Sampling – is the process of getting a small portion (known as sample) from the whole (known as population).
Sample – a representative of the population
Population – entire group or measurement
A sufficient number of sample can best represent the entire population
A sampling technique should be used to plot or collect the samples
In this activity simple random method was used, it will be applied using a square plot called quadrant
2 main types of sampling methods:
- Probability sampling – one in which every unit in the population has a chance ( >0) of being selected in the sample
Type of Probability Sampling Method
- Simple Random Sampling – the basic sampling technique where we select a group of subjects (a sample) for study from a larger group (a population). Each individual is chosen entirely by chance and each member of the population has an equal chance of being included in the sample.
- Systematic Sampling – statistical method involving the selection of elements from an ordered sampling frame. The most common form of systematic sampling is an equal-probability method.
- Stratified Sampling – the researcher divides the entire population into different subgroups or strata, then randomly selects the final subjects proportionally from the different strata.
- Probability Proportional to Size Sampling – It is a method of sampling that takes the varying size of each item within the population into account when selecting the audit sample.
- Cluster or Multistage Sampling – when “natural” but relatively heterogeneous groupings are evident in a statistical population. It is often used in marketing research. In this technique, the total population is divided into these groups (or clusters) and a simple random sample of the groups is selected.
- Non-probability sampling – any sampling method where some elements of the population have no chance of selection
Type of Non-probability sampling Method
- Accidental Sampling – is a type of non-probability sampling that involves the sample being drawn from that part of the population that is close to hand.
- Quota Sampling – the assembled sample has the same proportions of individuals as the entire population with respect to known characteristics, traits or focused phenomenon.
- Purposive sampling – starts with a purpose in mind and the sample is thus selected to include people of interest and exclude those who do not suit the purpose. Use when you want to access a particular subset of people.
Total Area = Length x Width
Actual Total Area = Total Area x Equivalent Size
Compute the sample size of the total area using 5% error instead of 10%.
Where: N – total area
e – percentage error
n – sample size
Sample size = ————————————–
1 + (Total Area x e2)
Quadrant sampling is one of the methods used to obtain a sample from the field. A quadrant is any circular, rectangular, or square plot used to count the sample.
Compute for the number of quadrats using a 25 mm2 quadrant size.
Number of Quadrants = —————————–
- Maps – are diagrammatic representation of the surface of the earth
- Compass rose – indicates which way is north, south, east, and west
- Scale – to estimate distance
- Cartography – study and practice of map making
- Included in a map is:
- Orientation – direction
- Scale – represented in ratio
- Data – depending on usage and map features
Types of maps:
- Climate maps – gives general information about the climate and precipitation of a region
- Cartographers/mapmakers – use colors to show different climate or precipitation zones
- Economic/resource maps – features the type of natural resources or economic activity that dominates an area
- Cartographers/mapmakers – use symbols to show the locations of natural resources or economic activities
- Political maps – they indicate state, national boundaries, capital, and major cities
- Capital city – usually marked with a star within a circle
- Physical map – illustrates the physical features of an area such as mountains, rivers, and lakes.
- Colors – are used to show relief
- Water is shown in – Blue
- Lower elevations is shown in – Green
- Higher elevations is shown in – Orange/Brown
- Road maps – it shows major and minor highways, it also shows roads, airport, railroad tracks, cities, etc.
- Used by people to plan trips and for driving directions
- Topographic/contour maps – includes contour lines to show the shape and elevation of an area.
- Lines that are close together indicate – steep terrain
- Lines that are far apart indicate a – flat terrain
- Characterized by large-scale detail and quantitative representation of elevations depicted by contour lines
- Isohype – contour lines that connect contiguous points of the same altitude
Parts of topographic map
- shows topography, or land contours represented by contour lines
- contour lines – curves that connect contiguous points of the same altitude
Rules in reading topographic maps
- Rule of V’s – sharp pointed v’s usually are in stream valleys, with the drainage channel passing through the point of V
- V – Pointing upstream, downstream is the flow of water. A consequence of erosion
- Rule of O’s – closed loops are normally an uphill on the inside and downhill on the outside
- Innermost loop – the highest area
- Loop – represents a depression
- Hachures – a loop with lines radiating from the inside of the loop, like volcanoes
- Spacing of contours
- Steep slope – close contours
- Shallow slope – distant contours
- Cliff – two or more contour line merging
Terrestrial climatic factors
- Ecosystem – a complex unit of environment consisting of major biotic communities and their interactions with the abiotic factors
- Can be classified as terrestrial and aquatic biomes
- Biome – a distinct ecosystem with define vegetation and climatic components
Abiotic factors – non-living components of the ecosystem
- Classified into climatic and physiographic
Climatic factors consists:
- Light – an electromagnetic radiation consisting of visible and non-visible light
- It is absorbed, reflected, and converted to other forms and end up us heat energy
- Direct light – light that directly felt
- Reflected light – light that is scattered due to shade
- Dispersed light – light that is bended
Importance of light:
- Affects the water temperature
- Affects the biological process
- For photosynthesis
Factors affecting light:
- Vegetation cover
- Seasonal patterns
- Temperature – measurement of intensity of heat and cold
- Difference between the soil and air temperature varies, the sun and air heats the soil. Air losses heat easy while soil holds the heat.
- Soil is warmer than air in the night
- air is warmer than the soil in the day
Factors affecting temperature:
- cloud cover
- winds and ocean current
- length of day
Importance of temperature
- affects the life cycle of plants and animals
- influences weather and tides
- controls the freeze and thaws of ice caps
- Wind – creates a mass density that gives pressure the lower elevation the less in high altitude
- Barometer – instrument used to measure air pressure
- Anemometer – instrument used to measure wind speed
- Air movement – result of uneven heating of the earth
- Coriolis effect – the rotation of the earth causes the wind to move horizontally and be deflected
- Wind gradient – the rate of increase of wind strength with unit increase in height above ground level
- Elevation is responsible for the difference in air pressure
- Air pressure decreases as the elevation increases, air becomes thinner
Importance of wind:
- Creates weather system in the atmosphere
- Responsible for different conditions (morphological features and adaptations for different organisms)
Factors affecting air pressure:
- Fire/Heat – result of converting the light to heat, air will tend to rise when temperature increase
- Moisture /Humidity – amount of water vapor present in the air
- Sling psychrometer – consists of wet and dry thermometer used to measure humidity
- Relative humidity – measurement of water content of air relative to saturation water vapor density
- Relative humidity decreases when the temperature is high
- The higher the temperature the water vapor air can hold increases
- Saturation water vapor density is lower when the temperature is low
Factors affecting humidity:
- Air temperature
- Amount of water vapor in the air
Measurement used in the activity:
- Light meter
- Soil thermometer
- Sling psychrometer
%relative humidity =
water vapor density
Saturation water vapor density
- Soil – the edaphic factor of the ecosystem which has physio-chemical characteristics
- Physical characteristics – particles present, profile, and moisture content
- Chemical characteristics – nutrients and trace elements
- The availability of these elements from the soil depends on soil pH, organic matter content, and soil texture
- Soil texture – influences the drainage characteristics which affect the transport of the elements
Composition of soil
- Soil is the product of physical, chemical, and biological weathering.
- Soil is composed of :
- 40% minerals
- 10% organic matter
- 25% water
- 25% air
- Gravitational water – when water saturates the soil and drains
- Capillary water – water that is left in the soil pores, the one used by plants
- Hygroscopic water – water that is present in the molecules of soil, can be removed only by oven drying
- Soil has 3 main size particles consisting of clay, silt, and sand
- Particle size analysis – the determination of soil texture
- Clay particles = less than 0.002 mm
- Silt particles = 0.002 mm to 0.02 mm
- Sand particles = 0.02 mm to 0.2 mm
Profiles of soil
- Soil profile can be observed through the direct observation of the layers or horizons of the soil.
- O horizon – organic materials consisting of litter, humus, and other decomposing materials
- A horizon – the topsoil
- E horizon – thin layer, boundary between A and B horizons
The accumulation area
- B horizon – the subsoil
- Where clays, soluble salts, and leached humus are stored
- C horizon – composed of disintegrated rocks and other particles from the parent material
- R horizon – parent material, composed of huge rock which is the foundation
- 3 major elements composing the soils:
- These are the main components of commercial fertilizers
- The soil organic matter came from decaying plants and animals such as the complex substance humus
- Decomposition of organic materials or other waste materials can cause the decrease the soil pH making the soil acidic
- Why are pore spaces so important in soils?
Pore spaces are important in the soil, because it determines the nature of living space, the amount of water and air it can hold.
- Why is it important for soil to have good drainage?
Soil that has good drainage helps plants to grow. It provides adequate oxygen to the roots of the plants to encourage proper root development.
- What are the traits of the soil perfectly suited for agricultural field?
A soil must be deep, well drained, neutral and retain sufficient soil moisture for crop growth. A soil must contain a mixture of both clay and sand, allowing for a gradual passage of both water and air to circulate around plant roots. It will also add a valuable amount of nutrition to the soil to feed new plants.
Loam is composed of sand, silt and clay in relatively even concentration (about 40-40-20% concentration respectively. It generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils. Loams are gritty, moist, and retain water easily. It retains nutrients well and retains water while still allowing the water to flow freely.
- What are the traits of the soil perfectly suited for a large building or major highway?
– Should be low in organic matter content and native fertility, low in ability to retain moisture and nutrients, low in cation exchange and buffer capacities, and rapidly permeable (i.e., they permit rapid movement of water and air). Sandy soils usually have high bulk densities and are therefore well-suited for road foundations and building sites.
- What does your pH value mean?
Soils may be classified as either acid or alkaline on a pH scale running from 0, the most acid to 14, the most alkaline, with a neutral at 7. Acidity is a function of chemical composition of parent material, rate of leaching which in turn is closely related to the amount of rainfall. Plants mostly prefer neutral or slightly acid soil.
- What factors affect the soil pH?
Parent material – either basic or acid rock
Rainfall – Water passing through the soil leaches basic nutrients such as calcium and magnesium from the soil. They are replaced by acidic elements such as aluminum and iron. For this reason, soils formed under high rainfall conditions are more acidic than those formed under arid (dry) conditions.
Fertilizers – both organic and chemical fertilizer makes the soil acidic
Plant uptake- Plants take up basic cations such as K+, Ca++, and Mg++. When these are removed from the soil, they are replaced with H+ in order to maintain neutrality.
Organic or decaying matter – makes the soil acidic