CHAPTER 17 ECOSYSTEMS

Ecology- the study of interactions of living organisms with one another and with their physical environment Habitat- place where a particular population of a species lives Community- the many different species that live together in a habitat

Ecosystem- includes a community and all the physical aspects of its habitat Biotic Factors- living organisms in a habitat Abiotic Factors- physical aspects of a habitat

Producers- organisms that make energy-storing molecules (plants) Consumers- organisms that consume plants or other organisms to obtain energy Trophic Level- shows how energy moves through an ecosystem Sunproducerconsumerconsumer

Food Chain- path of energy through the trophic levels of an ecosystem Food Web- interconnected group of food chains

Food Chains: 1st level 2nd level 3rd level Producers Herbivores- eat primary producers 3rd level Carnivores- eat herbivores Omnivores- both herbivores and carnivores Detrivores- obtain energy from organic wastes and dead bodies Decomposers- bacteria and fungi that cause decay

BIOLOGICAL COMMUNITIES CHAPTER 18 BIOLOGICAL COMMUNITIES

Predation- the act of one organism feeding on another Parasitism- one organism feeds on and usually lives on or in another organism Symbiosis- two or more species live together in a close, long-term association

Mutualism- a symbiotic relationship in which both participating species benefit Commensalism- a symbiotic relationship in which one species benefits and the other is neither harmed nor helped Competition- biological interaction that occurs when two species use the same resource

Niche- how an organism lives, the “job” it performs within the ecosystem Climate- prevailing weather conditions in any given area (temperature and moisture) Biome- a major biological community that occurs over a large area of land

7 Land Biomes

Tropical Rain Forests: 200-450cm of rain per year ½ of the Earth’s terrestrial species (2 million)

Deserts: Fewer than 25cm of rain per year Vegetation is sparse

Savannas: 90-150cm of rain per year Grasslands found between rain forests and deserts

Temperate Deciduous Forests: 75-250cm precipitation per year Trees shed their leaves in the fall

Temperate Grasslands: Prairies with fertile soil used for farming in Central United States

Taiga: Cold, wet climates; long winters Coniferous forests

Tundra: Between taiga and permanent ice of the North Pole Less than 25cm of precipitation per year Covers 1/5 of the Earth’s land surface

Freshwater Communities: Lakes, ponds, streams and rivers (2.1% of the Earth’s surface) Strongly connected to terrestrial habitats

Marine Communities: Oceans cover ¾ of the Earth’s surface Average depth = 3km (1.9 miles)