ENERGY FLOW IN ECOSYSTEMS SCIENCE 1206

Transcription

1 ENERGY FLOW IN ECOSYSTEMS SCIENCE 1206

2 TOPICS LIST ENERGY FROM THE SUN PERCENTAGES ALBEDO EFFECT PHOTOSYNTHESIS and CELLULAR RESPIRATION THERMODYNAMICS PYRAMIDS PYRAMID OF ENERGY PYRAMID OF BIOMASS PYRAMID OF NUMBERS ROLES IN ECOSYSTEMS KEYSTONE SPECIES ECOLOGICAL NICHE INTRASPECIFIC VS. INTERSPECIFIC COMPETITION EXOTIC SPECIES

3 Where Does our Energy Come From? The SUN is the source of energy for the vast majority of life on Earth. Observe the following diagram:

4 ENERGY FROM THE SUN What happens to the majority of the Sun s energy? It heats the atmosphere, earth s surface, and water. PERCENTAGES: 30 % is reflected by Clouds and Earth s Surface 69 % warms the atmosphere, land, and hydrosphere 1 % generates wind patterns % is used in the process of photosynthesis

5 ALBEDO EFFECT A measure of the AMOUNT of sunlight REFLECTED from an object. Expressed as a decimal value Example: 27 % reflection by clouds is 0.27 What are examples of objects that REFLECT sunlight? In general, LIGHT-COLOURED objects such as: These highly reflective objects have a HIGH ALBEDO. What are examples of objects that ABSORB sunlight? In general, DARK-COLOURED objects such as: These light-absorbing objects have a LOW ALBEDO. Also, GREENHOUSE GASES have a low albedo.

6 ALBEDO EFFECT

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8 PHOTOSYNTHESIS What is it? A biochemical process whereby PRODUCERS use the Sun s energy, carbon dioxide, and water to produce sugar and oxygen. GENERAL CHEMICAL EQUATION: 6 CO H 2 O + Sun s Energy C 6 H 12 O O 2 where CO 2 is carbon dioxide C 6 H 12 O 6 is glucose (sugar) H 2 O is water O 2 is oxygen Oxygen is necessary for CONSUMERS. Sugars are necessary as a usable form of energy for nearly ALL LIFE on EARTH.

9 CELLULAR RESPIRATION What is it? A biochemical process whereby CONSUMERS release the energy stored in the sugar they ingest. By eating sugars and breathing in oxygen, consumers produce carbon dioxide, water, and energy for life processes. GENERAL CHEMICAL EQUATION: C 6 H 12 O O 2 6 CO H 2 O + Energy Cellular respiration is the OPPOSITE reaction to Photosynthesis

10 What kinds of life processes?

11 HOMEWORK Page 33 Numbers 4 a), c), d)

12 4A) Hypothesis: If volcanic ash is released from a volcano, then less sunlight will enter the biosphere and more light will be reflected from the surface of Earth, causing lower air temperatures.

13 4C) Mt. Asama volcano was probably the largest because temperatures were affected for the longest period of time. This might indicate that the greatest amount of volcanic ash was released from that eruption.

14 4D) Temperatures would rise. Airborne particulates would eventually decrease and more sunlight would enter the biosphere.

15 THERMODYNAMICS What is THERMODYNAMICS? The study of ENERGY TRANSFORMATIONS from one form to another (ex: chemical energy to heat energy) 2 Thermodynamic LAWS that apply to ecosystems are: FIRST LAW OF THERMODYNAMICS Energy CANNOT be CREATED NOR DESTROYED, only TRANSFERRED FROM ONE FORM TO ANOTHER. SECOND LAW OF THERMODYNAMICS During energy transfers, SOME ENERGY is LOST as HEAT ENERGY and is not passed on.

16 PYRAMIDS PYRAMID OF ENERGY Recall from an earlier lesson that we can represent ENERGY TRANSFER in an ecosystem with a pyramid of energy, and that only about 10 % of energy is passed from one trophic level to the next. There are 2 other types of pyramids that are USEFUL GRAPHICAL INDICATORS of ecosystem patterns: PYRAMID OF BIOMASS PYRAMID OF NUMBERS

17 PYRAMID OF BIOMASS BIOMASS The mass of an organism WITHOUT water; its dry weight. Measured in kg. Water weight varies greatly in living tissue, so it is more accurate to eliminate it. A PYRAMID OF BIOMASS is a graphical representation of the TOTAL BIOMASS of all the members of each trophic level. Often similar in shape to a Pyramid of Energy.

18 PYRAMID OF BIOMASS

19 PYRAMID OF NUMBERS A graphical representation of the TOTAL NUMBERS of all members of each trophic level in a food chain. Sometimes, these are shaped liked pyramids, but there are exceptions!

20 PYRAMID OF NUMBERS AN EXCEPTION: For example, if the following was a rough sketch of our pyramid of energy, would the pyramid of numbers look the same?

21 PYRAMID OF NUMBERS ANSWER: No, of course not! There would be more caterpillars than any other organism, so our pyramid of NUMBERS would look like:

22 HOMEWORK Page 39, # 3, 4, 5, 7, 14 Draw 3 pyramids (energy, biomass, and numbers) for the following food chain: HAWK (1, 10 J, 5 kg) WOODPECKER (10, 100 J, 10 kg) WORM (1000, 1000J, 50 kg) FIR TREE (1, 10000J, 150 kg)

23 Page A heterotroph cannot produce its own food but consumes other organisms to obtain its needs. 4. A secondary consumer eats meat, usually primary consumers.

24 #5 A top carnivore eats lower-order consumers and is not itself eaten by any other organism (not while alive, and not including parasites). Possible examples include owls in meadows, sharks in oceans, polar bears in the Arctic, etc.

25 #7 An Arctic ecosystem is more fragile than a southern forest because it has much less biodiversity. If something catastrophic occurs to one organism, the food chain could be destroyed.

26 #14 The pyramid of numbers for a deciduous forest has a small base because it doesn t take many trees to produce a large biomass. The large biomass is shown by the large base of the pyramid of biomass.

27 ROLES IN ECOSYSTEMS It is time to discuss some of the interrelationships that take place in ecosystems between species. Some specific roles organisms can take on include: KEYSTONE SPECIES ECOLOGICAL NICHE INTRASPECIFIC VS. INTERSPECIFIC COMPETITION EXOTIC SPECIES

28 KEYSTONE SPECIES A species that is considered so important to ECOSYSTEM STABILITY, that if that species declined, the ecosystem might collapse. Why is it called keystone? It is an analogy for a keystone that holds together an archway. Example: SEA OTTER is a keystone in the CALIFORNIA KELP ecosystem Without otters, kelp does not grow.

29 SEA OTTER... youtube.com /watch?v=e puk3t2kfno

30 ECOLOGICAL NICHE An organism s NICHE is its role that it plays in a particular ecosystem. It includes everything an organism does to survive and reproduce, including: Feeding relationships Habitat Breeding grounds/behaviours Activity times Competitive relationships Organisms tend to have UNIQUE niches, based on where and how they are best adapted to survive.

31 ECOLOGICAL NICHE EXAMPLE Galapagos Island Finches Found on the Galapagos Islands, 600 miles west of Ecuador in South America This island is estimated to be 4 million years old, and largely untouched by human impacts for the bulk of its existence. Charles Darwin studied these finches in 1835 and his studies helped him navigate the theory of EVOLUTION in his book, THE ORIGIN OF SPECIES. By most accounts, a windstorm blew one finch species to the island. Left undisturbed for many centuries, and with very little competition and many available niches, this little finch evolved into many SUBSPECIES, all adapted to a DIFFERENT NICHE.

32 GALAPAGOS ISLAND FINCHES...

33 SPECIES COMPETITION Sometimes in nature there is COMPETITION for NICHES when two or more organisms have similar requirements for SPACE, FOOD, and/or WATER. Survival of the Fittest usually prevails 2 MAIN TYPES: INTRASPECIFIC COMPETITION Between the SAME SPECIES EX: INTERSPECIFIC COMPETITION Between DIFFERENT SPECIES EX:

34 INTRASPECIFIC COMPETITION Same species competing

35 INTERSPECIFIC COMPETITION Different species competing lion and hyena

36 EXOTIC SPECIES ` These are NON-NATIVE species that are not natural parts of ecosystems. Compete INTERSPECIFICALLY with native species in the area. Examples: Moose in NL 4 in 1904 Green Crab in Atlantic Canada Zebra Mussels (p ) Coyotes Coywolfs Introduced Species Zebra Mussels

37 EXOTIC SPECIES GREEN CRAB LINK

38 HOMEWORK Read p P. 44, # 2, 3, 4

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40 #2 Exotic species often have no natural predators when they enter a new habitat, allowing them to multiply so quickly that they crowd out native species. They are often hardy and aggressive and will literally force competitors to flee.

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42 4. In an ecosystem humans can occupy several niches. They are primary consumers because they eat plants, secondary consumers because they eat primary consumers such as cows and rabbits, and tertiary consumers because they eat secondary consumers, such as pigs and raccoons (both of which are omnivores). Humans also eat many secondary consumers from aquatic ecosystems, such as frogs, pike, salmon, etc. Humans are usually top carnivores because nothing eats them, only because of our modern lifestyle. We do not have to worry about tigers, lions, etc., which could be predators of humans.