Ecosystems & Communities

Ecosystems & Communities Dr. Donna Howell Biology I Blacksburg High School Chapter 4

Ecosystems • Two factors shape an ecosystem: • Biotic factors – biological influences • Plants, other animals, etc. • Abiotic factors – nonliving influences • Climate, rainfall, wind, sunlight, etc.

Habitat • Together, the biotic and abiotic factors of an ecosystem determine the survival and growth of organisms and make up their habitat.

Niche • A niche is the place an organism occupies in an ecosystem. • A bullfrog’s niche would be what it eats, when it reproduces, and where it lives.

Community Interactions • There are three main types of community interactions: • Competition • Predation • Symbioses

Competition • Competition occurs when organisms have to use the same resources, such as food.

Predation • Predation is when one organism captures and feeds on another. • Lion and antelope

Symbioses • Any relationship where two organisms live closely together is called a symbiosis. • There are 3 main types: • Mutualism • Commensalism • Parasitism

Mutualism • Mutualism is a type of symbiosis where both species benefit. • Example: bees and flowers

Commensalism • Commensalism is a symbiosis where one member benefits, and the other is not harmed nor does it benefit. • Example: barnacles on a whale

Parasitism • Parasitism is a symbiosis where one organism harms the other one. • Example: mosquito sucking on human blood

Ecological Succession • Ecosystems are constantly changing over time. • The series of predictable changes that occurs over time is called ecological succession.

Primary Succession • Primary succession occurs where no soil exists. • Example: years after a volcanic eruption covers ground with lava.

Primary Succession • The first species to populate an area after such an event is called the pioneer species.

Secondary Succession • Secondary succession happens after a disturbance, such as a wildfire. • The community interactions restore the ecosystem to its original condition.

Biomes • A biome is a complex of terrestrial communities that covers a large area.

Tropical Rain Forest • Hot and wet year-round. • Large trees with canopies. • Huge variety of wildlife. • Ex: Costa Rica

Tropical Dry Forest • Warm year-round, alternating wet and dry seasons. • Deciduous trees with canopy • Tigers, monkeys • Ex: Mexico

Tropical Savanna • Warm; seasonal rainfalls; frequent lightning fires • Tall grasses • Lions, cheetah • Ex: Africa

Desert • Hot year-round; little rainfall • Cacti • Scorpions, roadrunners • Middle East

Temperate Grassland • Hot summers; cold winters; seasonal rainfall • Grasses • Bison, Prairie chickens • Ex: central North America

Temperate Woodland • Hot dry summers; cool moist winters • Evergreen shrubs • Coyotes, deer • Ex: West coast of North America

Temperate Forest • Warm summers; cold winters; year-round rainfall • Deciduous trees • Bears, bobcats • Ex: Eastern US

Boreal Forest • Long cold winters, short mild summers • Conifers • Lynxes & moose • Ex: Washington State, US

Northwestern Coniferous Forest • Mild temperatures, lots of precipitation • Redwoods and hemlocks • Elk, owls • Ex: Pacific coast of US

Tundra • Permafrost; long, cold winters • Mosses, lichens • Caribou, Arctic fox • Ex: Northern North America

Aquatic Ecosystems • In addition to land biomes, we also have aquatic biomes. • Freshwater, estuaries, ocean, etc

Aquatic Ecosystems • The base of aquatic food chains are tiny free-floating creatures called plankton and zooplankton.

The End

Ecosystems & Communities