Kveldssanger

Welcome to the club.

I got these books earlier this week: The Structure and Life of Forest Trees Response of Plants to Multiple Stresses Growth and Development of Trees Volume I: Seed Germination, Ontogeny, and Shoot Growth. Growth and Development of Trees Volume II: Cambial Growth, Root Growth, and Reproductive Growth. Take your pick.

Of course - inter- and intra-specific variation will play a role. Unfortunately, Bob Watson provides only a few references, so I do not know where he got the information from. I suppose it would be more correct to suggest that low light and high humidity conditions provide an increased propensity for undifferentiated cells to form aerial roots. Ultimately, as long as the environmental and hormonal triggers are there, aerial roots can occur. And we don't know all of how a tree functions anyway, so we could be missing something from the equation. Karban's Plant Sensing and Communication publication from this year really opened my eyes to the fact that we are only just starting to comprehend the intricate inner-workings of plants, particularly on the chemical level.

14/11/15. Fact #77. When we think of hollowing (or hollow) veteran or ancient trees, oft is it suggested that aerial roots will utilise the mineralised nutrients, provided through the decay of the tree's own heartwood structure by fungi and bacteria, to aid with life processes. However, the presence of aerial roots may be over-stated. The author here suggests that aerial root formation (from undifferentiated cambial cells) requires specific conditions - namely, poor light conditions and high levels of localised humidity. Therefore, where these conditons are not present, internal aerial root formation is unlikely to occur. This almost certaily means the tree, where such conditions are lacking, will be unable to re-uptake such mineralised nutrients, as to do so it would need to grow fibrous roots from the periphery of the root crown (where roots are not covered by a corky bark layer) all the way to the centre of itself. Perhaps, therefore, the mineralised matter is more likely to become useful to future generations, with the veteran / ancient tree acting as a 'nurse' through the provision of its own nutrients to younger, more vigorous, individuals of the future. Source: Watson, B. (2006) Trees: their use, management, cultivation, and biology. India: The Crowood Press.

It would certainly be a good idea, as knowledge is critical in this industry. If there are any barriers to knowledge that arise because of language issues, then that must be remedied. Anyone here fluent in French and English?

12/11/15. Fact #76. Adventitious buds are capable of forming on many woody plant species, and are borne from parenchyma tissues not directly associated with the apical meristems, nor is their formation dictated by the prevailing 'phyllotactic' qualities of the woody plant (phyllotactic = leaf arrangement). When pruning, we may often state that many of the subsequent sprouts are adventitous in nature. Zimmerman & Brown suggest the opposite, and suggest that many of the sprouts are borne of pre-formed but suppressed buds that track just beneath the periderm. Most adventitious buds, they also state, are formed in the bark cambium (or cork cambium / phellogen, as it is otherwise called). Of course, once the adventitious sprouts are borne, they must make contact with the tree's vascular system, else they will die. Source: Zimmerman, M. & Brown, C. (1971) Trees: Structure and Function. USA: Springer.

Maybe the AA should translate their guide into other languages and sell them either as e-copies or actual copies.

Thanks for this. I knew I read that leaf factoid somewhere before! Forgot where, but now I know. A lot of people suffer from grasses with regards to asthma and hayfever.

12/11/15. Fact #75. In temperate regions of the world, the fruits and seeds of most tree species will ripen during the autumn and early winter, and this is down to, principally, the fact that the growing season is limited to only particular months of the year. Tropical regions do however also demonstrate seasonality, with regards to the ripening of fruits and seeds of constituent species. Ultimately, the phenology of each particular species, and variations also between a single spcies, determines exactly when ripening will take place. Interestingly, the manner in which a species will disperse its seed, in part, determines when the fruit and seeds will ripen. For example, deciduous trees that rely on wind dispersal will have their seeds ripen during very dry periods of the growing season, as the desiccation of seed and its subsequent 'mobility' is optimal under such dry conditions. Conversely, tree species that rely on animals to consume their fruits and then disperse the seeds elsewhere will have their fruits ripen during the wetter months of the growing season. In fact, plants in the USA that produce fruits will normally have their fruits ripen during the period where mass bird migration is taking place (during autumn). Of course, this trend is not necessarily true across the board, as Amelanchier spp. and Prunus serotina will ripen during the summer, though their means of seed dispersal is reliant upon mammals and non-migratory birds. Fruits that ripen during autumn are normally of high nutritional value, and are eaten in abundance by migratory birds as a result. This increases the chance of successful seed dispersal. Source: Sedgley, M. & Griffin, A. (1989) Sexual reproduction of tree crops. UK: Academic Press.

I had a fact posted but there was a 'database error' and the post didn't save. Will post it tomorrow!

All they need to do is sell the spores in sachets and we can have fungi-farms at each and every home.

^ Very professional! Good stuff.

You'd need to apply to the LPA with the TPO form, still.

^ The issue with limiting the availability on testing, such as with a driving test, is the subjectivity involved by the examiner. This means the system is open to abuse, by default. The answer is to do less in the way of implementing regulations, not more. If someone sucks at providing a service, let other people know and stay away from them. This applies for chainsaw instructors, driving schools, and so on. If one person does it, it's difficult. If many people do it, it's easy.

...so it's that time of year again when pollen starts getting everyone annoyed - noses clog up more readily than the junctions around the M25 at 8.30AM, eyes eject enough liquid to flood the Mississippi basin, and you could power the country on anger alone for a good two weeks... ...yeah no it's not that time of year, but alas. 09/11/15. Fact #74. Some people suffer from asthma or react otherwise adversely to tree pollen, which can lead to increased hospitalisation and medical care bills. The ill-health brought about by tree pollen can also bring about a drop in productivity of those affected, given time off of work may be necessary. In addition to this, the principal problem for urban residents during a survey undertaken on urban street trees was that of allergies, which indicates the potential scale of the issue. Sources: Alcázar, P., Cariñanos, P., De Castro, C., Guerra, F., Moreno, C., Domínguez-Vilches, E., & Galán, C. (2004) Airbone plane-tree (Platanus hispanica) pollen distribution in the city of Cordoba, South-western Spain, and possible implications on pollen allergy. Journal of Investigational Allergology and Clinical Immunology. 14 (3). p238-243. Dales, R., Cakmak, S., Judek, S., & Coates, F. (2008) Tree pollen and hospitalization for asthma in urban Canada. International Archives of Allergy and Immunology. 146 (3). p241-247. Lohr, V., Pearson-Mims, C., Tarnai, J., & Dillman, D. (2004) How urban residents rate and rank the benefits and problems associated with trees in cities. Journal of Arboriculture. 30 (1). p28-35. Lovasi, G., O’Neil-Dunne, J., Lu, J., Sheehan, D., Perzanowski, M., MacFaden, S., King, K., Matte, T., Miller, R., Hoepner, L., Perera, F., & Rundle, A. (2013) Urban tree canopy and asthma, wheeze, rhinitis, and allergic sensitization to tree pollen in a New York City birth cohort. Environmental Health Perspectives. 121 (4). p494-500.

I am a tree officer for a local authority, and there is a whole section of woodland management. I have a degree (BSc) in environmental conservation, which obviously helps massively, but I see no reason why you couldn't drift into the realm of woodland conservation. There is plenty of cross-over between arboriculture, woodland conservation, and forestry. In fact, they all need to work in tandem for a healthy tree population - particulrly if we class our urban trees as not individuals but an urban forest.

Doing the course at the moment. Covers a huge array of subjects. I believe it is recognised internationally. The ISA also offer a course.

08/11/15. Fact #73. Cladoptosis. We should by now, know what it means. If not, see this old fact I did. With regards to the hormones behind the process, ethylene is one of the principal plant hormones that features within the process. Ethylene encourages the re-allocation of resources away from shaded areas of the crown. When we understand that branches may likely be abscised due to poor photosynthetic capability (heavy shading it normally the cause), it begins to fall into place on the hormonal level. In certain species, such as oak, the process may in fact be staggered. The tree may first create a protection zone out at a distance from the junction, which leads to failure at that point. A long stub is then left, which can then be shed further down the line, by the same processes. Conifers behave slightly different to broadleaves. Whilst a conifer branch is alive, resin is impregnated into the core wood of the branch (that can at times propagate out into the branch itself). As the branch begins to die and the shedding process begins, the tree seals off the small area surrounding the branch base to resist progress of potential pathogens. Once the branch has died, it will break where the resin core ends. Sources: Karban, R. (2015) Plant Sensing & Communication. USA: University of Chicago Press. Shigo, A. (1986) A New Tree Biology. USA: Shigo and Trees Associates.

I am cursed by the name title of this thread, it seems! Of course, there's a large element of CF I don't talk about, though for a topic that can be so absurdly obfuscated by endless texts I tried to simple it down in a way that I can understand, and hope others can as well. Your addition, as well as Gary's, is great. And welcomed. This is exactly what I hoped this thread would do.

07/11/15. Fact #72. UK woodlands under private ownership may be at most risk of the threats of a warming climate and the evolving relationship between trees and their pests and diseases. A recent survey of private woodland owners highlighted that they are "not generally convinced of a need to adapt", as they "feel the future is uncertain, more usually in relation to tree disease than to climate change itself". Therefore, perhaps the (alleged) impending and growing threat is not simply due to climatic changes, but the lack of willingness to respond pro-actively. This may ring true for all threats of change, as well, if we use this research study as a proxy indicator. Source: Lawrence, A. & Marzano, M. (2014) Is the private forest sector adapting to climate change? A study of forest managers in north Wales. Annals of Forest Science. 71 (2). p291-300.

I know some of those words!

I hope my own calculations are right for the below - brain is nackered after writing about branch attachment for over three hours! 05/11/15. Fact #71. Chlorophyll fluoresence can be used as a means to determing plant health. As fluorescence gives information on the health of the photosystem II process of photosynthesis of a plant, overall plant health can be theorised by measuring fluorescence. This can be done by measuring fluroescence levels in the dark (min), when all electron carries for PSII are open, and fluorescence levels in high light exposure after taking the plant out from the dark and shining bright light onto the surface (max) - at this stage, all electron carriers are assumed to be occupied and therefore closed. From these measurements, the variable fluorescence level can be reached by 'maximum light - minimum light' (simply put). Basically, the closer to 1 then better, and the closer to 0 the worse health of the plant is. For instance if plant A is as follows: - f(minimum) is 3 - f(maximum) is 9 - f(variable) is therefore 6 (max - min) To calculate PSII efficiency, one divides f(variable) by f(maximum). In this case, that is 6/9, or 0.667. And plant B is as follows: - f(minimum) is 3 - f(maximum) is 4 - f(variable) is therefore 1 (max - min) To calculate PSII efficiency, one divides f(variable) by f(maximum). In this case, that is 1/4, or 0.25. Plant A is more efficient at PSII than plant B, as the figure is closer to 1 than in plant B. Plant B may therefore be under stress for whatever reason (drought, salinity, fungal attack, etc). Typically speaking, a good tree is able to use 75-85% of sunlight received (so the reading would be 0.75-0.85) for photosynthesis. When a tree is under stress, it is not able to utilise such high amounts of total light, thereby dissipating more light energy back (known as chlorophyll fluorescence). As any forms of stress have impacts upon fluorescence, calculating such fluorescence can aid with identifcation of stress and the current functionality of photosystem II. Sources: Badeck, F. & Rizza, F. (2015) A Combined Field/Laboratory Method for Assessment of Frost Tolerance with Freezing Tests and Chlorophyll Fluorescence. Agronomy. 5 (1). p71-88. Samy, É., Benoit, D., & Khanizadeh, S. (2014) Chlorophyll Fluorescence: A Novel Method to Screen for Herbicide Resistance. International Journal of Horticultural Science and Technology. 1 (2). p93-99. Tatagiba, S., DaMatta, F., & Rodrigues, F. (2015) Leaf gas exchange and chlorophyll a fluorescence imaging of rice leaves infected with Monographella albescens. Phytopathology. 105 (2). p180-188.

We were discussing mycorrhizal relationships today on the Lvl 4, so thought I'd make a post about how to improve mutual symbiosis between mycorrhizae and tree roots with regards to organic mulching / fertiliser application. 04/11/15. Fact #70. In certain instances, such as with phosphorus-limited soils, the application of organic fertiliser (particularly the application of nitrogen) can increase species diversity, richness and funtionality of mycorrhizae, thereby providing benefits for the rooting systems of trees present on the site. However, application of nitrogen in phosphorus-rich soils has the opposite effect. Therefore, fertilisation can improve conditions for mycorrhizae, though not in all instances - application in poor soils is far more preferable, as an improved nutrient profile can foster more substantial mycorrhizal relationships. Additional research highlights that organic fertilisation of soils increases the microbial respiration rate of mycorrhizae, in addition to their population density. Therefore, the relationship between roots and mycorrhiza is strengthened by fertilisation, given the benefits to the mycorrhizae. Furthermore, the application of phosphates can see marked increases in the assimilation of vital nutrients from the soil via the mycorrhiza, though care must of course be taken not to apply in excess. To build on the concept of excess, increases in nitrogen availability through deposition or fertilisation may reduce root colonisation and fruit body production by mycorrhizal fungi. Therefore, before any organic materials are added to a soil, it must be proven that the soil would benefit, ecologically (wth regards to the symbionts of roots and mycorrhizae), from any additions (as is outlined in BS 3998:2010). In addition, many mycorrhizae appear to prefer poorer soils in terms of nutrient availablity, so fertilisation may render mycorrhizae of less importance to root systems as nutrients are no longer lacking and the symbiosis is not as necessary. In turn, mycorrhizae may potentially become parasitic upon the roots. Additionally, fertilisation has the potential to make conditions more preferable for inferior mutualists, thereby having a negative impact upon the symbiosis of roots and mycorrhizae. It also appears that soil type can impact upon the efficacy of fertilisation. Research highlights that fertilisation does not influence mycorrhizal colonisation or abundance of soil hyphae in sandy loam soil, but in clay soil metabolically-active hyphae were more abundant with manure application than with mineral fertilisation. Sources: Egerton-Warburton, L., Johnson, N., & Allen, E. (2007) Mycorrhizal community dynamics following nitrogen fertilization: a cross-site test in five grasslands. Ecological Monographs. 77 (4). p527-544. Johnson, N. (1993) Can fertilization of soil select less mutualistic mycorrhizae?. Bulletin of the Ecological Society of America. 3 (4). p749-757. Kabir, Z., O'halloran, I., Fyles, J., & Hamel, C. (1997) Seasonal changes of arbuscular mycorrhizal fungi as affected by tillage practices and fertilization: hyphal density and mycorrhizal root colonization. Plant and Soil. 192 (2). p285-293. Shigo, A. (1991) Modern Arboriculture. USA: Shigo and Trees Associates. Tiquina, S., Lloyd, J., Herms, D., Hoitink, H., & Michel, F. (2007) Effects of mulching on soil nutrients, microbial activity and rizosphere bacterial community structure determined by analysis of TRFLPs of PCR-amplified rRNA genes. Applied Soil Ecology. 21 (1). p31-48. Treseder, K., & Allen, M. (2000) Mycorrhizal fungi have a potential role in soil carbon storage under elevated CO2 and nitrogen deposition. New Phytologist. 147 (1). p189-200. Wiemken, V., Laczko, E., Ineichen, K., & Boller, T. (2001) Effects of elevated carbon dioxide and nitrogen fertilization on mycorrhizal fine roots and the soil microbial community in beech-spruce ecosystems on siliceous and calcareous soil. Microbial Ecology. 42 (2). p126-135.

Ed Gilman's "An Illustrated Guide to Pruning" third edition. Not an e-book, but so worth it.

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.