Enhancing Post Transplant Success In Palms

At a resort development in Bagan, Myanmar.

Transplanting Borassus flabellifer (Sugar or Toddy Palm) from a farm to the resort for an instant landscape effect. The palms at the farm had their roots burlapped a month beforehand.

The palms would give the reception building in the background a "countryside" look.

Couriered over some rooting hormone (auxin), controlled release fertililser and measuring implements.

 Advised the landscape team there to use one litre bottles to measure out 20 litres or so in a large bucket.

Using my own rooting powder to gauge of the amount to scoop out on the field by the number of tablespoons.

Using a cup with a marking to give a gauge of the amount of fertiliser to be given to each palm on the field.

Workers had no troubles following the instructions.

Mixing some rooting hormone powder in a bucket of water.

Root Cuts

Urban environments often have trees planted in straight rows in order to make the space greener and smooth out its rough edges. And often, that landscape would have to grow by way of road widening, drain improvement, etc., and some trees would have to go. So what would go into the decision of which trees to be removed, and which could be retained?

Construction activities such as demolishing, building, excavation and heavy vehicles traversing the site would damage and cut roots, which diminishes tree health and/or structural stability.

When roots must be cut, they should be cut as far away from the trunk as possible to reduce impact to tree health. If the root space is permanently lost as a result of lowering the grade or construction of a structure, then the portion of root system cannot be replaced, and stress and stability issues may not be overcome.

Before any works, it is a good idea to locate roots by hand digging or excavation using compressed air tool. A new technology, ground-penetrating radar (GPR) can be used to detect roots as deep as 0.9 m and with a diameter as small as 1 cm. However, the size of roots cannot be determined, two roots close together cannot be distinguished, and the soil type is ideally in sandy soil. Resolution and depth of detection is reduced with soil with high water and clay content, which is the case in Singapore's soil.

In nature, root injuries are common and roots have evolved to have strong compartmentalisation. Just as flush-cutting branches is no longer an acceptable practice, pruning a root to its point of origin should not cut into the parent root. And preferably beyond sinker roots, and several smaller cuts instead of one large-diameter cut. Tools that are not sharp enough to cut roots such as excavators are used, they would result in torn and crushed. Such damaged roots should be pruned with a clean cut instead of being left as they are.

Trenching in a linear manner at a distance from the trunk that is less than three times the trunk diameter (or DBH x 0.5 x 5 from the center of trunk) can reduce stability. Adventitious roots may be formed by trees with root loss and are able to provide them with water and nutrients to maintain green foliage. However, those roots are too small to support the weight of the tree and may result in tree failure in wind conditions. Tree support systems and tree removal are possible remedies.

More research is needed to determine and recommended specific practices on the factors that affect decay development after root pruning: root diameter, distance from the trunk and presence of heartwood on the cut surface.

A Giant from Thailand - Tamarind Tree Transplanted within Hortpark

Tamarindus indica (Tamarind) somewhere in the middle of Hortpark, which was transplanted from the entrance of Hortpark.

Tamarind Road in Yishun is named after this tree. The fruit is known locally as "assam".

The area immediately around the trunk was sunken, as compared to the outer ring of the compost circle. This is possibly due to the root ball of the tree sinking, as it was transplanted when it was already a large tree.

Fungal fruiting bodies a.k.a. mushrooms observed at the root flare of the tree, presumably exacerbated by the compost that is piled around it.

Before being transplanted to the middle of Hortpark. Compare this root flare with the one above, the buttress roots were more apparent. Photo taken approximately 7 years ago (Feb 2010).

Somehow in the trenching process the rootball was raised, and the root flare was covered. Hence, resulting in the tree being planted at grade or lower than grade, even though it was thought to be planted higher than grade by using the top of the rootball as a guide.

 

Tamarindus indica (Tamarind) was located at the carpark entrance of Hortpark at Hyderabad Road. This tree was first brought in from Thailand. At the time when it was being transplanted to the middle of Hortpark, it had been there for 2 years (since 2008). Girth was 1.5m (DBH 0.48m or 18.78 inches) and height just under 10m.

The tree after its second transplanting.

Generally, this species has low chances of success when transplanted, which is in stark contrast to the other species in the same family (Leguminosae). It was being transplanted without trenching beforehand, and waiting a few weeks to encourage new fine roots*, and that would further lower transplant success. Trenching more than 10 weeks before moving the tree may reduce the advantage of root pruning, as regenerated roots will quickly grow outside of the rootball.

A rule of thumb was that transplanted trees would take one year to recover for every inch in diameter. Recovery was defined as being able to resume growth in girth, not just putting out new foliage. The tree would need, in "theory" (again, rule of thumb), almost 19 years to recover, based on a DBH of 18.78 inches. Hence, the tree would need 12 more years from today in order to increase in girth. That is, if it manages to overcome a possible basal decay as indicated by the fungal fruiting bodies.

*Fine roots refers to roots (0.05 - 2.0mm dia.) that are colonised by mycorrhizae, and both of them are responsible for the entry of water and nutrients into the plant from the soil.

Accumulation of years of leaves and debris covering root collar

Somewhere adjacent to the M+S building along Beach Road.

North-east facing heap approx. 0.5m height

 South-west facing heap approx. 0.3m height. One large surface root damaged.

Recent soil disturbance due to construction of the M+S building. Distance from edge of trunk to "heap cut" is 0.8m for both sides. The accumulated material was hard but a bit spongy. Width of planter 2.0m.

Peltophorum pterocarpum (Yellow flame tree) - 2.0m girth, 9m height, 12m spread. 

Recently crown thinned and topped.

Reminded me of some years ago, I spent nearly two hours breaking and clearing the accumulated material at the tree base of a Gymnostoma nobile (Bornean Rhu) with a hand hoe (see photo below). In this photo, my colleague Eina is putting on the finishing touches by filling up the depressions with a good soil mix and contouring. On the right was a tree that still had a compacted tree base.

Hand hoe

 The area where the bark did not develop fully the bark was decayed was the height of the accumulated material.

What seemed like a before-and-after photo but its not. The tree on the right, which was doing better to begin with had its accumulated material removed, and the tree on the left had not been worked on. This photo was taken just 4 days after the accumulated material was removed.

The root collar excavation should have been done on the tree on the left as the leaf density is lower than that of the tree on the right, which indicated a possible defect in the root collar.

Taken on 26 Mar 2016

Tree Branch Falls on Car at Cairnhill Road on 12 May 2017

Opposite of The Laurels @ 38 & 40 Cairnhill Road. The branch was so large I thought it was a whole tree at first. Photo: Stomp

Turned out to be one of the co-dominant branches. Photo: Stomp

View of the tree trunk and crotch taken on Aug 2016. Note the branch bark ridge. Photo: Google Maps Streetview

Overall view of tree taken on Aug 2016. Photo: Google Maps Streetview

Mr. Mattheck said that co-dominant branches are not bonded together like a branch-stem attachment and hence weaker, but they rarely fail because the branches rise vertically, as compared to a branch that hangs perpendicular to the stem.

Bogstadveien 19, Oslo, Norway

Continuation of the second part of this blogpost: http://openplants.blogspot.sg/2017/05/monitoring-at-risk-trees-using-spectral.html

Figure 1. Google Maps screenshots - the left photo was presumably from an earlier date, as compared to the right photo that has a tree missing in the middle.

Figure 2. A gap in the middle where a tree could have been. Credit: Google Maps.

Figure 3. Another angle of where a tree could have been. Note the house with orange window frames and the house with white walls in the background of the red ellipse. Credit: Google Maps.

Figure 4. Google Streetview taken on August 2014 screengrab. Could that tree be mislabelled as Alive Tree #2? That period was somewhere in summer, so that was maybe why the trees were having lush growth. Note the construction material laid on the area in front of the tree.

Figure 5. Google Streetview taken on May 2016 screengrab. Could that tree be mislabelled as Alive Tree #2? That period was somewhere in late spring, so that was maybe why the trees were still putting out leaves. Hence, hard to tell whether the reduced leaf density was due to stress. Note the slight difference in foliage colour between the two tallest trees. May have to wait till 2018 for the Google Streetview car to go past that park to see whether the fallen tree was mislabelled or not [if the tree is not there anymore, then its mislabelled].

Figure 6. Photo from Aftenposten (The Evening Post) 10 Aug 2016, taken by Rolf Øhman. Several other trees around the city fell in the same night, so presumably there was a short storm event? Note the house with orange window frames and the house with white walls in the background, as mentioned in Figure 3.

Is the tree fall related to the construction activity of converting soccer pitch surface from loose asphalt to paved asphalt? Fertilisation on the lawn behind the tree causing the tree to develop a smaller root system? Dutch elm disease? Leaching of heavy metals and PAHs from the paved asphalt?

Excerpt of News - Botanic Gardens Safe for Visit: NParks

Comprehensive tree management scheme in place and more checks will be done, it says.
Samantha Boh The Straits Times 13 Feb 2017

...
Singaporean plant expert Jean Yong, an eco-physiologist at the Australian Research Centre for Mine Site Restoration, said...

"Issues relating to urban trees are challenging and require good scientific allometric assessment to better predict tree stability when the soil is very wet, and when encountering a seasonal microburst of strong gale-force winds," Dr Yong said.

Besides tree health, which routine inspections now focus on, constraints to root space volume should also be recognised and documented, he added.