Accumulation of leaf needles at tree base and other updates

The below would be an update for this post on de-compacting a tree base:
http://openplants.blogspot.sg/2017/05/accumulation-of-years-of-leaves-and.html

Photos taken on 14 Feb 2018.

The tree that I de-compacted the tree base still looked lush as ever, but the tree beside it actually looked worst; the leaf density decreased.

The tree base that I de-compacted (left) is starting to compact again but still appeared flatter than the one on the right.

River bank failure possibly due to high velocity water. Self-sown plants were valiently holding on to the slope face but alas, it was too steep (or the water eroded away the soil it was rooted in).

Location marked with red arrow.

Lastly, one of the last few pages of the book "Trees of Our Garden City, 2nd ed" feature the iconic (at least to me) arching Callistemon viminalis, between the Chinese Garden MRT station and Garden. It was removed I think in 2016 to make way for a cookie-cutter landscaping at the peripheral of the MRT station.

Taken on 22 Sep 2014.

Taken on 14 Feb 2018.

Root development limited by surrounding shrubs

Shrubs surrounding a tree, Tabebuia rosea, along a roadside verge at Beach Road may have limited its spread of roots. The area is sheltered by buildings although it was located quite close to the coast. It used to be closer, hence the road name but reclaimation changed the actual moniker.

The tree may have been fine with not spreading its roots too far. But one day the leaf cover of the shrubs were taken off and coupled with the monsoon season, mercilessly dumping large volumes of rainwater onto the relatively small planting verge.

 Taken up one lane

Lifted root plate

Trees that can tolerate semi-shade sunlight

Frustrated that you cannot plant trees under mature trees or near tall buildings where there is semi-shade? Be angsty no more.

Species    Maximum known height    Description
1. Ardisia elliptica    8m    native; small tree, sparse columnar crown, edible small fruits
2. Artocarpus rigidus    35m    native; dense, spreading crown, edible large fruits, hard wood
3. Baccaurea parviflora    6m    native; small tree, edible small fruits, hard wood
4. Barringtonia racemosa    27m    native; sparse crown, drops flowers and seeds
5. Bauhinia purpurea    6m    sparse crown, Leguminosae
6. Brownea grandiceps   20m   sparse crown, pendulous young leaves are brown with green specks, flowers are arranged in a ball shape
7. Calophyllum soulattri    26m    native; dense, spreading crown, edible small fruits, hard wood
8. Cratoxylum cochinchinense   10m   sparse crown, pendulous leaves, flaky bark
9. Cynometra ramiflora    26m    native; dense, spreading crown, hard wood
10. Diospyros buxifolia    35m    native; sparse, spreading crown, hard wood
11. Elaeocarpus mastersii    20m    native; dense crown, edible small fruits
12. Erythroxylum cuneatum    33m    native; sparse crown, hard wood
13. Garcinia atroviridis    27m    native; sparse conical crown, edible large fruits
14. Heritiera littoralis    25m    native; sparse, spreading crown, drops seeds
15. Maniltoa browneoides    12m    sparse, spreading crown, prominent young flushes (handkerchiefs),  hard wood, Leguminosae
16. Palaquium gutta    30m    native; sparse spreading crown, hard wood (Nyatoh)
17. Saraca thaipingensis   20m   sparse crown, young pendulous flushes purplish, flowers after pronounced dry weather
18. Streblus elongatus    33m    native; sparse spreading crown, hard wood
19. Syzygium glaucum   10m   native; leaves with rounded tip, flaky bark
20. Syzygium polyanthum   30m   native; fruits eaten by birds, leaves used as spice

Some trees to feature (photos below are taken by me unless stated otherwise):

Calophyllum soulattri

 Photo taken at Hortpark, near Pasir Panjang Nursery.

 

Flowers

Cynometra ramiflora

This is a Cynometra cauliflora actually, but looks similar to a C. ramiflora from a distance. Flanked on the right by a Flacourtia inermis.

Different shades of young leaf flushes.

Diospyros buxifolia

Photo taken at Singapore Botanic Gardens.

Close-up on leaves. Image: Scott Zona, CC BY-NC 2.0

Maniltoa browneoides

Photo taken somewhere at a roadside in Tuas.

Prominent young flushes (handkerchiefs).

Streblus elongatus

A sapling planted behind park name signage (that is made of recycled timber). Photo taken at Tampines Eco Green.

The unique elongated flower clusters that develop at the leaf axils. Male flowers are whitish and small. Image: Cerlin Ng, CC BY-NC 2.0

And female flowers are larger, appearing almost like a large ant's head. Image: Cerlin Ng, CC BY-NC 2.0

Honourable mention: Ficus lyrata

 Multiple shoots branching - a form that is rarely seen locally. Image: Forest & Kim Starr, CC BY-NC 3.0

Ficus lyrata 12m Non-strangling fig tree, slow-growing, leaves resemble a fiddle, top the plant from an early age to encourage branching, toxic plant sap

Machinery Equals/Not Equals to Productivity 2

Continuing from the previous entry, the Husqvarna 430X takes about 22 hours a day, 7 days a week to mow 3/4 acre. It would mow for about 2 and half hours, then recharge for an hour, then mow for 2 and half hours and charge for an hour, cycling continuously rain or shine. The end result is that the lawn would be more lush and always look manicured, and since the clippings are returned to the soil, little application of fertiliser was required. As compared to, I suppose, a rotary mower used twice a month on the lawn, sweeping away the clippings, and perhaps applying fertiliser afterwards. In the shoes of a landscape worker, I would welcome such a widget that needs little to no "supervision" while I could spend more time and attention on pruning shrubs.

I think it was about 5 years ago that CUGE started a programme to rent machinery out to landscape companies in order to encourage them to use more machines or even purchase some of their own after trying the rentals out. Amongst the mechanical wonders were a backhoe, skid-steer + trench digger combo, wood chipper, and get this - a soil potting machine. I don't think the rental programme lasted for 2 years.

 A backhoe that has to be repositioned after digging was done at one spot.

A skid-steer that required the operator to stand. More suitable to dig trenches (on flat ground), as the brand name suggested.

This photo was taken from an area accessible to the public after the rental programme had closed. A soil potting machine out in the open with a tarp draped over it, which was breaking down due to being exposed to the elements.

Slightly more than a year ago, NParks released S$3 million for the Landscape Productivity Grant (LPG) to contribute towards the purchase of machinery by landscape companies and plant nurseries. The grant subsidised half of the machine price, and the Productivity and Innovation Credit (PIC) scheme subsidised 60% of the other half. The company would pay for the remaining, which is 20% of the machine price. NParks reported that a previous tranche of the LPG saw companies achieving the following improvements to their productivity through mechanisation.
- 77% savings in man-hours as a result of using wood chippers
- 60% savings in man-hours after switching to the use of ride-on mowers
- 50% savings in man-hours using tractor-mounted hedge-trimmers
- 80% savings in man-hours as a result of deploying a wireless remote mower

A tractor-mounted hedge-trimmer being utilised along an expressway. Not seen in this photo was the media posse in front of the tractor.

 One whole lane have to be closed just for this machinery to be used. I have not seen this on the roads myself.

 A similar attachment mounted on an Avant loader chasis. This machine was not used in the park ever again after photo taking.

 A stump grinder that I have not seen after taking this photo on Aug 2013.

Do we still have the same amount of productivity improvements despite of all these machines being put out of action? I think the answer would be resounding. The way these "x0% savings in man-hours" was derived is by demarcating a set amount of work - 1 km of shrubs, 1 acre of lawn, 1 lorryload of branches, etc. - and have the machine tackle the work, and have an appropriate number of human workers carry out the same work. The man-hours put into each set of work would be compared against one another. Outside these trials, landscape works were often back to square one. I heard that a company that owned a remote controlled mower used it rarely. When they have hordes of workers using backpack mowers, it was but a logical development. Of course not all landscape work are deprived of mechanisation. For example, in arboriculture.

Other than lifting workers up into the tree crowns and hauling trunks, apparently the crane could be used to grub out stumps. 

UPDATE

 Saw this stump grinder outside CCK Lot 1 on 3 Feb 2018.

Machinery Equals/Not Equals to Productivity

I was checking out Gebiz as usual in my down time and came across a tender for a "robotic mower", which I thought would be one of these remote controlled mowers featured along with the Landscape Productivity Grant (more on that later). But it turned out to be something less controlled and more automated.

Nah, not this type.

 

So. Refined.

Here goes the boring Gebiz details:

INVITATION TO QUOTE FOR THE PURCHASE OF A ROBOTIC MOWER UNIT AND THE OPTION TO PURCHASE SPARE PARTS AND ENGAGE TROUBLE-SHOOTING SERVICES

Quotation No.: NPB000ETQ17000133
Agency: National Parks Board

ITEMS TO RESPOND
1. Robotic mower unit
2. Blade
3. OTHER ITEM OF WORK AND/OR SERVICE NOT INCLUDED IN ITEMS ABOVE BUT WHICH ARE NECESSARY FOR THE FULL AND SATISFACTORY COMPLETION OF THE WORKS.
4. OPTIONAL ITEM - Supply and replacement of Battery, Rechargeable (12 months warranty against manufacturer's defect upon acceptance of item).
5. OPTIONAL ITEM - Supply and replacement of Sealing Strip (for control panel) or equivalent.
6. OPTIONAL ITEM - Supply and replacement of Sealing Strip (for main unit body) or equivalent.
7. OPTIONAL ITEM - Supply and replacement of Wheel Snap Function (for wheel) or equivalent.
8. OPTIONAL ITEM - Supply and replacement of Motor Assy or equivalent (at least 3 months warranty against manufacturer's defect upon acceptance of item).
9. OPTIONAL ITEM - Supply and replacement of Motor Assy Height Motor or equivalent (at least 3 months warranty against manufacturer's defect upon acceptance of item).
10. OPTIONAL ITEM - Supply and replacement of Joystick Kit Rear or equivalent.
11. OPTIONAL ITEM - Supply and replacement of Joystick Kit Rear ( for column kit ) or equivalent.
12. OPTIONAL ITEM - Supply and replacement of Motor Kit Drive Wheel or equivalent (at least 3 months warranty against manufacturer's defect upon acceptance of item).
13. OPTIONAL ITEM - Transportation & on-site inspection/service charge (Per trip).
14. OTHER ITEM OF WORK AND/OR SERVICE NOT INCLUDED IN ITEMS ABOVE BUT WHICH ARE NECESSARY FOR THE FULL AND SATISFACTORY COMPLETION OF THE WORKS.

[Edit: Seemed like items 3 and 14 are repeated. Below are the excerpts of the response of two companies that participated in the ITQ.]

Company A (Awarded)

1. $3980 - HUSQVARNA (SWEDEN) AUTOMOWER - MODEL 430X (PN 967 62 25-03)
GPS Assisted Navigation/ 0.8 Acre Working Area Capacity
2. $71.55 - Husqvarna Automower Blades
3. $1500 - Installation Package includes 2 x complimentary follow-up service/loop wire reset with 3 months from installation
4. $214.50 - Husqvarna Automower 430X Replacement Li-Ion Battery
14. $1105.30 - Additional Automower Ad-Hoc Replacement / Service Parts & Accessories

Company B

1. $7500 - Robotic mower unit
2. $2160 - Blade
3. $4500 - Labour $1500 Wire Laying/ Trenching / Material $4500
4. $850 - Replacement battery
14. $1500 - Labour

The awardee was a lot more competitive in pricing as compared to the latter, and even so they could have profited quite a bit.

This bundle, costing approx SGD 2900, includes an install kit that comes with guide wires (250 metres), which sets the boundary for the robot mower (see below).

 The yellow line around the property represents the guide wires that tells the robot mower not to go past. The dotted lines are its mowing path I suppose.

The guide wires were installed a few inches below ground, so I have no idea why the second tenderer have to go and cost in $1500 for laying it and $4500 in materials (which I guess are the guide wires and staples). Assuming the lawn that this mower was used on was exactly 0.8 acres (3237.5m2), and the guide wires were laid just around the boundary, then only 227.6m of it was needed. The install kit comes with slightly more than that length of guide wires.

No Country for Old (and Young) Trees

Perhaps in view of the incidences of large trees, especially Khaya sp. (African mahogany) falling down and causing loss of lives and damage in property, they have been felled in large numbers. Well except in the case below, that tree has been "halved".

 

Photo on the left mentioned in this post: http://openplants.blogspot.sg/2016/10/pruning-of-trees-for-wind-resistance.html

The Rain tree (Samanea saman... or as the rest of the world know it by Albizia saman) that used to be in that spot used to be as large as the one in the background. I suppose defects on the tree called for it to be removed, and it was replaced by this young Rain tree. But it did not last long, possibly broke in half by strong wind travelling through that "wind tunnel". Its root ball was dug up, and the hole was left uncovered.

Photo on the left mentioned in this post: http://openplants.blogspot.sg/2017/04/arboriculture-happenings-at-bugis-area.html

 A replacement tree of the replacement tree seen on 23 Oct 2017.

Papers Excerpt - Strength Loss Due To Decay

Journal of Arboriculture 18 (4): July 1992
Determining Strength Loss from Decay by E. Thomas Smiley and Bruce R. Fraedrich

SL% = d^4/D^4 x 100 ;Originally developed by engineers to compare the strength of pipes.
SL% = d^3/D^3 x 100 ;Wagener modified it to take into account the irregularity of  trees.

SL% =     d^3 + R(D^3-d^3) x 100
               -------------------------------
                              D^3
SL = Strength loss
d = Diameter of hollow and/or nonstructurally sound wood
D = Diameter of sound wood
R = Ratio of cavity opening to stem circumference

The R(D^3-d^3) modification was developed by the Bartlett Tree Research Laboratories to account for wood which is "missing" at a cavity opening.

Among trees that broke from internal decay, average strength loss was 33% with a SD of 22% [could be between 11% and 44%].

Severity of decay in the trunk predisposes trees to failure [felling, breaking into half, etc.]. Other factors include crown density, branching structure, leaning, location of decay (e.g., in crotches), site exposure, storm severity, [and might I include inherant wood strength]. A lower threshold (20-25%) may be used for trees that are more predisposed.


Journal of Arboriculture 27(2): March 2001
Comparing Formulae that Assess Strength Loss Due to Decay in Trees by Brian Kane, Dennis Ryan, and David V. Bloniarz