Chapter 52

1. Chapter 52 An Introduction to Ecology and the Biosphere Ecology - interactions between organisms and the environment

2. Fig. 52-2 Organismal ecology Population ecology Community ecology Ecosystem ecology Landscape ecology Global ecology

3. Fig. 52-6 Biogeography - good starting point for understanding what limits geographic distribution of species Why is species X absent from an area? Yes Area inaccessible or insufficient time Yes Habitat selection Does dispersal limit its distribution? Yes Predation, parasitism, competition, disease Chemical factors Does behavior limit its distribution? No Do biotic factors (other species) limit its distribution? Water Oxygen Salinity pH Soil nutrients, etc. No Do abiotic factors limit its distribution? No Temperature Light Soil structure Fire Moisture, etc. Physical factors Two kinds of factors that determine distribution: biotic, or living factors, and abiotic, or nonliving factors

4. Dispersal and Distribution • Dispersal - movement of individuals away from centers of high population density or from their area of origin

5. Fig. 52-7 Natural range expansions show the influence of dispersal on distribution Current 1970 1966 1965 1960 1961 1943 1958 1937 1951 1956 1970

6. Species Transplants • Species transplants include organisms that are intentionally or accidentally relocated from their original distribution • Species transplants can disrupt the communities or ecosystems to which they have been introduced

7. Behavior and Habitat Selection • Some organisms do not occupy all of their potential range • Species distribution may be limited by habitat selection behavior

8. Biotic and Abiotic Factors • Biotic factors that affect the distribution of organisms may include: • Interactions with other species • Predation • Competition • Abiotic factors affecting distribution of organisms include: • Temperature • Water • Sunlight • Wind • Rocks and soil • Most vary in space and time

9. Temperature • Environmental temperature is an important factor in distribution of organisms because of its effects on biological processes • Cells may freeze and rupture below 0°C, while most proteins denature above 45°C • Mammals and birds expend energy to regulate their internal temperature

10. Water • Water availability in habitats is another important factor in species distribution • Desert organisms exhibit adaptations for water conservation

11. Salinity • Salt concentration affects water balance of organisms through osmosis • Few terrestrial organisms are adapted to high-salinity habitats

12. Sunlight • Light intensity and quality affect photosynthesis • Water absorbs light, thus in aquatic environments most photosynthesis occurs near the surface • In deserts, high light levels increase temperature and can stress plants and animals

13. Rocks and Soil • Many characteristics of soil limit distribution of plants and thus the animals that feed upon them: • Physical structure • pH • Mineral composition

14. Climate • Four major abiotic components of climate are temperature, water, sunlight, and wind • The long-term prevailing weather conditions in an area constitute its climate • Macroclimate consists of patterns on the global, regional, and local level • Microclimate consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log

15. Global Climate Patterns • Global climate patterns are determined largely by solar energy and the planet’s movement in space • Sunlight intensity plays a major part in determining the Earth’s climate patterns • More heat and light per unit of surface area reach the tropics than the high latitudes • Seasonal variations of light and temperature increase steadily toward the poles • Global air circulation and precipitation patterns play major roles in determining climate patterns • Warm wet air flows from the tropics toward the poles

16. Fig. 52-10a Latitudinal Variation in Sunlight Intensity 90ºN (North Pole) 60ºN Low angle of incoming sunlight 30ºN 23.5ºN (Tropic of Cancer) Sun directly overhead at equinoxes 0º (equator) 23.5ºS (Tropic of Capricorn) 30ºS Low angle of incoming sunlight 60ºS 90ºS (South Pole) Atmosphere Seasonal Variation in Sunlight Intensity 60ºN 30ºN March equinox 0º (equator) June solstice 30ºS December solstice Constant tilt of 23.5º September equinox

17. Fig. 52-10d Global Air Circulation and Precipitation Patterns 60ºN 30ºN Descending dry air absorbs moisture Descending dry air absorbs moisture 0º (equator) Ascending moist air releases moisture 30ºS 0º 60ºS 23.5º 23.5º 30º 30º Arid zone Arid zone Tropics Global Wind Patterns 66.5ºN (Arctic Circle) 60ºN Westerlies 30ºN Northeast trades Doldrums 0º (equator) Southeast trades 30ºS Westerlies 60ºS 66.5ºS (Antarctic Circle)

18. Fig. 52-12 Air cools at high elevation. 2 Cooler air sinks over water. 3 Warm air over land rises. 1 Cool air over water moves inland, replacing rising warm air over land. 4

19. Fig. 52-13 • Mountains have a significant effect on • Amount of sunlight reaching an area • Local temperature • Rainfall Leeward side of mountain Wind direction Mountain range Ocean

20. Fig. 52-16 Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth Intertidal zone Oceanic zone Neritic zone Littoral zone Limnetic zone 0 Photic zone 200 m Continental shelf Pelagic zone Benthic zone Aphotic zone Photic zone Pelagic zone Benthic zone Aphotic zone 2,000–6,000 m Abyssal zone • Photic zone (photosynthesis) and aphotic zone (little light) • Benthic zone - organic and inorganic sediment at the bottom of all aquatic • Benthos - communities of organisms • Detritus - dead organic matter; important source of food

21. Thermocline separates the warm upper layer from the cold deeper water • Turnover - semiannual mixing of their waters • mixes oxygenated water from the surface with nutrient-rich water from the bottom Fig. 52-17-5 Summer Winter Spring Autumn 22º 4º 0º 4º 20º 4º 2º 4º 18º 4º 4º 4º 8º 4º 4º 4º 6º 4º 4º 4º 5º 4ºC 4ºC 4ºC 4ºC Thermocline

22. Major aquatic biomes can be characterized by their physical environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs Oligotrophic lakes - nutrient-poor and generally oxygen-rich Eutrophic lakes - nutrient-rich and often depleted of oxygen if ice covered in winter Wetland - inundated by water at least some of the time • supports plants adapted to water-saturated soil • among the most productive biomes on earth Streams and Rivers • most prominent physical characteristic is current

23. Estuary • transition area between river and sea • Salinity varies with the rise and fall of the tides • nutrient rich and highly productive • Intertidal zone • periodically submerged and exposed by the tides • challenged by variations in temperature and salinity and mechanical forces

24. Concept 52.4: The structure and distribution of terrestrial biomes are controlled by climate and disturbance • Climate is very important in determining why terrestrial biomes are found in certain areas • Biome patterns can be modified by disturbance such as a storm, fire, or human activity

25. Fig. 52-19 Tropical forest Savanna Desert Chaparral 30ºN Temperate grassland Tropic of Cancer Equator Temperate broadleaf forest Tropic of Capricorn Northern coniferous forest 30ºS Tundra High mountains Polar ice

26. Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms • This can be illustrated with a climograph, a plot of the temperature and precipitation in a region • Biomes are affected not just by average temperature and precipitation, but also by the pattern of temperature and precipitation through the year

27. Fig. 52-20 Temperate grassland Desert Tropical forest 30 Temperate broadleaf forest 15 Annual mean temperature (ºC) Northern coniferous forest 0 Arctic and alpine tundra –15 0 100 200 400 300 Annual mean precipitation (cm)

28. General Features of Terrestrial Biomes and the Role of Disturbance • Terrestrial biomes are often named for major physical or climatic factors and for vegetation • Terrestrial biomes usually grade into each other, without sharp boundaries • The area of intergradation, called an ecotone, may be wide or narrow • Layering of vegetation in all biomes provides diverse habitats for animals