4) Biogeochemical Cycles Carbon cycle Nitrogen cycle Phosphorus cycle Sulfur cycle Water cycle

1. Contents • 1) Biomes • Distribution of biomes • Classification of biomes • 2) Components of Ecosystems • Components of ecosystems • Factors affecting ecosystems • Habitats • Adaptations • 3) Energy flow in Ecosystems • Trophic structure • Energy in ecosystems • Ecosystem productivity • Ecological pyramids • 4) Biogeochemical Cycles • Carbon cycle • Nitrogen cycle • Phosphorus cycle • Sulfur cycle • Water cycle • 5) Ecosystem Stability • Environmental change • Key species • Ecological succession Click on the hyperlink title you wish to view

2. CO2 O2 Nutrients Ecology • Ecology is the study of the relationships between organisms and their physical and biotic environment: • Relationships involve interactions with the physical world as well as interrelationships with other species and individuals of the same species.

3. Biological Complexity Biosphere Biome Ecosystem Community Population Individual • Living organisms can be studied at different levels ofcomplexity. • From least to most complex, these levels are (in an ecological context): • Individual • Population • Community • Ecosystem • Biome • Biosphere

4. The Biosphere • The biosphere isthe region within which all living things are found on Earth. • It is the narrow belt around the Earth extending from the bottom of the oceans to the upper atmosphere. Image: NASA

5. Life exists in all places, from blind white crabsin lightless environments... Exploring the Biosphere • Our knowledge of what constitutes the biosphere continues to develop as scientists continue their exploration of the Earth. • The biosphere extends into the Earth’s crust, below the oceans and deep into rock fissures; it extends well into the Earth’s upper atmosphere. to tube worms in the crushing ocean depths.

6. Biomes • The biosphere encompasses all living things on Earth.It comprises a number of aquatic and terrestrialbiomes. • Biomes are the largest geographically based biotic communities that can be conveniently recognized. • Biomes within the same category have specific, characteristic features. Desert biome

7. Terrestrial Biomes • Terrestrial biomes are recognized for all the major climatic regions of the world and are classified on the basis of their predominant vegetationtype. • The same biome may occur in widely separated regions.

8. Air rising at the equator causes the formation of rain clouds Rising air allows cloud formation in temperate regions After losing its moisture, dry air descends Desert Desert Temperate Polar Temperate Tropical Polar Hadley cell Ferrel cell Biomes and Weather Cells • Three air cells circle each hemisphere of the Earth. • The interaction of these cells is a major contributor the formation of biomes. Dry air descends at the poles Polar cell

9. Hot Deserts • Deserts are arid regions (annual rainfall generally less than 25 cm). The hot desert biome is found in two belts, centered at 30° latitude north and south of the Equator. • Hot deserts receive most of their rainfall in summer. The driest regions are in central Australia and the middle of the Sahara Desert. • The temperature range is approximately 30°C, and the winter and summer are both very warm. Ayres Rock, Australia Sand dunes, Namibia

10. Temperature range:9°CThe winter and summer are both very warm. Annual total rainfall:15 cm Example: Khartoum, Sudan 15.5°N Khartoum Physical Factors: Hot Deserts

11. Cold Deserts • The cold desert biome is found in dry regions in the mid to high latitudes, especially in the interiors of large continents. Cold deserts also occur at high altitudes in the rain shadows of mountain ranges. • Cold deserts receive most of their small amount of rainfall in winter. Sierra Nevada, USA Arches National Park, USA

12. Temperature range:23°CThe winters are cold; summers are much warmer. Annual total rainfall:38 cm Example: Cheyenne, Wyoming 41°N Cheyenne Physical Factors: Cold Deserts

13. Savanna & Thorn Forests • Tropical savannas are found in central and eastern Africa, and in tropical and subtropical regions of South America and Australia. Thorn forests are found on the equatorial sides of hot deserts. • Both have mild, dry winters and mild, wet summers. • Unlike savanna, thorn forests generally lack grasses. This reflects the increased aridity of the climate.

14. Temperature range:10.7°C Annual total rainfall:74 cm Example: Kayes, Mali 14°N Kayes Physical Factors:Savannas

15. Tropical Rainforests • Tropical evergreen forests are found in equatorial regions where total annual rainfall exceeds 250 cm and the dry season lasts for no more than 2-3 months. These forests are species-rich. • The climate is warm and rainy all year round. Rainforest, Central America

16. Example: Iquitos, Peru 3°S Temperature range: 2.2°C Annual total rainfall:262 cm Iquitos Physical Factors: Tropical Rainforests

17. Temperate deciduous forest Temperate rainforest Temperate Forests • Temperate forests occur throughout mid latitudes where there is a high annual rainfall. • Temperate forests are usually deciduous, but where seasonal fluctuations are moderated by proximity to the coast, the forests are evergreen and are termed temperate rainforests. • Temperate rainforests occur in south-eastern Australia, New Zealand, along the Pacific North-West coast of the United States.

18. Temperature range:31°CThe temperature fluctuates dramatically between summer and winter. Total annual rainfall:81 cmAmple falls throughout the year. Example: Madison, Wisconsin 43°N Madison Physical Factors: Temperate Forests

19. Temperate Grasslands • Temperate grasslands or prairies occur in mid latitudes, in regions that are relatively dry for much of the year. They occur in many parts of the world, and include: • The Pampas of Argentina • The South African veldt • The Great Plains of the USA • Grasslands are highly productive and large regions have been converted to agriculture.

20. Temperature range:24°CThe temperature fluctuates widely, with hot summers, cold winters. In some grasslands, most precipitation occurs in the winter. In others, the majority falls in summer. Total annual rainfall:31 cm Example: Pueblo, Colorado 38°N Pueblo Physical Factors: Temperate Grasslands

21. Tundra: northern Canada Arctic tundra Tundra • The tundra biome is found in the Arctic and high in the mountains at all latitudes. It is dominated by low-growing perennial plants. • The Arctic tundra is very wet even though rainfall is low and this is because the water cannot drain down through the permafrost (permanently frozen ground).

22. Greenland Temperature range: 28°C Total annual rainfall: 23 cm Example: Greenland 73°N Physical Factors: Tundra

23. Mountains and Ice • Mountainous regions are associated with their own altitude adapted vegetation. • The icy regions of the polar ice caps (the Arctic and Antarctic) form sheets of ice that extend into and over the sea.

24. Polar Annual precipitation (mm) Latitudinal regions Arctic region Subarctic region Equatorial Temperate region Tropical region Predicting Biome Distribution 1 • Temperature and precipitation are excellent predictors of biomedistribution. Temperature decreases from the equator to the poles.

25. Predicting Biome Distribution 2 • Temperature and precipitation act together as limiting factors to determine the type of desert, grassland, or forest biome in a region.

26. Physical environment Community Components of an Ecosystem • A biome is a large geographical regioncomprising natural units called ecosystems. • An ecosystem encompasses the physicalenvironment and the community.

27. Abiotic factors atmospheresoilwater wind speed wind directioncurrent velocity Biotic factors competitors symbionts predators parasites pathogens Ecosystem Physical environment Community

28. Light intensity varies Flow rate varies Rainfall level varies Ecosystems Fast flowing water habitat Still water habitat • An ecosystem includes: • all of the organisms(the community) … • and their physical environment. • There are many different sorts of ecosystems from natural to artificial, and they range in size from large to small. Rock habitat Stream bank habitat

29. Communities • A community is a naturally occurring group of organisms living together as an ecological entity; the biological part of the ecosystem. A nudibranch snail feeding on rock encrusting organisms

30. Environments • The physical environment refers to the physical surroundings of any organism, including: • the medium, e.g. water • substrate, e.g. soil • climatic (atmospheric) conditions • light … • and other physical properties.

31. Climate and Vegetation • The type and extent of vegetation in a particular ecosystem is determined by physical factors on both a large scale and on a very localized (microclimate) level. • Vegetation patterns are governed largely by climate (which is broadly related to latitude) and altitude. High latitude climate Temperate climate

32. Factors Affecting Ecosystems • Abiotic (physical) factors are the influences of the non-living parts of the ecosystem. • Examples include pH, salinity, temperature, turbidity, wind speed and direction, humidity, precipitation, water pressure, and light intensity and quality. • Bioticfactors are the influences of the living parts of the ecosystem. Producers and consumers interact as competitors, parasites, pathogens, symbionts, and predators.

33. Monitoring Physical Factors • Devices for measuring the physical factors in the field include the following meters: • Quantum light meter • Dissolved oxygen • Oxygen meter • pH meter • Total dissolved solids (TDS) meter • Current meter • Multi-purpose meter • Hygrometer • Wind meter • Other equipment includes: • Secchi discs • Nansen bottles Photo: Courtesy PASCO scientific Pasco datalogger with attached sensor

34. Physical Gradients • Gradients in abiotic factors are found in almost every environment. • They influence habitats and microclimates, and determine patterns of species distribution. • The effects of these physical (or environmental) gradients are particularly evident where physical conditions change markedly within a short distance, e.g. in deserts, along rocky shores, in lakes and tropical rainforests, and on mountains.

35. Desert Environments • Desert environments experience extremes in temperature and humidity, but they are not uniform with respect to these factors. • Physical conditions vary widely within the one general environment. Crevices, burrows, and the presence of rock overhangs and vegetation create microclimates where extremes in physical conditions are reduced compared to the desert surface.

36. 300 m altitude 27°C, 20% humidity 1 m above ground 33°C, 20% humidity Desert surface 45°C, <20% humidity Burrow (2 m underground)25°C, 95% humidity Crack/crevice (1 m underground)27°C, 95% humidity Under rock 28°C, 60% humidity Desert Factors Hypothetical values for temperature (°C) and percentage humidity at midday in a desert environment.

37. Rocky Shore Environments • Rocky shore environments typically exhibit marked physical gradients as a result of tidal movements. Horizontal and vertical gradients in salinity, temperature, dissolved oxygen, and exposure time are reflected in the communities found at different positions on the shore. • Horizontal: from the low tide to the high tide marks • Vertical: from the bottom to top surfaces of rocks and boulders.

38. Salin: salinity Temp: temperature DO: dissolved oxygen Exp: exposure time (per 12 hour tidal cycle) Salin: 42 gl-1 Temp: 28° C DO: 20% Exp: 12h Salin: 39 gl-1 Temp: 28° C DO: 30% Exp: 10h Salin: 38.5 gl-1 Temp: 26° C DO: 42% Exp: 8h Salin: 37 gl-1 Temp: 22° C DO: 57% Exp: 6h Salin: 36 gl-1 Temp: 19° C DO: 74% Exp: 4h Salin: 35 gl--1 Temp: 17° C DO: 100% Exp: 0h Rocky Shore Factors Hypothetical values for physical factors in rock pools at different places on a rocky shore.

39. Canopy Subcanopy Understorey Ground layer A Tropical Rainforest • The high species diversity of tropical rainforests can be supported because of the wide variety of microhabitats provided by the layered structure of the forest. • The physical conditions at the uppermost level are quite different to those at the forest floor with respect to light intensity (and quality), wind speed, and humidity.

40. Light: 70% Wind: 15 kmh-1 Hum: 67% Light: 50% Wind: 12 kmh-1 Hum: 75% Light: 12% Wind: 9 kmh-1 Hum: 80% Light: 6% Wind: 5 kmh-1 Hum: 85% Light: 1% Wind: 3 kmh-1 Hum: 90% Light: 0% Wind: 0 kmh-1 Hum: 98% Light: light intensity Wind: wind speed Hum: humidity Rainforest Factors

41. Oxbow Lakes in Summer • Oxbow lakes are formed from old river meanders that have been cut off and become isolated from the main channel following the change in the river’s course. • Occasionally they may be deep enough to develop temporary, but relatively stable, gradients in physical factors from the surface to the bottom of the lake.

42. Temp: 24.6°C Oxy: 9.2 mgl-1 Light: 100% Zone of mixing Temp: 22.1°C Oxy: 9.7 mgl-1 Light: 25% Temp: 16°C Oxy: 5.2 mgl-1 Light: 10% Temp: 13°C Oxy: 3.4 mgl-1 Light: 5% Temp: 12.5°C Oxy: 0.2 mgl-1 Light: 2.5% Oxbow Lake Factors

43. Ecological Niche Adaptations Habitat • The ecological niche describes the functional position of an organismin its environment. • A niche comprises: • the habitat in which the organism lives. • the organism’s activity pattern: the periods of time during which it is active. • the resources it obtainsfrom the habitat. Activity patterns Presence of other organisms Physical conditions

44. The Fundamental Niche • The fundamentalniche of an organism is described by the full range of environmental conditions (biological and physical) under which the organism can exist. • The realizedniche of the organism is the niche that is actually occupied. It is narrower than the fundamental niche. • This contraction of the realized niche is a result of pressure from, and interactions with, other organisms.

45. Physical Conditions • The physical conditions influence the habitat in which an organism lives. These include: • substrate • humidity • sunlight • temperature • salinity • pH (acidity) • exposure • altitude • depth • Each abiotic (or physical) factor may be well suited to the organism or it may present it with problems to overcome.

46. Tolerance range Too acidic pH Too alkaline Optimum range Examples of abiotic factors that influence size of the realized niche Too cold Temperature Too hot Law of Tolerance • The law of tolerance states that “For each abiotic factor, an organism has a range of tolerances within which it can survive.” Number of organisms Unavailable niche Marginal niche Preferred niche Marginal niche Unavailable niche

47. Habitat • An organism’s habitat is the physical place or environment in which it lives. • Organisms show a preference for a particular habitat type, but some are more specific in their requirements than others. Most frogs, like this leopard frog, live in or near fresh water, but a few can survive in arid habitats. Lichens are found on rocks, trees, and bare ground.

48. Habitat Range • An organism’s habitat is not always of a single type. Some organisms occupy a range of habitats. There are various reasons why: • Highly adaptable in habitat requirements. • Different, but equivalent, resources available in different habitats. • Reduced competition for resources in sub-optimal habitats. • Habitat extremes may influence growth form, especially in plants.

49. Habitat Preference • Organisms may select particular areas within their general habitat, even in apparently homogeneous environments, such as water.This is termed habitat preference. • Example: Aquatic organisms may show a preference for a particular substrate type, water depth or velocity, water clarity, or degree of vegetation cover or habitat disturbance. • Knowledge of habitat preference can be used to protect species in their environment. Damselfly nymph Rainbow trout

50. Resources in a Habitat • The habitat provides organisms with the following resources: • Food and water sources • Mating sites • Nesting sites • Predator avoidance • Shelter from climatic extremes • However, the organism may or may not have the adaptations to exploit all the available resources fully.