Chapter 2 Ecosystems

Ecosystems: What are they? The biotic and abiotic factors in a specified area that interact with each other. Plants and animals’ interaction with their abiotic environment –Organisms try to reduce the effects of factors by adapting: waxy coats, pine needles, cactus spines

abioticbiotic Radiation Space Rainfall Temperature Elevation Humidity Wind Landform pH Salinity Food Immigration Emigration Natality Mortality Predation Parasitism Scavenging Competition

Structure of Ecosystems Feeding relationships Non-feeding relationships Limiting factors

Feeding relationships: Trophic Categories Producers create organic molecules by capturing light energy and converting into food energy Consumers feed on producers and without such would not exist Primary consumers (herbivores): Secondary consumers (carnivores): Omnivores: Detritus feeders and decomposers Detritus feeders can be primary or secondary Decomposers are primary detritus feeders

Trophic relationships Food chains are feeding pathways such as predator-prey and parasite-hostFood chains Food webs: are complex diagrams of feeding relationshipsFood webs Trophic levels exist:Trophic levels –All producers are on the first level –All primary consumers are on the second level –All carnivores (secondary consumers) are on the third level

Biomass pyramid All organic matter is biomass All biomass can be related to the producers About 10% of energy from one level moves to the next:% of energy –Because so little energy is transferred, it is necessary that most organisms are on the first level – limitations on this transferral create the pyramid –If organisms eat high on the pyramid, then fewer organisms can be supported.

Non-feeding Relationships Mutualism Competition –Reduction can be achieved by habitat and niche formation –If niches overlap, the competition increases

Limiting Factors Availability of factors affect the survival of an organism such as temperature, light, oxygen, CO2, and precipitation ↓ Law of Limiting Factors: quantities of any single factor above or below optimum levels will limit growth, reproduction, and survival

Global Biomes Climate –temperature and pecipitation determine biomes biomes Microclimate and abiotic factors: -light intensity, soil types, topography Biotic factors: organisms’ presence affecting another (shade, chemicals, presence of producers)

World Distribution of Biomes

Implications for Humans 3 revolutions: Neolithic: –Special skills –Settlements –Agriculture Industrial: creation of modern world Energized by fossil fuels More concentrated waste Greater increase in human population Environmental: Need to create sustainable human systems Need to reduce concentrated waste and use waste as a resource