Assessing root compaction and dysfunction

[David Humphries]

Woodland Beech colonised by Meripilus giganteus and early Kretzschmaria deusta presence.

 

 

Soil is bagshot sand over clay.

 

Path heavily compacted by regular footfall of dog walkers and runners.

 

Canopy showing signs of dysfunction predominantly on the path side of the tree.

(reduced by 3m to limit wind load)

 

Assessment of path compaction undertaken using basic penetrometer.

dropping weight at 1m increments from tree out toward drip line across path and also on opposite side of the root plate.

 

 

 

 

Variable readings (from 2 - 10cm penetration) but basically confirmed that the path was the most compacted area.

 

We then fired up the airspade to assess the roots within 3 trial pits.

One in the middle of the path and the other two off the path either side of the tree.

 

 

 

 

Unsuprisingly the pit in the middle of path took 30mins to excavate and had limited roots in whereas the other two pits were opened to the same extent within 10mins and had significantly more roots in.

 

 

 

 

 

In conclusion we believe the path compaction has led to the root dysfunction, developing ideal conditions for the Meripilus colonisation.

 

We are now considering path diversion or spreading the footfall weight at this and other similar tree locations across the site.

 

 

 

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[Steve Bullman]

Interesting post David, thanks for sharing.  I really must get over to the heath some time!

[Gary Prentice]

Great photos and well documented. 

 

[David Humphries]

20 minutes ago, Steve Bullman said:

Interesting post David, thanks for sharing.  I really must get over to the heath some time!

Get in the queue matey, we've hosted arbs from Hong Kong, Poland and the USA over the last few weeks, really must get on with some bloody work 

 

We're also on Country File next week, which will either be really cool or really embarrasing 

 

 

 

 

 

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[kevinjohnsonmbe]

Interesting exercise 

 

Could I ask some questions please David?

 

 - It looks like there are +/- 4 people involved?

 

- Could you place an indicative cost bracket on delivering this exercise (assuming it was a day?)?  (I'd like to try to understand if there is a realistic chance of delivering this level of care and attention to privately owned trees) 

 

- Where the roots were found to be diminished in the high compaction track area, would you expect them to recover if traffic was reduced and soil conditions improved or halt / reduce the denudation?

 

-  Was it freezing up North there or did you make them wear type C trousers as a punishment for some undisclosed misdemeanour?

 

 

[David Humphries]

53 minutes ago, kevinjohnsonmbe said:

Interesting exercise 

 

Could I ask some questions please David?

 

 - It looks like there are +/- 4 people involved?

 

- Could you place an indicative cost bracket on delivering this exercise (assuming it was a day?)?  (I'd like to try to understand if there is a realistic chance of delivering this level of care and attention to privately owned trees) 

 

- Where the roots were found to be diminished in the high compaction track area, would you expect them to recover if traffic was reduced and soil conditions improved or halt / reduce the denudation?

 

-  Was it freezing up North there or did you make them wear type C trousers as a punishment for some undisclosed misdemeanour?

 

 

There were actually 5 people there, I invited a tree officer from the Royal Parks along as they were experiencing similar situation with Beech and Merip and wanted to see (amongst other things) what the airspade could/would show.

 

We undertook assessment on 3 other trees with Merip and Grifola frondosa today (see other thread on air spading) so cost would be spread across the 4 trees. It's also our own compressor and airspade. 

Tbh, I don't think I could put a realistic cost to the day from a contractors perspective.

 

Due to an estimated 7million footfall per annum, we have big problems with managing access and reducing footfall on the roots of trees like this.

It's only an aspiration, but if we could divert or spread the weight load I would like to believe that there would be an improvement in soil conditions, but that would likely take considerable time if left to pure footfall management.

Ideally the compaction would need to be broken, organic material added and the footfall reduced/limited as an ongoing concern.

 

It was a chilly 14 degrees up here in 'North' London today, normally we undertake air spading in manikins but I didn't really want to inflict the watching Arbtalker membership to that particular sight 

 

 

 

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[Gary Prentice]

8 minutes ago, David Humphries said:

It's only an aspiration, but if we could divert or spread the weight load I would like to believe that there would be an improvement in soil conditions, but that would likely take considerable time if left to pure footfall management.

Ideally the compaction would need to be broken, organic material added and the footfall reduced/limited as an ongoing concern.

Peter, the Head Forester at Burleigh, has had similar issues with the horse trials and all the vehicles that attend the events. His solution was to tip woodchip by the wagon load up to a foot thick in places. It was still ongoing when I went, but the reduction in compaction even after two years was really significant, both in petrometer readings and improvement within the tree canopies.

[David Humphries]

13 minutes ago, Gary Prentice said:

Peter, the Head Forester at Burleigh, has had similar issues with the horse trials and all the vehicles that attend the events. His solution was to tip woodchip by the wagon load up to a foot thick in places. It was still ongoing when I went, but the reduction in compaction even after two years was really significant, both in petrometer readings and improvement within the tree canopies.

Yeah I've spoken with someone involved in the compaction study and mulch applications at Burghley.

 

would of also liked to have attended the tree radar demo up there last year.

 

 

 

 

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[kevinjohnsonmbe]

29 minutes ago, David Humphries said:

Due to an estimated 7million footfall per annum, we have big problems with managing access and reducing footfall on the roots of trees like this.

Thanks David, I'm a bit transfixed on financial planning at the moment so it fell into that bracket of my thinking!  Whatever the actual cost of that exercise, once measured against the assessed 'worth' of the individual tree, and factored against the number of trees in the park afflicted by footfall compaction...  the cost over potential benefit ratio must be massively favourable. 

[David Humphries]

Some useful promo/instructional videos for airspading/soil excavation here......

 

https://www.airspade.com/reference-library/instructional-videos