(Arboricultural-styled) 'Fact of the Day'

[Kveldssanger]

Absolutely. If the tree is grown as a specimen, you want it to adopt the most preferable form going from an aesthetic standpoint. The last thing I would want is ivy to swamp the tree's crown over time, detracting from its value.

[tree-fancier123]

Thanks. In terms of biomass weight ivy must be one of the most successful plants, bloody litter.

[Kveldssanger]

I'd say it probably is! Its shade tolerance is a testament to the durability of plants.

 

What I would say is that ivy has only become a 'problem' as man has sought to take trees out of the forest and into cultivation. In a woodland setting, ivy does a great job ecologically, and I suspect also genetically, in terms of 'weeding-out' less vigorous specimens by smothering the crowns entirely, thereby keeping species genetically more 'optimal' than if the ivy didn't exist. One could argue it is almost a parasite in its later life stages, once it smothers the entire crown of a tree.

 

In a cultivation setting however, where amenity is perceived as a principal driving factor in why a tree even exists in such a spot, ivy becomes a problem. It causes the tree to react in a manner that is divorced from amenity, and people therefore identify it as a problem. In addition to this, cultivated trees are usually more exposed, thereby meaning the ivy actually increases wind sail to a point where it may become a potential hazard, and the more readily-available light allows the ivy to really dominate.

 

As with all issues we have with trees, they are borne from our desire to cultivate and 'own' specimens for their amenity value, rather than their inherent value to landscape ecology. The lack of regeneration in the cultivated environment also means ivy is more noticeable as a problem, as there aren't 50 trees about with one being smothered in ivy - there is one tree, and it's smothered completely.

Edited October 10, 2015 by Kveldssanger

[Kveldssanger]

11/10/15. Fact #57.

 

As with any living organism, fungi must allocate resources available, both internally and externally, for successful continuation of the individual. Simply, the individual must maintain maximum energy 'credit' whilst minimizing energy 'costs'. Perhaps the most crucial issue is that of the relationship between energy gained as a result of exploitation of a resource, and the energy expended in successfully exploiting the resource. How this relationship develops ultimately governs the 'functional mode' the individual will adopt, as outlined in a previous fact of mine, and can be assessed through four simple questions:

 

(1) What is the relationship between external resource supply and internal resource (nutrient) concentration?

(2) How are resourced partitioned between the young and old parts of the mycelium?

(3) How are resources partitioned between exploratory and exploitative mycelial 'phases'?

(4) How are resources partitioned between mycelial and reproductive structures?

 

These four questions can now be broken down and individually analysed.

 

1. The relationship between external resource supply and internal nutrient concentration

 

The two principal elements required by fungi are carbon and nitrogen. The external availability of the two resources therefore governs the internal concentration, as the individual can only exploit what is available to it within the wood substrate.

 

With particular reference to nitrogen, individuals may 'adapt' and move into a 'low nitrogen state' when the ratio of C:N (carbon:nitrogen) is high - this is however common for all fungi; not just those that inhabit wood. It is also a rather obvious and expected adaption, given the external lack of availability of nitrogen. Such nitrogen supply, or in turn low carbon supply, does have the ability to impact upon growth of the individual, however - the adaption is merely a way of responding to an 'undesirable' situation, and both resources, where found lacking, should be viewed independently from one another in their ability to impact upon growth rate and resource allocation.

 

Where neither carbon nor nitrogen is available in gross abundance, low concentrations of nitrogen may facilitate deficiencies in the 'rate of supply' to the individual. This is because there is inter- and intra-hyphal competition for the resources. As a result, there is a different between what is 'absolutely available' from the substrate, and what is 'relatively available', so to speak.

 

 

2. Partitioning of resources internally between young and old parts

 

Evidence does suggest that individuals will recycle older, redundant parts of their mycelium structure, and supply the recycled material to the more 'active' regions - nitrogen is most commonly recycled in such a manner, as it is usually the more limited of the resources. Whilst such re-allocation of nitrogen occurs, the individual will metabolise carbon to facilitate such internal re-allocation.

 

Interestingly, individuals may not only be able to utilise their own redundant mycelium for such purposes, but also the redundant mycelium of other individuals. Further to this, there is also a suggestion that extracellular enzymes may be recycled as well.

 

 

3. Partitioning between exploratory and exploitative mycelial 'phases'

 

Individuals have been shown to utilise their successful exploitative structures to 'fuel' exploratory growth through very 'nutritionally inert' expanses of soil, with the intent of locating further areas of high nutritional value. Therefore, assuming an individual is readily exploiting a particular area, it may initiate growth elsewhere within its structure to find new sites to exploit, as long as it has the energy available to do so - all whilst continuing to supply energy to maintain and develop other parts of the mycelial structure.

 

Potential also exists for an individual to 'scavenge' any organic and mineral nutrients during its sojourn across otherwise nutritionally inert territory.

 

 

4. Partitioning between mycelial and reproductive structures

 

The progression from vegetative development to reproductive development is considered to be a 'landmark event' in the life processes of an individual. Such a landmark event is therefore not without its resource demand.

 

Research undertaken on perennial fruit bodies such as Ganoderma applanatum, Fomes fomentarius and Fomitopsis pinicola indicates that current-year growth of a sporophore may have up to six to twelve times the amount of nitrogen as the previous year's (or years') sporophore growth - this included, for the current-year, the spores themselves. The progressive decreasing of available nitrogen was so orderly that it cold be stipulated that mechanisms exist for the retrieval of nitrogen from older tissues.

 

As a slight aside, though nonetheless a very interesting observation, the nitrogen in 13.6g of wood in Betula sp. would be required to supply 1g of sporophore formation in Ganoderma applanatum. Further, if a 1.135kg sporophore existed and grew within a period of 20 days, as was the case for a particular Fomes fomentarius sporophore in 1936, then 40.3kg of birch wood would be required to supply all the needed nitrogen.

 

 

Sources:

 

Clipson, N., Cairney, J., and Jennings, D. (1986) The physiology of basidiomycete linear organs. I. Phosphate uptake by cords and mycelium in the laboratory and the field. New Phytologist. 104. p444-458.

 

Dowding, P. (1981) Nutrient uptake and allocation during substrate exploitation by fungi. In Wicklow, D. & Carrol, G. (eds.) The Fungal Community: Its Organization and Role in the Ecosystem. New York: Marcel Dekker.

 

Dowson, C., Rayner, A., & Boddy, L. (1986) Outgrowth patterns of mycelial cord-forming basidiomycetes from and between woody resource units in soil. Journal of General Microbiology. 132 (1). p203-211.

 

Dowson, C., Rayner, A., & Boddy, L. (1988) Foraging patterns of Phallus impudicus, Phanerochaete laevis and Steccherinum fimbriatum between discontinuous resource units in soil. FEMS Microbiology Ecology. 53 (5). p291-298.

 

Jennings, D. (1982). The movement of Serpula lacrimans from substrate to substrate over nutritionally inert surfaces. In Frankland, J., Hedger, J., & Swift, M. (eds.) Decomposer basidiomycetes: their Biology and Ecology. UK: Cambridge University Press.

 

Levi, M. & Cowling, E. (1969) Role of nitrogen in wood deterioration. VII. Physiological adaptation of wood-destroying and other fungi to substrates deficient in nitrogen. Phytopathology. 59 (4). p460-468.

 

Levi, M., Merrill, W., & Cowling, E. (1968) Role of nitrogen in wood deterioration. IV. Mycelial fractions and model nitrogen compounds as substrates for growth of Polyporus versicolor and other wood-destroying and wood-inhabiting fungi. Phytopathology. 58(5), 628-634.

 

Merrill, W. & Cowling, E. (1966) Role of nitrogen in wood deterioration-amount and distribution of nitrogen in fungi. Phytopathology. 56 (9). p1085-1090.

 

Meyer, H. (1936) Spore formation and discharge in Fomes fomentarius. Phytopathology. 26. p1155-1156.

 

Park, D. (1976) Carbon and nitrogen levels as factors influencing fungal decomposers. In Anderson, J. & Macfayden, A. (eds.) The Role of Terrestrial and Aquatic Organisms in Decomposition Process. UK: Blackwell Scientific Publications.

 

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

 

Rayner, A., Watling, R., & Frankland, J. (1985) Resource relations - an overview. In Moore, D., Casselton, L., Wood, D., & Frankland, J. (eds.) Developmental Biology of Higher Fungi. UK: Cambridge University Press.

 

Thompson, W. (1984) Distribution, development and functioning of mycelial cord systems of decomposer basidiomycetes of the deciduous woodland floor. In Jennings, D. & Rayner, A. (eds.) The Ecology and Physiology of the Fungal Mycelium. UK: Cambridge University Press.

 

Thompson, W. & Rayner, A. (1983) Extent, development and function of mycelial cord systems in soil. Transactions of the British Mycological Society. 81(2). p333-345.

 

 

Note 1: Back issues of Phytopathology can all be found here, usually as the entire texts (pre-1997).

 

Note 2: Under 'fair use', and for non-commercial purposes, in addition to aiding with private study of individuals, which are outlined as exemptions in part of the overall beast that is Copyright Law, I have attached the pages relevant to this aforementioned text (The Fungal Decomposition of Wood). If there is an issue here, I am more than happy to take the attachment down, or for the moderators to take the file (PDF) down. Please also note I have shared, for non-commercial purposes, no more than is necessary.

The Fungal Decomposition of Wood excerpt.pdf.pdf

[Kveldssanger]

Jules. I remember some pages back you commented on plants recycling their carbon dioxide. I just found a comment that echoes this in Trees - Their Use, Management, Cultivation, and Biology. It reads "photosynthesis releases large amounts of oxygen into our atmosphere and uses some of the carbon dioxide derived from respiration."

 

[Kveldssanger]

13/10/15. Fact #58.

 

One will often attribute air pollution with a higher rate of tree disease (impairing mycorrhizal associations and activities, modifying internal physiological processes, etc). However, the opposite may also manifest - diseases may function less optimally where conditions are adverse, due to air pollution (at least, in part).

 

For example, if sulphur dioxide, fluoride, or ozone are toxic to the particular pathogenic organism, their presence within the local atmosphere may hinder its development. Additionally, if such pollutants are also (or exclusively) beneficial for the tree, then the host may have heightened defence capabilities.

 

In essence, two concepts must be considered:

 

(1) how does the pathogen impact the tree's response to airborne pollutants?

(2) how do the airborne pollutants impact upon the progress of the pathogen both directly (by altering pathogen functionality) and indirectly (by altering host functionality)?

 

Ultimately, any factor that has an influence upon the functionality of a living organism has the potential to 'shape' its development over generations. Therefore, airborne pollutants have the ability to alter species composition within a forest (or other) ecosystem.

 

Source: Treshow, M. (1975) Interaction of air pollutants and plant diseases. In Mudd, J. & Kozlowski, T. (eds.) Responses of Plants to Air Pollution. USA: Academic Press.

[daltontrees]

11/10/15. Fact #57.

 

As with any living organism....

 

... no more than is necessary.[/i]

 

Tha't not a fact, that's a magnum opus!

[Kveldssanger]

Haha it took me two hours to sort it all from start to finish. Once I started writing I couldn't finish half way through. I cut the next section (partly relevant) off as it would have gone on for much longer otherwise.

 

I hope the opus is of use, of course.

[Kveldssanger]

15/10/15. Fact #59.

 

Exactly how plants respond to flooding depends on numerous 'macro' factors, ranging from species characteristics, genetic properties of the individual, soil properties, extent of flooding, duration of flooding, and more. These factors are the difference between a tree surviving two successive flood seasons, and not surviving a temporary flood lasting no longer than four weeks. At the same time however, the growth responses of the tree to flooding, the extent of injury suffered from the flooding, amongst other responses by the tree, will also influence survival.

 

It is largely recognised that angiosperms tolerate flooding more than gymnosperms, with a few exceptions. However, even two closely-related species may exhibit markedly different tolerance levels to flooding. For example, Nyssa aquatica tolerates flooding much better than Nyssa sylvativa. Similarly, Betula papyrifera fares less optimally when compared to Betula nigra.

 

Of the gymnosperms, well-adapted species include Taxodium distichum, Sequoia sempervirens, and to an extent Pinus echinata, Pinus taeda, and Pinus rigida.

 

With regards to fruit trees, there is 'wild' variation. In France for example, apples were more tolerant than pears, peaches, and cherries (in that order). Additional research has suggested tolerance is high for quince, pears, and apples, whilst citrus and plums possess some tolerance. Cherries, apricots, peaches, almonds, and olives are much more sensitive, in that order. Rootstock can also dramatically impact tolerance, as well - variation within individuals therefore exists, depending on the rootstock they were grafted on to.

 

Source: Kozlowski, T. (1984) Responses of Woody Plants to Flooding. In Kozlowski, T. (ed.) Flooding and Plant Growth. USA: Academic Press.

[Kveldssanger]

Any requests from anyone for specific types of fact?