Environmental Science Unit – Living Environment Investigating Ecosystems and Biodiversity Core Extension I can describe biodiversity within an ecosystem I can describe how adaptation effects distribution of organisms I can sample living things (biotic) from different habitats using a variety of sampling methods I can sample non-living (Abiotic) factors I can identify organisms using appropriate resources I can describe factors influence the distribution of living things I can identify and state ecological terms used to describe an environment including biodiversity I can describe how adaptation & competition effects distribution of organisms I can describe interdependence within example ecosystems I can sample and identify living things (biotic) from different habitats using a variety of sampling methods and give potential sources of error I can sample non-living (Abiotic) factor and give potential sources of error I can describe the effect of abiotic factors on the distribution of organisms I can identify organisms and constructing paired statement keys
5 – Sampling Techniques Sampling techniques can be used to sample living and non-living parts of an ecosystem. Factors related to living things such as amount of food, number of predators, incidence of disease and competition are called biotic factors Non-living factors such as temperature, rainfall, intensity and pH are called Abiotic factors. Biotic Technique Used to sample How to use Source of Error Minimising Error Quadrat Plants Slow moving organisms e.g. limpets, snails. Place randomly on the ground the number of squares the organism is found in Not placed randomly Small sample area Place randomly Sample larger area Pitfall Trap Small animals/ insects e.g. centipedes Place small container in the ground Disguise opening Leave overnight and collect and identify organisms found Lip not with ground Bird eat trapped animals / trapped animals eat each other Ensure lip with ground Disguise opening Set up multiple traps Tree Beating Small animals/insects a large tray/sheet under sample area Gently hit a branch Collect organisms that fall onto sheet and identify Some organisms fly away Small sample area Some organisms remain in the tree Take several samples Use larger tray/sheet
Dipping net Small animals/insects E.g. tadpoles Move net rapidly through back and forth Empty contents into tray Small animals escape through gaps in mesh Animals from different levels not collected Repeat Use net with mesh Sweep Net Small animals/insects e.g. butterflies Brush net close to the ground Animals fly away Some organisms remain of ground Repeat Identifying Organisms Organisms collected can be identified by comparing to pictures in suitable books however this takes a long time. A much better method is to use a key. A key may be branched or in the form of paired statements. Abiotic Technique Used to sample How to use Source of Error Minimising Error Moisture / pH Soil Moisture / pH Push the probe into the soil and take the reading from the meter probes are not cleaned between readings Clean probe between reading Repeat Light meter Light intensity Hold at the soil surface and point in the direction of the maximum light intensity, then take the reading from the meter Shading the meter Hold away from shading Repeat Factors affecting Distribution Abiotic factors affect the distribution of organisms. Here are some examples: Daisies The more light available, the more daisy plants will be present. This is because daisies need light energy from the sun to make their own food (photosynthesise).
and do not depend on any other organism for nutrition. Primary Consumers Herbivores that eat producers Deer, mice, fish Secondary Consumers Eat primary consumers Snake eating a mouse Tertiary Consumer Eat secondary consumers Eagle preying on the snake Herbivore Organism that only eats producers sheep Omnivore Organism that eats producers and other animals humans Carnivore Organism that only eats other animals Lions Detritivore Make up the last part of food chains, organisms that eat nonliving and animal remains. scavengers such as vultures eat dead animals. Dung beetles eat animal feces. Decomposers Turn organic wastes, such as decaying plants, into inorganic materials, such as nutrient-rich soil. They complete the cycle of life, returning nutrients to the soil or oceans fungi and bacteria Niches Each species in a habitat has its own role to play. Its role includes its general behaviour and its effect on the habitat and other organisms living there. The term used to describe this role is niche. Energy Flow At each link in a food web 90% of the energy is lost, so the organism next in the chain only gains 10%. Energy can be lost from a food web in different ways: Wasted as undigested food (faeces) Used by the organism for heat and movement 2 - Population Growth