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Ecosystems and Communities Abiotic and Biotic Factors What are abiotic factors? What are some examples of abiotic factors? What are biotic factors? What are examples of biotic factors? Abiotic Factors Physical or nonliving factors that shape ecosystems. Temperature Moisture Wind Nutrient availability Soil type Sunlight Biotic Factors The biological influences on organisms in an ecosystem. All the living organisms in an area. The Niche The physical and biological conditions in which an organism lives and the way that organism uses those conditions. Includes: – What it eats? – How it gets the food it eats? – What organisms use it for food? Community Interactions Competition – Occurs when organisms try to use a resource at the same time in the same place – A resource could be water, nutrients, light, food or space Community Interactions Competition often leads to a winner and a loser. Competitive exclusion principle – No two species can occupy the same niche in the same habitat at the same time Community Interactions Predation – One organism captures and feeds on another organism Predator/prey relationships – Predator-does the killing and eating Wolf – Prey-the food organism Deer Community Interactions Symbiosis – Any relationship in which two species live closely together Mutualism Commensalism Parasitism Community Interactions Mutualism– Both species benefit from the relationship – Flowers and insects Commensalism – One species benefits and the other is not helped or harmed – Barnacles and whales Parasitism – One species benefits while the other is harmed – Tick and dog Ecological Succession Is a series of predictable changes that occurs in a community over Two main types: primary and secondary Primary Succession Begins in a lifeless area with no soil as in a lava flow. Starts with bacteria, then to lichens and mosses, on to grasses and so on. The first species to populate the area are called pioneer species. Secondary Succession A disturbance has destroyed the community but left the soil. Old field succession is an example. Biomes A major terrestrial or aquatic life zone Characterized by soil, climate, plants and animals Biomes and Climate The climate of a region determines what can survive in that region. Main components of climate are temperature and precipitation Climate diagram Terrestrial Biomes Are grouped based on their vegetation type. Geographic distribution of plants depends on amount of available water and on the temperature. How many terrestrial biomes are there? Although there is some disagreement among scientists on how to divide up the Earth’s biomes, most can agree on the following eight: Tropical Rainforest Tropical Savanna Desert Chaparral Grassland Temperate Deciduous Forest Temperate Boreal Forest Tundra Tropical Rainforest Typically found near the equator Receives more than 200 cm of rain annually Temperatures typically fall between 20oC and 25oC for the entire year As many as 50% of all the world’s animal species may be found here Chaparral Also called the Temperate Woodland and Shrubland Found between 32o and 40o latitude on the west coast of continents Receives between 35 and 70 cm of rain, usually in the winter Extremely resistant to drought and weather events Savanna Grasslands with a few scattered trees Experience a wet and dry season Hot temperatures Annual rainfall is between 50 and 127 cm More species of grazing mammals than any other biome Desert Typically found between 25o and 40o latitude Receives less than 25 cm of rain each year Temperatures typically range between 20oC and 25oC but some extreme deserts can reach temperatures higher than 38oC and lower than –15oC Grassland Because of the dry climate, trees are found only near water sources such as streams Usually receives between 50 and 90 cm of rainfall each year Summer temperatures can reach up to 38oC, and winter temperatures can fall to –40oC Temperate Deciduous Forest Moderate climate Most trees will lose their leaves in the winter Temperatures range between – 30oC and 30oC Averages from 75 to 150 cm of precipitation Well developed understory Coniferous Forest Also known as Taiga Typically found between 45o and 60o North latitude Cold climate with summer rains Very few reptiles Limited understory Snow is primary form of precipitation (40 – 100 cm annually) Tundra Means treeless or marshy plain Characterized by permafrost – permanently frozen soil starting as high as a few centimeters below the surface – which severely limits plant growth Winter temperatures average –34oC while summer temperatures usually average below 10oC Low precipitation (15–25 cm per year) but ground is Aquatic Biomes Occur about 75% of Earth’s surface Determined by their salinity Freshwater biomes have less than 1% salinity Marine biomes are about 3% or more Freshwater Biomes Cover less than 1% of Earth and have about 0.01% of Earths water. But about 6% of all living species are here Plus we depend on this biome for drinking water, crop irrigation, sanitation and industry. Lakes and Ponds Standing bodies of water that can be very small farm ponds to the Great Lakes. Living organisms are distributed by the depth of the body of water and by the distance to shore. Lake and Pond Layers Photic Zone: light is available for photosynthesis Aphotic zone: light levels are too low for photosynthsis Benthic zone: the bottom of the lake or pond Rivers and Streams Flowing bodies of water Characteristics change between its source and the point it empties into a larger body of water (lake or ocean) Source: water is cold, low in nutrients and clear, runs fast Downstream: water gets warmer, slows down Greatly affected by human activity. Rivers and Streams Wetlands Transitional biome between aquatic and terrestrial biomes Freshwater: bogs, swamps and marshes Covered at least part of the time with water Provide flood control by storing water Improve water quality by trapping pollutants and organic compounds in sediments Wetlands Marine Biome Varies by depth Some areas receive sunlights; some don’t Photic and Aphotic zones Photic: extends down to a maximum of 200 m Aphotic: 200m and beyond Marine Layers Marine Layers In photic zones – Photosynthesis is done by phytoplankton and multicellular algae Marine Organisms Intertidal Zone Where ocean meets land Waves pound the shore at high tide Exposed to wind and sun at low tide Estuary Transitional area between rivers and ocean Saltiness varies from nearly freshwater to the same as the ocean