look to do some blog posts, however.
  7. Some great photos there. Agreed that the tree needs some management!
  8. Andy Overall showed me some of the Tremella looking like this last year and said it was more likely to be T. aurantia. Is there Stereum nearby? It's a parasitic fungus on another species, which would determine the species of Tremella.
  9. Wonder who that was Glad to see this is available online too now.
  10. "Later in the meeting the Highways manager when questioned several times finally admitted that this decision had been taken without any consultation or advice from the City's Arboricultural team, which to me beggars belief" This is some middle managers and some upper managers in the public sector doing what they do best: being absolutely diabolical at doing anything remotely useful.
  11. Looks like Hypholoma capnoides, which is the conifer tuft. Only a presumption though, due to the lack of close-ups.
  12. Nah Paul, I'd say you're bang on. Check the Stereum by running a blade over the fruiting body. If it turns red then it'll be Stereum rugosum, as S. gausapatum turns red and is found largely on oak only. Conversely, S. subtomentosum turns orange at the periphery on the underside and S. hirsutum doesn't do anything - the boring bugger. Oh no! Hold up. I see pores on the underside of the later image - Stereum species lack pores. It might all be Trametes versicolor.
  13. More commonly known as 'nail galls', I think.
  14. A few more photos of the same oaks.
  15. Unconventional in the sense all three oaks were colonised by Pseudoinonotus dryadeus and were spaced no more than 10m apart from each other. Makes me think about 1. the genotypes of the fungus within each oak (are they similar / of the same progeny?) and how they colonised (spore or other means?).


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