Detailed
Transplantation Proposal for Ehretia acuminata
1.
PROJECT INFORMATION
1.1
Introduction
The Drainage Services Department (DSD) is undergoing
the Project entitled “Drainage Improvement Works in Sai Kung” (Contract no.:
DC/2006/01). Hong Kong Landscaping
Company Limited was appointed for the Project to responsible for
transplantation of plants of conservation interest.
1.2 Background
The habitats of the rare tree species Ehretia acuminata were recorded in area
near Ho Chung Channel during the tree survey will unavoidably be modified by
the proposed construction works. As
a consequence, mitigation measures focused on transplanting plants of
conservation interest before commencement of the construction works at the
above-mentioned area are required under the Environmental Permit.
This Transplantation Proposal is submitted
under the Condition of Environmental Permit (EP-217/2005). This proposal is
prepared taking due to the considerations of the permit conditions and the
findings of the tree survey for the Project undertaken in 25 May 2007 and a
follow up survey was also undertaken in 30 August 2007. Under the requirement of the Environmental
Permit, this proposal provides details on the locations of the plants affected
by the works, the number of plants to be transplanted, locations of the sites
for transplantation, methodology, implementation programme,
post-transplantation monitoring as well as the qualification and experience of
the qualified persons responsible for the transplantation works.
1.3 Transplantation
specialist qualification
Mr.
Tsui Ka Hing, Stanley is
experienced in seed collection, transplantation, planting and preparation of
receptor site since 1981. Curriculum vitae of the specialist are provided in
Appendix C.
1.4 Structure of the Report
The report has been organized into the following Sections:
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Section
1 – Project Information
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Section
2 – Pre-transplantation Survey
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Section
3 – Seed collection Methodology
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Section
4 – Transplantation Methodology
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Section
5 – Transplantation Site
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Section
6 – Implementation Schedule
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Appendix A – Tree Location Plan
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Appendix B – Drawing of Proposed Receptor Site,
Temporary Nursery & Photographic Record
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Appendix C – Curriculum Vitae of Mr. K. H. Tsui,
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Appendix D – Photographic Record
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Appendix E – Tree Assessment / Monitoring Schedule
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Appendix F – Example of Root Pruning Works
1.
PRE-TRANSPLANTATION SURVEY
2.1 Methodology
Pre-transplantation surveys were taken to
identify the present conditions of the project site, the location of the
species of conservation interest and the most suitable receptor site for the
plant species. The terrestrial
habitats within the site boundary have been surveyed. The occurrence of the species of conservation
interest, the Ehretia acuminata, was
determined during the pre-transplantation surveys. All of the recorded individuals of the
species of conservation interests have been mapped and tagged. Photographic records of reach identified
individuals were taken and the detailed information on plants such as height
and health condition was recorded.
Results
The species of conservation interest, Ehretia acuminata, were recorded within
the site area in Ho Chung during the survey dated 25 May 2007 and 30 August
2007. Each of the identified
individuals of Ehretia acuminata was
tagged and the assessment of the individuals is presented in table 2.1. Photographic record during
pre-transplantation survey and the location of the Ehretia acuminata is presented in Appendix D.
Table
2.1 Assessment
of the Ehretia acuminata within the
Works Area
|
Tree Survey 1 – Dated 25 May 2007 |
||||||||
|
Tree No. (Tree No. Shown on drawing) |
Scientific Name of Species |
Size |
Health Condition |
Tree Form |
Amenity value |
Remarks |
||
|
Trunk Diameter (m) |
Height (m) |
Canopy Spread (m) |
Good / Fair / Poor |
( Good / Fair / Poor ) |
( High / Medium / Low ) |
|
||
|
HC093 |
Ehretia acuminata |
0.3 |
9.0 |
5.0 |
Fair |
Poor |
Low |
Rare Sp., Leaning, Vined |
|
HC094 |
Ehretia acuminata |
0.18 |
4.0 |
3.0 |
Poor |
Poor |
Low |
Rare Sp., Broken Trunk, Heavy Vined |
|
Tree Survey 2 – Dated 30 August 2007 |
||||||||
|
HC093 |
Ehretia acuminata |
0.3 |
9 |
5 |
Poor |
Poor |
Low |
30 August 2007 Rare Sp., Leaving thin Crown Heavily
Vined |
|
HC094 |
Ehretia acuminata |
0.18 |
4 |
3 |
Poor |
Poor |
Low |
Rare Sp., Broken Trunk, Thin Crown Heavily Vined |
2.
SEED COLLECTION METHODOLOPY
3.1
PREPARATION
OF SEED COLLECTION
Prior to transplantation of Ehretia acuminata, seed should be collected
for conservation of genetic resources for future generations. Due to its leaving form and uneven crown
shape tilted towards the river; an understorey netting system has been
installed in early July after initial preliminary tree survey in May, in
preparation of seed collection.
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Understorey
plants or ground covers shall not be trampled while collecting seeds,
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Keep
any collected seed in dark, dry, sealed containers,
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Record
the name of the species, and location and date of collection for any seeds collected,
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Do not
disturb other plants, nesting sites, tree hollows or animal habitat,
3.2
SEED
PROPAGATION
Rare species revegetation requires many
seeds to increase the chances of success. Propagation can be a great way to achieve
bioconservation and to reduce impact on the loss of biodiversity in any
project.
Ehretia
acuminata is a native
species found in Asia,
To propagate plants, a number of plastic
punnets with adequate drainage holes make good sowing boxes. Firmly press down the soil into the
punnet, before sowing seeds in good soil mix in tubes (example: 1 part peat, 1
part fine sand, 1 part coarse, sharp sand and 1 part isolite), ensure all
equipment has been disinfected to avoid introducing any diseases to damage the
health of new seedlings. In
addition, seeds should not be sow too thickly or they will not grow
properly. Seeds should be covered
with a general rule with a depth of twice the diameter of the seed. For very fine seed, use finer particle
sand in the soil mix.
3.3 SEED GERMINATION
The whole aim of propagation is to raise
healthy progeny or seedlings with deep vertical rooting systems that can be
replanted to its original local habitat in the most suitable planting season
after the completion of construction works.
Seedlings initially germinated in shade and
shall require full sun to germinate effectively. Seedlings are ready for planting in
autumn. Growing over summer
provides excellent growth rate but hot weather can cause desiccation and
dormancy. To avoid this problem, it
is therefore recommended to start the plants grown in shade, and transfer to
full sun after the main germination period. Wind can also be very drying, hence,
‘shade cloth’ shall be provided as good shelter for windy areas.
Seed boxes require good air flow to prevent
fungal and pest or disease problem.
Steam-air sterilization is recommended to reduce the chance of disease
invasion. Watering is essential and
critical to ensure seedlings survival.
Soil mix should not be dry out, it must be kept moist at all times
during the initial stages. Morning and afternoon are the most suitable timing
for watering. Finely sprinkle the
tubes with water or bottom watering is useful but should not be used in
unutilized soil.
Germination may vary from several days to
several weeks, as soon as germination occurs and a ‘true-leaf’ appears,
transplant the seeding into a plastic parallel-sided pot, as they prevent root
curl. Potting mix for the seedlings
should contain more loam or peat moss, for example, 1 part river sand, 1 part
loam and 1 part peat moss.
Once the seeds have germinated, watering
once in the morning will be sufficient (varies depending on daily weather condition). Night watering is avoided as it
encourages fungal disease and pests.
After three to four weeks, a light dressing of a slow release
fertilizers should be apply to encourage healthy growth.
3.4 SUMMARY AND SCHEDULE OF SEED COLLECTION, SEED
PROPAGATION AND GERMINATION
The below charts illustrate the schedule of
seed collection, seed propagation and germination from June 2007 to end of
September 2007.
3.
TRANSPLANTATION METHODOLOGY
4.1 Preparation of Receptor Site
Before transplanting, preparation work such
as site clearance at the receptor site will be carried out. The approved receptor site will be
cleared and tree pits will be excavated for the transplanted individuals of Ehretia acuminata. Soil conditioner or soil mix to tree pit
will be imported. Compacted soil
around the planting hole shall be loosened with a spade to aid air
penetration. The exposed soils will
be covered by tarpaulin to prevent any environmental disturbance.
The seedlings of approximately 300 to
4.2 Transplantation Works
The transplantation work will be undertaken
before the commencement of the construction works. The detailed transplantation methodology
is listed below:
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Crown
Pruning and tree Surgery
(Prior to any works, all branches or root
to be cut shall be advised to the Engineer)
Adequate crown reduction to prevent
transpiration to be carried out accordingly. Shape and form of crown to be retained;
Crossing branches to be selectively pruned;
Prune all diseased/malformed branches;
Remove lower branches to leave a minimum
All cuts shall be carefully made to avoid
splintering or tearing of barks.
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Root
Pruning (Refer to Appendix F for example of root pruning illustrative works)
The diameter and depth of root ball shall be
a minimum 10 times of the trunk diameter at
Root pruning shall be done in three
stages. Root activator and water
crystal shall be applied to increase the survival rate.
The 1st Stage
Cutting two circle trenches on two sides of
the root ball. The trench size
shall be
The 2nd Stage
Cutting two circle trenches on two sides of
the root ball. The trench size
shall be
The last Stage
The root ball container shall be made
Cutting of the underside of the root ball
and root ball shall be potted with geotextile container. The space shall be filled with moist
soil conditioner as transplanting of the tree to the final designated location.
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Planting
Area Preparation
Prior to the lifting of the trees, tree
pits and transplantation records shall be approved by the Engineer.
The tree pit shall be prepared as follows:
All pits should be greater than the size of
root ball in all dimensions except the depth.
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Transplanting
Works
Upon lifting, the root ball shall be
wrapped with damp Hessian and kept moist from the time of lifting until it is
transplanted.
During transportation, trees shall be
protected against excessive sunlight, wind and drought.
Trunk of trees should be wrapped to prevent
damage to the bark. Both trees will
be kept in holding nursery at the period between lifting and planting to its
final location, they shall be carefully protected and maintained. Maintenance
shall include watering and if necessary, addition of fertilizer, insecticide
and herbicide until the final planting location is available. Well drained soil in a sunny open area
will be suitable to hold both specimen in this temporary nursery for
approximately one to two years.
After the tree has been placed in its final
position, adjust orientation of crown, backfill with topsoil which has been
mixed with a slow release fertilizer.
Backfilling shall be done in layers, each being firmly consolidated to
eliminate air pockets. The base of
the tree shaped depression of the diameter of the root ball shall be left to
facilitate watering.
The trees shall be
thoroughly watered in after planting.
4.3 Post-Transplantation Monitoring
The receptor site was selected based on its
similar characteristics to the donor sites which are considered to be the
favored habitat of the Ehretia acuminata. The transplanted individuals of Ehretia acuminata are expected to be
self-sustaining and can be established well in the receptor site in the
future. In order to secure the
survival of the transplanted individuals of Ehretia
acuminata, regular checking will be undertake in the first year after the
transplantation. Watering and
application of fertilizer will be undertaken if necessary. The area around the tree should be
mulched-care and should be taken not to place mulch against the tree
trunk. The monitoring details are
scheduled as follows.
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The
transplanted plant will be watered once every week except wet season and will
be fertilized once every 3 months after transplantation.
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Weeding
around the seedlings plant will be carried out once per month.
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Photographic
record should be used as one of the methods for monitoring the survival and
growth condition shall be monitored once per month.
4.
TRANSPLANTATION SITE
5.1 Proposed
receptor site for the species of conservation interest
Pre-transplantation surveys were undertaken
to identify the most suitable receptor site for the transplantation of the
species of conservation interest.
The selection of the suitable receptor site has generally been based on
the following criteria:-
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Area
of similar habitat characteristics as the donor site (within the project site)
and preferable with previous records of the species in the areas.
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Area
not affected by the construction activities and away from human disturbance.
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Area adequately
away from the project site but not difficult to access in order to minimize the
transportation time as well as the impacts on the transplanted individuals.
The receptor site of the transplanted trees
HC093 and HC094 is shown in the drawing no. 72302/3012B in Appendix B.
6. IMPLEMENTATION SCHEDULE
In accordance with the construction
programme, the Contractor intends to commence the work activities in November
2007.
All the transplantation work will be
completed before any construction works commence at the affected area.