Download
1 / 40
400 likes | 404 Views
Explore the relationship between weather and climate, the greenhouse effect, the impact of latitude on climate, biotic and abiotic factors, community interactions, and ecological succession in this informative chapter.
E N D
Chapter 4 Ecosystems and Communities
Weather vs. Climate • Weather: day to day condition of Earth’s atmosphere at a particular time and place. • Climate: refers to the average, year-after-year conditions of temperature and precipitation in a particular region.
The Greenhouse Effect • Carbon dioxide, methane, water vapor, and a few other greenhouse gases trap heat energy and maintain Earth’s temperature range. • These gases trap the heat energy of sunlight inside earth’s atmosphere. • This process is known as the greenhouse effect. • If these gases were not present in the atmosphere, Earth would be 30°C cooler than it is today.
The Effect of Latitude on Climate • Latitude: the distance north or south of the equator of a point on the earth's surface. • The equator receives the most direct sunlight. • As a result of differences in latitude and thus the angle of heating, Earth has 3 main climate zones: • Polar • Temperate • Tropical
Polar Zones • Cold areas where the sun’s rays strike Earth at a very low angle. • These zones are located in the areas around the north and south poles, between 66.5° and 90° North and South latitudes.
Temperate Zones • Sit between the polar and tropical zones. • These zones are characterized by a change in temperature over the course of a year. • The reason: they are more affected by the changing angle of the sun causing ranges in heat from hot to cold, depending on the season.
Tropical Zone • Located near the equator between 23.5° North and 23.5° South latitudes. • The tropics receive direct or nearly direct sunlight year-round, making the climate almost always warm.
What shapes and ecosystem? • Biotic and Abiotic Factors • The Niche • Community Interactions • Ecological Succession
Biotic and Abiotic Factors • Biotic factors: the biological influences on organisms within an ecosystem. • The ecological community • Abiotic factors: physical, or nonliving, factors that shape ecosystems. • Temperature • Precipitation • Humidity • Nutrient Availability • The biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives: habitat.
The Niche • A niche is the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions. • An organism’s niche includes: • Type of food • How it obtains food • Which other species use the organism as food.
Community Interactions • Competition • Predation • Symbiosis
Competition • Competition: when organisms of the same or different species attempt to use an ecological resource in the same place and at the same time. • Resource: any necessity of life. • Competitive exclusion principle: states that no two species can occupy the same niche in the same habitat, at the same time.
Predation • Predation: an interaction in which one organism captures and feeds on another organism. • Predator: the organism that does the killing and eating. • Prey: the organisms that is eaten.
Symbiosis • Symbiosis: any relationship in which two species live closely together. • 3 main classes of symbiosis: • Mutualism: both species benefit. • Termite and protist • Commensalism: one species benefits and the other is not affected • Barnacles and whales • Parasitism: one species benefits and the other is harmed • Tapeworm and pig
Ecological Succession • Ecosystems are constantly changing in response to natural and human disturbances. • As an ecosystem changes, older inhabitants naturally die out and new organisms move in, causing further changes in the community. • This series of predictable changes that occurs in a community over time is called ecological succession.
There are 2 Types of Ecological Succession • Primary Succession • Secondary Succession
Primary Succession • Occurs on land where no soil exists. • Ex: Occurs on the surfaces formed as volcanic eruptions build new islands or cover the land with lava rock or volcanic ash. • When it begins there is no soil, just ash and rock. • The first species to populate the area are called pioneer species. • The pioneer species on volcanic rock are often lichens. • Lichens are organisms that are formed from the mutualistic relationship between algae and fungi. • As they grow they break up the rock. • When they die they add organic matter to help form the soil on which plants can grow.
Secondary Succession • Follows a disturbance that changes an existing community without removing soil. • Occurs when land cleared for farming or mining is abandoned, or when wildfires burn woodlands. • Certain plants have adapted to a regular cycle of fire and re-growth. • Their seeds won’t sprout unless exposed to fire.
Biomes • A biome is a complex of terrestrial (land) communities that covers a large area and is characterized by certain soil and climate conditions.
There are at least 9 biomes scientists recognize: Tropical rain forest Tropical dry forest Tropical savanna Temperate grassland Desert Temperate woodland and shrubland Temperate forest Northwest coniferous forest Boreal forest (taiga) Tundra The Major Biomes
Aquatic Ecosystems • Aquatic ecosystems are determined primarily by the depth, flow, temperature, and chemistry of the overlying water. • There are 3 categories of aquatic ecosystems: • Freshwater • Estuaries • Marine ecosystems
Freshwater Ecosystems • Flowing-Water Ecosystems • Standing-Water Ecosystems • Freshwater Wetlands
Flowing-Water Ecosystems: • Rivers, streams, creeks, and brooks • Organisms that live there are well-adapted to the rate of flow.
Standing-Water Ecosystems: • Lakes and ponds • Relatively still waters provide habitats for many organisms that would be quickly washed away in flowing water:
Freshwater Wetlands: • An 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
Estuaries • Wetlands formed where rivers meet the sea. • They contain a mixture of freshwater and salt water. • Examples: • Salt Marshes: temperate-zone dominated by salt-tolerant grasses above the low-tide line, and by sea-grasses underwater. • Mangrove Swamps: coastal wetlands that are found in tropical regions, including southern Florida (everglades) and Hawaii. • The Dominant plants are salt-tolerant trees, collectively called mangroves.
Marine Ecosystems • Zones based on depth: • Photic zone: well-lit upper layer of the ocean, where photosynthesis can occur (depth of about 200 meters). • Aphotic zone: below the photic zone, permanently dark area where only chemosynthetic autotrophs are the producers. • Zones based on distance from the shore and depth: • Intertidal zone • Coastal zone • Open Ocean
Intertidal Zone • Organisms in the intertidal zone are exposed to regular extreme changes in their surroundings. • Once or twice a day they are submerged in seawater, while the remainder of the time they are exposed to sunlight, air, and temperature changes. • There are many different types of intertidal communities.
Coastal Ocean • Extends from the low-tide mark to the outer edge of the continental shelf, the relatively shallow border that surround continents. • The continental shelf is often shallow enough to fall mostly or entirely in the photic zone, so photosynthesis can occur throughout this depth. • Kelp forests: a collection of giant brown alga (seaweed) that can grow as quickly as 50 cm/day. • Coral Reefs: found in the warm, shallow water of tropical coastal oceans.
Open Ocean (Oceanic Zone) • Begins at the edge of the continental shelf and extends outward. • It is the largest marine zone. • Ranges about 500 m deep – > 11,000 m • Organisms in the deep ocean are exposed to high pressure, frigid temperatures, and total darkness. • Benthic zone: ocean floor
