Ecosystems

1. Ecosystems Objectives: I can … Describe the factors affecting the weather and climate of an area. List the major climate zones and biomes. Explain the types of relationships that can occur in a community. Compare and contrast primary and secondary succession. Develop a likely succession scenario of species. Evaluate the role of various biomes on global conditions. Characterize the conditions and species found in each major biome. List the factors that help determine which life forms will exist in a freshwater environment. Compare and contrast wetlands: bogs, marshes, swamps, and estuaries. Explain the importance of aquatic ecosystems.

2. Vocabulary: ecosystem * biotic factors * climate * latitude * conduction * convection currents * radiant energy * shore breeze * sea breeze * microclimate * niche * symbiotic * mutualism * commensalism * parasitism * pioneer species * primary and secondary succession * climax communities * dominant species * abiotic factors * biome * transpiration * canopy * emergent layer * understory * deciduous * succulents * temperate * freshwater * plankton * phytoplankton * zooplankton * wetlands * bogs * marshes * swamps * estuaries * marine * continental slope * continental rise * abyssal plain * midocean ridges * photic * aphotic * benthos * open ocean

3. An ecosystem (a collection of all of the biotic and abiotic factors in an area) has specific life forms (biotic factors) based primarily on the area’s climate (average daily weather conditions/seasonal changes over years). All weather, and the resulting climate, is affected by the sun’s energy. How direct the sun hits an area is dependent on the tilt of the Earth and the Earth’s position in its revolution around the sun. Therefore, the northern hemisphere experiences summer during June, July, and August because the Earth is tilted toward the sun during this part of Earth’s revolution around the sun. This is true in spite of the fact that the Earth is actually FURTHER AWAY from the sun during our summer. The sun’s heat also affects evaporation (and therefore rainfall) and wind generation (hot air rises and the surrounding air moves in, creating wind). Wind patterns can also be affected by mountains, etc. And, atmospheric gases and cloud cover can affect temperatures.

4. Abiotic and Biotic Factors Section 4-2 Abiotic Factors Biotic Factors ECOSYSTEM Go to Section:

5. Sunlight Some heat escapes into space Greenhouse gases trap some heat Earth’s surface

6. CO2 and water vapor (greenhouse gases) help hold heat in the atmosphere, away from outer space. Cloud cover at night also helps hold heat in. Latitude (distance from the equator) plays an important role in how directly the sun’s rays hit an area. This creates different climates at different latitudes. The three main climate zones are the polar, temperate, and tropical zones. The polar zones fall between 66.5 and 90 degrees North and South latitudes. Between 23.5 and 66.5 degrees North and South latitude lies the temperate zones. These are characterized by warm summers and colder winters. The tropical zones fall between 23.5 degrees North and 23.5 degree South latitude. These areas are characteristically warm year round but often have wet and dry seasons instead. The rotation of and unequal heating of the Earth drives winds and ocean currents. Air heated near the equator rises and travels toward the poles while cold air from the poles sinks and travels toward the equator. But, the flow is not directly north or south due to the spin (rotation) of the Earth.

7. Polar Temperate Tropical: direct sunlight Temperate Polar

8. The ocean warms from the sun’s radiant energy (electromagnetic waves - the only form of heat transfer that can occur in the vacuum of outer space). Warm ocean waters keep coastal areas warmer during the winter than inland areas. Warm water heats the air above it via conduction (heat transfer due to direct contact). The warm air rises above cold air due to convection currents (hot air is less dense and therefore rises). The warm air over the water is then replaced by the flow of cool air along the surface from the land. This is called a shore breeze. However, in Spring, water is slow to warm up after winter but the sun’s heat quickly heats the landmasses. This makes the hot air over the land rise and the breeze from the ocean (or Great Lakes in Wisconsin) moves in, cooling the air (hence, “cooler near the lake” in Wisconsin). These “sea breezes” can dramatically affect temperatures on shore.

9. Heat Transport The currents in the ocean will transport heat throughout the Earth Ocean Currents

10. Microclimates along shorelines or in mountains, due to altitude (higher altitudes are colder due to fewer air molecules vibrating in the sun’s radiant heat energy), are common. But other factors can create small areas with significantly different climates from the surrounding area (aka microclimates) too. Microclimates may help provide a niche (the right climate and other physical conditions to support a species) for a particular species that might not otherwise live in that area. For example, much of the ocean has very little life, but coral reefs provide a niche suitable for many species to survive. A species’ niche will provide the right food, shelter, climate, etc. for its survival. Many organisms living in the same community must compete for resources such as light (plants), food, etc. Often there are predator/preyrelationships. And, symbiotic (living together) relationships which includemutualism (both organisms benefit), commensalism (1 benefits, the other is neither harmed nor helped), and parasitism (the parasite benefits, the host is harmed).

11. A community or ecosystem develops and changes over time. This is referred to as ecological succession. Primary succession occurs in barren areas devoid of soil. Pioneer species are the first to arrive and begin influencing the environment. For example, lichens can breakdown rocks and add organic (living or once living) material back to the soil. Lichens are often the first species in areas covered by a volcanic eruption. The first species in sandy areas, like beaches or desert sand dunes, are often grasses. The pioneer speciesmodify the environment and that allows other species to take hold. So lichens add soil nutrients that allow mosses and grasses to grow. These allow insects to move in and help create deeper soil for shrubs and tree seedlings to start growing. This provides food and habitat for birds, mice, etc. Then, the shading that occurs due to the growth of the first sun-loving trees now allows shade- loving species to grow , and so on. Coyotes, etc move in and the succession of new species continues.

12. Secondary succession occurs in an area where soil is present but barren. For example, after a forest fire, plowing a field, a mudflow, etc. Succession usually occurs faster here than in primary succession. Eventually, if left undisturbed, an area somewhat stabilizes. This is seen as old growth forests in some areas, grasslands in the Great Plains, etc. These stable environments, where changes occur much more slowly, are sometimes referred to as climax communities. The dominant species (most prevalent species) gives the area its name (Ex. grass in a grassland). Together, the characteristic species living in an area and the physical (non-living, or “abiotic” factors) environment (weather, etc.) create a biome. For example, the Great Plains area is a “temperate grassland”, the very dry areas of Antarctica are “polar deserts”, the deserts in and near California are “temperate deserts”, etc. Obviously, climate (both temperature and moisture conditions) has a major impact on what species survive in an area and what type of biome exists.

13. Major Biomes 1) Tropical Rain Forest - these constantly warm, wet areas lie close to the equator. Not only do they provide much of the world’s oxygen but transpiration(evaporation from plants) from the rain forests provides much of the moisture in the atmosphere. Tropical rain forests have more species of plants and animals than any other land biome. (Coral reefs are the tropical rain forests of the ocean.) The forest itself is characterized by a canopy (dense tree top leaf coverings at the same height from mature trees), an emergent layer (a few tree tops that rise above the canopy layer), and the understory (shorter plants). 2) Tropical Dry Forest - have less yearly and seasonal rainfall than the tropical rain forests. During the driest months, trees in these forests drop their leaves. This is much like our trees losing their leaves before winter. Trees that lose their leaves are called “deciduous”. The tropical dry forests are usually found surrounding the tropical rain forests.

14. 3) Tropical Savannah - also known as tropical grasslands, get little rainfall. They contain some grass and a few scattered, low growing trees. Much of Africa and parts of Australia and South America are covered by tropical savannahs. 4) Deserts - very dry areas whether they are in cold areas (like Antarctica) or warmer regions. They receive less than 25 centimeters (10 inches) of precipitation yearly. The deserts of the U.S. can get below freezing at night but over 100 degrees during the day. The soils have little organic material but many minerals. Succulents (plants that store water well), like cacti, are found in parts of some deserts. 5) Temperate Grassland - usually relatively flat plains like in the central area of North America. The soils are fertile but there is insufficient rainfall to support trees. 6) Chaparral - occur in temperate, semi-arid (dry) areas. They are covered with shrubs and other low growing plants. *** temperate areas have seasonal conditions that are neither continually hot like the tropics nor continually cold like the polar regions

15. 7) Temperate Forest - deciduous and coniferous trees dominate. Cold winters allow the trees to “rest”. The soil has a lot of organic matter (humus) from leaf and pine needle litter. Precipitation is relatively good. 8) Temperate Rain Forests - also called northwestern coniferous forests. Lots of rain, mild seasonal temperature changes, and characterized by redwoods, spruce, firs, and hemlocks. 9) Taiga - or boreal (north) forests, occur in areas with very cold winters. Heavily populated by needle bearing trees. 10) Tundra - polar areas with permanently frozen subsoil called the permafrost. Summers are short and cool. The ground only thaws at the surface and can get soggy in summer. Plants are very short and sparse due to cold, windy conditions and frozen subsoil. Mountains and the surrounding area can provide a vertical shift (change in altitude) in climate and communities/ecosystems just as changes in latitudes does. The peak of a tall mountain is much like the tundra, below that areas resemble the taiga or chaparral, etc.

16. Compare/Contrast Table Section 4-3 Go to Section:

17. Figure 4-17 The World’s Major Land Biomes Section 4-3 Tropical rain forest Temperate forest Tundra Temperate grassland Desert Northwestern coniferous forest Mountains and ice caps Tropical dry forest Temperate woodland and shrubland Tropical savanna Boreal forest (Taiga) Go to Section:

18. Aquatic Ecosystems The Earth’s surface is covered about 70% by oceans and another 3% by freshwater. Water has a higher specific heat than air. That means that water gains and loses heat slower than air. This can have a dramatic effect on climate but can also greatly affect life forms living in water. (Note: Freshwater does NOT mean clean water. It means it is not considered “salty.”) Which life forms can exist in aquatic ecosystems depends on nutrient availability (Ex: P, K, N for algae), temperature of the water, depth of sunlight penetration, pH, flow/current, dissolved O2, etc. The smallest aquatic organisms are the plankton. Phytoplankton are the plant-like algae. Because water covers such a huge percentage of the Earth’s surface, algae (phytoplankton) are responsible for much of the oxygen in our atmosphere. Through photosynthesis, algae also help remove CO2, the biggest greenhouse gas, from the atmosphere. Zooplankton are the animal-like organisms. Plankton form the base of aquatic food webs.

19. Compared to ponds and lakes, wetlands are relatively shallow areas with fresh water at or near the soil. These are not only primary feeding grounds for many types of birds, but are also important areas for filtering out sediments, contaminants, etc. before surface water soaks into the soil to become part of the groundwater or before the water enters another area, like a lake. Wetlands include bogs, marshes, swamps, and estuaries. Bogs are usually acidic with a lot of moss growing in these areas - sometimes creating thick mats dense enough to walk on. Marshes tend to occur along the edges of rivers. They are often associated with cattails and reeds. Swamps are similar to marshes however swamps will have trees and shrubs growing in the water. Estuaries form where flowing fresh water (rivers, streams) meets the ocean and creates a shallow area of mixed salt and fresh water.

20. Marine Ecosystems “Marine” refers to saltwater. Oceans are divided into zones and regions based on light, temperature, depth, etc. For example, the area between high and low tide is called the intertidal zone. This area is out of water part of each day and under water the rest of the day. Sea anemones, crabs, clams, etc. can take the crashing waves and changing water levels found here. Just beyond the low tide area is the relatively shallow, gently sloping “continental shelf.” The water here is relatively warm because sunlight penetrates to the bottom. Plenty of plankton offer food for larger organisms. Wave action here mixes oxygen into the water. And, water pressure is minimal. Kelp beds grow rapidly here. It is a very important area for ocean life. Coral reefs require warm water that is shallow enough for photosynthesis to occur. So, they often live on the continental shelf in tropical areas. The coral itself is a symbiotic partnership between a cnidarian animal and an algae. The coral provides a great habitat to so many organisms that it is often called “the rainforest of the ocean.”

21. The region that quickly slopes down and away from the continental shelf is called the continental slope. The top reaches of this area has plenty of sunshine for photosynthesis, wave action for oxygen distribution, and low pressure. Descending down the slope brings a proportional drop in ocean temperatures called the thermocline. Organisms preferring cooler water and tolerant of slightly higher water pressure, like this environment. At the base of the continental slope is a huge hill called the continental rise. This is debris from underwater landslides, dead organisms that have been carried down the slope, etc. This marks the true edge of the continental granite based material and the start of the basalt based oceanic floor. The abyssal plain is the term for the wide expanse of oceanic floor. It is dotted with volcanic seamounts, but more importantly, it offers a unique area called the midocean ridge. This is where magma rises to the surface between tectonic plates. The warmth and gases here allow certain bacteria to thrive. These are the basis for tube worm survival and they are the basis for a whole ecosystem.

22. Organisms living on the ocean floor must be tolerant of high pressure, lower oxygen conditions, and lack of sunlight. Organisms from the photic zone (area of water where light can penetrate for photosynthesis) often fall into the aphotic zone (area where light can’t penetrate) when they die. This also provides a food source for organisms deep in the ocean. Those organisms on the ocean floor are often referred to as benthos - because they live in the benthic zone (ocean floor) rather than in the open ocean (area of water extending from the continental slope outward.