1. 4.1 What Is an Ecosystem? I. Ecosystems A. Community
1. a group of various species that live in the same place & interact with one another
B. Ecosystem
1. A community of organisms & their physical environment
C. Biotic factors
1. describes living factors in ecosystems
2. include once living things (dead & waste)

2. D. Physical Factors
1. Abiotic factors – physical or nonliving
a. oxygen, water, rocks, sand, sunlight, etc.
2. Shape organisms
a. ex – organisms in deserts are small because not enough water to support large animals
3. Habitat – the place where an organisms lives
E. Biodiversity
1. The variety of organisms in a given area
2. Physical factors greatly influence biodiversity

3. 3. When ecosystems have high biodiversity they can resist damage.
a. ex – rain forests & coral reefs
II. Succession
A. The replacement of one community by another at a single place over time
B. Pioneer species
1. the first organisms to appear in a new habitat
2. often small, fast growing, quickly reproducing plants
a. ex – mosses & lichens break down volcanic rock into soil for other plants

4. C. Equilibrium
1. An ecosystem responds to change in a way that balance is restored
III. Major Biological Communities
A. Climate
1. the average weather conditions in an area over a long period of time
2. Plants & animals adapt themselves for particular climates
B. Biomes
1. a large region characterized by a specific kind of climate & certain kinds of organisms

5. 2. Temp. & precipitation determine biomes
IV. Terrestrial Biomes
A. Tropical Biomes
1. located near equator
2. Tropical rain forests
a. large amounts of rain & warm temps.
b. greatest biodiversity
c. ½ the world’s land species live here
3. Savannas
a. warm & receive less rain
b. long dry seasons & short wet seasons

6. 4. Tropical Deserts
1. get very little rain
B. Temperate Biomes
1. located at mid-latitudes, wide temp. ranges 2. Temperate grasslands
a. moderate temps & cooler than savannas
3. Temperate forests
a. receive plenty of rain
b. deciduous forests shed leaves in the fall
c. coniferous forests do not shed needles

7. 4. Temperate deserts
a. receive little precipitation but have a wide temp. range throughout the year
C. High Latitude Biomes
1. Taiga
a. coniferous forests in cold, wet climates
2. Tundra
a. gets very little rain, so plants are short
b. most water is unavailable because it’s frozen most of the year

8. V. Aquatic Ecosytems
A. Freshwater ecosystems
1. lakes, ponds, and rivers
B. Wetlands
1. link land & fully aquatic ecosystems
2. moderate flooding and clean the water that flows through them
C. Estuary
1. area where freshwater meets salt water
D. Marine
1. salty water of the oceans