environment in agric extension material

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AED 316

INTRODUCTION TO ENVIRONMENTAL EXTENSION

A. E. ADEKOYA AND O. T. YEKINNI

DEPARTMENT OF AGRICULTURAL EXTENSION AND

RURAL DEVELOPMENT

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AED 316

INTRODUCTION TO ENVIRONMENTAL EXTENSION

General Introduction and Course Objective

The lecture on AED 316 is designed to facilitate understanding of the environment as it

concerns sustainable living. Sustainable living implies the need for people to live with therealisation to ensure enduring environment for people in future. It examined the components of

human environment; the interaction of biotic and abiotic factors. It also examined the natural

processes involving the components, equilibrium and relationships among other specificcomponents. It also looked at the dependence on the environment for food, energy, water and

oxygen. Also considered are significant activities that influenced the environment especially the

components and nutrient cycles. Thereafter, there was the assessment of the direct implicationsof some of the interactions with the environment as manifested in local issues like degradation,

desertification, pollution, erosion; and global issues like global warming, green house gases,

ozone layer depletion, climate change and acid rain. The course specifically examined theimplication inherent in agricultural activities and the environment. It also looked at the

environmental reclamation and protection activities such as agroforestry practices and the

international initiatives on sustainability and biodiversity conservation i.e. carbon footprint,

carbon banking and carbon tax.

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Contents

LECTURE 1. The environment

LECTURE 2. Components of the environment

LECTURE 3. Interaction of biotic and abiotic factors on environment

LECTURE 4. Natural processes involving the components, equilibrium and

relationships among the specific components.

LECTURE 5. Natural processes involving the components, equilibrium and

relationships among the specific components (2).

LECTURE 6. Dependence on the environment for food, energy, water and oxygen.

LECTURE 7. Significant activities as they influence the environment especially thecomponents and nutrient cycles (Monocropping and Agricultural

Chemical Use).

LECTURE 8. Significant activities as they influence the environment especially the

components and nutrient cycles (species depletion in wildlife and

fisheries),


components and nutrient cycles (Fossil fuels use and anthropogenic

wastes disposal).

LECTURE 10. Local issues like degradation, desertification, pollution, erosion.

LECTURE 11. Global issues (I): global warming, green house gases, ozone layer

depletion.

LECTURE 12. Global issues (II): climate change and acid rain,

LECTURE 13. Agriculture and the environment

LECTURE 14. Environmental reclamation and protection through agroforestrypractices.

LECTURE 15. International initiatives on sustainability and biodiversity conservation(carbon footprint, carbon banking, carbon tax).

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LECTURE 1. The environment

Introduction

The environment has a simple and very general meaning and it is often loosely used in the

context of this meaning. It is taken as the general surrounding of an individual, object or

structure although most definitions refer to humans as the central occupier of the environment. Inthis case it just implies things that are within the vicinity of man. Many of us are familiar with

our so-called environment and can give vivid descriptions of the structures both natural and

artificial which make up the environment. In fact some locations are named with reference tosome of the things existing in the vicinity for example Odoona, Ogunpa, Osun State.

Many of the things in our environment are often taken for granted and the usual posture is thatwe are not directly, if ever, linked to this components and that they are just there on their own to

the extent that whatever we do can not affect them. Even our idea about what should compose

the environment is not complete and we easily do not include some due to lack of knowledgeabout the concept. It is therefore necessary to have a change of perception and knowledge in this

matter.

The environment is very vital to our day-to-day activities, often linked with means of livelihood,impacting our health and generally shaping our lives. How we interact with, exploit and manage

the environment will somehow directly or indirectly impact our lives one way or the other. It is

necessary to have a complete understanding about the environment, far and near, local andglobal, as well as how best to act to ensure that the environment will always be there to serve us.

Objectives

At the end of the lecture, you should be able to:

1. have a wholesome understanding of what the environment is.

2. identify some of the components of the environment.

3. explain how the environment influences man and his livelihood.

Pre-Test

1. Mention 5 living components of the environment.

2. Which environmental components can serve as sources of income for man?

3. Which of the components is often used to describe or name a place?

Content

The environment

The environment can be generally defined as the surrounding of an object and thereforedescribed with respect to that particular object. For instance, my own environment will include

all things, living and non-living with which I usually interact directly or indirectly. This implies

that everything has a corresponding environment which can be as dynamic as the activities and

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changes occurring therein. A dictionary definition has it as a complex of external factors that acts

on a system and determines its course and form of existence. An environment may be thought of

as a superset, of which the given system is a subset. An environment may have one ormoreparameters, physical or otherwise. The environment of a given system must necessarily

interact with that system.

In some other literal situations, the environment can be described with respect to its major

constituents. Hence there can be the forest environment which will describe the predominance of

forest species. However, what results from the assemblage of the components is always taken asimportant and not just the mere existence. This means that the interaction between the

components as they generate the characteristics of the forest system is crucial to the system. This

interaction is what determines how the environment will serve its guests (man) as the latter

ekes out survival within the former.

In a sense, organisms become adapted to their environment in all aspects of life be it feeding,

movement and other activities that may be important as aspects of life. This underscores theimportance of the environment in the life of every creature. In fact the environment has been

responsible for certain physical differences observed in same species existing in different places.Hence, the free dictionary explains the environment as the totality of circumstances surrounding

an organism or group of organisms, especially:

a. The combination of external physical conditions that affect and influence the

growth, development, and survival of organisms.

b. The complex of social and cultural conditions affecting the nature of an individual

or community. The implication of this is that the environment directly interacts withindividuals and communities and a right understanding of it must require considering it as a

living entity and thus entitled to high level concern because on the long run we only thereby

show concern for our survival.

The environment is also seen as an entity that can be subjected to modification either through the

interaction ensuing or directly as an activity towards an end. This definition is more germane to

interventionary sciences like medicine where the environment is known to impact the well beingof people depending on how it is treated or managed. Included environmental factors are the

modifiable parts (or impacts) of:

pollution of air, water, or soil with chemical or biological agents;

UV and ionizing radiation

noise, electromagnetic fields;

occupational risks

built environments, including housing, land use patterns, roads; agricultural methods, irrigation schemes;

man-made climate change, ecosystem change;

behaviour related to the availability of safe water and sanitation facilities, such as

washing hands, and contaminating food with unsafe water or unclean hands.

It therefore goes without saying that the environment is the bedrock on which every life form

survives. It provides support for whatever is carried out by the subject like feeding, energy

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generation, production activities and many more. However, the dependence on the environment

has consequences which may inhibit it from providing the usual benefits after sometime unless

sufficient concern is shown to ensure that the environment is not impoverished.

Summary

The surrounding of man, animal or other objects constitute the respective environment. The

environment may comprise of living and non-living things. Some of the constituents are

used to describe the environment by referring to them in the identification. The concept ofenvironment is explained according to predilection; therefore a farmer sees the

environment differently from a medical practitioner. While the environment forms a vital

part of the life of the dweller, it is affected by the life of the dweller and the relationshipneeds to be managed in a symbiotic manner.

Post test

1. List three human activities that influence the environment.

2. What 2 conditions determine the state of the environment and how does man influencethese.

3. Can the environment shape the nature and activity of man? Explain.

References

http://www.wordiq.com/definition/Environment

http://www.thefreedictionary.com/environment

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LECTURE 2. Components of the environment

Introduction

The significance of the environment in sustenance of life can not be over-emphasised and so the

components of the environment which enable it to perform this onerous task become very

important. The environment is everything that creates natural conditions for the existence oforganisms including Man, and it is a precondition of their further development. Its components

are mainly the air, water, minerals, soil, and living organisms.

The environment comprises of living and non-living components which give it specific

characteristics and facilitate the functions it performs. Depending on what services or benefits

are provided by the environment, each component has a big role to play and may even becomeused up while performing the role. Knowledge of the components and the specific role each

plays will be an interesting experience and probably bring forth an appreciation of the

components. It will also inform about what becomes of the component as it renders services toman as well as what has to be done to ensure sustainability of the components.

Objectives


1. create awareness of what the environment is composed of.

2. identify predominant components of the environment.

3. describe the various functions of the components in the environment.

4. classify the components of the environment.

Pre-Test

1. Identify the components of your immediate environment.

2. Classify the environmental components into living and non-living things.

3. Name the roles of any 3 components of the environment.

Content

Components of the environment

People have many different ideas as to what comprises The Environment. Its physicalcomponents can be divided into Land (landscapes), Sea and the Air, in other words everything

around us. Animals and plants live within the environment, not forgetting that human beings are

themselves animals and part of the environment. The environment, the entire surrounding ofman, is composed of several things. These range from gases in the air to liquids like precipitation

and soil water, and also solids like soil. There are at the same time the living components like

microbes, plants and animals. These components are present in varying proportions and the

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proportions define the environment. So, the aquatic environment will be different from terrestrial

ones and will therefore impact on the organisms existing there differently too.

a. Gases in the environment: Regardless of the type of environment, gases are always

present although the proportion will vary. In the atmosphere, the most common gases are

nitrogen, oxygen, carbon IV oxide, halogens and so on. These gases are important for certainnutrient cycles and various life forms. For instance, animals breathe in oxygen and exhale

carbon IV oxide, while the reverse is the case when plants photosynthesise. The gases are

also found in soils as they penetrate soil pores to impact on life in these places. Some of thegases have the ability to dissolve in liquids especially water in seas and oceans. The greater

functions of gases are to: support life especially respiration, be available for certain cellular

reactions towards tissue building, primary production by producers and environmental

temperature regulation.

b. Solids in the environment. These will include the soil together with rocks/stones which

span the entire crust of the earth. These solids serve as bases on which other things includingliving forms exist. So it can be said that solid fill the spaces in the entire creation where gases

and liquids are not found. All animals walk and live on solids while plants also grow theretoo. The solids also serve as store of materials that can be useful to living forms. For

example, the soil is a pack of nutrients (minerals) which plants depend on. Other solids stillserve various uses to man in the form of minerals and ornaments.

However, there is a level of stability expected in the solids to enable them serve expectedroles in the environment and yet they are subject to degradation when not well managed.

Degradation makes them loose firmness and they slowly wear off setting in motion a set of

reactions that eventually render the environment unstable and even affect some othercomponents. For instance, soil degradation eventually leads to silting and sea level rising

which may cause flooding. Degradation also prevents the soil from being able to support

plant growth.c. Water in the environment: Water exists in different forms in the environment, as natural

water, fluid in living things or solvent to some other substances, the reason why it is regarded

as a universal solvent. There is the need to move a lot of substances from one place toanother either and water assists in this matter by providing a medium where substances can

dissolve and thus transported.

As a liquid, water can be found in the soil as soil water which contains other substances

mostly solids. In the air, water exists as vapour in the pure form. Ordinarily water comes in

the form of precipitations which eventually collect in streams, ponds, rivers, seas and oceans.

In the solid form, water exists as ice especially in the Polar Regions or where temperature is

considerably low.

The form in which water exists and the substances dissolved in it go a long way to determinethe usefulness of water. This is because the role expected of water also varies and when, for

example, if it is needed in the plain form, another form will not suffice. Water management is

a serious issue and often determines the survival of populations; it is even responsible forwars among nations.

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d. Other organisms. Apart from the specific organism of concern in the environment, there

are usually other life forms which usually engage in interactions with other components of

the environment and by and large contribute to the functioning of the environment. Suchorganisms act on the air, liquid or solid and facilitate their usefulness. Some of them are

involved in the conversion or decomposition cycles which help ensure that the components

are available in the form they are required. For instance, primary producers that is, plants,convert carbon in the air to carbohydrate for animals to consume. Without plants, animals

can not have access to carbon. This kind of role is clearly explained in food chains.

Also, there are microorganisms which help in conversion and combination of substances to

produce forms of certain components that can be used by man.

e. Finally, there are the earth forces of wind and temperature (solar) which come into playto shape the environment in a particular fashion. These forces, also called the elements, act

upon the components of the environment, causing certain chemical reactions which tend to

change the nature and structure of the components. For instance, when there is precipitation,water becomes available for components of the environment but the same water can, under

substantial velocity, cause dislocation of some of the components thus affecting the stabilityof the environment. Subsequent action of temperature or wind can then act on the

components in such a way that results in degradation. The described action can cover largeexpanses and eventually defining the plant and animal species that will cope in the adjusted

environment.

Understanding the environment involves studying the complex relationships between people and

the typical physical and social settings in which they conduct their daily lives. As the demands

from the environment increases much impact on the components results which in turn weakensthe environment and the resulting vicious cycle has man at the receiving end. Experiences

gathered by man however become useful in guiding future interactions which put the

environment on the pedestal it rightfully belongs, engendering respect and concern for it.

Post-Test

1. List three components of an aquatic environment and classify them according to their nature.

2. Which of the elements is of important consideration in the aquatic environment?

3. What is the role of producers in the environment?

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Summary

Components of the environment are essential in enabling it to perform expected roles and

services. These components are of different types like gases, liquids and solids. The

components are found in varying proportions depending on the particular environmentand the facilitate survival of life forms. For instance, organisms are enabled to respire,

grow and move. It is important to note that the components form the basis of the

environment and when they are misused, they lose the ability to function and the

environment eventually becomes irritable if not even harmful to life.


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References

Environment Society of Oman: http://www.environment.org.om/index/list.php?categoryId=310

http://nptel.iitm.ac.in/courses/Webcourse-contents/IIT-Delhi/Environment%20and

%20Ecology/mod1/2.htm

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LECTURE 3. Interaction of biotic and abiotic factors on environment

Introduction

Components of the environment are never left alone as the community, groups and individuals

continue to impact them with demands through exploitation of the components in other to realise

livelihoods. The exploitation takes various forms and dimensions.

Abiotic factors will refer to non-living things and forces that impact the environment including

rainfall, sunshine, time and chemicals. While the biotic factors will imply plants and animals interms of their dependence on the environment and the consequence of their actions as these

influence the ability of the environment in its roles. The unregulated actions of biotic factors

boomerang on them in the long run as the environment may become rendered unsustainable. Andthe existence of life forms depends on forces of nature, that is, sun, wind, temperature and

precipitation and all these have a strong relationship with vegetation.

Objectives


1. recognise and understand the biotic and abiotic components of the environment.

2. know the relationship between vegetation and the components of the environment.

3. understand the significance of environment on the living populations of a place.

Pre-Test

1. How does the environment give rise to vegetations?

2. What relationship exists between environment and climate?

3. How does environment influence population settlements?

Content

Interaction of biotic and abiotic factors on environment

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind,rainfall, atmospheric particle count and othermeteorological elemental measurements in a given

region over long periods. This ordinarily suggests that these elements are not constant and even

vary across locations on the globe. The climate of a location is affected by its latitude, terrain,and altitude, as well as nearby water bodies and their currents. Climates can be classified

according to the average and the typical ranges of different variables, most commonly

temperature and precipitation. The major difference between climate and weather is time span as

the latter covers a shorter period while the former may be for over twenty years. The difference

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http://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Atmospheric_pressurehttp://en.wikipedia.org/wiki/Windhttp://en.wikipedia.org/wiki/Rainfallhttp://en.wikipedia.org/wiki/Meteorologyhttp://en.wikipedia.org/wiki/Latitudehttp://en.wikipedia.org/wiki/Terrainhttp://en.wikipedia.org/wiki/Altitudehttp://en.wikipedia.org/wiki/Climate_classificationhttp://en.wikipedia.org/wiki/Temperaturehttp://en.wikipedia.org/wiki/Humidityhttp://en.wikipedia.org/wiki/Atmospheric_pressurehttp://en.wikipedia.org/wiki/Windhttp://en.wikipedia.org/wiki/Rainfallhttp://en.wikipedia.org/wiki/Meteorologyhttp://en.wikipedia.org/wiki/Latitudehttp://en.wikipedia.org/wiki/Terrainhttp://en.wikipedia.org/wiki/Altitudehttp://en.wikipedia.org/wiki/Climate_classification


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between climate and weather is usefully summarized by the popular phrase: Climate is what you

expect, weather is what you get.

Vegetation can be explained as the sum total of all plant life in a place. This will present a

picture of the components of the environment and the extent to which plant life is supported.

Primary among the components responsible for vegetation pattern are the solids in the form ofsoil, water in the form of precipitation and ending as soil water and temperature as dictated by

sunlight intensity thus determining the humidity. It should also be clear that vegetation has

important roles in most food chains and nutrient cycles.

Vegetation plays an important part as a biotic component of the environment and in its

dependence on the latter for sustenance; it has so much impact in ensuring that the balance

among the components is not impaired.

Biotic factors like vegetation live on abiotic factors that is, the chemicals in the form of nutrients

and the forces which predetermine what type of vegetation can survive in the area. On the otherhand, vegetation is involved in several nutrient cycles and also helps to stabilise the condition

under which the abiotic factors operate. The ensuing nexus is vital in sustainability of theenvironment.

When the environment is completely understood in terms of the abiotic and biotic components, it

is possible to determine the vegetation that will predominate there. This relationship is always

very specific to a location of the earth surface and as translocation ensues, the vegetation alsochanges. This is summarised as: morphological characteristics represent behavioural strategies of

plants to cope with environmental pressures.

Abiotic components: they are the raw materials of ecosystems (such as minerals) and the forcesaffecting the ecosystems (such as geological processes). They create pre-existing and changing

conditions for a ecosystem. Therefore, they are the foundation of eco-equilibrium. By their

power (such as a volcanic eruption, flood, hurricane), they can change the equilibriumdramatically.

Bioticcomponents: if abiotic is the foundation, then biotic is the actual building. By the bioticinteractions in the form of an ecological network the biota affects each other but can also affect

abiotic elements by manipulating them (such as the recycling of elements). Their existence will

not be possible if abiotic is too hostile to their existence, but once after they establish existence

they can manipulate abiotic. They affect equilibrium mainly by biological processes such asreproduction, technology and aggressive production activities which over-exploit nature.

Depending on the soil structure and composition, vegetation of varying species can be supported.

The vegetation in an area describes the extent of adaptation that has been developed by the

species occurring there. And actually, it is the species which really describes the vegetation.

Similarly, as the abiotic forces influence the environment, much is on shaping the nature of theenvironment and thus determining the condition under which life forms can thrive. To this end,

the vegetation type is defined by the temperature, wind, humidity and precipitation, all weather

and climatic elements.

Plants and animal population, including human, are found in different populations to the extent

to which the place is conducive or adaptable. The populations depend on the vegetation while

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coping with the environment. In the act of living, components of the environment are consumed

or used up thereby impacting on the environment. The nature and extent of the impact will

determine the harm inflicted on the environment and its ability to continue rendering necessaryservices.

However, when the environment is carelessly impacted to a level described as abuse of theenvironment, then a chain of events ensues. The environmental components either become

depleted or unavailable and the balance among the resources breaks down. The natural tolerance

of the forces of wind, temperature etc weakens and the environment becomes unprotected fromthe forces, leading to devastating effects like flooding, erosion, desertification etc. This then

affects the vegetation which loses its support from the environment and loses its population.

Finally, the animal population gets affected as the vegetation can not support them. Together,

abiotic and biotic components create and change equilibrium by a combination of static anddynamic, active and passive, living and nonliving, processes.

In several cases, animals especially man, is implicated in the mismanagement of theenvironment. Unbridled exploitation of the environment, overpopulation and technological

advancement place much pressure on the environment. The environment has inbuilt capability torecover from impacts suffered and this is because there are cycles that ensure replacement of

exploited resources as well as still putting the environment in good stead to cope with abioticforces, but this has a limit. When the carrying capacity of the environment is exceeded, the in-

built processes for recovery cannot cope and the described trail of woes result with the whole

weight crashing on man who initiated the abuse abinitio.

Post-Test

1. Design a cycle linking components of the environment.

2. Which of the components will you consider most important and why?

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Summary

The complexity of the relationship between all the components of the environment clearly

establishes the importance of each. This relationship is a significant determinant of the

environment because the various interactions among the biotic and abiotic componentsinfluence the vegetation and vice versa, and eventually determine the nature of the

environment and what flora and fauna can be sustained therewith. A cycle of interaction which

is unending is developed becomes a perpetual factor for defining the environment. Each

component is supported, maintained and also supported to a level where its presence isbeneficial to the environment and when this limit is exceeded, events are set in motion to

correct the anomaly.

The overall interplay among the components gives rise to weather and climate which also haveimpact on the interactions and even determines the vegetation, thus joining the train of events

that dictate the final biotic and abiotic components. Similarly, when a change occurs to the

weather and climate, the components are directly affected and if the effect is to a large extent

and sustained, it will in turn affect the weather and climate on the long run.


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3. Describe the vegetation pattern of Nigeria and link this with intensity of the sun.

References

Zavala-Hurtado JA, Valverde PL, Daz-Sols A, Vite F, Portilla E. Vegetation-environmentrelationships based on a life-forms classification in a semiarid region of tropical Mexico.

http://www.ncbi.nlm.nih.gov/pubmed/9246368

http://en.wikipedia.org/wiki/Climate

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http://www.ncbi.nlm.nih.gov/pubmed?term=%22Zavala-Hurtado%20JA%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Valverde%20PL%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22D%C3%ADaz-Sol%C3%ADs%20A%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Vite%20F%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Portilla%20E%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed/9246368%20accessed%2029/8/2011http://en.wikipedia.org/wiki/Climatehttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Zavala-Hurtado%20JA%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Valverde%20PL%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22D%C3%ADaz-Sol%C3%ADs%20A%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Vite%20F%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed?term=%22Portilla%20E%22%5BAuthor%5Dhttp://www.ncbi.nlm.nih.gov/pubmed/9246368%20accessed%2029/8/2011http://en.wikipedia.org/wiki/Climate


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LECTURE 4.Natural processes involving the components, equilibrium and relationships

among the specific components.

Introduction

The general components of the environment comprise specific substances, elements or

compounds, which make up the liquids, solids and gases. Abiotic components are nonliving andconsist of soil, minerals, air, water, and sunlight. Biotic components are living organisms of the

ecosystem. Ecosystem is a community of organisms interacting with one another and within their

environment. There are a vast number of species living in any ecosystem and these organismsdepend on one another and their environment for sources of food and energy. Matter and energy

is recycled through ecosystems, and the amount of life any environment can support is limited by

the available energy, oxygen, water, and minerals. Interactions between biotic and abiotic factorscause the ecosystem to constantly shift and adjust to maintain balance in the system.

Objectives


1. know the essential substances making the components of the environment function.

2. understand the relationships among the substances.

3. know the type of reactions or processes that maintains the substances.

Pre-Test

1. Name 3 cycles and substances involved in them.

2. How does oxygen get replenished in the environment?

3. In what cycle does the ocean play a role and which substance is involved?

Content

Natural processes involving the components, equilibrium and relationships among the

specific components

All of life on earth revolves around a few key nutrients and in combination with energy from thesun it is these nutrients which are required by all of earths producers. These nutrients are

essentially contained within a closed system on earth, which means no nutrients enter or leave

the biosphere in large quantities. For this reason there is a limited amount of the essentialnutrients available to the producers, so the available nutrients such as carbon, nitrogen andphosphorus must be recycled and reused by organisms. The recycling of these nutrients involves

interactions between both the living organisms and the physical environment, so they are called

biogeochemical cycles. These cycles are often considered to be leaky since nutrients such asnitrogen and phosphorus may be carried away in rain water to the deep ocean where it is

removed from the cycle, other sources of nutrient loss include harvesting and burning of organic

material. The nutrient and water cycles are of utmost importance to all life on earth.

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Nutrient cycles

Biogeochemical Cycles: Besides energy, all organisms require various nutrients. In addition to

water molecules, the elements of primary importance in these nutrients are carbon, nitrogen,

oxygen and phosphorus. Nutrients, unlike energy, are recycled through ecosystems in nutrient

(biogeochemical) cycles. For each element, the cycle may involve:

1. A reservoir, in which the nutrient is present but temporarily unavailable,

2. An exchange pool, which is the primary source of nutrients, and

3. The biotic community, which consists of the organisms through which nutrients pass at

various stage of the food chain.

The reservoirs are naturally occurring stores of abiotic components of the environment but when

they are exposed to certainbiochemical forces of

physical forces involvingthe elements, they mayweather or decompose to

release the stored

substances or energy. These

are then passed on to theenvironment in a state

whereby they are available

for use by bioticcomponents. This marks the

entry into the food chain

and subsequent movementof the nutrients through the

chain in biomass

development and energy

release. One thing to note isthat the constant movement

of the nutrients between the

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Water Cycle
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biotic and abiotic components hardly get them back into the reservoirs in a short time but only

after centuries or even more.

Earth has a stable water supply which 98 percent of the earths water is contained in, oceans,

lakes, rivers and streams with the remaining found in, the form of ice, water vapour, and in the

bodies of living organisms. The constant movement of water, from earth to the atmosphere iscalled the water cycle. This cycle is driven by solar energy which facilitates the transformation of

water from the different forms of solid, liquid and gas. It makes it possible for the Earths water

supply to be available for use over and over again. The sun evaporates water off water bodiessuch as rivers and lakes, as well as from moist surfaces, air and bodies of living organisms.

This water is drawn back up into the atmosphere, and falls back to earth in the form of rain.

There is a greater amount of evaporation, from the ocean than the amount of precipitation(rainfall) this results in a movement of water vapour by the wind to inland areas, areas closer to

the ocean receive more precipitation (rainfall) than those which are further from the ocean or are

protected by a mountain range. Water is also absorbed from the bodies of terrestrial plants andanimals as well as the soil, the collective process of evaporation from the soil and plants is called

evapotranspiration - the constant movement of water through evaporation by the sun. Waterwhich is not evaporated by the sun may re-enter the water cycle by seeping down through the

soil, until it reaches the zone of saturation, here all of the holes and cracks of the soil are filledwith water below which there is a bed of solid rock which the water cannot penetrate. This

region is referred to as aquifer.

Post-Test

1. In what form does water exist in biotic components of the environment?

2. How is the energy present in fossil fuels available to humans?

3. How are the nutrients lost during erosion available for human use?

References

17

Summary

Life is generally sustained by matter and energy. These two are present in all forms of life.

However, all life is constantly in a sort of relationship whereby the matter and energy required

is in constant motion through a series of exchange from one life form to the other. Usually

there is a natural store where the substances are held like in rocks but on being subjected to

some forces, they get free and move freely in the environment. From then, the natural cyclesof nutrient and energy exchange take over.

In the case of water, it is the bulk of life forms, in tissues and circulatory systems. Generally in

the environment, water can exist as liquid, solid or vapour. The form it assumes is dependenton the amount of energy inherent in the water. Thus solar energy is important in the

transformation of water between the various forms as it facilitates evapotranspiration which is

followed by condensation and eventual precipitation. The two cycles therefore operate theperpetual mutual exchange of matter and water.


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http://wiki.answers.com/Q/How_do_the_biotic_and_abiotic_components_change_the_equilibriu

m_of_the_ecosystems#ixzz1WXnWjmXe

http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ec/m3/s3/index.htm

http://library.thinkquest.org/C007506/cycles.html

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LECTURE 5. Natural processes involving the components, equilibrium and relationships

among the specific components (2).

Introduction

The act of use and reuse of environmental components is an ever happening process. The

continual availability of the substances is however predicated on cycles which combine,breakdown and again recombine the substances to transform them into useable forms at the

various stages of the cycles. Without the cycles, one can visualise a stage where a particular

components will be converted into another form in a unidirectional way until the basic source isdepleted and all life dependent on the component eventually ceases.

Two important components will be discussed in this lecture: Carbon and Oxygen. Arguably,these two are the most important of all the basic components as they are found in all life forms

and in many abiotic components as well.They function significantly in most of the cycles and all

food chains.

Objectives


1. understand the uses of carbon and oxygen in the environment.

2. know the processes through which carbon and oxygen are replenished in theenvironment.

3. link the two cycles and understand human activities relating to each.

Pre-Test

1. Describe 2 ways of oxygen uptake in the environment.

2. What is the significance of vegetation to oxygen and carbon availability in the

environment?

3. Of what importance is the sun in the 2 cycles?

Content

Carbon CycleCarbon is a basic element occurring in all life either in tissues, organs or in the energy cycle. It is

variously produced and at the same time used up in stages of the food chains and the main issue

in primary production and subsequent consumption involves carbon compounds. It exists in theelement form as coal and others but its major use is in energy storage and release. The cycle

described in the diagram below is informative in this regard:

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Carbon cycle

During photosynthesis producers convert carbon dioxide in the atmosphere into carboncontaining compounds such as sugars and cellulose. These compounds are then utilized by

primary consumers such as cattle or elk, which, by the process of respiration, convert the carbon

containing compounds into carbon dioxide and water. These processes viewed on a global scale,

is called the Carbon Cycle.

In the carbon cycle the primary photoynthesizers are the plants, phytoplankton, marine algae, and

cyanobacteria. These organisms utilize carbon dioxide and water to produce carbohydrates and

oxygen which the photosynthesizers use themselves. Plants do release carbon dioxide from theirleaves and roots, and phytoplankton and marine algae and cyanobacteria, release carbon dioxide

into the water where it remains in equilibrium with the carbon dioxide of the air.

Not only is carbon dioxide released by plants, it is also released by animals which eat the plants

and animals which eat those animals, during the process of respiration which is a basic process

of life. Carbon dioxide is also released by the combustion of organic carbon sources such aswood, coal and oil. An enormous amount of organic carbon resides in the bodies of dead plants

and animals, along with the wastes of living animals. Decomposers, such as fungi and other

small invertebrates, consume this Carbon; these decomposers also release carbon dioxide.

Up until the industrial revolution the processes of photosynthesis and respiration were essentially

in balance with one another. Although carbon dioxide is only a portion of the atmosphere, along

with water vapour, and methane and the other greenhouse gasses, it plays a major role in theecosystems on earth.

These green house gases absorb infrared radiation from the sun, while allowing sunlight to passthrough. It also blocks infrared radiation (heat) from being lost in space by enveloping the earth.

So as the amount of these green house gases increase the amount of heat lost from the earth

decreases causing the overall temperature of earth to increase. Global warming produced in this

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manner is known as the greenhouse effect. The green house effect is due mainly to our use of

fossil fuels such as coal and oil, the ploughing of the soil and the destruction and burning of the

tropical forests. When deforestation occurs, plants that act as carbon sink (arbsorb CO 2) aredepleted and this leads to an accumulation of CO2 which is a greenhouse gas.

The Oxygen Cycle

Almost all living things need oxygen. They use this oxygen during the process of creating

energy in living cells.

Just as water moves from the sky to the

earth and back in the hydrologic cycle,

oxygen is also cycled through theenvironment. Plants mark the

beginning of the oxygen cycle. Plants

are able to use the energy of sunlight toconvert carbon dioxide (CO2) and water

into carbohydrates and oxygen in aprocess called photosynthesis.

CO2 + H2O + sunlight

carbohydrates + O2

This means that plants breathe in

carbon dioxide and breathe out

oxygen.

Animals form the other half of the oxygen cycle. They breathe in oxygen which is used to break

carbohydrates down into energy in a process called respiration.

Carbohydrates + O2 CO2 + H2O + energy

Carbon dioxide produced during respiration is breathed out by animals into the air. So oxygen iscreated in plants and used up by animals, as is shown in the figure above. But the oxygen cycle

is not actually quite that simple. Plants must break carbohydrates down into energy just as

animals do. During the day, plants hold onto a bit of the oxygen which they produced in

photosynthesis and use that oxygen to break down carbohydrates. But in order to maintain theirmetabolism and continue respiration at night, the plants must absorb oxygen from the air and

give off carbon dioxide just as animals do. Even though plants produce approximately ten times

as much oxygen during the day as they consume at night, the night-time consumption of oxygenby plants can create low oxygen conditions in some water habitats.

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Summary

Carbon and oxygen are essential elements not only as building blocks of life but also in the

energy generation and utilisation. Carbon is taken up by plants in the form of gaseous carbon

IV oxide which they combine with water and in the process store sun energy which is lateravailable to animals in the food chain.

The two cycles again reemphasise the interdependence among components of an environment.

The importance of plants in an environment is crucial for the survival of animals including

man. The basic producers ensure that primary and other consumers have energy and nutrientsto survive.

Post-Test

1. Describe the reaction occurring among plants in the night.

2. What happens when massive deforestation takes place in an area?

3. How do animals help plants to survive?

References

http://water.me.vccs.edu/concepts/oxycycle.html

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Human activities and the environment

LECTURE 6. Dependence on the environment for food, energy, water and oxygen.

Introduction

The environment comprises of plants and animals both at micro and macro sizes as well ashumans, the most highly developed animals, although the combination will depend on the

particular environment. For several years there have been various forms of interaction among

and between these strange bed-fellows. The interaction also involves sets of processes whichfacilitate transformation of solar energy and other nutrients, and also the exchange of the energy

and nutrients across the inhabitants of the environment.

However complex the workings of living organisms, they share with all other natural systems the

same physical principles of the conservation and transformation of matter and energy. Over long

spans of time, matter and energy are transformed among living things, and between them and the

physical environment. In these grand-scale cycles, the total amount of matter and energy remainsconstant, even though their form and location undergo continual change.

Almost all life on earth is ultimately maintained by transformations of energy from the sun.Plants capture the suns energy and use it to synthesize complex, energy-rich molecules (chiefly

sugars) from molecules of carbon dioxide and water. These synthesized molecules then serve,

directly or indirectly, as the source of energy for the plants themselves and ultimately for allanimals and decomposer organisms (such as bacteria and fungi).

Objectives


1. know benefits derivable from the environment

2. understand the impact of human activities on the environment.

3. understand waste management and waste generation.

Pre-Test

1. List three human activities that impact the environment.

2. How does human uncontrolled human population affect sustainability of environment?

3. Can materials be actually wasted in life?

Content

Dependence on the environment for food, energy, water and oxygen

The elements that make up the molecules of living things are continually recycled. Chief amongthese elements are carbon, oxygen, hydrogen, nitrogen, sulphur, phosphorus, calcium, sodium,

potassium, and iron. These and other elements, mostly occurring in energy-rich molecules, are

passed along the food web and eventually are recycled by decomposers back to mineral nutrients

usable by plants. Although there often may be local excesses and deficits, the situation over the

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whole earth is that organisms are dying and decaying at about the same rate as that at which new

life is being synthesized. That is, the total living biomass stays roughly constant, there is a cyclic

flow of materials from old to new life, and there is an irreversible flow of energy from capturedsunlight into dissipated heat.

An important interruption in the usual flow of energy apparently occurred millions of years agowhen the growth of land plants and marine organisms exceeded the ability of decomposers to

recycle them. The accumulating layers of energy-rich organic material were gradually turned

into coal and oil by the pressure of the overlying earth. The energy stored in their molecularstructure we can now release by burning, and our modern civilization depends on immense

amounts of energy from such fossil fuels recovered from the earth. By burning fossil fuels, we

are finally passing most of the stored energy on to the environment as heat. We are also passing

back to the atmosphere - in a relatively very short time - large amounts of carbon dioxide thathad been removed from it slowly over millions of years.

The amount of life any environment can sustain is limited by its most basic resources: the inflowof energy, minerals, and water. Sustained productivity of an ecosystem requires sufficient energy

for new products that are synthesized (such as trees and crops) and also for recycling completelythe residue of the old (dead leaves, human sewage, etc.). When human technology intrudes,

materials may accumulate as waste that is not recycled. The accumulation will gradually becomea distortion in the cycle that involves the particular substance.

The interdependence of organisms in an ecosystem often results in approximate stability overhundreds or thousands of years. As one species proliferates, it is held in check by one or more

environmental factors: depletion of food or nesting sites, increased loss to predators, or invasion

by parasites. If a natural disaster such as flood or fire occurs, the damaged ecosystem is likely torecover in a succession of stages that eventually results in a system similar to the original one.

Like many complex systems, ecosystems tend to show cyclic fluctuations around a state of

approximate equilibrium. In the long run, however, ecosystems inevitably change when climatechanges or when very different new species appear as a result of migration or evolution (or are

introduced deliberately or inadvertently by humans).

Any form of intervention in a natural cycle is resisted or adjusted to by the system in order to

annul the effect of the intervention. The adjustment of the system may result in shocks to the

components which also try to adjust to accommodate the shock. Usually, the adjustment iscompleted over a long term during which normalcy or a semblance of it is attained. However, if

the adjustment is drastic or the new equilibrium is intolerable to some components, then

extinction or evolution of new species may result. This dimension will begin a process of total

overhaul of the environment to accommodate the new entrants or displacement of another.

Imagine a change that will require elimination of lions in a particular environment, if a new setof predators do not evolve, the primary consumers will simply multiply out of proportion beyond

the carrying capacity of primary producers. This will naturally weigh down the plants and makethem extinct in a matter of time and truncate the energy cycle.

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Summary

Basic nutrients for life support exist in the environment while the sun provides the energy.

Conversion of the nutrients to usable forms is done through several processes in both biotic and

abiotic means. The nutrient cycles are linked to places where the nutrients are stored or storableand they engender conversion mechanisms which not only translocate the nutrients but also

convert to different substances.

In the same way, solar energy is captured and processed into chemical forms that can again be

reconverted for use when and where needed.

The significance of the role players in each cycle cannot be overemphasised as they serve at dutyposts of nature and foster the survival of the environment. Another form of balance is

established among role players of various cycles to ensure sufficiency and avoid waste. The

latter balance is a delicate one and a key to environmental sustainability.

Post test

1. In what ways do mankind influence the ecosystem?

2. What are the long term consequences of ecosystem alteration?

3. List five elements that are important in life.

References

http://www.project2061.org/publications/sfaa/online/chap5.htm

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LECTURE 7.Significant activities as they influence the environment especially the

components and nutrient cycles (Monocropping and Agricultural Chemical

Use).

Introduction

The environment is crucial for life support and plays a significant role in biodiversityconservation which inadvertently ensures its maintenance. The interaction with the environment

however requires a lot of caution so as to consciously preserve it. As the humans are engaged in

activities in the bid to satisfy individual and group social and economic desires, the environmentprovides the means and materials towards these ends. And when the ends are satisfied, the

wastes are dumped back into the environment. The environment is thus being treated as an

unappreciated and possibly abandoned thing. Perhaps, this attitude is engendered by a lack ofknowledge on appropriateness of human activities, or a compromise of proper behaviour for

other gains or a mix of these. It is deemed necessary to understand the consequences of our

actions especially as they affect the environment.

Objectives


1. highlight how human production activities affect the environment.

2. show ways in which domestic activities affect the environment.

3. know significant components of the environment affected by human activities.

Pre-Test

1. How can a productive enterprise become environmentally unsafe?

2. Is planting many crops better than just one?

3. What is the meaning of persistent chemical and how does it harm the environment?

Content

Significant activities as they influence the environment especially the components and

nutrient cycles

There activities which are undertaken in pursuit of certain goals and which while realising the setgoals generate negative consequences on the environment. These activities include

monocropping and use of chemicals in agricultural production.

Monocropping is the agriculturalpractice of growing the same crop year after year on the sameland. Monocropping is most frequently practiced in industrialised countries agricultural

systems; where large plantations ofmaize (corn), soybeans and wheat are three common crops

often grown using monocropping techniques. It is increasingly being done in developingcountries as genetically modified organisms (GMO) and industrial farming are displacing native

crops and local farmers.

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While economically a very efficient system, allowing for specialization in equipment and crop

production, monocropping is also controversial, as it often leads to depletion of the nutrients of

the soil and problems with weeds and pesticides. These in turn lead to the monocropping systembeing dependent on pesticides and artificial fertilisers. It also leaves the crop more susceptible to

disease as genetic similarity between plants makes them equally vulnerable. An example of this

would be thepotato famine ofIreland in 18451849, and is the main cause of the current foodcrisis with monoculture rice crops failing as the effects ofclimate change become more acute.

This procedure, known as monocropping, is very chemical intensive. Monocropping also raises

problems because farmers who practice the technique often remove large patches of trees andleave the land fallow for a shorter duration.

Mono-cropping is commonly seen as the solution to one problem, whether the problem is

economic, environmental or political, but simultaneously hosts many other problems.

While there are some distinct advantages to monocropping, it is environmentally questionable,

and it can potentially lead to serious economic problems for farmers, as well. Manyenvironmental advocates would like to see a shift away from monocropping, as would people

who work in the developing world.

The obvious advantage to monocropping is that it allows a farmer to specialize in a particularcrop, which means that he or she can invest in machinery designed specifically for that crop,

along with high-yield seeds which will generate a large volume of the crop at harvest. With

staple crops like wheat, corn, and soy, farmers can also be confident that the crop will produce ahigh income, although this scheme can backfire; if demand declines radically, a farmers

monocrop may become a liability.

From an environmental perspective, monocropping is harmful for a number of reasons. For one

thing, it severely depletes the soil, as the plant will strip the soil of the nutrients it needs thereby

distorting the nutrient balance in the soil. This forces farmers to use fertilisers, which can further

disturb the natural balance of the soil and contribute to a host of environmental problems, frompollution to desertification. Monocropping can also contribute to the proliferation of crop pests

and diseases, which can be a serious liability when a farmers land is planted exclusively with

one crop.

As an alternative to monocropping, farmers can rotate crops, planting different crops in each

field annually, and they can also periodically allow fields to lie fallow to recover. Some farmersalso encourage the practice of mixing crops in the field each year, using a combination of crops

to strengthen the soil and create a more diverse yield.

Chemical use: There has been a long speculated link between agricultural chemicals and

environmental pollution. The agricultural chemicals most often linked to environmental pollutioninclude veterinary medicines, pesticides, non-organic fertilisers, and other chemicals designed to

eradicate disease in crops and animals. Since these chemicals are responsible essentially forpoisoning forms of life (diseases are forms of life too), it stands to reason, then there should be a

concern about runoff from the application of agricultural chemicals entering groundwater,

streams, and soil.

It is well known that pesticides in the environment DDT in particular are responsible for the

massive die-offs of birds in regions of America that depend on agriculture for survival. And its

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equally well-known that veterinary hormones and other chemicals used in agriculture have

harmful effects on human beings upon direct exposure. The main issue of concern here is that

what particular path does an application of a chemical follow in a biotic of abiotic component.For instance, when fertiliser is applied to the soil, does the soil utilise all the substance(s) applied

and if not are there residual effects on the soil or other components of the environment? In the

same vein, in a biotic system like poultry, thus the bird convert all the hormones applied to itsfeed and if not what are the residual effects? These questions presented scary answers which led

and is still leading to proscription of certain chemical confirmed more persistent in the

environment than others.

Agricultural chemical use and soil and water quality degradation associated with agricultural

production are significant among the environmental problems confronting the United States. In

fact, these are now perceived as environmental problems comparable to other environmentalproblems such as air quality deterioration and the release of toxic pollutants from industrial

sources. While the growth of agricultural chemical use is an integral part of the technological

revolution in agriculture that has generated major changes in production techniques, uncertaintiesabout the health effects of agricultural chemicals are very important concerns. Severe soil

degradation from erosion, compaction, or salinization can destroy the productive capacity of thesoil. It can also impair water quality from sediment and agricultural chemicals.

The human-health consequences of drinking-water contamination by non-fertiliser agricultural

chemicals are less well documented than the effects of excess nitrates. However, there is

widespread concern about potential adverse human-health consequences from long-term, low-level exposure to agricultural chemicals in drinking water. There is particular concern about

potential effects of these pesticides as carcinogens or as endocrine disruptors.

In addition to human health concerns, water pollution by agricultural chemicals adversely affects

fish and wildlife, commercial fisheries, recreational uses of surface waters, and water treatment

facilities. Excess nutrients, particularly nitrogen and phosphorus from fertilisers canpromote eutrophication of surface waters. Pesticide residues in waters may affect the health andvigour of aquatic and riparian wildlife species. Also, the runoffs of excess fertiliser nutrients and

toxic agricultural pesticides are thought to be the major causes of the Dead Zone in the Gulf of

Mexico and coastal estuaries.

Summary

It is gradually becoming obvious that the balance in nature is precarious and that most things

exist because they are useful and have important roles in the ecosystem. Attempts by man to

classify certain components as beneficial and others not, has led to preferences and focus onpreferred products with an all out war on the perceived useless. This has brought distortions

to the ecosystem. The way things are carried out to remove unwanted and enhance thewanted components has titled the balance in nature leading to overall adjustments which isresulting into unsavoury situations. The procedure which often involves use of chemicals

leaves a trail of damage to the environment and the outcome interferes with natural

selection, tolerance and balance.

Post-Test

1. How is monocropping related to famine in some parts of the world?

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2. What consequences should be expected from the introduction of GM crops?

3. How does agricultural chemical harm the human?

References

http://agroforestry.net/events/afwksp2006/pres/Nelson_Monocrops_script.pdf

http://www.wisegeek.com/what-is-monocropping.htm

http://www.controllingpollution.com/agricultural-chemicals-environmental-pollution/

http://books.google.com/books/about/Agriculture_and_the_environment.html?

id=xMnWugCfQSwC

http://wps.prenhall.com/wps/media/objects/1027/1052055/Regional_Updates/update30.htm

http://www.enotes.com/topic/Monocropping

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LECTURE 8.Significant activities as they influence the environment especially the

components and nutrient cycles (species depletion in wildlife and fisheries)

Introduction

It has been severally mentioned that the existence of any component in an environment implies

its importance among others there. This means that it plays a significant role in the energy andnutrient cycles of that environment. When something happens to impede or prevent this

component from functioning, a gap is created with the result that the environment loses its

balance. A chain of reactions is thereby set off as other components requiring the functioning ofthe missing one become endangered.

Species get depleted in the field of agriculture, wildlife, forestry and fisheries. This has a lot ofimpact on science as gene banks become inadequate and genetic materials that may be useful in

developing vaccines, genetic modification and other uses are lost.

Objectives


1. know the importance of trees in the environment

2. understand the implication of over harvesting of trees in the environment

3. ascertain why some trees go into extinction

Pre-Test

1. What is the importance of trees to the environment?

2. What happens to the environment when trees become over harvested?

3. How can some tree species go into extinction?

Content

Significant activities as they influence the environment especially the components and

nutrient cycles

The proliferation of species on the planet serves a lot of purpose which vary from the human

point of view to the basic purpose of existence and establishment of links among the numerous

species. Some of the specific importances of the species are as discussed below:

Scientific and Ecological Importance of Species

Every species can help scientists understand how life has evolved and functions, and how it willcontinue to evolve on this planet. Wild species also provide many of the ecological services that

make up earth capital and thus are key factors in sustaining the earths biodiversity and

ecological integrity.

They supply us (and other species) with food, recycle nutrients essential to agriculture, and help

generate and maintain soils. They also produce oxygen and other gases in the atmosphere, absorb

pollution, moderate the earths climate, help regulate local climates and water supplies, reduce

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erosion and flooding, and store solar energy. Moreover, they detoxify poisonous substances,

break down organic wastes, control potential crop pests and disease carriers, and make up a vast

gene pool for future evolutionary processes.

Aesthetic and Recreational Importance

Wild plants and animals are a source of beauty, wonder, joy, and recreational pleasure for manypeople. Wildlife tourism, sometimes called ecotourism, is the fastest growing segment of the

global travel industry. It does not merely serve for sightseeing but as knowledge bases and means

of comparing the numerous species. This has helped to develop information which eventuallybecomes useful in handling the various species.

Ethical Importance

Some people believe that each species has an inherent right to exist, or to struggle to exist. This

ethical stance is based on the view that each species has intrinsic value unrelated to its usefulness

to humans. According to this view, we have an ethical responsibility to protect species frombecoming prematurely extinct as a result of human activities.

Extinctions

Extinction is a natural process and eventually all species become extinct. Each year, a small

number of species becomes extinct naturally at a low rate. Based mostly on fossil record,evolutionary biologists estimate that the current average natural rate of extinction is 3 species per

year if there are about 10 million species. In contrast, mass extinction is an abrupt rise in

extinction rates above the natural level. It is a catastrophic, often global event in which large

groups of existing species (perhaps 25-70%) are wiped out. Most mass extinctions are believedto result from one or a combination of global climate changes that kill many species and leave

behind those able to adapt to new conditions.

Conservationists believe that we are facing a new mass extinction, which is taking place in only

a few decades, rather than over thousands to millions of years. Such rapid extinction cannot be

balanced by speciation because it takes 2,000-100,000 generations for new species to evolve.Fossil and other evidence related to past extinctions indicates that it takes millions of years to

recover biodiversity through adaptive radiations. Thus repercussions for humans and other

species from the current human-caused mass extinction will affect the future course of evolution

for 5-10 million years.

Factors that cause species extinctions

There are many reasons why animals become extinct:

1. Habitat Destruction is one of the most obvious forms of damage to ecosystems today. Coral

reefs are subject to dynamite fishing in some parts of the world and other marine ecosystemssuffer from substrate damage done by boat anchorages. Deforestation is a key form of

destruction brought about by logging, clearing for farming and habitat destruction that occurs

slowly, bit by bit. Singapore in Southeast Asia has had 95% of its native lowland rainforestscleared after extensive deforestation. As many as 26 forest bird species became extinct between

1923 and 1949 while 35 forest species disappeared between 1949 and 1998.

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2. Fragmentation is a form of habitat destruction in that much of the original habitat gets

removed or modified, leaving patches of the remaining habitat. Even though these patches may

initially have most of the species that were once there, the diversity will degenerate. This isusually because life cycles of plants and animals are so disrupted that many species simply die

out over time. Many animals do not like crossing open or bare ground from one patch to another,

so they remain isolated in an island of habitat, which is vulnerable to further damage.

3. Introduced species create major problems. This form of destruction happens without direct

human interference, once the introduced species is released. This has been a major concernagainst the use of Genetically Modified Crops. Yet, the effects can be devastating. Introduced

species create major problems in the following ways:

They can become predators and kill native species so quickly and thoroughly that the nativespecies becomes extinct.

They can breed out of control, without natural checks and balances. In this way, the introducedspecies eat far more than the native vegetation can support. Since vegetation is usually the basis

for an ecosystem food chain, if that gets destroyed, the rest of the food chain will most likelycollapse.

Introduced species can compete for space, nutrition and mineral resources. In severe cases, an

introduced species will push out the native species over time, resulting in significant changes in

the ecosystem as a whole. E.g. On islands in the Gulf of California, many species and subspeciesof rodents are relict species, restricted to the islands, and are now considered extinct or verging

on extinction. Five native taxa are now considered extinct (e.g. Neotoma bunkeri). The most

probable cause for extinction was the introduction of non-native species, specifically cats.

4. Over harvesting refers to the catching of wild populations of animals, which are left to their

own devices to recover their numbers. In the marine environment, vast numbers of fish and

marine animals are harvested every year. Little or no effort is put into assisting their increaseafter harvesting, and the populations get smaller each year and risk extinction.

5. Local forms of pollution may be absorbed by a large healthy ecosystem. Excessive release ofchemicals over extended time periods will poison forests and render lakes almost sterile. Liquid

chemical pollution can destroy the biological fabric of river systems. Pollution also has a

tendency to spread out ever further and find its way into food chains

Human impacts on the environment, such as habitat loss and pollution, do not threaten all groups

of species equally. At greatest risk are species with small population sizes, species whose

populations vary greatly and species with slow rates of population growth.

Inbiology and ecology, extinction is the end of an organism or of a group of organisms (taxon),normally a species. The moment of extinction is generally considered to be the death of the last

individual of the species, although the capacity to breed and recovermay have been lost beforethis point. Because a species potential range may be very large, determining this moment is

difficult, and is usually done retrospectively.

The increase in the rate of extinction is directly related to the increase in the human population

over the same period of time. The vast number of humans has caused great damage to the planet,

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as wild habitats have been taken over, forcing animals and plants into smaller and smaller areas,

until some of them have become extinct. We have also polluted some habitats with chemicals

and refuse, making them unfit for wildlife. These causes of extinction are known as indirectdestruction.

Animals may also become extinct through direct destruction. This includes the hunting andcapturing of animals. Humans have always hunted and killed wildlife but early humans lived

more in harmony with nature, they killed animals for essentials like food and clothing. When

guns were invented mass destruction of species was possible. Animals have been, and still are,killed for meat, clothing, medicines, feathers, eggs, trophies, tourist souvenirs - and sometimes

just for amusement. Some species are still captured in the wild for the live pet trade, even

though their numbers are dwindling.

Summary

Every species created is important in life. Even if the usefulness is yet to be known, technology

will eventually get around to it. Generally speaking, the ecosystem, food chain and other

linkages have a pot for every species component of the environment; therefore, its absence will

be felt and may even degenerate to unpalatable situations. Apart from this, the fact that theorganism can be studied is important because through this, knowledge and understanding

which may be applicable to other more useful species can be generated. The onus is thus on

man to respect the ordinary existence off species and only live in a way that will not jeopardisebiodiversity.

Post test

1. Describe 2 importances ascribable to tree species in the environment.

2. How can over harvesting harm the ecosystem and how can this be avoided in the face of

the rising human population?

3. Describe what generally happens when a species become extinct.

References

http://www.admwebstudios.co.uk/Biodiversity3.htm

http://en.wikipedia.org/wiki/Extinction

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components and nutrient cycles (Fossil fuels use and anthropogenic wastes

disposal).

Introduction

This lecture looked at the issues concerning the use of fossil fuels, the essence and implicationon the environment. Despite the fact the fossil fuels are the mostly available fuels to the people;

their uses have implications on the environment. There is also a mention of the implication of

disposal of anthropogenic wastes that are not biodegradable.

Objectives


1. know the effect of the use of fossil fuels on the environment2. identify what anthropogenic wastes are3. understand the implication of indiscriminate waste disposal on the environment

Pre-Test

1. How should wastes be managed for healthy environment?

2. What is bad to the environment in the use of biofuels?3. How best should the anthropogenic wastes be disposed?

Content

Fossil fuels

Fuels are substances generally combusted to generate heat energy which can be applied to a

variety of uses like cooking, machine powering, electricity generation which in turn can be put to

a myriad of uses. In the process of biomass production, solar energy is often converted to formplant bodies as leaves, stems and other parts including fruits and grains. Thus much carbon and

potential energy is stored in these parts and which can eventually be liberated through the

process of oxidation during combustion or in animal bodies.

Consumption of fuel can therefore be simply seen as a process involving:

1. Release of carbon earlier withdrawn from the environment as the formed compoundsbreakdown.

2. A way of accessing solar energy earlier trapped through biochemical reactions.

Fossil fuels have been largely indicted for contributing immensely to global warming through the

release of carbon IV oxide gas (CO2) which is a greenhouse gas. However alternative fuels, so

called biofuels, do not fair better despite the campaign supporting their superior environmental

friendliness. This is because so much land has to be cleared and much forest cover destroyed ifthe plants are not to compete with the already inadequate human food supply. The result is such

that the production of biofuels release more CO2 which more than accounts for the expected

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reduction from combusting the fuel. Thus overtime, biofuels are not that environmentally

supportive as being campaigned.

Anthropogenic waste disposal

Each time something is thrown as garbage, think of where it will finally end up. Whether it is a

plastic glass, your broken cell phone or the used up battery cells from your portable CD/MP3player, they all contribute in some way to environmental pollution and are also hazardous to life.

Not only are they biodegradable, but also disposing of them has their own risks as they release

harmful toxins into the air, surrounding soil and ground water.

Accumulation of wastes due to its improper disposal is a major problem. As population grows at

a rapid rate there is an increase in the amount of wastes being produced especially in the cities.In the absence of proper waste management, this waste lies littered on our streets, road corners

and improperly disposed of in vacant land. All of these are serious health hazards apart from

being eyesores. If they are not cleared regularly at the earliest, they invite host of problems likeincreasing numbers of insect vectors like flies, mosquitoes, etc., scavengers such as stray dogs,

pigs and rats which spread dangerous diseases. It also generates bad odour and causes pollution.

The disposal of solid waste is a problem which grows with the growth of population anddevelopment of industries. Disposal of waste in open pits has become routine in majority of

places.

Semisolid or solid matters that are created by human or animal activities, and which are disposed

because they are hazardous or useless are known as solid waste. Most of the solid wastes, like

paper, plastic containers, bottles, cans, and even used cars and electronic goods are not

biodegradable, which means they do not get broken down through inorganic or organicprocesses. Thus, when they accumulate they pose a health threat to people, plus, decaying wastes

also attract household pests and result in urban areas becoming unhealthy, dirty, and unsightly

places to reside in. Moreover, it also causes damage to terrestrial organisms, while also reducingthe uses of the land for other, more useful purposes.

Solid wastes typically may be classified as follows:

Garbage: decomposable wastes from food

Rubbish: non-decomposable wastes, either combustible (such as paper, wood, and cloth)

or non-combustible (such as metal, glass, and ceramics)

Ashes: residues of the combustion of solid fuels

Large wastes: demolition and construction de

environment in agric extension material

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