Visualizing Environmental Science

156

4

Community Responses to Changing

Conditions over Time: Succession 151

1. Ecological succession is the process of community
   development over time, which involves species in one stage
   being replaced by different species.


2. Primary succession is the change in species composition
   over time in an environment that was not previously inhabited
   by organisms; examples include bare rock surfaces, such
   as recently formed volcanic lava and rock scraped clean by
   glaciers. Secondary succession is the change in species
   composition that takes place after some disturbance destroys
   the existing vegetation; soil is already present. Examples include
   abandoned farmland and open areas caused by forest fires.


3. Scientific evidence supporting evolution comes from the fossil
   record, comparative anatomy, biogeography, and molecular
   biology.

10 20

Human Pig Duck

Rattlesnake

Tuna Moth Yeast

03040506070

Number of nucleotide base differences

Time

Key Terms

biome 128
boreal forest 133
chaparral 137
desert 138
ecological succession 151
ecosystem services 145

estuary 146

evolution 147

flowing-water ecosystem 144

freshwater wetlands 145

natural selection 148

savanna 140

standing-water ecosystem 142

temperate deciduous forest 135

temperate grassland 136

temperate rain forest 134

tropical rain forest 140

tundra 132

What is happening in this picture?

s This 1994 image from Yellowstone
National Park shows young
lodgepole pines growing among
trees burned in the massive
1988 wildfires. What community
process is taking place?

s What type of biome is pictured
here? What other biomes are
susceptible to fires? How do
humans increase the fire risk in
these biomes?

Fzançois Gohier/Science Source Images