(Arboricultural-styled) 'Fact of the Day'

[Kveldssanger]

11/09/15. Fact #30.

 

Work undertaken in Manchester, UK, recognised that the disparity between surface temperatures recorded within the shade of trees and out in the open were vastly different.

 

Peak surface temperature covered in concrete and in full sun were 40 degrees Celsius (17 degrees Celsius above air temperature), whereas peak tree shade temperature in a concrete environment was 28 degrees Celsius (4 degrees Celsius above air temperature).

 

Plots surfaced with grass however were 23 degrees Celsius (1 degree Celsius below air temperature) when the area was purely grass and the site in full sun, and 19 degrees Celsius (4 degrees Celsius below air temperature) where a tree cast shade over the grassed area.

 

Differences become more distinct at higher temperatures - where days are milder, there will be less variation between any of the surfaces.

 

Sources:

 

Armson, D., Stringer, P., & Ennos, A. (2012) The effect of tree shade and grass on surface and globe temperatures in an urban area. Urban Forestry & Urban Greening. 11 (3). p245-255.

 

Dover, J. (2015) Green Infrastructure: Incorporating plants and enhancing biodiversity in buildings and urban environments. UK: Routledge.

[Kveldssanger]

Anyone know of any articles assessing the potential for utilising selective white rotting fungi for delignifcation purposes within the commercial wood pulping industry?

[Kveldssanger]

12/09/15. Fact #31.

 

Interesting one here from Shigo on Armillaria spp. Perhaps more of a hypothesis by Shigo than a proven fact (unless there are more recent articles?), he suggests that spores of Armillaria species may have to pass through the digestive system of insects (gnats, predominantly) associated with the genus' sporophores before the spores can germinate. Such gnats end their life-cycle in the soil, so spores may be deposited during the gnat's later stages of life Therefore, if his theory is correct, assuming the insects are not present, then perhaps sporal germination simply cannot occur.

 

Source: Shigo, A. (1986) A New Tree Biology. USA: Shigo and Trees, Associates.

Edited September 12, 2015 by Kveldssanger

[bansobaby]

I just found this thread today, and have read it through.

 

It's absolutely fascinating!!

 

Many thanks to Kv for starting it and taking the time to post such interesting stuff. Likewise to all the others who have contributed.

 

I have enough scientific knowledge (just) to grasp the more esoteric subject matter and if I ever come across anything worthy of the thread will happily post it.

 

Keep up the good work:thumbup:

 

Cheers

Paul

[Kveldssanger]

Glad you like it, mate. And by all means share any links or interesting bits of info here - news articles of scientific advances are also greatly appreciated.

[Kveldssanger]

13/09/15. Fact #32.

 

This one is paraphrased from my notes for my upcoming course, so if it reads a little 'note-like', it's because they are from my notes!

 

Saproxylic species are species which are involved in or are (to varying degrees, and at varying stages) dependent on the process of decay of the wood structure by microorganisms (principally due to saproxylic species lacking the necessary gut enzymes to digest sound wood), or on the products of that decay. Such species are associated with living as well as dead trees, and will include include beetles most notably (which make up, on their own, 22% of a woodland ecosystem on average), though also ants and other insects.

 

Many species are reliant upon particular stages of the wood decay process. Those species that require fresh phloem tissue will only be able to colonise briefly in the first summer post-death. Other species require significantly-decayed wood of a particular micro-climate, and even of a particular tree species. Oak is a particularly crucial species that supports saproxylic species, because it generally lives for much longer than other species and thus provides a wider array of different micro-habitats through its greater internal complexity created by different stages of decay that are present throughout the structure.

 

The species are found particularly on older, veteran trees, including within cavities that possess wood mould, water-filled rot holes, dead bark, exposed wood, sap flows, fruiting bodies / mycelia of fungi, dead branches and dead roots. To illustrate this, 75% of saproxylic beetles are reliant upon coarse woody debris of 7.5cm-12.5cm diameter. Big trees ultimately provide habitat for a greater number of species of a greater number of sizes, all whilst supporting greater potential population sizes - and if healthy the trees live for long periods of time, sustaining such habitat for decades (if not centuries?), and continue to provide well beyond the point of ultimate death as well.

 

It is important to note that veteran trees within wood pasture, or other open area, are best for saproxylic species. The warmer conditions brought about by direct sunlight reaching the tree, increasing internal temperatures that in essence incubate the larvae within the tree, hasten generational turnover. Trees in cooler conditions within old high forest stands may experience fewer generations within the same time frame in comparison. Trees across all contexts are necessary however, and it is important for all veteran trees in all environments to be conserved for their value to such saproxylic species.

 

Such 'deadwood' species will also create entire 'necromass' sub-systems within an ecosystem (from mold fungi, to species that feed on mold fungi and the conditions created, to species that predate on lower-tier species within the food web, and scavengers that feed on dead organisms).

 

A prime example of a saproxylic beetle is the ecological 'engineer' Carambyx cerdo (Capricorn beetle), which creates viable habitat for many other species. The larval stage of the beetle bores into the wood, in turn causing localised expansion and altered wood properties (which are attractive for later successional species), and its exit holes are used by solitary bees and wasps as nesting holes that they otherwise would be unable to create themselves. Other saproxylic species also rely on such exit tunnels for entry into the wood.

 

As one can hopefully ascertain from the above, dead wood and associated saproxylic species, particularly beetles (Coleoptera), in forests, woodlands, parklands or open pasture-woodland, are indicative of high quality habitat. Let us not just focus on the macro, but the micro!

 

Sources:

 

Alexander, K. (2008) Tree biology and saproxylic Coleoptera: issues of definitions and conservation language. Rev Écol (Terre Vie). 63 (1). p1-5.

 

Alexander, K. (2013) Ancient trees, grazing landscapes and the conservation of deadwood and wood decay invertebrates. In Rotherham, I. (ed.) Trees, Forested Landscapes and Grazing Animals: A European Perspective on Woodlands and Grazed Treescapes. UK: Routledge.

 

Buckley, P. & Mills, J. (2015) The Flora of Fauna of Coppice Woods: Winners and Losers or Active Management or Neglect?. In Kirby, K. & Watkins, C. (eds.) Europe's Changing Woods and Forests: From Wildwood to Managed Landscapes. UK: CABI.

 

Davies, Z., Tyler, C., Stewart, G., & Pullin, A. (2008) Are current management recommendations for saproxylic invertebrates effective? A systematic review. Biodiversity and Conservation. 17 (1). p209-234.

 

Hammond, H., Langor, D., & Spence, J. (2001) Early colonization of Populus wood by saproxylic beetles (Coleoptera). Canadian Journal of Forest Research. 31 (7). p1175-1183.

 

Hermy, M. (2015) Evolution and Changes in the Understorey of Deciduous Forests: Lagging Behind Drivers of Change. In Kirby, K. & Watkins, C. (eds.) Europe's Changing Woods and Forests: From Wildwood to Managed Landscapes. UK: CABI.

 

Macagno, A., Hardersen, S., Nardi, G., Lo Giudice, G., & Mason, F. (2015) Measuring saproxylic beetle diversity in small and medium diameter dead wood: The “grab-and-go” method. European Journal of Entomology. 112 (3). p510-519.

 

Siitonen, J. & Ranius, T. (2015) The Importance of Veteran Trees for Saproxylic Insects. In Kirby, K. & Watkins, C. (eds.) Europe's Changing Woods and Forests: From Wildwood to Managed Landscapes. UK: CABI.

 

Stokland, J., Siitonen, J., & Jonsson, B (2012) Biodiversity in Dead Wood. USA: Cambridge University Press.

 

Volney, W. & Hirsch, K. (2005) Disturbing forest disturbances. The Forestry Chronicle. 81 (5). p662-668.

[Kveldssanger]

Few things associated with learning:

 

1. The Research for Amenity Trees 4 - The Body Language of Trees: A Handbook for Failure Analysis by Mattheck will not be reprinted - ever.

 

2. The Arboricultural Practice Notes are going to feature in the digitisation process the Forestry Commission are going through with regards to their publications. They should therefore be available online at some point in the future.

[tree-fancier123]

Does the new Mattheck encyclopedia of VTA contain all the stuff that was in 4: Body Language?

[Kveldssanger]

Most of it, yes. I do prefer the RFAT4 however - it's set out brilliantly and more formally.

[Jon Heuch]

Trouble with this research, other than stating the obvious that trees provide shade and cooling, is that Manchester is a cold, wet miserable place and a bit less shade might make it a bit more tolerable. And if it ever did get a bit hot on a few days of the year, go and buy a fan or even an air conditioner!

We can learn a lot from the people of Manchester, who, in all those hot stinking days in Manchester when they are gasping for a bit of shade do what? Head to the airport to go somewhere a bit warmer!

 

I am of course joking to some degree but the blinkered logic of more-trees-must-be-good because, god help us, climate change is going to make life SO unbearable needs to be challenged.

 

May be too many Smilies?