Download C. Threats to Natural Habitats and Wildlife

Theme: Our Earth Resources
Topic 2. Wildlife and Natural Habitats
A.
What is Ecosystem?
Basic concepts of ecology
Ecosystem: a biotic community and its interaction with its abiotic environment.
 Abiotic refers to nonliving objects, substances or processes.
 Biotic: of or relating to living organisms
 Niches: An organism and its immediate relationships with both biotic and abiotic environment.
 Habitat: The sum of environmental conditions where an organism, population or
community lives.
 Species: a group of similar organisms that can interbreed with one another to produce
fertile offspring. ‘Species’ is a more inclusive term than ‘population’ because a species
may include several geographically separated populations.
 Biodiversity: describes the richness or variety of living organisms found in an area or a type of
environment, including both the number and frequency of genes, species and ecosystems.
 Population: a group of organisms of the same species lives in the same region.
 Community: all the living organisms of various species found in a particular environment.
 Ecology is the study of relationship of living organisms to one another and to their environment.
1. Global Environment
 Biome is a geological region with the characteristic climate and characteristic community
of living organisms.
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Table 1. The various terrestrial biomes on earth (simplified from Chiras et al., 2002)
Biome
Tundra
Coniferous forest
Temperate forest
1. Deciduous forest
2. Grassland
Desert
Savannah
Tropical rain forest
Temperature (ºC) Rainfall (cm)
-57 - 16
10 - 50
-54 - 21
35 - 200
75-150
-30 – 38
60 – 225
13 - 40
25 - 90
2 - 57
0 -25
13 - 40
25 - 90
18 - 35
125 - 1250
Typical Plants
Lichens, mosses
Black spurce, birch, aspen
Oak, beech, maple, yellow polar
Buffalo grass, gram grass
Cactus
Acacia tree, grasses
Great species diversity, e.g.
Orchids, palm
 These natural habitats provide resources for clothing, medicines, timbers, foods, etc.
 Owing to the unique abiotic factors of these habitats, the wildlife adapted to a particular
habitat is rather unique, leading to characteristic biological communities as a variety of
natural beauty on earth.
Suggested Student Activity：
View movies, videos and pictures：
-
Endangered species, protected areas, e.g. coral reef, tropical rain forest.
Hong Kong native plant and animals.
Types of terrestrial
 Tropical Rain Forest
The tropical rain forests are located near the equator. The total rainfall for the year is between
1500 and 2500 mm. There is no dry season. The average temperature for the year is around
25oC - 35oC. There is a little difference between the warmest and the coolest months.
 Temperate Forest
Temperate forests are located at temperate areas such as eastern North America, Europe, Asia.
The total rainfall for the year is 750 to 1500 mm. The average temperature for a year is
roughly 20°C.
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 Desert
Deserts are located to areas of extreme heat and dryness such as Africa, central Australia,
southwestern United States. The total rainfall for the year is less than 500 mm. The average
temperature for a year ranges from 20 to 25°C. The extreme maximum ranges are from
43.5-49° C. The minimum temperature sometimes drops to -18° C.
3.
Nutrient Cycle

Nutrient cycling ensures that nutrients do not get stuck somewhere. For instance, when a
plant or an animal dies, all its nutrients end up in the soil. Bacteria and fungi break down
the tissues and free up the nutrients which can be utilized by plants growing in the same
soil.
Carbon Cycle

The following figure shows a carbon cycle

In carbon cycle:
— Carbon is stored in organisms as starch, glycogen, glucose, nucleic acids, fat, etc.,
— Organic carbon in organisms is decomposed to carbon dioxide and
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— Carbon dioxide is converted to glucose by photosynthesis. Plants are the food source
of secondary and tertiary consumers in a food chain/ food web.
Nitrogen Cycle

The following figure shows a nitrogen cycle

In nitrogen cycle
— Plants secure their nitrogen in "fixed" form, i.e., incorporated in compounds, e.g.
proteins, nucleic acids.
— Degradation of proteins release ammonia, and further form nitrites and nitrates which
are readily utilized by plants
— Lightning and leakage of artificial chemicals (e.g. fertilizers) produce nitrates
— Few micro-organisms can ‘fix’ atmospheric nitrogen into biomolecules.
4.
Relationships between population, community and species

Population is a group of organisms of the same species that live in the same region.
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Community is all the living organisms of various species found in a particular environment.

In a community, the species-species relationship can be:

Predation: one is a predator and the other is prey.

Neutralism: both species do not interact nor affect the survival of each other.

Commensalism: in which both species benefit from the existence of each other. E.g.
lichen in which algae or blue-green bacteria carry out photosynthesis to provide food
while the fungi provide the anchorage and water-conserving tissues.

Competition: overlap of niches of species that they share similar / same kinds of
resources, e.g. leopard and lion.

Parasitism: the parasite harms its host to obtain energy, e.g. Fleas live on cat
 Within an ecosystem, we study the relationships among the organisms with the concept of
energy flow and nutrient cycling using food chains.
 In a food chain, there are:

Primary producers that capture and convert the solar energy to chemical energy via a
metabolic process, e.g. photosynthesis. Plants, algae and some bacteria are primary producers.

Herbivores that are plant consumers only, e.g. elephants;

Omnivores that consume both plants and animals as food, e.g. human beings and cockroach.

Carnivores that consume only animals as food, e.g. tigers, lions
 Both omnivores and carnivores are higher trophic level consumers.

Decomposers that degrade the dead matters leading the cycling of elements in an
ecosystem, e.g. fungi and many bacteria.

For example: a terrestrial food chain
Leaves  worms  birds
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Here is an example of food web:
Hawks
Snakes
Frogs
Birds
Spider
Squirrel
Birds
Insects
Insects
Grasses and plants
B.
Importance of Conservation of Natural Habitat and Wildlife
1. Habitat

A habitat could vary in size, an ocean is a large habitat and a rotting log is a small habitat.

Different habitats make up a biological community and form a complex network:
habitats of different plants, animals and microorganisms will interact with each other in
the network and finally forms an ecosystem.

A natural habitat, as a component of an ecosystem, will affect biodiversity when it is
being disturbed.
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
Disturbance to the species in the habitat would lead to species extinction in worst case.
This is a serious problem with the evolution of human beings on earth.

Many species are threatened, encountering the danger of extinction.

The rate of species extinction after the human appearance is so great that the earth is
said to show the fifth mass species extinction.

The previous one is related to the great climatic changes leading to sudden and mass
disappearance of species.

Conservation of natural habitats will not only favour natural changes in biodiversity, but also
provide a suitable environment for wildlife, which are precious and should be conserved.
2. Wildlife

Wild species is not only important to biodiversity of the ecosystem.

Conservation of wild species also have very important role for human life.

They provide economic, medical, scientific, ecological, aesthetic and recreation benefits to human:
—
Economic and Medical Importance
 A lot of today’s food crops were domesticated from wild tropical plants, the
scientists still developing some plants for new crop strains.
 Many useful products, e.g. rubber, paper and dyes are derived from wild plants.
 Extraction of medicinal compounds from plants.
—
Scientific and Ecological Importance
 Provide ecological services for the Earth. (Figure 1)
 Key factor for sustaining biodiversity and ecological integrity.
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—
Aesthetic and Recreational Importance
 A source of beauty and provide recreational pleasure for people.
 A source of economic income by ecotourism.
 Bioethics
—
Each species has intrinsic value.
—
We should focus on conserving wildlife from permanent extinction by saving their
habitat and not disrupting the complex ecological interactions.
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—
C.

Some people believed that each species has a right to survive with human interference.
Threats to Natural Habitats and Wildlife
Due to increasing human activities and development, the disturbances to the ecosystem
and wildlife also increase.

Number of causes lead to threats in natural habitats and wildlife, below shows some of
the major causes: Deforestation, Over Hunting and Urban Development.
1.
Deforestation

The world’s most serious environmental problem.

There are several varieties:
—
Rain forest, which receives rainfall almost daily;
—
Tropical deciduous forest, with one or two dry seasons each year;
—
Dry and very dry deciduous forests; and
—
Forests on hills and mountains

Tropical forests cover about 6% of the earth’s land area.

Human colonization on land is the most serious threat and cause of deforestation. This is
because the land is used for housing, industrial activities and agricultural activities.

Nowadays, the timber industry contributes significantly to forest depletion.

The area of the tropical forest drops significantly from the year 1800 until present.

An accelerated decrease is observed from Year 1950 to Year 2000.
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Area of Tropical Forests
Millions of Hectares
3500
3000
2500
?
2000
1500
1000
500
0
1800
1850
1900
1950
2000
2050
Year
Decrease in the Area of Tropical Forests since 1800 (Reference source: Canadian
International
Development
Agency.
Forestry
Advisers
Network
(CFAN),
http://www.rcfa-cfan.org/english/issues.12.html) .

These forests are homes for 50-90% of the terrestrial species. Deforestation will lead to
the loss of biodiversity.

Annual destruction of tropical forests means the extinction of thousands of species (a
wide variety of plants and animals), in which some may be unknown species.

Some estimated that 50,000 separate species were loss annually and altered the balance
of ecosystems.

Deforestation is one of the causes of increasing the atmospheric carbon dioxide on earth.
This is simply by handicapping the carbon cycle (described in Topic “The importance of
air” of Theme “The Air We Breathe”). (The effects of increasing atmospheric carbon
dioxide are found in Topic “Global warming” of the Theme “ The Air We Breathe”)
2.
Over Hunting
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
Feeding the human needs by natural resource is not a question. But problems arise when
the harvest from the wild exceeds the human needs. For wildlife, this is called over –
hunting, it is the most serious threat to wildlife nowadays.

Wildlife provides various resources. Wild harvest (not artificial cultivation) is a major
source of many such resources especially when we are handicapped by our knowledge
in keeping stocks of some wildlife, e.g. tigers.

International trade of wild plants and animals is a big business due to its huge profit. As
there is a demand and a market for a particular wildlife, people will hunt the wildlife to
earn for their living.

Some international trading involves illegal sale of threatened species or their parts.
—
Threatened species are those species whose population size has dropped to a significantly
low level and if action is not taken, the trend of decreasing population size will continue.
Thus in the future, it may become extinct. This type of trading gradually becomes an
organized crime and leads to wildlife smuggling. For instance,
 A rare Siberian tiger (only 450 left) is in threat as the pulverized bones are
very worthy for producing medicinal powder.
 All five species of Rhinoceros are threatened with extinction because people
killed them for their horns and also due to loss of habitats. Their horns are
carved onto ornate dagger handles, powdered horns are used for medicinal
purpose as a proven fever reducer, etc.

Apart from illegal trading, wild species may also be killed, as they will lead to economic loss.
—
For example, the American Bison is killed; as they will damage crops, fences,
compete with cattle and sheep for grass.

Over hunting could also be caused by a non-discriminative catch. For instance, the
fishing net used in open water system can catch larger animals such as sea birds and
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tortoise that is a protected species.
3.
Urban Development

Expansion of urban area, include:
—
Development of infrastructures, e.g. road construction, development of mass
transit network;

—
Development of public facilities, e.g. recreational areas;
—
Expansion of residential, industrial and commercial regions, etc.
Urban development will increase human activities in the area and lead to deterioration of
the quality of surrounding natural habitats and causes disturbance of wild species.
—

E.g. Constructing dams to provide hydropower disturb living habitats for much wildlife.
Fragmentation, or even loss of natural habitat may be resulted because of land removal
for urban development.
—
Acts as a selection force for changing the survival community of living organisms. E.g.
 More of the habitat will become exposed to sunlight and thus providing an
unfavorable environment for shady plants.
 Animals that tolerate human disturbance will be favored.
—
But the fragmented area limits the territory of an animal in finding mates for
species propagation and in finding sufficient food for survival.

The loss of natural habitats will cause species to concentrate in refugee areas and
decrease in the population of species or even lead to species extinction.

Besides, the human urban environment, e.g. the noise during infrastructure construction and the
turbines of flying aeroplanes, accidentally kill wildlife or damage the health of wildlife.

With the increasing human population, we generate more wastes and other pollutants.
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The nature faces the greatest challenge of handling and recycling these wastes.
— Some pollutants are artificial and even toxic. Thus the wildlife is harmed, e.g.
pesticides DDT and pentachlorophenol.
— Plastics, a human invented material, may not be degradable and thus traps the
elements in the polymer format without recycling.
。
D.
How Can We Conserve Natural Habitats and Wildlife
1.
Active Management of Natural Habitats

Active management strategies include management of resources
— Active management for sustainable yield.

Natural resources are not evenly distributed on earth and many types of resources are not
renewable.
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
Management of resources is essential not just for the present generation but also for the future.
Global Fish Catch
Yield (Mt)
140
120
Fish catch
100
Aquaculture
80
Total harvest
60
40
20
0
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
Year
The impact of science and technology to develop aquaculture and open-water catch on global
fish yield.

Resource Management
— An active management of resources.
— As human beings are part of the nature and should not just exploit the resources
without considering the nature system’s ability of recycling the elements.
— Continuous exploitation will lead to the risk of depleting the natural resources,
deteriorating the environment and driving many species into extinction.
— Thus active management is in the sense that we apply:

The knowledge of the nature and manipulate the environment,
— By creating and following the natural rhythm, to produce yield in a sustainable way,
e.g. ecotourism, captive breeding, sustainable fishery and artificial reef.
Role of artificial reefs in Fisheries Protection Areas

Most of the natural nursery habitats for fishes have been destroyed due to over
fishing, pollution and reclamation.
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
No protection is given to the nursery habitats outside of marine parks and marine reserve.

All sectors of fishing community in South China Sea and Hong Kong Water are
heavily exploited.
Fisheries Restoration Initiative

To protect Hong Kong marine ecosystems and fisheries through:
— Territorial – wide fishing licence system,
— Establishment of Fisheries Protection Areas (FPAs),
— Depolyment of artificial reefs (Ars) within FPAs.

The programme of artificial reef deployment is being implemented in 2 phases.

First around the marine parks, and establishment of fisheries protection areas,
which have been selected specifically for their sustainability for AR employment,
fish spawning and nursery ground protection.

Artificial reef: Installation of artificial materials by sinking to the sea bottom.
— Serve as substratum for the corals to attach and establish communities there.
— Many algae species also anchor to the corals established and serve as food for the
herbivorous fishes.
— Through the food chain relationship, more fishes are attracted and bred there as a
nursery areas.
Artificial reef.
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Conservation for Wildlife
— An ideal reserve design consists of the core region where the wildlife is left as its original
wilderness with the periphery as the buffer zone.
— In this way, economic activities such as ecotourism, fishery, agriculture, etc. are allowed.
— The idea is to have the habitat protection and human economic activities together.
— Thus, allowing people employing the land for generating income and participate in
the protection of the area.

The Concept of Sustainable Forestry
— Active management of the reserve is for the sustainable yield of timber and
non-timber products.
— Sustainable forestry means timber collection is allowed, but plantation is also
practiced in an appropriate schedule.
Example: Ge Wei shrimp & Mai Po Nature Reserve
Mai Po Nature Reserve:
It is a Ramsar site of international recognition.
There are 50,000 waterfoul in mid-winter and it is a type locality for 17 species of
invertebrates including a crab (endemic to Mai Po).
Gei Wais:
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Gei wais are artificial inter-tidal marshland in muddy ground. They operate with a dyke to let
high tide water flood in and a sluice gate to drain at low tide and retain economical valuable
fish and shrimp inside the gei wais. It is an ancient mixed and semi-artificial mariculture
practice. Shrimps (Metapenaeus ensis) are collected and harvested at the sluice gate during
the low tide.
Mangrove plants provide nutrient rich leaves fallen onto the mudflat for decomposition and
going into detritus food chains. When abandoned, gei wais develop into mangrove and reed
marshes suitable also for bird communities. Fish ponds are however devoid of vegetation and
provide mixed culture of carps and mullet in Hong Kong.

Problems of Active Management in Hong Kong
— Because of increasing population and expansion of urban areas, our wilderness is in threat.
— A balance between urban or economic development and conservation has to be
taken. For example: the judgment between protection of damaged coastal area with
mangroves and removal of wetland for housing development.
Student Activities：
Fieldtrip/ virtual fieldtrip: wetland, country park or marine park.
2.
Legal Protection of Species and Habitats
Environmental Protection by Legislation
Legislation
Air Pollution Control Ordinance (APCO)
Ozone Layer Protection Ordinance (OLPO)
Noise Control Ordinance (NCO)
Waste Disposal Ordinance
Waste Pollution Control Ordinance
Environmental Impact Assessment Ordinance (EIAO)
Year of Introduction
1989, 1991 amended
1989
1980
1980
1980
1999
Conservation of wildlife and natural habitats by legal protection:
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
For maintaining the biodiversity, protection of endangered species must be enforced:
— The animals and plant (protection of endangered species) ordinance, Chapter 187:
 The import, export and possession of endangered species are strictly regulated.
 The ordinance gives effect to the Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES) – an international
convention signed in 1973 and now implemented by over 158 countries.
(http://www.info.gov.hk/afcd/conserv/pes.htm).

For habitat protection:
— 4 marine parks and 1 marine reserve were setup, e.g. Tung Ping Chau Marine Park.
 In these areas, fishing is restricted to protect marine habitat.
— Site of Special Scientific Interest (SSSI) are established.
3.

Environmental Impact Assessment (EIA)
The decision of EIA is made for the best benefits of the present as well as the future
generations. In sustainable development, this assessment is regularly carried out and
leads to modification of strategies to be implemented from time to time.

EIA ordinance, an ordinance formulated based on the concept of sustainable development,
aims to: balance between economic, social, cultural and environmental aspects

For any infrastructure development, a proposal together with an environment impact
assessment report must be submitted for the Government to consider.

Public consultation in the EIA process is a major component of this EIA ordinance.

The Director of EPD (Environmental Protection Department) must consult with the
Director of AFCD (Agricultural, Fishery and Conservation Department) to make a final
decision whether to approve an Environmental Permit allowing the project to proceed.

Thus, according to EIA ordinance, we have a legal procedure to disapprove projects that
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damage our environment.
The figure below shows the statutory environment impact assessment process (EPD):
Suggested Student Activities：
Role-play: the compromise between economic development and nature protection (Tai
Long Wan).
References:
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1. Canadian International Development Agency. Forestry Advisers Network website,
Forestry
issues,
Deforestation:
Tropical
Forests
in
Decline.
Web
address:
http://www.rcfa-cfan.org/english/issues.12.html.
2. Department of Natural Resources and Environment web site, The coast kit: A Victorian
costal
resource
information
kit:
coastal
system
-
ecology
Web
address:http://www.nre.vic.gov.au/coasts/coastkit/ch1/ecology.htm
3. Fiedler, P.L. and Kareiva, P. M. (1998) Conservation Biology: for the Coming Decade. 2nd
ed. New York: Chapman & Hall.
4. Kohn, K. A. (1991) Balancing on the Brink of Extinction: the Endangered Species Act
and lessons for the future. Washington, D.C.: Island Press.
5. Miller, G. T. (2003) Environmental Science: Working with the Earth. 9th ed, Pacific Grove,
CA: Brooks/Cole/Thomson Learning.
6. Ruland, J. (1992) Urban Development in Southeast Asia: Rregional Cities and Local
Government. Boulder: Westview Press.
7. Yeung, Y. M. (1998) Urban Development in Asia: Retrospect and Prospect. Hong Kong:
Hong Kong Institute of Asia-Pacific Studies, Chinese University of Hong Kong.
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