EGE+222+BIOGEOGRAPHY


 * This material is meant for BIOGEOGRAPHY CLASS OF DECEMBER 2014 MEANT TO SIT FOR EXAMINATION IN APRIL 2014. THANK YOU **
 * FOR YOUR PATIENCE. THE DELAY TO AVAIL THE MATERIAL IS BECAUSE MWALIMU WAS VERY BUSY. BUT I HOPE YOU ALSO READ **
 * ON YOUR OWN. SHUKRANI AND GOD BLESS YOU IN THE EXAM AND AFTER ** POSTED ON 23/3/2014


 * Biogeography** deals with the spatial and temporal chracteristics of living organisms (Biosphere). The biosphere 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.

Read other Topics in the Course Outline e.g., more introduction, role of Biogeography etc - A system is a set of elements or components which are inter-related and which interact with each other. Have inter-relationships. - A system has identifiable linkages that lead to a number of outcomes. - A system may be seen as an organized assemblage/whole/combination of things/parts into a unit. - System components transform inputs into outputs. - The geosystem and ecosystem are examples of systems in physical geography and biogeography in particular. - A system focuses upon the functioning processes and relationships within the system as well as from outside. NB- Incase part of the system has a problem, the functioning of the whole system disrupted due to the interconnectedness of the components.
 * Systems Analysis in Biogeography**

- System identification has five steps (a) Identification of components/elements/parts (b) Relationships among the components (c) Evaluation of the results of interaction among the components (d) Effects of outside forces/processes on the system (e) Understanding the dynamic natures of the system
 * System Identification**

Systems are not static. They may change and these changes need to be understood.

(a) It enables biogeographers to identify interactions in the biosphere system (b) It gives explanations for the interconnections/interrelationships (c) It helps to integrate various knowledge about the interrelated phenomena (d) It helps to identify the hierarchy of the components (e) Systems approach allows us to use knowledge from different disciplines Quiz – Using an example from biogeography, explain the relevance of the systems approach.
 * The need for using systems approach in Biogeography**

**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: (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. **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. **Pyramid of Numbers –** The number of producers is more than consumers. Primary consumers are more than secondary consumers. Every island has one king.. **Pyramid of energy –** Producers have more energy than consumers and little energy is lost during transpiration. This energy decreases as one moves into consumers. During respiration, food is oxidized to release the energy which is then used for locomotion and reproduction. **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: (a) Water Cycle (b) Carbon Cycle (c) Nitrogen Cycle (d) 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.
 * The Ecosystems Concept**

- This is the amount of solar energy fixed by producers. Ecosystem productivity varies in both space and time. - Ecological productivity deals accumulation of dry matter per m2. - Ecological productivity is influenced by: (a) Water – it is the raw material during photosynthesis. This is also the moisture condition. (b) Carbon dioxide – it is also a raw material during photosynthesis (c) Temperature/sunlight – as temperature raises, the rate of photosynthesis increases. This is also known as incident solar energy (d) Light intensity and duration – the longer the period, the higher the energy (e) Nutrient availability – productivity requires nutrients from soils e.g., N, Ca, P and S. (f) Leaf Area Index (LAI) – The large the leaf, the higher the productivity.
 * Ecological Productivity**


 * Primary Productivity per Biome/plant community**
 * **Community** || **Net Production**  ||
 * Tropical Forest || 50  ||
 * Temperate Forest || 15  ||
 * Savanna || 14  ||
 * Woodland & Shrub land || 6  ||
 * Semi-desert & Desert || 2  ||
 * Cultivated Land || 9  ||

- An established plant community in a place may not remain the same. There may occur disturbance by natural factors e.g., flood, fire, volcanic activity, locust invasion among other. - Disturbance may also be anthropogenic that is by human activity such as shifting cultivation, charcoal burning among others. - Both cases destroy the original vegetation which is gradually replaced by newer vegetation less rich compared to the original one. - ** Succession ** is a change in composition and nature of vegetation at a given location. An area of bare ground when stripped of its original vegetation by fire, floods does not remain without vegetation for a long time. The area is quickly colonized by a variety of species. - ** Primary succession ** is an invasion by plants of an area that had no previous plant growth; it begins with a bare or uninhabited area. - ** Secondary succession ** is re-colonization of areas that have been disturbed. Primary succession occurs in areas where volcanic eruption has cleared out the existing vegetation, seashores, or retreated glaciers. Secondary succession occurs in areas affected with serious fires, areas previously farmed or grazed or used in various ways that lead to removal of vegetation. - A marked modification in stable vegetation initiates secondary succession. A tsunami can initiate secondary succession in the affected areas. Generally in primary succession unlike the secondary, the soil is not fully developed. - Initial or first species that modify habitat making it suitable for more new species are known as **colonizers.**
 * Plant Succession/Ecological Succession**

- **Process/phases of Plant/Ecological Succession** The process of succession can be divided into several important phases as follows: i) ** Nudation ** : which is the initiation of the succession by a major disturbance in the environment.   ii) ** Migration ** : of available seeds (species) to fill the vacant ecological niches. In secondary succession, spores and seeds may already be present in the soil awaiting the right conditions. Some plants may delay their germination – these species can be said to be better adapted to colonization than others. iii) ** Ecesis ** : is the establishment or subsequent ability of the seeds to germinate, grow and reproduce successfully.   iv) ** Competition ** : the struggle of species for the available resources (nutrients, water, light, space). Some plants are eliminated; where as the most competitive plants are adapted. v) ** Reaction ** : The plants continue to interact within the existing conditions.   vi) ** Final Stabilization ** : The plant community becomes stable and is referred to as the climax community. Succession is a directional vegetation change induced by environmental or other disturbances, the initial rates of vegetation change is high and subsequently falls to a low level often which further development is governed by very slow change - the relative stable state is referred to as the climax.

The **climax community** is the last stage of an ecological succession of communities and is the most stable condition within a succession, stable vegetation being in equilibrium with its environment.


 * Question for further reading**
 * 1) What are dispersal mechanisms?
 * 2) Explain the role of adaptation.

**Threats to biodiversity**

1. **Conversion of natural ecosystems in agricultural** land for the purpose of increasing food production to meet the needs of the increasing population, that is, six billion global populations.

The use of fertilizer (in-organic fertilizers) and pest sides/fungicides interfere with certain organisms.

Agriculture forms the backbone of many economies particularly on many developing countries.

2. **Urban growth-many** countries are expanding their urban centres mainly due to migrations. Conversion of natural ecosystems into urban areas/urban activities.

Remember proposal for excision of Karura forest into a residential/hotel facility. Urbanization modifies the natural habitats of environments in many ways for example urban surface reduces soil moisture due to reduced infiltration and increase surface runoff. Increased demand for energy particularly charcoal also leads to destruction of forests around the city despite the acts that protect forests.

**3. Pollution**

Chemical substances discharged into the ecosystem which may be solid, liquid or gaseous form. For example a discharge of chemical substances into rivers affects aquatic life/ecosystem. It includes discharge of untreated discharge into river systems. This interferes with D.O (dissolved oxygen). DO supports aquatic animals like fish. The oxygen may combine/react with other chemical substances reducing available oxygen.

In Naivasha, discharge from flower farms led to dead and floating of fish.

Pollution of the soil system which kills the microorganisms like bacteria AND Other important in the soil for aeration or organic matter.

**4. Climate change**

Has also contributed a threat tom biodiversity. Climate change is both natural and antropogenetic (human activities). Climates have change in the past, are changing now and therefore there is every reason to believe the climate may change in future. With climate change many species may mix. Some species may adopt, some may migrate and yet some may die/become extinct. More worrying is human induced climate change (climate change due to human activities-antropogenetic). They include in dust/they release to the green house


 * Industry
 * Agriculture
 * Transport

Global warming is increase in global temperatures as a result of natural and largely antropogenetic activities like Industry, Agriculture, Transport and deforestation. Global warming, part of the climate change.

**Consequence of climate change**

Increased precipitation due to high temperature/increase in evaporation

Floods-high temperatures may cause heat waves, people/living organisms due to high temperature. Melting of ice

These are pesticides and diseases.

**Biodiversity conservation**

The need to save biodiversity is very key agent. This will retain and support. Maintenance of species is important in sustainable development. A number of steps may be taken to conserve biodiversity. Such steps should be on micro level(small scale) and international scale.

**Question -**

Using examples, examine the man environment interaction and their impact on the environment.

Steps in **Biodiversity conservation**

What can we do to have a rich species/ variety of environment/ecosystem.


 * 1) Acts of parliament to protect biodiversity, i.e in Kenya we have forest act, EMCA (1999). They can be international agreement on biodiversity conservation-coordinated by global bodies such as UNEP etc to become member countries in signing and observing the agreement. For example global environmental facility which was initiated by world bank(united nations development program; UNDP and UNEP). The bodies set aside funds for biodiversity conservation.
 * 2) Establishment of protected areas. Human activities are restricted in such areas. There is controlled grazing. The places are guarded i.e forests guards.

Examples of protected areas are:


 * National parks
 * Game reserves
 * Wet lands

Protected areas have/develop/retain variety of plant and animal species. Wildlife varieties-hunting of wildlife for food and water are prohibited.


 * 1) Watershed management

This helps to control erosion to reduce sedimentation, afforestation, reduce pollution. Check and control activities with the watershed.


 * 1) Establishment of botanical gardens. Established variety of plants which will atrcat insect, birds and this creates biodiversity.
 * 2) Population control especially human population. This will reduce threat to biodiversity and vice versa. More people means tragedy of commons (water, air, soil etc).
 * 3) Research-especially on different aspects of plants, animals and their adaptations, reproductions, feeding habits among others. More funding into biodiversity research which encourage scholars to invest in biodiversity research.
 * 4) Management of coastal zones, this promotes marine ecosystem and biodiversity, controlled pollution and human activities generally.
 * 5) Biotechnology (use of biotech). Coming up with species well adopted tom the environment. Improve on species diversity.
 * 6) Resource conservation and reduction of waste. Use resources efficiently/optimally.

SORRY BIODIVERSITY IS REPEATED BUT SEE OTHER TOPICS AFTER BIODIVERSITY AND READ MORE ALSO ON YOUR OWN BY MWALIMU OBIERO K.

- Refers to species richness in an ecosystem i.e. variety of plants, animals and micro-organisms. The more the species of plants and animals, the richer the biodiversity. - In a rich biodiversity, there is little or no human interference. - There is value in biodiversity. - In a rich biodiversity, plants, animals and micro organisms interact among themselves and the environment. - Biodiversity emphasizes on totality of species and ecosystems. - Biodiversity conservation emphasizes on taking care or conserving the whole spectrum of biota and their activities on small level (micro-level) to large scale (macro-level).
 * Biodiversity**

- This is the number of species of plants and animals present in a region both in natural and artificial system. - The natural systems have greater species diversity than manmade ecosystems e.g., agricultural ecosystem. - A timber plantation will will still have less species compared to a natural forest with greater species diversity. - With species diversity people get food, fruits, fodder, plywood, fibre, medicine among other products. - A timber plantation has less species diversity and therefore less benefits. (i) Food – one of the most significant values of biodiversity. Initially plants were consumed directly from the field – gathering. (ii) Medicine – A rich biodiversity is a source of a variety of medicines both herbal and conventional medicine. In modern medicine, pure chemical substances are extracted from species of plants and animals. Potential for more medicine from a rich biodiversity exist. (iii) Source of energy or fuel in terms of firewood, biomass and charcoal. (iv) Provides ornamental plants values for their good colours. (v) Plants in a rich biodiversity help in carbon fixation during photosysnthesis. (vii) Helps in pollination due to variety of insects. (viii) It maintains the water cycles. Biodiversity protects the watersheds or catchments from extreme conditions such as flooding and drought. (ix) Regulates climates at micro and macro-levels. (x) It absorbs and decomposes pollutants (xi) Contributes to soil formation with high organic matter (OM) content. (xii) Has recreational and aesthetic value.
 * Species Diversity**
 * Value of Biodiversity**

(1) Conversion of natural ecosystems into agricultural systems for purposes of increasing food production for increasing population. (2) Urban growth – expansion of the centres for settlement and related activities such as business and other functions. Reduces size of biodiversity. (3) Deforestation for create room for settlement, agriculture and energy demand (firewood, charcoal and biomass). (4) Pollution – chemical substances discharged into the ecosystem which may be solid, liquid or gaseous form affect aquatic ecosystem. Discharged of untreated sewage reduces dissolved oxygen as micro organisms compete for the oxygen in water. Pollution of soil system kills micro organisms. (5) Climate change largely anthropogenic (human induced) climate change has changed environmental conditions in terms of temperature and moisture content. This has posed a new threat to biodiversity. Global warming has been hastened by release of Green House Gases from industry, agriculture and transport. Deforestation has reduced carbon sinks, increasing carbon dioxide concentration in the atmosphere and gloal warming with its consequences.
 * Threat to Biodiversity**

- The need to save biodiversity is very urgent due to its significance. A number of steps must be taken to conserve biodiversity both ob micro and macro scale. - The steps include; (a) Acts of parliament to protect biodiversity e.g., Environmental Management and Coordination Act of 1999 (EMCA). There are also international agreements on biodiversity conservation. (b) Establishment of protected areas with restricted access such as national parks, game reserves and wetlands. (c) Watershed management to control erosion, sedimentation, afforestation among other measures. (d) Establishment of botanical gardens for variety of plants that attract insects, birds, micro organisms creating a rich biodiversity. (e) Population control will reduce threats to biodiversity in terms of natural resources also referred to as ‘the tragedy of the commons’. (f) Research mainly ecological research on different aspects of plants, animals e.g., reproduction, feeding habits and adaptation. More funding will improve on research on biodiversity. (g) Management of coastal zones to protect aquatic/marine ecosystems from human activities such as pollution. (h) Biotechnology – Coming up with new species of plants well adapted to the environment. (i) Resource conservation to avoid wastage. Optimize the use of resources.
 * Biodiversity Conservation**

- Refers to the maximum number of individual species that can be supported by a particular ecosystem on long term basis. - Maximum number of species of plants and animals an environment will support without degrading the environment or habitat. - If the number of organisms is not observed and is therefore exceeded, the natural supporting system will be negatively affected. - Carrying capacity reflects the limits imposed on a population of living organisms by the finite space and resources. - Carrying capacity varies from one environment and species to another. - Even human beings can be limited by available physical space and resources. - In ecology, ecologists argue that there are limits to organisms that an environment can support. - For human beings, carrying capacity vary with (a) Type of diet – meat/vegetarian diet with a vegetarian diet having a higher carrying capacity than a meat diet. Ten calories of plant food are required to produce one calorie. A lot of energy is in the transfer between tropic levels that is between plants, animals and human beings. (b) Life style – modern life style require more space and resources e.g., parking, supermarkets, play grounds, swimming pools among others. This reduces carrying capacity as space available for plants is reduced. (c) Technology – advances in technology means a small space can produce more money hence increasing carrying capacity.
 * Carrying Capacity**

Biomes refer to the plant and animal systems on the earth’s surface.
 * Major Biomes in East Africa**

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

(ii) Savanna biome - Savanna woodland - Savanna grassland

(iii) Desert biome - Semi desert scrub - Dry desert

(v) Mountain biome - High Altitude biome - Low temperatures - Specialized plants and animals

Increasing activities of man as cultivators, graziers, woodcutters among others have modified the natural plant and animal pattern.

The most distinct forests in this biome are the Equatorial rainforests/tropical forests.
 * The forest biome**

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 outside East Africa 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.

Human interaction with the biome; - Deforestation to create room for agriculture - High rates of erosion due to heavy rainfall - Charcoal burning for sale and source of fuel - High rates of leaching due to heavy rainfall - Nutrient depletion due continues cultivation - 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.
 * Savanna Biome**

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.

(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.
 * Human influence** on this biome includes:

This is characterized by dense growth of grass and herbs. The biome is mainly composed of temperate grasslands such as the Prairies of Canada outside East Africa.
 * Grassland Biome**

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.

This biome is found in areas where the demands for evapotranspiration exceed precipitation. It is found in arid and semi arid areas..
 * Desert Biome**

In terms of flora, it has woody shrubs, thorny grass mainly xerophytes that is plants adapted to dry desert conditions.

Adaptation include; being deep rooted to obtain water from deep underground, umbrella shaped to protect roots from hot sun, small leaves to reduce water loss through transpiration, fleshy stems and leaves to store water among other characteristics.

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 near water sources, cultivating quick maturing and drought resistant crops, practicing bee keeping, keeping camels, drilling boreholes, exploiting minerals among other activities.

This is the high altitude biome. Part of it is frozen. Vegetation and fauna specialized according to altitude. Temperatures very low sometime snow in some of the mountains such as Mt Kilimanjaro and Kenya Lowest altitude is savanna, then rainforest, heath and moorland, bare rock and then snow. Vegetation is mainly composed of grasses and flowering herbs among others.
 * Mountain Biome**

Human pressure on mountain ecosystem; deforestation, fire outbreak and destruction of forests, encroachment on steep slopes, soil erosion, over cultivation, exotic trees among others.

An understanding of the world’s major biomes is crucial in human attempt to exploit biomes and biome resources.
 * Conclusion**

Human beings have often run into difficulties because of incomplete understanding of biomes and biome resources.

- Plants are studied more in Biogeography due to their large biomass. - They are ease to study because they are fixed to their environment. They are not mobile as animals. - The main research methods in biogeography are on plants. - Plants and animals may also be studied through careful observation of photographs. However, the vegetation and animal communities are best understood in the field through field research. - Analysis of plants and animals may be qualitative or quantitative. - The following procedures are used. (a) **Sampling** – Involves selecting part of the vegetation community for detailed analysis.The sample should be carefully selected in order to be representative. - In selecting the sample, quadrats are used to mark sample areas. Originally quadrats were square frames but various shapes have now been developed (circular, rectangular among others). - In equally or evenly distributed species, small quadrats can give a good picture of the population. - In heterogeneous/non uniform vegetation, quotrats of sufficient size have to be used - Species area curve determines the number and size of quotrats to be used. - A quotrat may be square 1mx1m or more sometimes less. The number of quotrats depend on the nature of the study and the degree of accuracy. <span style="font-family: 'Times New Roman','serif';">- The least is 25 but 50 to 100 are used in most studies. There are also point quadrats. (b) **Frequency** – This involves counting the number of species present in the quadrant. For each species, the number of times it occurs in each quadrant represents its frequency expressed as a percentage. <span style="font-family: 'Times New Roman','serif';">- It can help to compare plant communities. It disadvantage is that it depends on quadrant size. <span style="font-family: 'Times New Roman','serif';">- Small quadrant may have low frequency and a large quadrant high frequency. NB – Frequency as a measure of regularity classes can be developed depending on the nature of the research e.g.,
 * RESEARCH METHODS IN BIOGEOGRAPHY**
 * Research on Plants Communities**
 * Random sampling; It i**s the best because all species of plants have equal chance of being selected in the sample.
 * Classes ||  Frequency  ||
 * 1-20 ||  5  ||
 * 21-40 ||  10  ||
 * 41-60 ||  5  ||
 * 61-80 ||  10  ||
 * 81-100 ||  5  ||

(c) Density – This is the number of species per unit area. The number of individuals in each quadrant is counted and the average is determined. The exercise is time consuming. (d) Cover – This is the proportion of the surface covered when the aerial parts of each plant is projected perpendicularly <span style="font-family: 'Times New Roman','serif';">- The cover is expressed in terms of % of the total area.


 * Classes ||  Cover (%)  ||
 * 1 ||  0.5%  ||
 * 2 ||  5%  ||
 * 3 ||  17%  ||

<span style="font-family: 'Times New Roman','serif';">- Animals are mobile and their study faces a lot of challenges as the animals move from one place to another in search of food. <span style="font-family: 'Times New Roman','serif';">- Some of the methods used include; direct observation in the field, done in transects or niches of animals. <span style="font-family: 'Times New Roman','serif';">- Traps are used to catch certain animals. <span style="font-family: 'Times New Roman','serif';">- The traps should be selective. Some are expensive while some are affordable. <span style="font-family: 'Times New Roman','serif';">- Pitfalls may also be used as traps where an animal falls. <span style="font-family: 'Times New Roman','serif';">- For insects, light traps may be used to attract insects NB – While trapping the animals or insects ensure little interference on animals for conservation reaso**ns.**
 * Analysis of animal communities**
 * Trapping animals** – Some animals have to be trapped for detailed analysis or study.

<span style="font-family: 'Times New Roman','serif';">- The methods used in vegetation community analysis are both quantitative (frequency, density, cover among others) and qualitative). <span style="font-family: 'Times New Roman','serif';">- Qualitative measures include: (a) Sociability class <span style="font-family: 'Times New Roman','serif';">- Plants growing in one place. <span style="font-family: 'Times New Roman','serif';">- Plants growing in groups <span style="font-family: 'Times New Roman','serif';">- Plants which grow in troops i.e. small patches <span style="font-family: 'Times New Roman','serif';">- Plants that grow in crowds (large patches) <span style="font-family: 'Times New Roman','serif';">- Plants in colonies (small numbers)
 * Qualitative Measures**

(b) Abundance classes <span style="font-family: 'Times New Roman','serif';">- Very sparse (very rare) <span style="font-family: 'Times New Roman','serif';">- Sparse <span style="font-family: 'Times New Roman','serif';">- Not numerous <span style="font-family: 'Times New Roman','serif';">- Numerous <span style="font-family: 'Times New Roman','serif';">- Very numerous

The method to be used in research for biogeography depends on the nature of the research. There is no best method without its own limitations. Method is dictated by the purpose/objective of the study, the level of accuracy required especially where life is involved. Reconnaissance may be required/necessary. Generally a variety of methods are recommended.
 * Conclusion**

__**THIS TOPIC IS ALSO REPEATED**__


 * Carrying capacity**

Carrying capacity is the maximum number of individuals of any species gthat can be supported by a particular ecosystem on a long term basis.

Is the maximum number of people/species of living organisms that can be supported by a given environment? If the number is not observed/controlled living organisms can exceed an environment life supporting system. Carrying capacity reflects the limits imposed on population of living organisms by the finite (fixed) space and finite resources. The carrying capacity varies from one environment to another. It varies among living organisms. The earth’s resources would never support all numbers .even human numbers can be limited by physical space and resources.

In ecology, ecologists argue that there are limits to organisms that an environment/natural system can support. For human beings carrying capacity varies with a number of factors.


 * 1) Vegetation diet and meat diet

If human population depends on vegetation diet, the carrying capacity will be high. Energy flow into ecosystem.

diagram

ten calories of plant food are used to produce one calorie of beef. A lot of energy is lost in the transfer between tropic levels i.e between planmts, animals and human beings.


 * 1) Lifestyle- support modern lifestyle more space is required for residential areas, parks, swimming pools,, gold courses, shopping malls, rods. This reduce the overall space for plants and reducing carrying capacity.
 * 2) Technology-advances in technology means a small space can produce more money hence increasing the carryoing capacity.


 * QUESTION**

Explain the factors that determine carrying capacity.

** Living organisms vary both in space and time (spatio-temporal variation). This variation is influenced by factors classified into two: ** ** 1. Abiotic Factors ** ** 2. Biotic Factors **
 * Factors Influencing Distribution of Living Organisms **


 * __ Question __**** – Discuss abiotic and biotic factors influencing distribution of living organisms **