EGE+311+PHYSICAL+GEOGRAPHY+III


 * THIS IS PHYSICAL GEOGRAPHY III as taught by Dr. Kennedy Obiero, MKU - Main Campus - Thika, April 2013. **


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(i) LATITUDE (ii) AIRMASSES (iii) ALTITUDE (iv) LAND & WATER MASSES (v) RELIEF FEATURES Airmass refers to a large body of with similar characteristics in terms of temperature and moisture conditions. In terms of temperature we have; ** W__arm airmasses__ ** that originate from the Equatorial region and the tropics. They are characterised by warm temperatures. ** Cold Airmasses ** – These originate from high latitudes or polar regions (40 – 90 degrees north and south). In terms of temperature we have - Tropical airmasses – 0o-30oN & S, - Temperate airmass – 40o - 60o - N & S  - Polar Airmasses - 60o - 90o - N & S  In terms of moisture we have: (i) ** Wet/moist airmasses ** – airmasses with high moisture content originating from water bodies preferably oceans. They are known as maritime airmasses. Maritime airmasses can be Tropical maritime, temperate maritime, and polar maritime airmasses. ** Maritime airmasses bring a lot of rainfall. ** (ii) ** Dry airmasses ** – These originate from the land. They are continental airmasses. Some originate from the desert in desert areas. These air masses are associated with dry conditions. Classified into: ** polar continental airmasses ** – cold airmasses from continents of northern latitudes, (60o - 90o - N & S). Very dry. No moisture/rainfall. Tropical continental airmasses – originate from low latitude continents (15o - 45o - N & S). Have high temperatures to to high amount of radiation received. They have very low moisture content. Very dry and associated with a lot of dust./ ** Convergence of Airmasses ** - ** Cold ** ** and warm ** airmass can converge. The boundary where two airmasses converge in known as a ** front **. There are two main types of fronts. ** Warm front ** – The is formed when a warm airmass intrudes or moves into a cold airmass region. Warm airmass is forced to rise over the cold air mass and some precipitation may be formed**. Cold Front ** – Formed when cold airmass moves into a region of a warm air mass. - The cold airmass originates from the cold latitudes and moves into the tropics, a region of warm air. Cold air will displace warm air i.e., the cold airmass will push the warm airmass back to the tropics. (** Exercise – draw both warm and cold front **). ** 3. Altitude ** – This is ** the height above sea level ** of any place. Some of the climatic elements are affected by altitude for example in the lower level of the atmosphere upto a height of 15 km and 9 km in the tropical and temperature regions respectively, temperatures and atmospheric pressure decrease with increase in altitude. The higher you go the cooler it becomes. For temperature, the decrease with altitude is at a rate of 6.5oC for a rise of 1000m. This is known as adiabatic lapse rate. Mountainous areas have lower temperatures but the sun’s rays passing through the clear atmosphere may cause sun burn to the exposed skin and hands. 4. ** Land and Water masses ** – Land and water behave differently in response in response to solar radiation absorption. They have differences in terms of their thermal conductivity. During the day and in summer, land absorbs heat very fast and becomes hot leading to high temperatures. Water on the other hand tends to take time to absorb energy and become warm. Therefore land stations are warm during the day while stations near water bodies are cool during the day. At night and in winter, land loses heat very fast and becomes very cold. Water on the other hand takes time to lose heat and therefore station on the land will be very cold while that near the ocean will be warm. Weather stations on the land have high temperature ranges compared to station on or near water masses. ** 5. Relief and Aspect ** – Mainly affect rainfall with windward sides experiencing more precipitation while leeward sites are dry because of descending and warming wind. In terms of temperatures, east facing slopes are warm in the morning as they are the first to be struck by the sun’s rays. In the evening, the west facing slopes are warm as the sun sets to the west. In the northern hemisphere, north facing slopes experience chilling temperatures while the south facing slopes are warmer. In the southern hemisphere, north facing slopes are warm as face the sun in the Equatorial region. The south facing slopes are cold experiencing extremely cold temperatures. ** 6. Role of vegetation ** – Examine role of vegetation in relation to climate such as the shades creating micro-climates (small scale climate – under a tree temperatures are cool providing a comfortable place to rest away from the hot son. ** 7. Continentality ** – Areas far from the coast are very dry as the winds have no moisture. Those stations near coast areas record more rainfall due to the influence of the ocean.  I am sorry for missing the class. Have these notes and read.
 * TOPIC 2: CLIMATIC CONTROLS AND FACTORS **
 * (2) AIRMASSES **

** TOPIC 3: CLIMATIC CLASSIFICATION SCHEMES ** - Climatologists have drawn methods of classifying climates. Climatic classification did exist even during the time of the Greeks who classified climates into: Frigid zone – very cold regions, temperate zones with cool climates and torrid zone the Equatorial hot zone.

(a) To come up with a variety of climates i.e. different types of climates e.g., Equatorial, temperate, hot, dry among others. (b) Through classification, the large number of observations and records are reduced into what people can understand and appreciate. (c) Classification enables people to begin asking scientific questions e.g., why does such type of climate exist in an area and not in others. - There a number of methods or approaches of classifying climates. (i) ** Genetic classification ** – This is the type of classification based on the behavior of the atmosphere. - Climates are classified according ** causes ** of atmospheric behavior e.g., trade wind climate – climate influenced by NE & SE trade winds. Here, cause of climate is the trade winds. - In genetic classification, climates are classified according to ** physical causes or origins **. - Examples – Polar climates, tropical climates, trade wind climates, continental climates, highland climate and maritime climates. (ii) ** Empirical classification ** – Classification based on ** observation of climatic elements **. The common elements are; rainfall and temperature- ** examples **- Hot climates, warm climates, cool climates and cold climates. - ** When rainfall or precipitation is included, then we have **; hot and wet climate, hot and dry climate among others. - ** In empirical classification, **heat and moisture fluxes are used. (iii) ** Applied classification/generic classification ** – A problem solving classification. - It is designed to solve a specific problem related to climate. - It is also termed as technical/functional classification. - The ** problem ** being solved must be ** a climate related ** ne. - Example of ** applied classification ** is ** generic classification ** – classification of climate by relating it to climate and vegetation. - Natural ** vegetation integrates many aspects of climate ** better than any instrument so far invented by man. - Vegetation is a very good index of climatic conditions. - The common terms used in generic classification include; Equatorial climate, Desert climate, Savanna climate, Steppe climate, Tundra ** Examples of classification schemes ** (a) ** Genetic classification ** – based on behavior of atmosphere - ** Strahler classification, Budhiko’s classification and Flown’s classification **. (b) ** Genetic classification ** – Applied classification – ** Koppen and Thornwaite ** classifications. NB – ** From these classification schemes, we are able to come up with Climatic regions of the world. ** - It is intentional climate modification. - Examples – ** mulching ** to conserve soil moisture; ** Crop protection from frost ** by smoking warm air; ** Deliberate warming icebergs ** – solve problem of icebergs in cold regions of the world; ** Electrical switches ** along roads affected by snow and frost and ** cloud seeding ** for precipitation formation and solving the problem of hailstone. ** Air conditioning ** in houses is also an example of manmade climates.
 * CLIMATIC CLASSIFICATION SCHEMES **
 * Purpose/Basic Reasons for Climatic classification **
 * Approaches to climatic classification **
 * Manmade climates ** – This involve the ** deliberate modification of climate by man **

** Micro-climates /Microclimatology ** - These are small scale climates or local climates. - It terms of area; few sq cm e.g., around a plant to few sq km for example a city. ** Causes of micro-climates ** - ** Built up areas ** create warm climates e.g., ** urban heat island ** where towns are warmer than surrounding areas. - ** Industrialization – **emissions into the atmosphere** from industries create a warm atmosphere. **  - ** Presence of small water bodies e.g., **dam create micro climate which is cool. - ** Tarmac road **surfaces absorb a lot of heat hence raise urban temperatures. Alter surface physics. - ** Local winds – **may lower temperatures creating micro-climate**. ** = = = CLIMATE CHANGE = = Introduction = - Climates have changed in the past, are changing now and there is every reason to believe that they will change in the past.  Ø The earth’s climate is not constant <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l8 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> Ø Temperature and rainfall vary from year to year and fluctuate widely over much longer periods of time. <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l8 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> Ø Most mountain glaciers have been retreating since 19th century and 1980s =<span style="line-height: 150%; margin-left: .5in; mso-list: l8 level1 lfo5; tab-stops: list .5in; text-indent: -.25in;"><span style="font-family: Wingdings; font-weight: normal; mso-bidi-font-family: Wingdings; mso-bidi-font-weight: bold; mso-fareast-font-family: Wingdings;">Ø The reasons are not always understood and are always unpredictable. = <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l8 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> Ø The changes cause major disruptions in normal activities <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l8 level1 lfo5; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> Ø Anthropogenic causes are man-induced factors responsible for climate change = Anthropogenic Causes/Manmade Climate Change = <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l12 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> a) Industrial activity remits CO2 into the atmosphere. The clouds of smoke cause temperature inversion in the atmosphere <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l12 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> b) Deforestation has been blamed for reduced rainfall as interference of hydrologic cycle <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l12 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> c) Automobiles also release greenhouse gases partly responsible for warming <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l12 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> d) Agricultural production releases methane gas with greenhouse effects. <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l12 level1 lfo6; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> e) Burning of fossil fuels release CO2

Impact of climate change
<span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .75in; margin-right: 0in; margin-top: 0in; mso-list: l2 level1 lfo8; tab-stops: list .75in; text-align: justify; text-indent: -.5in;">** (i) ****On environment** <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> a) Decrease in area covered by ice and snow <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> b) Rise in sea levels due to melting of ice – coastal lands are inundated <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> c) Deforestation interferes with the hydrologic cycle particularly precipitation <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> d) Change is rainfall patterns <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> e) Incidences of pests and diseases <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> f) Change in vegetation zones and species mix <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> g) Increase in global temperatures almost in all continents <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l9 level1 lfo7; tab-stops: list .5in; text-align: justify; text-indent: -.25in;">** (b) ****Impact on man – society** <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> a) Decrease in pure water supplies due to pollution <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> b) Decreased agricultural production due to reduced rainfall <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> c) Floods on coasts due to rise in sea levels <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l9 level2 lfo7; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> d) Industries affected due to decrease in raw materials. ** (c) **** Managing Climate Change **   - These are responses to climate change  ** Management of climate change divided into two: ** <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-indent: -.25in;"> (a) ** Mitigation ** - - Efforts to reduce atmospheric temperatures e.g., use clean energy, increase soil carbon, afforestation, reduce livestock emissions <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-indent: -.25in;"> (b) ** Adaptation ** – adjusting human behavior and practice e.g., improve on water use efficiency, conserve soil moisture, introduce new crop varieties, agroforestry, soil water management = Conclusion = Though timing and magnitude of climate change may not be accurately assessed, steps must be taken to reduce greenhouse gas emissions to mitigate the effects of climate change and help society to adapt. ** SECTION B ** __** THE BIOSPHERE **__ This is one of the components of physical geography. It is very central as this is the life layer. Main partly occupies the biosphere. Mainly covers plants, animals and microbes. This is studied in biogeography. Other special areas in biogeography include; **Zoogeography** involving the study of the spatial aspects of animals; **phytogeography** involving the study of the spatial aspects of plants. ** Ecosystem, its components and cycles ** **Ecosystem** – Refers to entire living organisms with their physico-chemical environment. Defined by inter-relationships among living organisms (animals, plants and microbe) and the physico-chemical environment. An ecosystem is a self-sustaining association of living plants and animals and their nonliving physical environment. An ecosystem includes both biotic (living) and abiotic (non-living) components. All ecosystems depend on direct input of solar energy to drive them. Ecosystems are divided into subsystems with the biotic made up of producers (plants), consumers (animals) and decomposers (bacteria and fungi). Abiotic flows in an ecosystem include gaseous, hydrological and mineral cycles. Earth’s biosphere itself is a collection of ecosystems within the natural boundary of the atmosphere **Therefore Biotic components are** made up of the living part of the environment. Largely composed plants, animals and microbes. **Abiotic components are made up of** the non-living part of the physical environment. Made of inorganic elements and compounds. Include; water, soil, climate solar radiation, mineral substances. ** The Basic Structure of an Ecosystem ** In an ecosystem, living organisms (biotic elements/factors) interact with the non-living substances (abiotic elements/factors) to produce and exchange marterials. The basic structure of an ecosystem is composed: <span style="line-height: 150%; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l0 level1 lfo13; text-align: justify; text-indent: -.25in;"> (a) ** Abiotic components ** – made up of basic inorganic and dead organic compounds of a habitat (an environment in which an organism resides or is biologically adapted to live). Most species have specific habitat requirements. This include water, soil, climate solar radiation, mineral substances. Nutrients are part of the ** abiotic components ** that sustain ecosystems. They include gases, water and minerals. The sun is also a major source of energy (insolation) driving ecosystems. The illustration below shows the main components of the ecosystem.

**Components of an Ecosystem** **(i i) Biotic Components** This represents the living part of the ecosystem and has a number of components which include:

**Producers** These are mainly green plants able to manufacture their own food using simple inputs that is water and carbon dioxide in the presence of sunlight. 6CO2 + 6H2O + Light = C6H12O6 + 6O2 Carbon Water Solar (Glucose, (Oxygen) Dioxide Energy Carbohydrate) From the equation, photosynthesis unites carbon dioxide and hydrogen derived from water in the plant to form glucose and starches within the leaves. This means that photosynthesis removes carbon (in the form of carbon dioxide) from the earth’s atmosphere. In this way plants act as carbon sinks. **Consumers** These are animals including man. They obtain their food requirements by consuming producers. They are divided into two that is primary consumers that mainly depend on plants such as herbivores (elephant, cows, sheep, goats, zebra, and giraffe) and secondary consumers (that feed on primary consumers) such as lions, dogs, hyena among others. These animals obtain their organic materials (food) from producers. **Decomposers** These are micro-organisms made up of bacteria and fungi. They help to decompose dead plant and animal material and in the process obtain their food and other organic requirements. **Energy flow in the ecosystem** The sole source of energy is the sun. From the sun, energy enters the ecosystem through photosynthesis. Producers use sunlight energy to manufacture their food. They loose some of their energy through the process of transpiration. Consumers get their energy requirements from producers by feeding on them since on their own they do not manufacture as does plants. During respiration energy is released from the organic material obtained from plants and the energy is used in locomotion and reproduction. Decomposers obtain their energy requirements from the breakdown of dead plants and animals. They also loose some of the energy during respiration. **Nutrient Cycling** For an ecosystem to function, it requires chemical elements (nutrients). The nutrients are useful to both plants and animals. The nutrients are mineral substances or inorganic substances such as calcium, potassium, magnesium, phosphorus among others. Some of the nutrients originate in parent rocks and are released by weathering. Some are dissolved and suspended in rain water. The nutrients are absorbed by plant root and converted into organic matter in their bodies. When animals feed on plants, the nutrients are transferred into their body tissues. When the leaves fall from plants, they are decomposed and nutrients in them are released back into the ecosystem. When plants and animals die, they are decomposed and nutrients in them are released back to the ecosystem for use by plants. Examples of nutrient cycles you need to read on include: <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (c) Water Cycle <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (d) Carbon Cycle <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (e) Nitrogen Cycle <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (f) Oxygen Cycle

**Ecotone** – The transitional zone between two ecosystems. May accommodate more species as it borrows characteristics from both eco-systems. **Niche** – part of the environment occupied by a given organism without much competition from other organisms. In case of competition, one of the organisms is eliminated.


 * World Vegetation distribution and Classification**

These are also known as **- Biomes** Biomes refer to the plant and animal systems on thesw3s earth’s surface. OR A biome may also be defined as a major ecosystem extending over a large area and it is viewed as a total assemblage of plants and animals interacting within the life layer. In a biome, plants tend to predominate because of their enormous biomass. The principle biomes include: (i) The forest biome - tropical rainforest - monsoon forest - temperate rain forest - conferous forests (ii) Savanna biome - Savanna woodland - Savanna grassland (iii) Grassland biome - tall grass praire - short grass praire (steppe) (iv) Desert biome - Semi desert scrub - Dry desert (v) Tundra biome - Alpine tundra - Arctic tundra Increasing activities of man as cultivators, graziers, woodcutters among others have modified the natural plant and animal pattern. **The forest biome** The most distinct forests in this biome are the Equatorial rainforests, monsoon and coniferous forests. Equatorial rainforests cover about 17% of the earth’s land surface. The Equatorial rainforest is found in moisture surplus area with precipitation being in excess of potential evapotranspiration. The forests are luxuriant – tall, evergreen, broadleaved among others. The remnants of this biome are found in the Congo and Amazon basins. The biome has a variety of fauna both small and large mammals such as monkeys, chimpanzees among others. Monsoon forest is mainly found in Asia while coniferous forests are found in temperate regions or latitudes. Human interaction with the biome; <span style="line-height: 150%; margin-left: 1.0in; mso-list: l11 level2 lfo14; tab-stops: list 1.0in; text-indent: -.25in;"> - Deforestation to create room for agriculture <span style="line-height: 150%; margin-left: 1.0in; mso-list: l11 level2 lfo14; tab-stops: list 1.0in; text-indent: -.25in;"> - High rates of erosion due to heavy rainfall <span style="line-height: 150%; margin-left: 1.0in; mso-list: l11 level2 lfo14; tab-stops: list 1.0in; text-indent: -.25in;"> - Charcoal burning for sale and source of fuel <span style="line-height: 150%; margin-left: 1.0in; mso-list: l11 level2 lfo14; tab-stops: list 1.0in; text-indent: -.25in;"> - High rates of leaching due to heavy rainfall <span style="line-height: 150%; margin-left: 1.0in; mso-list: l11 level2 lfo14; tab-stops: list 1.0in; text-indent: -.25in;"> - Nutrient depletion due continues cultivation <span style="line-height: 150%; margin-left: 1.0in; mso-list: l11 level2 lfo14; tab-stops: list 1.0in; text-indent: -.25in;"> - Introduction of exotic tree varieties and crops The biome covers 20% of the earth’s land surface with areas adjacent to the Equator and along river courses characterized by wood land. In wet areas coverage is mainly tall elephant grass. In relatively dry areas of the biome, scattered threes such as acacia and thorn bushes dominate. The biome is characterized by wildlife – the gazelle, zebra, giraffe, antelope among others. The fauna is relatively impoverished due to unfavourable and sometimes hostile environment. ** Human influence ** on this biome includes: (a) Introducing cultivation such as wheat and maize with crops sometimes dying due to bad weather. (b) This leads to famine which is sometimes chronic leading to malnutrition and sometimes starvation. (c) There is destruction of vegetation cover for charcoal burning. (d) Area characterized by man-wildlife conflicts – poaching, crops destroyed by animals. (e) Irrigation to make crops survive during hostile weather. This may create saline soils due to high rates of evapotranspiration. (f) Human beings practice soil and water conservation. ** Grassland Biome ** This is characterized by dense growth of grass and herbs. The biome is mainly composed of temperate grasslands such as the Prairies of Canada. The biome experiences moisture deficit in summer and conditions during this period are somewhat unfavourable for vegetation. Buffalo grass and wheat grass are the common flora. In terms of fauna, it does not have distinct animals though few exist such as the buffalo, pronghorn among others. Due to human influence, wheat is the main crop and cattle as well as sheep have also been introduced in the biome. ** Desert Biome ** This biome is found in areas where the demands for evapotranspiration exceed precipitation. It is found in desert areas such as the Sahara, Sinai, Mojave and California. In terms of flora, it has woody shrubs, thorny grass mainly xerophytes that is plants adapted to dry desert conditions. Fauna are diverse largely scorpions, locusts, grasshoppers, ostrich among others. Though the climate is hostile, human beings have tried to improve their livelihood by settling in oases, cultivating dates, keeping horses, drilling boreholes, exploiting minerals among other activities. ** Tundra ** This is the treeless biome of Arctic mostly frozen. There is permanently frozen ground below the soil (Parma Frost). Vegetation is mainly composed of mosses, grasses and flowering herbs. The main fauna include squirrels, chipmunks among others. An understanding of the world’s major biomes is crucial in human attempt to exploit biomes and biome resources. Human beings have often run into difficulties because of incomplete understanding of biomes and biome resources.
 * Savanna Biome **
 * Conclusion **

- These are areas of moisture deficit. Demands for evapotranspiration exceed available moisture. - Plant an animal life is impoverished. Less plant and animal variety. Primary productivity is less due to limited moisture. - Biological deserts divided into two (i) Hot deserts (ii) Cold deserts (tundra)
 * BIOLOGICAL DESERTS **

(a) Explain the characteristics of the Biological deserts (b) Examine plant and animal characteristics of biological deserts (c) How have plants and animals adapted themselves to desert conditions? (d) How have human beings interacted with biological deserts and with what results?
 * Revision Question **

The Soil System
Soil is a dynamic mixture of water, air, mineral and organic materials over the earth’s surface. Inorganic materials are derived from rock weathering while organic materials derive from decomposition of vegetation. Soil provides a medium for linking organic and inorganic compounds and controls movement of nutrients. Soil itself has inputs and outputs hence acting as a system.

Soil Development
Soil is a product of mechanical and chemical weathering. Chemical weathering releases important nutrients into the soil such as magnesium, phosphorus, potassium and calcium. Other sources of nutrients in the soil include; decomposition of leaves and other dead organic matter. Decomposition of plants releases nitrogen, magnesium, oxygen, and carbon into the soil. Both inorganic and organic substances are moved within the soil by soil moisture.

Factors affecting soil development
Soil development was expressed by an American pedologist (Jenny, 1940) using the following equation. =Jenny’s equation= Soil formation has been expressed as; **S = f(C,P,V,R)T** Where S = soil formation/condition F = function of C = Climate Relie P = Parent material V = Vegetation R = Relief T = Time <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (g) **Climate** – Climate affects the rate of weathering. High rates of physical and chemical weathering are recorded in hot and wet climates such as the Equatorial climate. Climate influences the vertical movement of moisture and dissolved substances. Precipitation provides soil water, without which chemical and biological activity are not possible. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (h) **Parent material** – Most physical and chemical characteristics of soils are obtained from the parent rock. The parent rock determines the chemical elements in the soil. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (i) **Vegetation**- Soils formed in areas with a lot of vegetation have high content of organic matter. Decayed vegetation add organic matter to the soil Bush fires negatively impact on the soil. Deforestation therefore is an evil to eliminate. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (j) **Relief –** Steep slopes have shallow soils due to high rates of erosion. On flat or gentle, soils are saturated with water. Steep slopes have young soils. Valleys have deep, mature soils due deposition and reduced erosion. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: 1.0in; margin-right: 0in; margin-top: 0in; mso-list: l12 level2 lfo6; tab-stops: list 1.0in; text-align: justify; text-indent: -.25in;"> (k) **Time**-Soils vary geographically in terms of time. Mature soils have taken relatively longer period to develop. It takes many thousands of years for a deep mature soil to form. **Soil components** There four main elements that make up the soil <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l4 level1 lfo10; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> (i) Inorganic matter –mineral fraction. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .75in; margin-right: 0in; margin-top: 0in; mso-list: l16 level1 lfo9; tab-stops: list .75in; text-align: justify; text-indent: -.5in;"> (i) Organic matter from decay of vegetation and living organism <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .75in; margin-right: 0in; margin-top: 0in; mso-list: l16 level1 lfo9; tab-stops: list .75in; text-align: justify; text-indent: -.5in;"> (ii) Soil air – oxygen, nitrogen etc. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .75in; margin-right: 0in; margin-top: 0in; mso-list: l16 level1 lfo9; tab-stops: list .75in; text-align: justify; text-indent: -.5in;"> (iii) Soil water – facilitates movement or translocation of soil components.

Soil Properties
Vertical slice through soil from the surface to the parent rock. Develops due to weathering in addition to organic matter and translocation of materials within the soil. Mature soils is differentiated into layers/horizons
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O – Organic matter A – Top Soil B - Subsoil C – Parent material

Soil Catena
Arrangement of soil along a slope. Valley bottom to the top of the hill.

Soil texture
Describes the relative proportion of sand, silt and clay in the soil. It is the physical feel of the soil. Determines the ability of soil to retain water. Texture must be considered for irrigation purposes.

Soil Structure
Refers to how soil particles are bound together. <span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l10 level1 lfo11; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> (a) **Granular structure** – individual loose grains e.g., sand. **….** **….**  (b) **Crumb structure** – more less rounded aggregates
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**( c) Prismatic structure –** vertical elongation
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<span style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0in; margin-left: .5in; margin-right: 0in; margin-top: 0in; mso-list: l5 level1 lfo12; tab-stops: list .5in; text-align: justify; text-indent: -.25in;"> (d) **Platy structure** – horizontal alignment
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=Soil chemistry= This is abundance of chemical elements in the soil. **Soil Ph.** Concentration of hydrogen ions in the soils. Below 7 – soils are said to be acidic. Above 7 are alkaline soils.

Soil Colour
Humid tropics – reddish soil – high concentration of iron oxide. Grasslands – balck soils – high organic content Coniferous forests – grayish – high leached soils.

Soil Classification
**Zonal soils** – mature soils with well developed soil horizons. Affected by climate and vegetation e.g., podzols and latosols. **Azonal soils** – immature soils with no developed soil profiles. Soil has not had enough time to be in equilibrium with climate e.g., steep slopes. ** Intra-zonal soils ** – soils influenced by local factors (may non-climatic factors). Such factors include drainage and limestone.
 * // Exercise: Describe the different types of soils globally. // **