Ecology

1. Ecology Unit 10

2. Words to know… • Ecology = The scientific study of interactions among organisms and between organisms and their environment • Biosphere = Area of the earth where life exists; extends from the ocean’s depths to a few kilometers above land • Biome = Extensive areas of similar climate and vegetation; ecologists recognize at least ten different biomes

3. Words to know… • Biotic factors = living factors, such as plants and animals • Abiotic factors = non-living factors, such as climate, water, sun, rock, etc.

4. Terrestrial Biomes

5. Tropical Rain Forest • Abiotic factors: hot and wet year-round; thin, nutrient poor soils • Dominant plants: broad-leaved evergreen trees; ferns; large woody vines and climbing plants • Geographic distribution: parts of South and Central America, Southeast Asia, parts of Africa, southern India, and northeastern Australia

6. Tropical Dry Forest • Abiotic factors: generally warm year-round; alternating wet and dry seasons; rich soils subject to erosion • Dominant plants: tall, deciduous trees that form a dense canopy during the wet season • Geographic distribution: parts of Africa, South and Central America, Mexico, India, Australia, and tropical islands

7. Tropical Savanna • Abiotic factors: warm temperatures; seasonal rainfall; compact soil; frequent fires set by lightning • Dominant plants: tall, perennial grasses; sometimes drought-tolerant and fire-resistant trees or shrubs • Geographical distribution: large parts of eastern Africa, southern Brazil, northern Australia

8. Desert • Abiotic factors: low precipitation; variable temperatures; soils rich in minerals but poor in organic material • Dominant plants: cacti and other succulents; plants with short growth cycles • Geographic distribution: Africa, Asia, Middle East, United States, Mexico, South America, Australia

9. Temperate Grassland • Abiotic factors: warm to hot summers; cold winters; moderate, seasonal precipitation; fertile soils; occasional fires • Dominant plants: lush, perennial grasses and herbs; most are resistant to drought, fire, and cold • Geographic distribution: central Asia, North America, Australia, central Europe, and upland plateaus of South America

10. Temperate Woodland and Shrubland (Chaparral) • Abiotic factors: hot, dry summers; cool, moist winters; thin, nutrient-poor soils; periodic fires • Dominant plants: woody evergreen shrubs with small, leathery leaves; fragrant, oily herbs that grow during winter and die in summer • Geographic distributions: western coasts of North and South America, areas around the Mediterranean Sea, South Africa, and Australia

11. Temperate Forest • Abiotic factors: cold to moderate winters; warm summers; year-round precipitation; fertile soils • Dominant plants: broadleaf deciduous trees; some conifers; flowering shrubs; herbs; a ground layer of mosses and ferns • Geographic distribution: eastern United States; southeastern Canada; most of Europe; and parts of Japan, China, and Australia

12. Northwestern Coniferous Forest • Abiotic factors: mild temperatures; abundant precipitation during fall, winter, and spring; relatively cool, dry summer; rocky, acidic soils • Dominant plants: Douglas fir, Sitka spruce, western hemlock, redwood • Geographic distribution: Pacific coast of northwestern United States and Canada, from northern California to Alaska

13. Boreal Forest (Taiga) • Abiotic factors: long, cold winters; short, mild summers; moderate precipitation; high humidity; acidic, nutrient-poor soils • Dominant plants: needleleaf coniferous trees such as spruce and fir; some broadleaf deciduous trees; small, berry-bearing shrubs • Geographic distribution: North America, Asia, and northern Europe

14. Tundra • Abiotic factors: strong winds; low precipitation; short and soggy summers; long, cold, and dark winters; poorly developed soils; permafrost • Dominant plants: ground-hugging plants such as mosses, lichens, sedges, and short grasses • Geographic distribution: northern North America, Asia, and Europe

15. Other land areas • Mountain Ranges – found on all continents, abiotic and biotic conditions vary with elevation • Polar Ice Caps – cold year-round, very few plants and algae • North polar region – dominant animals are polar bears, seals, insects, and mites • South polar region – dominant animals are penguins and marine mammals

16. Aquatic Biomes

17. Aquatic Ecosystems • Nearly ¾ of Earth’s surface is covered with water • Determined by depth, flow, temperature, and chemistry of the over-lying water

18. Flowing freshwater • Rivers, streams, creeks, and brooks • Animals have adaptations, such as hooks, suckers, streamlined bodies, etc. • Often come from underground water source • Turbulent water = plenty of dissolved oxygen

19. Standing freshwater • Lakes and ponds • Water flows in and out, usually circulates  helps distribute heat and oxygen • Relatively still water allows organisms like plankton to survive

20. Freshwater wetlands • Wetland – ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year • Bogs, marshes swamps • Support very specific plants and animals

21. Estuaries • Wetlands formed where river meets sea • Brackish = fresh water + salt water • Most organic material enters as detritus – made up of tiny pieces of organic material, consumed by clams, worms, sponges, etc. • Salt marshes = temperate zone estuaries • Mangrove swamps = tropical coastal regions

22. Marine Ecosystems • Photic zone – relatively thin (200 meters) upper layer where light can penetrate  photosynthesis can occur • Aphotic zone – permanently dark, chemosynthetic producers only • Marine biologists divide ocean by photic and aphotic zones as well as depth and distance from shore

23. Intertidal Zone • Submerged in sea water once or twice a day, otherwise exposed to air and sunlight • Zonation – prominent horizontal banding of organisms that live in a particular habitat

24. Coastal Ocean • Extends from low-tide mark to outer edge of continental shelf • Shallow enough to mostly fall in photic zone  allows for plankton, kelp, etc. to survive

25. Coral Reefs • Warm, shallow water of tropical coastal oceans • Named for coral animals whose hard, calcium carbonate skeletons make up their primary structure • Need warm water, bright sun, and salt, grow with help of algae

26. Open ocean • Begins at edge of continental shelf and extends outward • 90% of the surface area of the world’s ocean • Organisms are exposed to high pressure, frigid temperatures, and total darkness • Most productivity occurs in photic zone

27. Benthic zone • Ocean floor • Creatures that live here (such as sea stars, anemones, marine worms, etc.) are called benthos • Often depend on food from organisms that grow in the photic zone that drifts down

28. Ecosystems, Populations, and Communities

29. Ecosystems • An ecosystem is a physically distinct, self supporting unit of interacting organisms and their environment • Includes biotic and abiotic factors • Four important processes: • Production of energy (usually from sunlight) • Energy transfer • Decomposition • Reuse of nutrients

30. Communities and Populations • Community = all of the ecosystem’s interacting biotic factors • May be broken down into smaller units called populations • Population = a group of individuals that belong to the same species, occupy the same area, and share common resources • Each population has a specific niche, which means total way of life  habitat, place in food web, competition, interrelationships, and resource needs • A community may have 1000’s of populations (rain forest) or relatively few (tundra)

31. How does energy move through an ecosystem? • Organisms in a community survive by either producing or consuming food • Trophic level = level of feeding in a community • Producers produce food for themselves • Consumers must take in food from other sources

32. How does energy move through an ecosystem? • Primary consumers eat producers  “herbivores” (eat only plants) • Secondary and Tertiary consumers can be carnivores (eat only meat) or omnivores (eat plants and meat) • Decomposers break down wastes and dead organisms, return nutrients to soil

33. Food webs • Made up of overlapping food chains • Shows feeding connections • Arrows illustrate energy transfer  flow in direction of energy

34. Energy efficiency • Producers have most available energy (from sun) • Energy is lost as it moves up through the food web  “10% rule” = only 10% of the energy is transferred to the next highest trophic level • The “lost” energy is used to catch, eat, and digest food. • Decomposers return nutrients and energy to soil.

35. How do populations change over time? • Population growth – populations will grow until they reach their carrying capacity  exponential growth – “J curve” • Limiting factors, such as availability of food, space, mates, etc. establish the carrying capacity (the # of individuals an environment can support) – “S curve”

36. Ecological Succession • Succession = the idea that communities will replace other communities in a predictable, orderly way because every community alters the physical factors of the environment • Two kinds: • Primary – occurs in areas that have not supported communities before • Secondary – occurs in areas that have supported communities before

37. Ecological Succession • Pioneer species – first organisms to inhabit an area, must be able to survive harsh conditions • Intermediate communities – multiple communities that each change the environment and “pave the way” for other communities • Climax community – final stage in succession, most stable community for that biome

38. Community interactions

39. How do living things interact in a community? • Competition = a struggle for resources among organisms • Predation = organisms consume other organisms • Predators = organisms doing the eating • Prey = organisms getting eaten • Symbiosis = two organisms of different species living together in a close, permanent relationship

40. Symbiosis • Mutualism – the two organisms benefit each other • Commensalism – one organism benefits and the other is neither benefitted nor harmed • Parasitism – one organism benefits and the other is harmed

41. Biogeochemical Cycles

42. Biogeochemical Cycles • Pathways through which a substance is recycled. • Water cycle • Carbon cycle • Nitrogen cycle

43. Water Cycle • Enters ecosystem through precipitation, could be absorbed into soil or run-off into surface water • Returns to atmosphere through evaporation or transpiration (loss of water by plants)

44. Carbon Cycle • Powered by two main processes: • Photosynthesis – plants and algae capture CO2 from air and change it to sugar which contains carbon • Respiration – all living things break down sugars for energy, which returns CO2 to atmosphere • Other factors: • Decomposition returns carbon to soil and atmosphere • Humans burn fossil fuels which adds CO2 to atmosphere

45. Nitrogen Cycle • Nitrogen is essential for living organisms so that they can build proteins • Nitrogen is plentiful in the atmosphere, but not usable in this form • Nitrogen fixation = bacteria living in the root nodules of bean plants convert nitrogen from the air into a more usable form • Nitrogen fixation is the first of many steps that involves bacteria and changing the form of nitrogen

46. Studying Ecology

47. What technology helps scientists study the complex systems in ecology? • Global positioning system – satellite based navigation system that allows the exact determination of a location. This is used for GIS (geographic information systems) which can: • Store, manage and integrate data relating to points (individual trees), lines (rivers, roads), and boundaries • Search for areas with a particular factor (ex. species) • Perform geographical analysis • Display data in maps

48. What technology helps scientists study the complex systems in ecology? • Biological Sampling – techniques that allow scientists to quantitatively evaluate an area in terms of its biotic factors • Mark/recapture method – allows scientists to estimate a population number in area, scientist captures a segment of population, marks them, releases them, and then recaptures another segment of the population, counting the number of “marked” individuals recaptured, using these numbers to estimate the total population size.

49. What technology helps scientists study the complex systems in ecology? • Quadrant analysis – scientists use a quadrant to select an area of an ecosystem  reduces space a scientist must analyze, ensures the size of area remains the same if the scientist chooses to analyze several areas or the same area over a period of time • Water/soil analysis – using chemical tests or sampling techniques to determine the chemical or physical characteristics of water or soil

50. Human Impact