(Arboricultural-styled) 'Fact of the Day'

[Kveldssanger]

I'm confused. If Alnus can create better plant growth conditions because it can fix Nitrogen (with F. alni), why does it create Phosphorus poor conditions? i.e. if it accumulates both N and P why and how does it make N available to other plants but not P? Sorry, complex question, but I don't have access to Jakobsen et al.

 

Taken from: Põlme, S., Bahram, M., Kõljalg, U., & Tedersoo, L. (2014) Global biogeography of Alnus‐associated Frankia actinobacteria. New Phytologist. 204 (4). p979-988.

 

"The prominent roles of host phylogeny and spatial factors on Frankia community structure corroborate the results of a global study addressing Alnus-associated EcM fungal communities (P~olme et al., 2013). The Procrustes statistic revealed significant coupling of the two microbial communities, which probably results from the mutually shared host phylogeny effect as revealed by the partial Mantel test. Alternatively, the direct effects of symbionts on each other may be produced through their complementary effects on plant nutrition (Chatarpaul et al., 1989; Horton et al., 2013; Walker et al., 2013). As a result of N fixation, Alnus-dominated ecosystems are phosphorus-limited (Uliassi & Ruess, 2002). Therefore, the efficiency of mineral nutrition may play a role in indirect or direct selection of symbiotic EcM fungi and Frankia by the host tree (Walker et al., 2013)."

 

The reference takes us here: Uliassi, D. D., & Ruess, R. W. (2002). Limitations to symbiotic nitrogen fixation in primary succession on the Tanana River floodplain. Ecology. 83(1), p88-103.

 

A quick scan doesn't locate where the reference may have come from, though the entire article talks about P and N relationships.

[Gary Prentice]

Hahah. Your knowledge is not sparse!

 

You're definitely confusing me with someone else:blushing:

[Kveldssanger]

Nope!

 

Lost track of time today so nothing in the way of facts. Will do one or two tomorrow - will keep on the woodland theme, perhaps.

[Kveldssanger]

Again taken from my notes, so there are various references and the reading may be a little disjointed at times.

 

31/10/15. Fact #67.

 

Ecologically-speaking, there are thee distinct subsystems that can be found within most, if not all, environments: the plant subsystem, the herbivore and carnivore subsystem, and the decomposer subsystem. This post will focus exclusively on the decomposer subsystem.

 

Put simply, the decomposition system is reliant upon, and therefore works in tandem with, both the plant and herbivore / carnivore subsystems. 'Decomposers' are usually the microflora, fungi and bacteria, or worms / nematodes, molluscs and arthropods (amongst other things, as well).

 

Decomposers depend upon necromass (dead organic matter), typically in the form of plant remains, but also on the remains of dead animals, faeces, or shed skins. Relating to the field of arboriculture and forestry, the fungi are a very important decomposer, as are termites - particularly in woodlands.

 

Decomposition will usually require more than one 'pass' through the subsystem, with different decomposers exploiting the different stages of the decomposition process. Some necromass 'types' will require more cycles through the decompositon process than others; this can vary with species for the same type of tissue, such as different species of leaf taking different times to ultimately decay fully. Dead remains of decomposers, such as fungal brackets that have desiccated, also contribute to necromass and require decomposition themselves, so there is an element of 'intra-system feedback'.

 

The decomposition process will ultimately revert everything back to organic matter / humus, which is nutrient rich and available for utilisation by the plant-subsystem for uptake. Decomposition essentially 'mineralises' immobile nutrients locked within an organism, such as nitrogen, potassium or sulphur, and creates essential humus molecules. The decomposition process also releases carbon dioxide.

 

As the decomposer subsystem directly breaks down dead plant material it directly regulates plant growth and (plant) community composition by determining the supply of available soil nutrients to existing plant communities on the site, thereby taking the process full-circle and back to the plant subsystem (which is the 'start' of the cycle). The amount and type of nutrients mineralised determines how the entire plant sub-system succeeds, which has knock-on effects for the herbivorous / carnivorous and decomposition sub-systems. We can therefore begin to see how the three are inter-woven, and a healthy system requires all three systems to be functioning optimally. If one suffers, the rest will (in time - of course, there may be lag periods).

 

To finish off, and as a somewhat aside, the decomposition and herbivore subsystems vary in the sense that decomposition can, as established, be a process that happens more than once over, whereas herbivores only get one 'chance' at consuming a single leaf. However, both systems do compete somewhat for the uptake of carbon, though the herbivore / carnivore subsystem does still provide the decomposer subsystem with faeces and other necromass, whilst the decomposition subsystem does not directly provide herbivores / carnivores with anything (unless we enter the realm of fungivores, though I am sure there could be an entire post on that).

 

Sources:

 

Colpaert, J. & Tichelen, K. (1996) Decomposition, nitrogen and phosphorus mineralization from beech leaf litter colonized by ectomycorrhizal or litter‐decomposing basidiomycetes. New Phytologist. 134 (1). p123-132.

 

Frankland, J. (1982) Biomass and nutrient cycling by decomposer basidiomycetes. In Frankland, J, Hedger, J, & Swift, M. (eds.) Decomposer basidiomycetes: their biology and ecology. UK: Cambridge University Press.

 

Freschet, G., Cornwell, W., Wardle, D., Elumeeva, T., Liu, W., Jackson, B., Onipchenko, G., Soudzilovaskia, N., Tao, J., & Cornelissen, J. (2013) Linking litter decomposition of above‐and below‐ground organs to plant–soil feedbacks worldwide. Journal of Ecology. 101 (4). p943-952.

 

Krivtsov, V., Bezginova, T., Salmond, R., Liddell, K., Garside, A., Thompson, J., Palfreyman, J., Staines, H., Brendler, A., Griffiths, B., & Watling, R. (2006) Ecological interactions between fungi, other biota and forest litter composition in a unique Scottish woodland. Forestry. 79 (2). p201-216.

 

Pradhan, G. & Dash, M. (1987) Distribution and population dynamics of soil nematodes in a tropical forest ecosystem from Sambalpur, India. Proceedings: Animal Sciences. 96 (4). p395-402.

 

Wardle, D., Bardgett, R., Klironomos, J., Setälä, H., van der Putten, W., & Wall, D. (2004) Ecological linkages between aboveground and belowground biota. Science. 304 (5677). p1629-1633.

 

Wardle, D., Walker, L., & Bardgett, R. (2004) Ecosystem properties and forest decline in contrasting long-term chronosequences. Science. 305 (5683). p509-513.

[Kveldssanger]

Went on a walk around some of the fields at the back of the house and walked past a line of mature ash, of which most were host to Inonotus hispidus. I thought, therefore, I'd post some information about the fungus. Again, this is all from my notes that I will be using for my Lvl 4, so it is thus set out in such a manner here.

 

 

31/10/15. Fact #68.

 

Hosts: Most commonly found on Fraxinus spp. and Platanus x hispanica , though can also be found on other broadleaved species such as Malus spp. Juglans spp., Ulmus spp., Sorbus spp. and Acer pseudoplatanus.

 

Colonisation strategy: Infection sets in via a branch stub, wound (either naturally or artificially-borne) or through tunnels made by wood borers. After entering exposed sapwood, Inonotus hispidus breaks out of the reaction zone formed by the tree by entering 'soft rot mode' and moves into the heartwood, where it colonises and begins to decay the host. However, it can colonise sapwood and has been observed in some young ash branches between 5-7 inches thick.

 

Rot type: Most commonly a simultaneous white rot, though soft rot can also be observed during early stages of development. Canker development has also been observed in instances where a cambium strip has been destroyed. Selective white rot has also been observed in Tilia platyphyllos, which is likely due to Inonotus hispidus' inability to decay heavily-lignified lamellae and rays.

 

Significance: The extent and mode of decay can vary greatly between host species, so ascertaining the potential significance of decay is species-specific. As heavily lignified cells are resilient to Inonotus hispidus, wood rays are usually degraded only in the later stages of decay. As a result, the heavily lignified rays of Platanus x hispanica have a greater innate resilience than the less lignified rays of Fraxinus spp., which can lose significant compression strength very rapidly (within weeks). Therefore, presence on Fraxinus spp. is more significant than on Platanus x hispanica, where co-existence can persevere for many years. Failure is usually a result of brittle fracturing.

 

Part of host impacted: Both the main stem and large branches are the principal hosts for Inonotus hispidus, though smaller branches may also act as viable hosts.

 

Treatment and prevention: Given decay can originate from wounding of the host, limiting pruning wound sizes and extent of pruning can reduce the potential for the onset of decay.

 

Sources:

 

Koyani, R., Sanghvi, G., Bhatt, I., & Rajput, K. (2010) Pattern of delignification in Ailanthus excelsa Roxb. wood by Inonotus hispidus (Bull.: Fr.) Karst. Mycology. 1 (3). p204-211.

 

Lonsdale, D. (1999) Principles of Tree Hazard Assessment and Management (Research for Amenity Trees 7). London: HMSO.

 

Mattheck C., Bethge, K., & Weber, K. (2015) The Body Language of Trees: Encyclopedia of Visual Tree Assessment. Germany: Karlsruhe Institute of Technology.

 

Rayner, A. & Boddy, L. (1988) Fungal Decomposition of Wood: It's Ecology and Biology. UK: John Wiley & Sons.

 

Schwarze, F. (2008) Diagnosis and Prognosis of the Development of Wood Decay in Urban Trees. Australia: ENSPEC.

 

Watson, G. & Green, T (2011) Fungi on Trees: An Arborist's Field Guide. UK: The Arboricultural Association.

 

Weber, K. & Mattheck, C. (2003) Manual of Wood Decays in Trees. UK: The Arboricultural Association.

Edited October 31, 2015 by Kveldssanger

[tree-fancier123]

so how soon do you think before these mature ash fall over? I mean an ash that it is feeding on, does it take 10 years or so to kill it?

[Kveldssanger]

That would really depend on the genetic properties of the ash, the environmental conditions within and directly surrounding the wood substrate, the genetic proeprties of the fungus, and the presence (and genetic properties) of any other decay-(or non-decay-)causing fungi and bacteria. The general point is that its presence on ash is less desirable. It wouldn't be possible to give a guideline, though I suppose where decay is upon the main stem there is potentially a greater 'window' before probable failure when compared to decay upon a smaller limb.

 

Unless a very long-term study was done ascertaining average 'life expactancy' of ash with this fungal pathogen, we'd be in the realm of guess-work.

 

If the ash successfully compartmentalises the decay, infection is likely non-fatal. If it doesn't, then fracture may occur and this may lead to the death of the individual - given this fungus principally degrades heartwood. However, if it acts as a canker pathogen, if the main trunk is girdled then it may kill the host - or initiate sprouting below the girdling point.

Edited October 31, 2015 by Kveldssanger

[tree-fancier123]

ok thanks, this makes me wonder if there is more to come regarding the 'Arbrex' style pruning paints, at the moment the received wisdom seems to be 'let the air get to it, will heal over quicker', maybe pruning methods can still be improved upon. The flush cutting v mirror the collar instructions, maybe one day they'll say leave stubs, so it gives the tree a chance to compartmentalize inbound pathogen decay in the stubs, well away from the main stem. I appreciate you can only go with current best practice, especially if it has to pay the bills.

[Kveldssanger]

The defence systems of the tree are typically activated by the presence of oxygen and / or compounds (enzymes, etc) secreted by pathogens.

 

In relation to pruning cuts, leaving a stub is (currently) considered to be undesirable where a proper cut can be made, because the stub acts as a food source for any fungi (amongst other things). They can take advantage of this food source and gain extra energy to mount an attack on the natural barriers within the branch junction, that would not be available if the cut was finished to the industry standard.

[Kveldssanger]

02/11/15. Fact #69.

 

Oft, there is little regard of how the time of year will impact upon the ability for the tree to recover from pruning. However, the timing of any pruning is crucial, and deviation from the 'ideal' can have adverse impacts above and beyond the adverse impacts of artificial pruning.

 

Pruning during the spring flush should be avoided, as not only is pruning removing energy that the tree has 'invested' into its growth, but the jelly-like cambium easily separates from the wood.

 

Research from Europe indicates that pruning during late summer results in less decay than pruning during the dormant period. Wounds will seal more swiftly, and the defence mechanisms available to the tree are active as the tree is not dormant. Additionally, sapwood-exposed pathogens may struggle to successfully colonise during the summer, though it must be noted that rather dry sapwood is preferable for sapwood-exposed strategists. Where there has been significant drought over the summer period therefore, heavy pruning should be avoided.

 

Late summer (or even early autumn) pruning can however delay dormancy and initiate further growth flushes (such as with elms and maples). This is undesirable, as the oncoming frosts may damage the fresh growth, or damage foliage due to delayed dormancy. Pruning during the autumn also leads to increased wood discolouration following pruning. As sapwood is typically dry during autumn, pathogens may also colonise more readily.

 

Winter pruning is also considered 'good'; particularly just before spring flush. Energy reserves are not depleted whatsoever, and the oncoming sap flow will reduce the ability for fungi to colonise. Defence processes can also be activated soon after the pruning.

 

Spring and autumn - no. Summer and winter - yes. In theory. In practice, however...

 

Source: Gilman, E. (2012) An Illustrated Guide to Pruning. 3rd edition. China: Cengage Learning.