(Arboricultural-styled) 'Fact of the Day'

[Kveldssanger]

Eh well; I lied. Only a little fact, but think it's pretty cool (albeit rather obvious when you think about it).

28/08/15. Fact #17.

 

The benefits of organic mulching are clear, though asphalt and concrete may act as a mulch for young and newly-planted trees in city areas. Both surfaces not only protect the roots physically, but also aid with water retention and reduce potential compaction effects (thus keeping the soil nicely aerated).

 

Source: Shigo, A. (1991) Modern Arboriculture. USA: Shigo & Trees, Associates.

 

Obviously once secondary thickening really kicks in the concrete / asphalt is shattered apart and there are quite literally trip hazards everywhere. If you're lucky you may even be able to spot a root tapering away from the tree for many metres (I find planes, poplars and cherries are very good at this, inspecting street trees daily).

[Kveldssanger]

Are there any articles on what to do if a tree has been struck by lightning, and how to reduce the risk of lightning strikes? I know there's this book by the ISA, and I have an article by Bartlett on lightning rods, but is there anything more extensive (such as studies into the effectiveness of such rods)?

[Gary Prentice]

Are there any articles on what to do if a tree has been struck by lightning, and how to reduce the risk of lightning strikes? I know there's this book by the ISA, and I have an article by Bartlett on lightning rods, but is there anything more extensive (such as studies into the effectiveness of such rods)?

 

I think Guy at Historic Tree Care (Treeseer) posted something up a few years back. It may only have been the ANSI for installation though. He's probably the fellow to ask.

[Kveldssanger]

30/08/15. Fact #18.

 

Underground sewer pipes within urban areas will, particularly as they depreciate, facilitate entry of roots, via cracks, into the inner structure of the pipe, where roots can exploit the freely-available moisture (and nutrients). Such invasion by roots has lead to the development of pipes that possess, in theory, greater resistance to root intrusion, with the industry moving away from clay and concrete pipes of old to modern PVC and modern concrete pipes of today.

 

Historically, manufacturers would have focused pipework design on ensuring pipes are impervious to incoming and outgoing water. Little to no focus was on making pipes resistant to tree roots, and where research was undertaken into resistance to root invasion the species used were grasses (Poaceae spp.) and lupines (Lupinus spp.) - not willows and poplars! Perhaps this is why, today, so many problems exist - particularly when one recognises many pipes (around 24%) are operating 'beyond' their life expectancy and are in poor (or worse) condition, within the UK.

 

But how effective are these new pipes?

 

Tests were thankfully more robust with these new forms of pipework, with this study's research in particlar seeing poplars (Populus x canadensis var. Robusta) planted directly above PVC and modern concrete pipework systems that were laid approximately 70cm below the surface (for reference, the groundwater table in the area was down at 1m in depth).

 

Now for results.

 

Put succinctly, even these new pipes were found not impervious to tree roots. Particularly at joins between two pipes and at junctions (for example, where PVC pipe met concrete pipe, or where two PVC pipes are joined together), root entry was still a common occurrence (which is no real surprise) - even where self-vulcanising (self-amalgamating) tape was wrapped around joints, roots still intruded into PVC pipes but not concrete pipes - this was thought to be due to the tape's ability to stick better to concrete than PVC. However, roots that penetrated into PVC pipes were usually only 0.1-0.3mm in diameter, whereas roots that penetrated into modern concrete pipes were up to 3mm.

 

The study also concluded that the density of roots in the vicinity of the pipework demonstrated that leakage was not a driver in roots invading the pipework itself. Instead, condensation upon the pipework seemed to be a principal factor behind root intrusion and density upon and immediately around the inner and outer surfaces of the pipes - particularly when 12 of the 17 penetration points involved roots growing through air within the pipe; only 5 were below water level within the pipe.

 

Concluding remarks suggest that it is almost a given that tree roots will still invade modern pipework systems, so other means of damage mitigation / postponement should be practiced, particularly around inherent weak points within the structure of pipework. These include: (1) plant trees only where soil conditions are suitable and roots need not readily invade pipes to acquire needed moisture, (2) plant appropriate species at appropriate distances away from pipes, and (3) install root barriers.

 

Source: Ridgers, D., Rolf, K., & Stal, O. (2009) Observations of Tree Root Penetration into Modern PVC and Concrete Sewer Pipes. In Watson, G., Costello, L., Scharenbroch, B., & Gilman, E. (eds.) The Landscape Below Ground III: Proceedings of an International Workshop on Tree Root Development in Urban Soils. USA: International Society of Arboriculture.

[Kveldssanger]

I think Guy at Historic Tree Care (Treeseer) posted something up a few years back. It may only have been the ANSI for installation though. He's probably the fellow to ask.

 

Found an old one from the JoA.

p0145-0149.pdf

[Kveldssanger]

Not so much a fact here but more of a comment. From reading Shigo's A New Tree Biology and Modern Arboriculture, it is clear how he advocated arborists and those alike to consider their actions before exercising them. One particular point I wish to pick up on here is the use of chemicals to control pests that may not be abundant, but merely 'undesired' (in a human sense).

 

For instance, say one sprays an Ilex to rid it of P. ilicis. In doing so, yes the leaf miner is killed, though what about the parasitoids and pathogens of the insect? Their populations will suffer, too.

 

It's important that when undertaking control methods, we consider the non-target effects also.

[daltontrees]

Maybe a subject for a new thread, but can anyone explain why beech doesn't coppice, or many/most coniferous species.

 

I speculated recently about this on UKTC, in short (most) conifers produce adventitious buds but these are reabsorbed within a few months unless used byt the tree. Beeck bark, for all that it is smooth and one might be tempted to think it is thin, is impenetrable by dormant buds. Cut a Beech back to any diameter more than a few inches and you will get no regeneration.

[Kveldssanger]

Interesting. Got a source for that at all?

[openspaceman]

I speculated recently about this on UKTC, in short (most) conifers produce adventitious buds but these are reabsorbed within a few months unless used byt the tree. Beeck bark, for all that it is smooth and one might be tempted to think it is thin, is impenetrable by dormant buds. Cut a Beech back to any diameter more than a few inches and you will get no regeneration.

 

Yes is it size or age of the wood at the cut? Beech hedges survive trimming.

 

For 20 years I worked on an estate which had a hanger of beech coppice, 90 years since last coup from a ring count, and complete with charcoal hearths every 50 metres cut into the bank. The estate boundaries were laid beech hedges that had been left and grown into linear beech features.

 

In 1984 we stored the coppice to see if the canopy would take advantage of the light and upgrade the stems into saw timber, At that time there were several markets for 8"+ clean beech and these were 20 metre clear stems but too small because of the competition from other stems.

 

As an experiment it was an abject failure because on October 16th 1987 90% of it blew down. Whilst the loss of mutual support probably exacerbated the loss all the estate woodlands were affected.

[David Humphries]

................Cut a Beech back to any diameter more than a few inches and you will get no regeneration.

 

 

I'm not sure this is an entirely accurate fact Jules.

 

I think it's a given that as a species it's not the choice of coppicers, but my observations suggest that it is capable of regenerating from large diameter stumps (12" stump in first 3 images) and I've also witnessed beech putting out epicormic growths from buttresses where there is basal decay on a number of different examples.

 

 

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