ch20 (biotic community)

habitat

physical area where organism lives

niche

the specific ecological role each species is adapted to

• no same, or else competition

species diversity

• species richness 鬥多

• relative abundance (proportion) 平均

⬆ richness, ⬆ abundance → ⬆ diversity

dominant species

most abundant 最多

• eg. grass

predation (+ / --)

• prey > predator (eat)

• predator lag behind

1. prey⬆, food available⬆, grow & reproduce, predator⬆

2. predator⬆, ⬆prey captured, ⬇ prey

3. ⬇prey, ⬇food supply, ⬇predator, ⬆prey again

• when prey⬇, hard for predator to locate, feed on other prey

competition (-- / --)

for same limited resources, eg. light, food

• intraspecific

  • same species, more intense (~ niche)

• interspecific

  • diff. species

commensalism (+ / 0)

eg.

• epiphytes 附生植物

  • grow on other plants to obtain more light

• egrets

  • riding on the back of cattle (cow)

• barnacles

mutualism (+ / +)

eg.

• lichens

  • fungus & alga tgt

• sea anemone & crab

• leguminous plants & nitrogen fixing bacteria

parasitism (+ / --)

parasite live on host

eg.

• tapeworms

• ticks

primary succession where?

barren area: no community exist

eg. volcano eruption, glacier retreat

secondary succession where?

destroyed existing community

eg. fire / storm

soil already exit

primary succession pioneer community

lichens & mosses

secondary succession pioneer community

more complex,

eg. small plants, grass

time needed to reach climax community

primary longer (hundreds of years)

sec (15 years)

quadrats

abundance

line transect

distribution

belt transect

combine both methods