UNIT 3 EFFECT OF HUMAN ACTIVITIES ON ECOSYSTEM
UNIT 3: EFFECT OF HUMAN ACTIVITIES ONECOSYSTEM
Key Unit Competence
Evaluate the effects of human population size, resource use, and technology on
environmental quality.Learning objectives
– Explain how modern agricultural technology has resulted in increased food
production
– Explain the negative impacts to an ecosystem of large scale monoculture of
crop plants
– Explain the reasons for habitat destruction (agriculture and extraction of natural
resources)
– Explain the undesirable effects of habitat destruction
– Explain the sources and effects of the pollution of air, water and land
– Explain the causes and effects of acid rain, eutrophication and non
biodegradable plastics
– Explain the main methods of the conservation of resources
– Describe an example of conservation in action
– Assess the negative impacts to an ecosystem of intensive livestock production
– Conduct shows and dramas on wildlife conservation
– Research the effects of the excessive use of fertilisers on the environment
– Assess the different methods of the conservation of nature
– Carry out a research project on recycling sewage
– Carry out research on the African species endangered by human activity
– Evaluate the reasons for conserving wildlife
– Demonstrate ways of reducing pollution and protecting the environment
– Organise clubs focused on environmental and wildlife protection
– Suggest ways in which one could take positive action to help conserve biological
resources
– Appreciate the balance between society, environment and the economy
– Recognise that extinction is a natural part of the evolution of life on earth but
has taken place in an unprecedented rate, mainly as a result of human activities
– Support the Rwandan government policy of protecting the environment– Adapt regulations designed to prevent overfishing into action
Introductory activityThe illustrations below show two inhabited areas by human population.
1. Based on your observations, discuss what would be the impact of
humans on natural ecosystems.2. Suggest what can be done to sustainably conserve natural ecosystems.
The increase in human population size causes changes in natural ecosystems.
Intentionally and unknowingly, human activities on Earth have negative impacts for
all kind of life form of an ecosystem. This unit intends to describe different human
activities on the Earth’s natural ecosystems and their effects. It also informs different
biodiversity conservation methods and indicates how disturbed ecosystems can be
restored. It raises the awareness towards the restoration of degraded environmentsas well as biological conservation.
3.1 Modern agricultural technologies for food production
Activity 3.1
1. Based on everyday experience, identify the modern agricultural
technologies.
2. Discuss how modern technologies increase food production in terms
of; agricultural machinery, chemical fertilisers, insecticides, herbicides,and selective breeding.
The increased population size brought changes in different sectors of any country
including agriculture, one of the most human activities that is practiced on ecosystem
for increasing food supply. Currently, agriculture is practiced with advancement
in science and technology where contemporary farming methods were invented
and adopted mostly in monoculture and intensive farming. Modern agriculture is
named mechanized agriculture or mechanized faming. It uses different equipment
including; tractors, trucks, sprayers, harvesters, aeroplanes and helicopters
depending to their manufactured purposes. It even uses computers in junction with
satellite imagery among others for easy and effective management and monitoringof land and crops.
Figure 3.1: Tools and techniques in modern agriculture
The agricultural equipments are used in all process of farming starting from preparing
the land to crop storage. Beside efficient production, mechanisation encourages
large-scale production and sometimes it can improve the quality of the land. Despite
their role in increasing food production, mechanized farming intentionally or due tounskilled farm labour and awareness harms the soil, biodiversity, water and air.
Figure 3.2: Nitrogen spreading machine
Apart from farming machineries, there are chemical fertilisers that are used on
farm land to boost levels of soil nutrients needed by plants for growing faster andproducing more food. Some of the most used fertilisers are nitrogen, phosphorus,
and potassium or a combination of them. Use of fertilizers is expensive and improper
use can harm the environment. If too little is added, crops will not produce as much
as they should. If too much is added, or applied at the wrong time, excess nutrients
will run off the fields and pollute streams and groundwater. These are the reasons
why the right amount chemical fertilizers have to be used at the right time, to avoidpotential negative effects to the environment.
Modern agriculture uses also pesticides which are organic compounds or substances.
They include; insecticides, herbicides and fungicides, used with the purpose of
killing unwanted plants, insects or fungi which might harm the plants. Utilization
of pesticides escalate food production in case of their effective use. However, some
of the pesticides present negative effects on the environment. Examples include
the 3, 5, 6-Trichloro-2-pyridinyloxyacetic acid which inhibits soil bacteria that
transform ammonia into nitrite, Glyphosate (C3H8NO5P) which reduces the growth
and activity of free-living nitrogen-fixing bacteria in soil, and oryzalin and trifluralin
which inhibits the growth of certain species of mycorrhizal fungi. Insecticides can
contaminate non-targeted organisms including; insects, fish, or plants through thespray onto eroding soil or when heavy rain falls right after an application.
The last but not the least among the modern agricultural technologies is the selective
breeding also called artificial selection. It is used in order to produce varieties of
plants or animals having phenotypic traits suitable to a particular area and of high
productivity. It allows natural evolutionary process, eliminates diseases, influencing
the production of food coming from plants in a positive way, giving to plants the
ability to grow on lands that are previously not suitable for farming, sustainability of
food chain, creation of higher-quality products, and contributes to the availability ofanimals and plants that produce higher yields.
Application 3.1
1. Explain your understanding of the term modern technology.
2. Research and discuss how the use of selected breeds is beneficial infood production
3.2 Impacts of human activities on ecosystem
Activity 3.2
Use the books from school library and search further information from the
internet. Use the searched information and do the following questions.
1. Explain the negative impacts of large scale monoculture on ecosystems.
2. Assess the negative impacts of monoculture and intensive livestock on
ecosystems.
3. Discuss the contribution of deforestation on flooding and desertification.
4. Explain how fishing and deforestation can impact aquatic ecosystems.5. Discus how mining and industrialization impact different ecosystems.
3.2.1. Negative impacts of large scale monoculture on ecosystem
Intensive cropping practices and its impacts on ecosystem
A key component of agricultural intensification is monoculture, the cultivation of
a single crop species in a given area. Unlike traditional polyculture (which mix crop
varieties or intersperse crops with trees or domesticated animals), monoculture
allows farmers to specialize in crops that have similar growing and maintenance
requirements. Monoculture is increasingly adopted by farmers to achieve higher
yields through economies of scale. However, monoculture may negatively impact
biodiversity, soil, water and air.
a. Impacts on Biodiversity
By reducing natural plant biodiversity to include only one crop, monoculture affects
the composition and abundance of associated biodiversity. For example, the balance
of plant pests and their natural enemies that may exist in polyculture fields can be
disrupted in monoculture systems, which provide habitat for a narrower range of
insects. Populations of; bees, flies, moths, bats, and birds, which provide important
pollinating and pest pressure services to crops, also tend to be lower in monoculturesthan in fields containing diverse forage and nesting sites.
b. Impact on soils
Continuous cropping impacts soils properties whereby soil fertility declines as
consecutive crop cycles reduce the amount of nutrients from soils. As plants grow,
they absorb nutrients from the soil such as nitrogen, phosphorous, potassium,
and calcium. Harvesting crops is another mechanism contributing to the removal
of these nutrients from the soil. In addition, when monoculture is continuously
applied in the same area, it affects soil organisms due to soil pesticides. Natural soil
properties including aeration and water infiltration might be affected due to theloss of soil organisms that increase these soil properties and hence soil fertility.
In addition, due to population pressure and land scarcity, farmers in some areas are
increasingly adopting intensive cultivation methods on hillside areas characterised
by steep slopes with the soils often inherently poor quality. As rainfall hits loose or
unprotected soil on cultivated sloping land, soils erode and carry away sediments
and nutrients. The resulting redistribution of nutrients may leave upward sloping
soils less fertile than lower areas, and fertilizers or other chemical particles in run-off
may negatively impact aquatic ecosystems and water quality.
c. Greenhouse effects
Tillage as one of the practice in continuous cropping, impacts on greenhouse emissions
whereby increases carbon dioxide (CO2) emissions by causing decomposition of soil
organic matter (SOM) and soil erosion. Intensive tillage practices also emit CO2, a
greenhouse gas that contributes to climate change. Mechanical tillage release CO2
and stimulates CO2 emissions by enhancing decomposition of soil organic matter.
The tendency for tillage to increase erosion also contributes to CO2 emissions. A
large percentage of soil carbon particles carried by erosion are emitted into the
atmosphere as CO2 rather than buried and sequestered in deposit sites.
Intensive livestock farming and its impacts on ecosystem
Livestock play an important role in agricultural systems. Cattle, sheep, and goats
can provide manure for soil fertilization and a diversified source of food and income
generation. Traditional livestock management involves mixing animals and crops
on the same farm or grazing livestock on grasslands. Intensive livestock systems
exacerbate the impacts that livestock activities have on the environment, including
effects on soil conditions, biodiversity, water quality and quantity, and greenhousegas emissions.
a. Impacts on Soils
Increased animal stocking rates puts pressure on grazing lands, leading in some
cases to soil compaction, erosion, grasslands degradation, and desertification in
semi-arid areas. Concentrated “hoof action” compacts wet soils, making them less
able to absorb water and more prone or more likely to run-off and erosion. Livestock
grazing between land and streams can destabilize stream banks and release large
amounts of sediment into fragile aquatic ecosystems. Additionally, high rates of
nitrogen contained in bovines’ manures can lead to topsoil acidification.
b. Impacts on Biodiversity
Intensive grazing impacts biodiversity in several ways. Populations of birds, rodents,
and other wildlife that depend on grasslands for food and habitat may decline as
livestock densities increase. In addition, intensive grazing often involves reseeding
natural meadows, resulting in a loss of native grassland plants. Higher rates of
organic or inorganic fertilizer application typically accompany reseeding, which
may degrade water quality through nitrogen or phosphorous leaching. Nutrient
contamination in water bodies reduces oxygen levels and harms fish and plantpopulations.
Leaching of nitrogen and other fertilizer nutrients into fresh and saltwater
environments can lead to a state of eutrophication (overabundant nutrient
concentrations), resulting in increased algae blooms and oxygen depletion.
Thus, dead zones may develop in these areas, whereby decreased oxygen levels
dramatically reduce fish populations and species diversity.
c. Impacts on water quality and quantity
Untreated livestock waste causes high nutrient concentrations in water bodies,
also known as eutrophication. Untreated livestock waste can significantly impact
water quality. Livestock manure contains high amounts of nitrogen, phosphorous,
and potassium and may enter water directly when livestock graze near streams
or indirectly through run-off or percolation into groundwater. Confined livestock
systems present high risks of water pollution due to difficulties containing and
treating large quantities of manure. Degraded water quality may also pose health
risks to humans who rely on water for drinking and household uses.
d. Impacts on greenhouse gas emissions
Enteric fermentation and livestock manure are significant sources of methane (CH4)
and nitrous oxide (N2O) greenhouse gases emissions. Ruminant livestock such
as cattle and sheep release CH4 during enteric fermentation and the microbial
digestion of fibrous plants. Animal manure emits N2O and CH4 during storage and
after application to croplands or grazing areas. Additional activities related to raising
livestock are responsible for emissions such as releases of CO2 in producing fertilizer
for grazing lands and animal feed, N2O emissions from applying fertilizer, and CO2emissions from overgrazing and land degradation.
e. Impacts on air quality
Nitric gas contributes to smog, ozone, and acid rain. During the microbial processes
of nitrification and denitrification that take place in fertilized soils, nitric gas is
released. Nitric emissions impact local and regional air quality by contributing to
the formation of smog, ozone, and acid rain.
Fishing and their impacts on the ecosystem
Techniques for catching fish include hand gathering, spearing, and netting, angling
and trapping. It is normally done in fish farms including ponds, rivers, lakes, seas,
oceans where fish are raised commercially. With the advancement in technology,
rearing of aquatic animals is known as “aquaculture” aiming at producing more
aquatic food due to the drastic increase of the population. Despite the significance
of fish farming and harvesting technologies, fisheries are in danger of collapsing,
due to overfishing and pollution.
Fishing nets called ghost nets used by fishermen are sometimes left or lost in
oceans whereby they can entangle fish, dolphins, sea turtles, sharks, dugong,
crocodiles, seabirds, crabs, and others. These living things are restricted from
movement which led to laceration (cut in skin), infection, starvation and suffocation
sometimes causing the death. Other effects include overfishing which is a form of
overexploitation where fish stocks are reduced to below accepted levels. It can result
in resource depletion, reduced biological growth rates and low biomass levels. Since
organisms ecologically depend each other, overfishing of one species decreases the
presence of other species and favour the invasive species. For example, with the
shark population reduced, in some sea places almost totally, the rays have been free
to dine on scallops to the point of greatly decreasing their numbers. Since then, avariety of sharks have fed on rays, which are the main predator of scallops.
Deforestation and its effects on ecosystem
Deforestation is the permanent clearing or removal of trees and undergrowth.
Deforestation happened in the past and continues extensively today particularly
in tropical area. The forests are cut mostly for mainly searching agricultural land.
In Rwanda like elsewhere, deforestation was driven by the need for food, charcoal,
and timber, especially for commercial products. Worldwide agriculture continues to
be the main cause of the loss of natural forests. Other reasons include supplying
firewood as fuel, constructing houses, industrial buildings, roads, and dams, removal
of trees for pulp and paper, cutting trees for timber used in the construction industry,
replacement of native trees with fast growing species such as conifers, eucalyptus,
and rubber trees.
a. Effects of deforestation on biodiversity
Deforestation has the dramatic effect on biodiversity particularly in tropical
rainforests. Complete replacement of native plantations with introduced species or
keeping only a few native species, leads to a reduction in biodiversity. Organisms are
being driven to extinction by the loss of their suitable habitat. In tropical rainforest,
attention should be paid to species with great human value including medicines,where forest plant products are used as anticoagulants, tranquillisers, and antibiotics.
b. Effect of deforestation on nutrients cycles
Deforestation is contributing to an increase in carbon dioxide due to the removal
of forests which actually use this gas for photosynthesis. Forests burning release
huge amounts of carbon dioxide directly and very quickly into the atmosphere and
is probably a major contributor to rising carbon dioxide levels. Burning trees was
also found to significantly reduce the nitrogen held in the ecosystem. In addition,
tree roots bind soil particles together, and tree canopy prevents rain beating down
on the soil. Deforestation therefore causes nutrients to be lost through leaching and
runoff.
c. Desertification
Deforestation is also one of the process speeded by deforestation even though some
scientists believed that it was caused mainly by climatic changes. Deforestation
disrupts water cycle and soil structure. Reduction in tree cover means reduced
transpiration, few clouds, and less rain fall in the area. Removing trees increases the
risk of flooding following heavy rains. Agricultural land becomes heavily populated,
it is likely to be over cultivated or overgrazed, and the soil will be less fertile and
more easily eroded during periods of droughts.
Mining and industrialization
a. Effects of Mining on the Ecosystem
Mining as one of economic activity applied on natural ecosystem plays an important
role to humans. It is at the same time affecting environmental ecosystem through
soil compaction, lowering overall soil fertility, erosion, soil pollution and minimizing
the availability of nitrogen and phosphorus. Soil compaction is one of the most
severe effects mining has on ecosystems and it is often the result of large machines.
As the soil is compacted, there are fewer pore spaces for oxygen and water to move
through the soil profile, minimizing the potential for plant establishment. Mining
operations often contaminate the soil with toxic heavy metals and acids, preventing
plants and soil micro-organisms from thriving
b. Effects of industrialization on ecosystem
Industrialization contributes for the nation economic development and prosperity
by providing employment opportunities and generating wealth. It is also one of the
human activity that negatively deteriorates ecosystems. The major negative effects
of industrialisation include depletion or reduction of natural resources, air, water and
soil pollution, global warming and climatic changes. Industrialization expose living
organisms to acid rain and it is among the major causes of land degradation. Thus
poor land quality, and issues generated by hazardous waste lead to some diseases
including silicosis and pneumoconiosis, tuberculosis, skin diseases and deafness.
By metallic contaminant like Cd, Zn, Hg, radioactive industrial pollutant bacteria and
beneficial micro-organisms in the soil are exposed to death. There is also a number
of undesirable effects caused by toxins from industrial wastes that enter in the food
chain. Moreover, industrial effluent damages the natural biological purificationmechanism of sewage treatment causing several soil and water borne diseases.
Application 3.2
1. Can modern agriculture and extraction of natural resources, cause the
habitat destruction. Explain why and how.
2. Explain the undesirable effects of habitat destruction.
3. Research the effect of the excessive use of fertilizers and pesticides.
4. Explain how intensive monoculture and livestock impacts on soil as
well as water ecosystems.5. Suggest what can be done for effective farming on hillsides.
3.3 Pollution
Activity 3.3
1. Produce a picture of a polluted area.
a. Explain the sources and effects of the pollution of; air, water and land.
b. Explain the causes and effects of acid rain, eutrophication
c. Demonstrate ways of reducing pollution and protecting theenvironment.
Pollution refers to the introduction of substances or energies into the natural
environment that cause adverse change. A pollutant may be physical (for example;
noise, heat, and other form of radiation), chemical (such as heavy metals in industrial
wastes), or biological (sewage for example). A pollutant may be a substance of
natural origin present in excess (such as a volcanic dust or particles of sea salt)), but
the term is more used often used to describe changes brought about by human
activities such as the emission of industrial pollutants, or the discharge of domesticwastes. The pollutant can be in any part of the biosphere: in air, land, or water.
Air pollution and its effect on the ecosystem
Air pollutant can be in form of gases (such as carbon monoxide from car exhausts),
or aerosols (soil or liquid particles suspended in the atmosphere). Pollutants have
many and different effects on the health of humans and other organisms, as well
as on the natural and built environments. Oxides of nitrogen and sulphur emitted
as industrial gases can form acid precipitation. Some pollutants can cause the
greenhouse effect as well as ozone depletion.
a. Greenhouse effect
Solar energy reaches the Earth in the form of short-wave radiation. When the
radiation strikes a surface, much of its energy is converted into heat, a form of
radiation which has a long wavelength. CO2, H2O vapour, and other gases present in
the atmosphere absorb and retain long wave radiation or reflect it back toward the
surface of the earth. These gases therefore act like panes of glass in a greenhouse,
letting light in, but retaining some of the heat before it escapes into space, hencethe term greenhouse effect.
Figure 3.4: Illustration of the greenhouse effect
The retention of heat by the greenhouse effect is a natural process, essential for
the evolution of life on the earth. It has been calculated that without it, average
surface temperatures would be between -17 and -230C; the actual average surface
temperature being +150C. However, the greenhouse effect appears to be increased
by emission of certain industrial gases, called greenhouse gases, the most importantbeing carbon dioxide, water vapours, chlorofluorocarbons, methane, and ozone.
b. Global warming
The increase in the concentration of greenhouse gases in the atmosphere cause a
rise in global temperatures, and hence could bring about changes in climate. The
global warming was detected to rise the sea levels, increase melting of ice, causechanges in vegetation, and contributes to unusual weather patterns.
c. Acid precipitation
Figure 3.5: Illustration of the formation of acid rain
The burning of wood and fossil fuels, including coal and oil, releases oxides of sulphur
and nitrogen that react with water in the atmosphere, forming sulphuric and nitric
acid, respectively and forming acid precipitation or rain, snow, sleet, or fog that has
a pH less than 5.2. Acid precipitation lowers the pH of streams and lakes and affectssoil chemistry and nutrient availability.
d. Depletion of Atmospheric Ozone
Life on Earth is protected from the damaging effects of ultraviolet (UV) radiation by
a layer of atmospheric ozone (O3) layer located in the stratosphere, around 17–25
km above Earth’s surface. Like carbon dioxide and other greenhouse gases, ozone
has also changed in concentration because of human activities. The destruction of
atmospheric ozone results primarily from the accumulation of chlorofluorocarbons
(CFCs) widely used in refrigeration and manufacturing. In the stratosphere, chlorine
atoms released from CFCs react with ozone, reducing it to molecular O2. Subsequent
chemical reactions liberate the chlorine, allowing it to react with other ozonemolecules in a catalytic chain reaction.
The decrease of ozone thickness in the stratosphere increase the intensity of
ultraviolet (UV) rays reaching Earth’s surface. The consequences of ozone depletion for
life on Earth may be severe for plants, animals, and microorganisms. Some scientists
expect increases in both lethal and nonlethal forms of skin cancer and in cataracts
among humans, as well as unpredictable effects on crops and natural communities,
especially the phytoplankton that are responsible for a large proportion of Earth’s
primary production. The most severe consequence of ozone depletion is DNA
damage which could occur if ozone layer is continually destroyed or when filters to
decrease or block the UV radiation in sunlight are not used as ecologists reportedbased on their experiments using filters.
Water is also polluted by industrial sewage from abattoirs, factories, hospitals and
or domestic waste such as human faeces, urine and detergents. Adding organic
material to water stimulates the growth of microorganisms which feed on the
material. As the density of microorganisms increases, their demand for oxygen also
rises. Water that is very heavily polluted with raw sewage become deoxygenated
and this can lead to the death of aerobic aquatic organisms such as fish.
Eutrophication occurs when organic material or inorganic nutrients, especially
nitrates or phosphates, enter a freshwater habitat, either naturally or as a result ofpollution by sewage or agricultural runoff containing fertiliser.
Fig 3.6: Flowchart showing the sequence of events which may result from eutrophication
Oxygen depletion and eutrophication are not only caused by sewage pollution,
they may be caused by any pollutant containing high concentrations of organic or
inorganic nutrient, such as fertilisers (inorganic or organic), slurry (animal faeces and
urine), or silage (a fermented grass product used to feed cattle in winter) effluent
which can leach off farmland and pollute water. Marine water like fresh water is
contaminated by agricultural fertilisers which have negative effects on aquaticlivings.
Soil pollution and its effects
Figure 3.7. Water polluted by home garbage “Ikimoteri”
Soil is polluted as a result of human activities. It is polluted by both inorganic and
organic pollutants. These two main soil pollutants are human-made chemicals or
other alteration in the natural soil environment. It is typically caused by industrial
activity, agricultural chemicals, or improper disposal of waste such as plastics bottles
and bags. Contamination is correlated with the degree of industrialization andintensity of chemical usage.
Application 3.3
1. Question is so irrelevant and does not cater for all schools
2. Explain how plastic bags and polythene bags are dangerous for farmers
and other soil dwelling animals.
3. Suggest ways of mitigating water, soil, and air pollution. How can youimplement the suggested strategies in your school area?
3.4 Biological conservation and restoration
Learning activities 3.4
1. Carry out research and list African species threatened by human
activities
2. Explain some main methods of the conservation of resources.3. Discuss the consequences due to the loss of biodiversity.
To date, scientists described and formally named about 1.8 million species of
organisms. About 10 million more species are not yet identified. A greatest portion
of species is found in tropics particularly in the tropical forests. Additionally, over
half of all accessible surface water is used for different purposes. Throughout the
biosphere, human activities altered trophic structures, energy flow, chemical cycling,
and natural ecosystem processes. Considering the above background, it is now timeto rethink about and seek how to preserve life on the Earth.
a. Biological conservation
Biological conservation integrates; ecology, physiology, molecular biology, genetics,
and evolutionary biology to conserve biological diversity at all levels. It is aimed to
maintain the quality of natural environments and their biological resources. Unlike
preservation which tries to prevent human interference, conservation involves
actively managing biotic and abiotic components to ensure the survival of the
maximum number of species and genetic diversity. Common reasons for conservingwildlife are:
Utilitarian reasons: Species are conserved due to their benefits to humans in terms
of food, medicines including quinine and codeine among plants, and snake venom
used as anticoagulants and anaesthetics, aspirin to antibiotics are made from natural
resources, and alkaloids that inhibit cancer cell growth), industrial use (timber, fuel,
gums, dyes, and oils), natural genetic resistance to pests, and whether they providenew variety.
Aesthetic reasons: Wild animals and plants biodiversity are conserved for thepleasure they provide human well-being.
Ecological reasons: Biodiversity is conserved due to the complex ecosystem
goods and services they provide including network of relationships which maintainbiogeochemical cycles in the biosphere and the energy flow in an ecosystem.
Ethical reasons: Most of the people conserve biodiversity due to the moral duty
to look after the environment and that all species have right to live. It is thereforemorally wrong to destroy ecosystems or to allow species to become extinct.
b. Conservation methods
Zoned reserves or protected areas approach
A zoned reserve is an extensive region that includes areas relatively undisturbed
by humans surrounded by areas that have been changed by human activity and
are used for economic gain. In Rwanda, there are now four national parks namely,
Akagera National Park, Nyungwe National Park, Volcano National Park, and Mukura-
Gishwati National Park which are the reserves for natural wildlife. The key challenge
of the zoned reserve approach is to develop a social and economic climate in the
surrounding lands that is compatible with the long-term viability of the protected
core. These surrounding areas called buffer zones continue to be used to support
the human population, but with regulations that prevent the types of extensive
alterations likely to impact the protected area. As a result, the surrounding habitats
serve as buffer zones against further intrusion into the undisturbed area. The
neighbouring communities should be involved in ecotourism activities as one wayof benefiting from ecosystem services.
Eco-farming approaches
Eco-farming is a modern method for conserving natural ecosystems. It combines
science and innovation with respect for nature and biodiversity. It ensures healthy
farming and healthy food. It protects soil, water and the climate from pollutants.
It does not contaminate the environment with chemical inputs or use genetically
engineered crops. And it places people and farmers, consumers and producers at its
very heart rather than the corporations who control the food now. It is envisioned
for sustainability and food sovereignty in which food is grown with health and safety
first and where control over food and farming rests with local communities, ratherthan transnational corporations. The methods have seven principles which are:
– Food sovereignty in which producers and consumers, not corporations, should
control the food chain and determine how food is produced.
– Rewarding rural livelihoods for ensuring food security and fighting poverty
in rural development.
– Smarter food production and yields which aimed at creating higher yields to
help feed the world.
– Biodiversity for promoting diversity in crops, instead of monocultures like corn
and soy, essentially to protecting ecosystem.
– Sustainable soil fertility is improved using eco-farming methods and refraining
from chemical fertilizers and inputs.
– Ecological pest protection where farmers can control pest damage and weeds
effectively through natural means instead of chemical pesticides.
– Food Resilience where diverse and resilient agriculture, not monoculture
crops, is the best way to protect communities from shocks from climate andfood prices.
Other conservation practices
In additional to the conservation methods, there are other practices that can be
applied for biological restoration since the above methods may be difficult andexpensive for some countries. They include:
– Restricting urban and industrial development and reclaiming abandoned sites
or other areas.
– Legally protecting endangered species and prohibiting the release or
introduction of non-native animals and plants into an area.
– Controlling pollution in sensitive environments in which species are at risk of
extinction.
– Recycling materials such as paper, glass bottles, clothes, and limiting the
exploitation of renewable resources to sustainable yields.
– Restricting trade of endangered species and providing breeding programs for
endangered species for example in zoos and botanic garden.
– Avoiding poaching and forest fires and voids habitat loss.
– Not introducing new species or exotic species and avoid overharvesting and or
overfishing.– Preventing global change through practices like afforestation.
Biodiversity conservation improves the quality of life for local people and leads to
a sustainable development. Many nations, scientific societies, international and
local NGOs embraced the concept of sustainable and economic development that
meets the needs of people today without limiting the ability of future generations
to meet their needs. In Rwanda, the Rwanda Environmental Management Agency
(REMA) and Rwanda Development Board (RDB) aims at protecting and conserving
ecosystems. The main conservation initiatives include forbidding people to use
swamps, not cultivating near the streams, rivers, and lakes, reforestation, ecotourism,
buffer zones, polythene or plastic bags not allowed to be used and enter inthe country are highlighted.
Application 3.4
1. How does coppicing contribute to the restoration of species?
2. Discuss the ways in which one could take action to help conserve
biological resources.
3. a) What could happen to Nyabarongo river ecosystem if there are
continuous soil erosions from the hillsides?b) How could the effects due to erosions be resolved?
End of unit assessment 3
1. Discuss how could human activities have negative impacts on
ecosystem.
2. Explain the major causes of deforestation in tropical area?
3. What are the advantages and disadvantages of agricultural practices?
applying nitrogenous fertilizers to crops, burning agricultural wastes,
growing crop plants with genetically engineering resistance to
herbicide e.g. glyphosate)?
4. Zoologists and conservationists fear that many if not all species of
amphibians would be extinct due to global pollution and climate
change. Explain how global pollution and climate change contribute to
the extinction of amphibians.
5. How can the addition of excess nutrients to a lake threaten its fish
population?
6. Based on biological magnification of toxins, is it healthier to feed at a
lower or higher trophic level? Explain.
7. Describe how the newly introduced species may damage natural
ecosystem.
8. Appreciate how modern agricultural technologies are a challenge aswell as a solution.