訪問[HK01] 山竹遺禍 粉嶺華明邨現塌樹危機 專家：風災後至少一年先安全

20190422 [HK01] 山竹遺禍　粉嶺華明邨現塌樹危機　專家：風災後至少一年先安全

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The Direction of Urban Forestry in Hong Kong

(The original version of this article was written for ISA Hong Kong Chapter Newsletter Vol. 2)

In last article we have briefly reviewed the fundamentals of Urban Forestry.  We will continue to elaborate the concept through understanding the situation in Hong Kong this time.  It is important to acknowledge and evaluate our diverse urban forest asset as the foundation for developing a strategic plan.

Notwithstanding being a small city, there are quite diverse and relatively sufficient area of urban forest to sustain the living quality of more than 7.3M population.  Merely our country parks have covered more than 40% of total land area of the territory.  Our current urban forest asset was mostly established since 1950s through massive plantation, planned greenery programmes, or by unintended neglect in some areas.  Together with parks, gardens and other green open space, the per capita urban forest area in a board sense is 105 sq. m (Annon, 2011), a figure quite high amongst cities in the South-east Asia (Table 1).  However, the figure would drop to just ~2.5 sq. m (comparable to some cities in developing countries) if country parks are excluded (Jim, 1998).

City	Population (density person/km2)	Sq. m/capita (year)
UN’s target (World Health Organization, 2010)	-	Min. 9.5 Ideal 50
Hong Kong	7M (6362.2)	105 (including country parks)
Bangkok	5.7M (3607.4)	3
Beijing	17.6M (1069.4)	88
Deihi	17.4M (11733.0)	19
Guangzhou	7.9M (2067.5)	166
Hanoi	6.5M (1935.1)	11
Jakarta	9.2M (13889.9)	2
Kuala Lumpur	1.7M (6811.1)	44
Manila	11.6M (18165.1)	5
Seoul	10.5M (17288.8)	23
Singapore	5M (7025.2)	66
Taipei	2.7M (9789.9)	50
Tokyo	13M (5946.9)	11

Table 1 – Comparison of green open space accessible by the public (including planted areas with trees) (Annon, 2011)

Our urban forest has provided various services to the society of Hong Kong (Fig. 1).  There are quite diverse components of urban forest locally (Wong, 2017) and they have some shared services to the city, such as carbon sequestration, reducing heat island effect, improving physical and physiological health of the citizens.  On the other hand, some services are quite specific to particular sites.  For example, roadside tree rows for shading and screening, slope planting for erosion control, roof top planting for reducing energy consumption, country park for conservation and water catchment.

Fig. 1 – Major components of urban forest in Hong Kong and their key services to citizen life.

Through often taken for granted or even being unnoticed, such diverse functions of urban forest are comparably important to the services that other city infrastructures such as roadworks, water and power supply, drainage, hospital provide.  In the past, budget and standard for designing, building and maintenance of urban forest (green infrastructure) were very low when compared with other aspect.  Tree planting (usually absorbed in landscaping) mostly if not all comprise less than (if not much less than) 10% of the total contract sum of any development project.  As plantings were generally classified as “landscape” (amenity, or aesthetic) only, the real services of them were always masked.  With underestimated importance of urban forest, then the performance standard and requirements on personnel, who were responsible for stages from planning, design, implementation to maintenance were insufficient for the actual need.  Appropriate planting space, similarly had to give way to other infrastructure such as utilities readily without bother formulating a compromised or perhaps a win-win option.

The old mind set needs to be changed fundamentally so that “urban forestry” under promotion will be on the right track.  There is no corner-cut, but wise direction will be achieved with collective mind and innovative trials.

An increased expectation on urban forest’s quality and services implies possibility of an increased budget, which would sound a burden to municipal authorities.  Currently, majority of urban forest is solely funded and managed by the government.  While the public has little involvement, noise is made quite often on the quality of government’s greening and tree management work.  It appears far from satisfactory to rely solely on public funding in management of green infrastructure up to public’s expectation.  In fact, the community has become highly enthusiastic and involved in greening issues in recent years.  This trend has already created an environment that government-community collaboration in urban forestry is becoming possible, a situation that had never happened before.  There are many possibilities in collaboration and here listed 2 for further exploration:

1. Active participation of community on urban forestry management

There is long practice in many developed countries that community was engaged to actively participate in the planning, design, implementation and maintenance of pieces of urban forest.  Entrusting pieces of abandoned lands to non-profits or community groups which have strong mission in greenery is one way.  Partnering of municipality and these groups in planting and maintenance works is another direction that can be explored in already-established green space.

The Plantation Enrichment Programme (PEP) at Country Parks by Agriculture, Fisheries and Conservation Department is a frontier scheme locally in which different groups from the community are engaged and they actively participate from planning, design to hands-on planting and maintenance work for a relatively long period of time, with funding raised from different sectors of the community.  The scheme has formed a good model for reference in other urban forestry programmes.

2. Alternative funding from the community

Upgrading the standard of care to urban forest and their function involves a lift in recurrent expenses.  There are various private funding sources which have strong mission in serving the community and improving the environment.  A matching of them with the real need is necessary for wise use of resources.  A popular local electronic-payment system had launched a scheme for some years in funding tree planting (for each transaction) at private locations and small communities.  Such kind of initiative would have more effective and positive impact if there are well coordination and stronger support from the authorities which own the largest pieces of land.  Nevertheless, this scheme was ground-breaking and would also become a valuable experience for future fund-raising scheme.

Being a component of city’s infrastructure, urban forest requires a strong team of professions in planning, design, implementation and maintenance, as in the case of roadworks, drainage, electricity, etc.  Different stage in urban forestry requires the collaboration of various professions and their importance also varies depending on site nature (habitat) (Miller, et al., 2015).  Fig. 2 elaborates the general concept further for the situation of Hong Kong.

Fig. 2 – Flow chart for urban forestry including resources and involvement of professions.

Nearly 10 professions should be involved in holistic urban forest management.  In the planning and design stage the goal of the urban forest is laid down in response to the society needs.  This involves urban planner and usually ecologist as well for benefiting the environment in a bundle.  While trees are the backbone of urban forest, the urban forester / municipal arborist plans for the life cycle of the forest, designs the appropriate species to deliver different functions and enhancement, and determine the required space.  Landscape architect considers the leisure and recreation needs of users and plans for the site function and spatial arrangement, and designs for other associated facilities.  Engineers from different specialities contribute when there is need in coordination with other infrastructures during the development.

During the construction stage, all building / planting works delivered are supervised by various professions on their specific aspects.  Arborists, ecologists and horticulturists may usually get involved in many practical works during the planting and establishment stage.

Compared with the previous two stages, maintenance stage of urban forest lasts much longer in time before the components are to be replaced.  The timeframe is likely much longer than any other built infrastructure (e.g. roadworks, drainage) in general.  While there are smaller plants which may be replaced after a few years, the backbone – trees usually last for more than 80 years in urban scenario without interference or damage.  However, growth of trees requires different level of care so that their services to human will be maintained or preferably enhanced along age.  The larger the tree size is, the higher chance would it come into conflict with human and other facilities.  More professionals in arboriculture then join the team - arborists, tree workers and utilities specialists.

As the Seoul Action Plan has expected, awareness of the functions and benefits of urban forests and trees would increase urban forestry investment (FAO, 2017).  With increased budget, the services that the existing green space can provide to the city would be advanced too – which will benefit not only the city dwellers, but the overall climate of the globe.  The key players should acknowledge this movement and get prepared for the change.

Chiky, Cheuk Yuet Wong

Immediate Past President, ISA Hong Kong Chapter
Education Committee Chairperson

Reference:

·        Annon. (2011). Asian Green City Index.  Economist Intelligence Unit, London

·        EPS iDo website: https://www.eps.com.hk/ido/chi/

·        FAO’s Urban Forestry website: http://www.fao.org/forestry/urbanforestry/en/

·        FAO (2017).  Seoul Action Plan for the Development of Urban Forestry in Asia-Pacific Region.  Released in 2^nd Asia-Pacific Urban Forestry Meeting 13-15 Sept 2017.

·        JIM, C.Y. (1998). Impact of Intensive Urbanization on Trees in Hong Kong. Environmental Conservation. 25(2):146-159

·        Kuchelmeister, G. (1998). Urban Forestry: Present Situation and Prospects in the Asia and Pacific region, FAO Asia-Pacific Forestry Sector Outlook Study. Food and Agriculture Organization of the United Nations, Forestry Policy and Planning Division, Rome

·        Miller, R.W., Hauer, R.J., Werner, L.P. (2015).  Urban Forestry: Planning and Managing Urban Greenspaces. Waveland Press, Long Grove, IL.  pp.17-22

·        Wong, C.Y. 2017. Change of Forest Role and the Approach of Management in Hong Kong. Proceeding of 2nd Asia Pacific Urban Forestry Meeting. Food and Agriculture Organization, UN

·        World Health Organization (2010). Urban Planning, Environment and Health: From Evidence to Policy Action. Meeting Report, http://www.euro.who.int/__data/assets/pdf_file/0004/114448/E939 87.pdf?ua=1