With reference to question 9: Is Greening (e.g. hydroseeding and monoculture of exotic species) of a derelict landscape
an end itself or a means to an end? Critically analyze the objectives of landscape restoration in Hong Kong and
differentiate between slop revegetation and ecosystem restoration. What criteria should be used to assess the success of
ecosystem restoration? Justify.
　
Introduction
This paper is to analysis the landscape restoration in Hong Kong with reference to the case of Tai Tong Borrow Area
(field trip on 12-2-2000 ) and Tai Mo Shan (field trip on 26-2-2000). Greening is usually used as a means of derelict
landscape restoration. Is it an end itself or a means to an end? It is the first part discussion. In the second part, we will
critically analyze the objectives of landscape restoration in Hong Kong and differentiate between slop revegetation and
ecosystem restoration. Is Hong Kong government implementing ecosystem restoration or just revegetation? Finally, the
criteria used to assess the success of ecosystem restoration will be introduced and justify.
　
I. Common restoration methods in Hong Kong: Hydroseeding and Plantation of exotic species
The original climax vegetation over Hong Kong was believed to be evergreen broad-leaved forest. However, due to
centuries of human impact, most of the hillsides were barren or covered with coarse grass and low shrub. In these harsh
areas, regeneration through natural processes is impossible. Restoration, such as hydroseeding and plantation of exotic
trees, is implemented to those disturbed land or derelict land mainly by government. Nowadays, forest coverage in Hong
Kong is 14%, two-thirds of which is natural secondary forest and one-third plantation. (Zhuang and Yau,1999)
　
Hydroseeding involves suspending the seed in a water-mulch mix and spraying it onto a site with a special
high-pressure pump. (Morgan 1997) At the time of spraying, fertilizer, mulch, a soil-binding agent and a dye are added to
Hydroseeding mix. The grass seeds are carefully selected and mixed to suitable the growing seasons. For example,
Bermuda grass is suitable for whole year in Hong Kong, Manhattan grass is suitable for dry seasons. (Chong 1999) Grass
seeds can germinate within a week and the degraded land can be covered with a luxuriant growth of grass in about a
month. (Chong 1999) It is widely used as it introduces lawn grasses in a fast time. For example, in the Tai-Tong
borrowing area, the original soil structure are completely destructed so hydroseeding is used to provide vegetation cover
in the shortest time.
　
The aim of hydroseeding is to establish a vegetation cover rapidly on the degraded land to stabilize the soil. Grass
cover reduces the impact of direct raindrop to surface erosion. Also, grass has provided an effective dense physical
barrier against the downwash of loose material, maintaining a stable growing environment for the later seedling trees.
(Webb 1995) In addition, grass also provides the first litter and humus layer on those soil, thus provides nutrients in the
soil for future plants. Therefore, grass provides a useful aid to the reestablishment of woodland in eroded areas.
Vegetation cover is provided on the degraded land surface in the shortest possible time, to control soil erosion and aid to
develop a new landscape. (Chong 1999)
　
Tree planting is carried out in the wet seasons following the successful establishment of grass. Pioneer species are used
such as Acacia and Pinus as these species can tolerate those nutrient deficit environment. Tree seedlings are collected
from the nursery of the Agriculture, Fisheries and Conservation Department. The faster-growing pioneers would provide
shelter within a year. Some of trees are nitrogen-fixers, such as Acacia species. Humus layer can be formed soon after.
Also, soil erosion has been steadily arrested as the tree canopy closes, slow down the direct hit from raindrops. Also, the
roots of trees can stabilize the soil from run off. Therefore, the amount of nutrient storage in the soil will be further
increased.
　
Plantations using fast-growing pioneer tree species can speed up the formation of forest cover and improve physical
conditions on degraded lands. (Lau and Fung, 1999) Pioneer species has played and important role for the restoration but
the resulting woodland might not be as diverse in species or as attractive to wildlife succession. It should be noticed that
single species planting with exotic species, such as Acacia or Pinus, would not achieve an ecologically stable landscape
as there is not enough ground surface area for the invasion of other species. These exotic species are not favorable for the
invasion of other species. As only some shading tolerant species, such as Schefflera octophylla can germinate under those
closed canopy shaded ground surface. (Chong 1999)
　
Native species are introduced in last decade during restoration to encourage the development of a higher ecological
acceptable restoration as native species are the habitats and food for wildlife. It is suggested that mixed planting with
exotic and native species can provide a higher degree of biodiversity, accelerates ecological succession, and provides
good habitat for wildlife conservation. (Lau and Fung, 1999)
　
It is showed that plantations can facilitate natural succession. The major function of plantation is to create less harsh
habitats on degraded lands by increasing soil humidity and reducing competition of weeds by shading, thereby enhancing
successful invasion and establishment of native species. (Lau and Fung, 1999)
　
Hydroseeding and plantation of exotic species are the vital stage of restoration. They provide the first vegetation cover
on the degraded land surface. No doubt, these measures can provide vegetation cover on those degraded areas. From the
engineering point of view, it is the end of a restoration project. However, from the ecological point of view, they are just
the first step of a comprehensive ecological restoration. A biodiversity restoration can be developed base on the
succession growth of these plants.
　
　
II. Objectives of restoration in Hong Kong
The main objective of reforestation in Hong Kong is to provide a quick soil cover at low cost and short time. The
secondary objectives are to improve the landscape, to enhance biodiversity in the long term. (Lau and Fung, 1999)
　
Objectives of restoration in Hong Kong have been enriched. In the past, restoration projects were mainly carried out
for community and social use, which were carried out by the government. However, as there is an increasing concern of
the quality of living, people demand a greener environment and it stimulates both the government and private developers
to put more effort in restoration.
　
Most of restoration projects were carried out by the government. Since 1950’s, a large scale of restoration were
carried out on the hill side badlands around Tai Lam Chung and Tai Mo Shan to decrease material runoff to the
reservoirs. Pinus massoniana were the main species in planting. The result is so successful. (Cheung 1999)
　
The concerned areas were around the countryside, where it is planned for the conservation of flora and fauna,
conservation of water and soil, and also for the recreational and educational uses to the public. There were SSSI (Site of
Specific Scientific Interest), for examples in Mai Po, Long Valley and Tai Mo Shan where the wildlife habitat is protected.
There are country-parks with vegetated slopes, in order to stabilize the slope and conserve the soil, retain the
underground water, and the plants might act as fire breaks to prevent hill fire and enhance social security. There are
family walks and nature trails with benches and barbecue pits, for the convenience of the public users. (Lee, 1984) Also,
there are educational walks, arboretums and visitor centers provide information to the people. (Progress Report 1985-88)
　
These are all concentrated in the countryside, and associated with some restoration projects, but may be of smaller
scale compared to recent projects. There are tree nurseries for various Government afforestation projects in the
countryside. (Lee, 1984) The objectives of such restoration might reveal by the Forestry Authority. It is claimed that "the
objective of conservation is to conserve the countryside by the effective protection and management of its scenery,
vegetation and wildlife for the benefit of the present and future generations of Hong Kong, with particular reference to
rare and endangered species of plants and wildlife". (Progress Report 1985-88, pp9) It can be concluded that, due to the
less degraded situation in the past, restoration in smaller scale may aim to maintain the natural scene and biodiversity, and
to promote a better understanding of the natural environment.
　
However, with the increasing in income of the Hong Kong people, it associates with the concern of the quality of
living. It stimulates the government to restrict further degradation through legislation, and put more effort to enhance
restoration. Restoration is now aimed to increase biodiversity and protect wildlife habitat, especially the native species.
Many nurseries have been setting up aiming at the protection of the native species. Some exotic species were introduced
to improve the soil quality. The government also enforced the private developers to carry out restoration projects, through
the EIA to require companies to do some mitigation measures, it is hoped minimize the negative impact on the
environment along with further development in Hong Kong. The companies are forced to restore the environment, but
may not ecological-based.
　
The latest objective of restoration is embedded with the idea of eco-tourism. Although Hong Kong is only a small
piece of land, there have many valuable wildlife. For example, the Chinese White Dolphins, the birds in Mai Po and Long
Valley, the fung shui forest, the wetlands, as well as the corresponding topography, biomass, and vegetation species, they
are of great scientific valuable, and are worth protecting. As some of them may suffer from extinction, green groups and
volunteer organizations are anxious to managing them. Besides, it attracts tourist and of commercial values, therefore,
even developers who are the profit-seekers also welcome the idea. As a result, the restoration projects may receive much
"investment" from the private developers, and can be carried out in large scale.
　

Differentiate slope revegetation and ecosystem restoration

Revegetation and restoration are two confused concepts. Restoration refers to the return of a degraded site to the exact
ecological condition it exhibited prior to disturbance. Revegetation is restricted to the vegetation phase to construct the
topography, soil, and plant conditions after disturbance, which may not be identical to the predisturbance site, but permits
the degraded land to function adequately in the ecosystem of which it was. (Munshower, 1994)
　
Restoration is viewed as the most concentrated effort to correct the problems introduced by degradation of the site, and
occurs along a continuum. (Hobbs, 1996) Revegetation is only an attempt to manipulate the surface plant covering, and
not aim to return the site to its original, so it can be finished in a shorter period. (Munshower, 1994) Ecosystem restoration
is even more complicated, as it is in a system scale, but slope revegetation is only carried out on a limited small area.
　
Although they are different in objectives, practically they are similar to each other. For example, the techniques of
seeding, planting and the mechanism of using plants to alter the micro-environment, both of them are site-specific and
situation-specific. Hence, revegetation can be one of the ways to achieve restoration goals. As a result, revegetation can
be an end itself but restoration cannot. Since they are of high specificity, projects should designed to be dynamic though
sometimes a reference system is needed.
　
It is sometimes say that restoration is quite impossible, because of the changing ecological paradigms. (Hobbs, 1996)
Ecosystem is not static but a dynamic system, and constantly changing, therefore return the system to the original one is
quite difficult. Slope revegetation is said to be more realistic, it is only aim to reach a equilibrium on the slope
environment and its vegetation.
　
　
III. What criteria should be used to assess the success of ecosystem restoration? Justify.
It is very important to set criteria to assess what have been done in order to keep track with the process (Zedler,
1988). The comparison of the actual situation with what is promised let us know what is still needed to be improved in the
actual situation. But at present there are still few established criteria for assessment of ecosystem restoration, beyond
catchall statements on restoring the natural ecosystem (Hobbs & Norton, 1996). Some scholars such as Westman, Berger,
Carins suggested the use of indicators, which are developed from some reference system. Another effective approach is
to use structure, compositional and functional measure to estimate the health of ecosystem (Costanza 1992). The
approach can be further developed as an ecological reference model. Aronson (1993) had suggested a list of “vital
ecosystem attributes” which group a set of parameters of structure and function for monitoring. The approach of
Costanza (1992). will be used as reference in this report to divide the criteria three categories, which are structure,
function and composition.
　
Setting criteria is usually related to objectives. There are different objectives, like, restoring natural diversity,
preventing erosion, mitigate visual impact (Chong 1999), etc. In general, the aim of ecosystem restoration is to return the
current situation to the predisturbance, presettlement condition (Harker D., Libby, G., Harker, K., Evans, S. & Evans, M.,
1999).
　
But it may not be easy to restored to such condition as the environment is changing. The objectives of
ecosystem restoration in general are mostly composed of the sustainability, self-regulating ability, stability, productivity
and cost-effectiveness of an ecosystem. A successful restored ecosystem should be self-regulated without any human
maintenance work, and is similar to surrounding and predisturbance situation. For more comprehensive analysis, a
ecosystem is subdivided into subtle criteria, which are put into the groups: structure, composition and function, for
assessment.
　

Structure

A healthy and stable ecosystem is usually of high density and rich in vegetation cover. Such cover shows high
productivity of an ecosystem. But it does not mean ‘the richer the better’ as tropical rain forest is richer in vegetation
than savanna. Standard of different kinds of ecosystem should be refereed. Density and richness are measured in the
number and amount of biomass of vegetation cover per unit area respectively. For, example, the restored vegetation
cover on high altitude of Tai Mo Shan after fire is much sparsely distributed and less rich. The ecosystem restoration work
is not successful mainly because of climatic stress such as low temperature and strong wind. Thus the system is not stable
and the productivity is low.
　
Growth rate of plant shows whether the restoration work is cost-effective. Plant of the same species may grow
unevenly because of various reasons, mainly water and nutrient stress (Tsang 1997). Acacia confusa grow above 700m
on Tai Mo Shan are much slower than that in lower altitude because of the aforesaid reasons. Species-interaction effect,
such as fast growing species dwarfing the slow-growing species, caused by unsuitable plantation will lead to uneven
growth of species too. The criterion can be assessed by growth height at different time period. As (Tsang 1997)
suggested, uneven growth is an indicator of poor restoration work, no matter it is of high density, wasting money of
taxpayer.

For smaller restoration project, slow growth rate cannot be reflected by the comparison of the same
species within the same area. Standard data then should be acquired as reference.
　

Composition

A stable and sustainable ecosystem is composed of great variety of species. As in Tai Tong East Burrow Area,
native species such as Castanopsis fissa, Cinnamomum camphora, Sapium discolor; exotic species of Acacia confusa, A.
mangium, Pinus eliottii, etc. are planted for ecosystem restoration. This practice can prevent severe damage to ecosystem
by sudden ecological change, which may seriously retarded growth of a certain dominant species.
　
On the other hand, a successful ecosystem contains more native than exotic species. Exotic species are fast
growing and so they are commonly use as pioneer for restoration. However, it should be a means to an end. We should
not neglect that, besides vegetation, an ecosystem is also composed of organism, like, insects and animals. Native species
have much greater ability to attract them, which can stimulate growth of decomposers and act as pollinators, in order to
construct a more sustainable and self-regulating ecosystem.
　

Function

Nutrient cycle is vital for a self-regulating ecosystem with high productivity. A complete and rich nutrient cycle
can help nutrient retention, and hence raise productivity and maintain sustainability. Erosion rate, presence of nitrogen
fixing species, storage and capture of nutrients in the soil and soil microbial activity are the key criteria for the
assessment.
　
Erosion rate can be measured by loss of fertile soil in specific area and time. The higher the rate, the lower will
be the sustainability of the ecosystem. Litter cover, ground stability and even transpiration rate of vegetation will affect
runoff rate, and hence erosion rate (Bellairs, 1999).
　
Amount of nitrogen fixing species such as Acacia confusa and Acacia mangium is very important in restoration
work of Tai Tong Burrow Area because it lacks nutrient, especially nitrogen. The recommended Total Kjeldahl Nitrogen
(TKN) is 0.2%, while the initial TKN level before excavation of the area is only about 0.14% (Tsang 1997). It clearly
shows that the area lacks nitrogen. Nevertheless, it should be noted that the most commonly planted nitrogen fixing
species in Hong Kong are exotic species, which may retard the existence of pollinators. A successful ecosystem should
maintains a balance of it.
　
Storage and capture of nutrient in soil can be assessed by soil texture, together with soil microbial activity are
vital for a sustainable ecosystem. Soil microbial activity is assessed with the amount of organic matter, soil pH and
salinity. Besides, human disturbance is the main source of unsuccessful ecosystem restoration. Tai Mo Shan is a
remarkable example with many fires, caused by human activities, disturbing the function of an ecosystem. A successful
ecosystem is one that with minimal negative human disturbance.
　

Conclusion

It is much more complicated than greening disturbed sites as ecosystem is a complex product of climate and
biology. Clear objectives must be set, as the assessment of the success of ecosystem is highly related to objectives of
restoration project Each ecosystem is unique in natural condition, so site-specific objectives are needed to be set for
restoration. Nonetheless, a generally successful ecosystem restoration work should be composed of sustainable, stable,
self-regulating and high productivity objectives. It is reflected by high density and richness of vegetation, and regular
growth rate of species, which are structure components; great variety of species and higher proportion of native species,
which are compositional components; complete nutrient cycle and minimum human disturbance, which are functional
components. The greatest weakness of the restoration work in Hong Kong is lacking a clear objective on ecosystem
restoration set by authority (Tsang 1997).
　
Moreover, it may be a pitfall to assume that there is a reference system for comparison (Harker D., Libby, G.,
Harker, K., Evans, S. & Evans, M., 1999) as ecosystem is changing all the time and the detail of predisturbance condition
may not in our hand. However, assessment is still needed to determine whether a restored ecosystem is healthy. Long
time assessment is recommended, as restoration of ecosystem does not produce instant effect, but need several ten years
to accomplish.

Lastly, money, just like nutrient, is scare resource. A successful ecosystem restoration should be
cost-effective.
　
　

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