Ecology CO 2 O 2 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. Nutrients
Biological Complexity Living organisms can be studied at different levels of complexity. From least to most complex, these levels are (in an ecological context): Biosphere Biome Ecosystem Community Individual Population Community Population Individual Ecosystem Biome
The Biosphere The biosphere is the 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 troposphere. Image: NASA
Exploring the Life exists in all places, from blind white crabs in lightless environments... Biosphere Our knowledge of what constitutes the biosphere continues to develop as scientists continue their exploration of the Earth. As we learn more about the biosphere, we find new kinds of life in areas we previously thought were lifeless! to tube worms in the crushing ocean depths.
Biomes The biosphere encompasses all living things on Earth. It comprises a number of aquatic and terrestrial biomes. Biomes are the largest geographically based biotic communities that can be conveniently recognized. Biomes within the same category have specific, characteristic features. Desert biome
Terrestrial Biomes Terrestrial biomes are recognized for all the major climatic regions of the world and are classified on the basis of their predominant vegetation type. The same biome may occur in widely separated regions.
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. Rising air allows cloud formation in temperate regions Air rising at the equator causes the formation of rain clouds After losing its moisture, dry air descends Dry air descends at the poles Hadley cell Ferrel cell Polar cell Polar Temperate Desert Tropical Desert Temperate Polar
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
Physical Factors: Hot Deserts Example: Khartoum, Sudan 15.5 N Temperature range: 9 C The winter and summer are both very warm. Annual total rainfall: 15 cm Khartoum
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
Physical Factors: Cold Deserts Example: Cheyenne, Wyoming 41 N Temperature range: 23 C The winters are cold; summers are much warmer. Annual total rainfall: 38 cm Cheyenne
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.
Physical Factors: Savannas Example: Kayes, Mali 14 N Temperature range: 10.7 C Annual total rainfall: 74 cm Kayes
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 speciesrich. The climate is warm and rainy all year round. Rainforest, Central America
Physical Factors: Tropical Rainforests Example: Iquitos, Peru 3 S Temperature range: 2.2 C Annual total rainfall: 262 cm Iquitos
Temperate Forests Temperate deciduous forest 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. Temperate rainforest
Physical Factors: Temperate Forests Example: Madison, Wisconsin 43 N Temperature range: 31 C The temperature fluctuates dramatically between summer and winter. Total annual rainfall: 81 cm Ample falls throughout the year. Madison
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.
Physical Factors: Temperate Grasslands Example: Pueblo, Colorado 38 N Temperature range: 24 C The 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 Pueblo
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). Tundra: northern Canada Arctic tundra
Physical Factors: Tundra Example: Greenland 73 N Temperature range: 28 C Total annual rainfall: 23 cm Greenland
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.
Latitudinal regions Predicting Biome Distribution 1 Temperature and precipitation are excellent predictors of biome distribution. Temperature decreases from the equator to the poles. Polar Arctic regio n Subarcti c region Temperate region Equatorial Tropical region Annual precipitation (mm)
Components of an Ecosystem Physical environment Community A biome is a large geographical region comprising natural units called ecosystems. An ecosystem encompasses the physical environment and the community.
Ecosystem Physical environment Abiotic factors atmosphere soil water wind speed Community wind direction current velocity Biotic factors competitors symbionts predators parasites pathogens
Ecosystems Light intensity varies 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 Flow rate varies Rainfall level varies
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
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.
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
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. Biotic factors are the influences of the living parts of the ecosystem. Producers and consumers interact as competitors, parasites, pathogens, symbionts, and predators.
Photo: Courtesy PASCO scientific 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 Pasco datalogger with attached sensor Nansen bottles
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.
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.
Desert Factors Hypothetical values for temperature ( C) and percentage humidity at midday in a desert environment. 300 m altitude 27 C, 20% humidity Desert surface 45 C, <20% humidity 1 m above ground 33 C, 20% humidity Under rock 28 C, 60% humidity Crack/crevice (1 m underground) 27 C, 95% humidity Burrow (2 m underground) 25 C, 95% humidity
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.
Rocky Shore Factors Hypothetical values for physical factors in rock pools at different places on a rocky shore. 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: 12 h Salin: 39 gl - 1 Temp: 28 C DO: 30% Exp: 10 h Salin: 38.5 gl - 1 Temp: 26 C DO: 42% Exp: 8 h Salin: 37 gl - 1 Temp: 22 C DO: 57% Exp: 6 h Salin: 36 gl - 1 Temp: 19 C DO: 74% Exp: 4 h Salin: 35 gl- - 1 Temp: 17 C DO: 100% Exp: 0 h
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. Canopy Subcanopy Understorey Ground layer
Light: light intensity Wind: wind speed Hum: humidity Rainforest Factors 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: Light: 85% 1% Wind: 3 kmh - 1 Hum: 90% Light: 0% Wind: 0 kmh - 1 Hum: 98%