22: Ecological Successions

Question 1

What is ecological succession?

Answer 1

gradual replacement of one community by another in response to environmental changes

Question 2

What is primary succession?

Answer 2

community is developing in a site previously unoccupied by living organisms, a barren habitat with very little topsoil
- habitat with no previous life on it
- going where no one has ever gone before
- start from a point in which there is no life at all

Question 3

What are examples of area where primary succession would occur?

Answer 3

areas after a volcanic eruption, earthquake or after a glacier has been moved out

Question 4

What are lichens?

Answer 4

a pioneer species, contribute to the formation of soil

Question 5

What contributes to soil formation?

Answer 5

biological factors (like lichens), together with physical and chemical factors

Question 6

How is soil formed?

Answer 6

through weathering of big rocks

Question 7

What 3 factors cause weathering?

Answer 7

1. biological
   - lichens (produce acid), tree roots
2. chemical
   - acid helps corroding, crumbling, breaking down the rock
   - water dissolves rock, erodes the rock little by little
3. physical
   - wind, rain, thermal expansion and contraction, water freezing
   - ex: thermal expansion and contraction produces breakage, crumbling

Question 8

What is secondary succession?

Answer 8

occurs in an area where vegetation and soil were already present; begins in an area where natural vegetation has been disturbed but soil remains

Question 9

What are examples of areas where secondary succession can occur?

Answer 9

abandoned farmlands, cut forests, forest fire

Question 10

Which of the following events is likely to precede primary succession?
a. tsunami
b. deforestation
c. a wildfire
d. a volcanic eruption that creates a new island
e. a flood

Answer 10

d, a volcanic eruption that creates a new island

Question 11

What is a primary/old growth forest?

Answer 11

forest that has not been disturbed for a long time (at least 200 years)

Question 12

What can be seen in a primary forest?

Answer 12

1. usually uneven-aged
   - trees of different ages and heights
2. many different species
3. have few invasive species

Question 13

What is a secondary forest?

Answer 13

forest that has regrown after some human disturbance
- result of secondary succession

Question 14

What can be seen in a secondary forest?

Answer 14

1. usually have less diversity of species
2. may be even-aged
   - if all trees were planted at the same time
3. may lack very old and very tall trees

Question 15

What are tree plantations/farms?

Answer 15

they are managed by humans, and it only contains one or very few species that are commercially valuable

Question 16

What is monoculture forestry?

Answer 16

a single type of tree is grown

Question 17

What percent do the types of forests make up?

Answer 17

70% of forests are secondary growth
25% are primary growth
5% are tree plantations

Question 18

The first species to inhabit an area after a disturbance are called?

Answer 18

pioneer species

Question 19

What is the location of the tropical rainforest?

Answer 19

areas near the equator

Question 20

What is the climate of the tropical rainforest?

Answer 20

precipitation is plentiful, strong sunlight and maintain a relatively constant temperature year round
- warm and wet conditions

Question 21

What do the trees of the tropical rainforest look like?

Answer 21

grow in different layers
1. emergent layer (tallest trees)
- grow and emerge into direct sunlight
2. canopy
- tall trees that receive 95% of sunlight
3. epiphytes
- use trees to live, grow on tall trees for support
4. understory
- trees and shrubs that are adapted to shade grow here

Question 22

What is the soil of the tropical rainforest like?

Answer 22

decomposers break down matter quickly and return nutrients to the soil but plants quickly absorb them; nutrients are removed so efficiently from the soil
- water running in soil can be as clear as distilled water

Question 23

What is the location of the temperate deciduous forest?

Answer 23

located between 30 and 50 degree north latitudes (east and west sides of continents)

Question 24

What is the climate of the temperate deciduous forest?

Answer 24

range of temperatures can be extreme
- growing season lasts for only 4 to 6 months
- summer temperatures can soar to 35 C
- winter temperatures fall below freezing

Question 25

What do the trees look like in the temperate deciduous forest?

Answer 25

drop their leaves each fall; vegetation changes with the seasons
- grow in layers
- ex: maple oak and birch dominate the forest canopy
- small trees and shrubs cover the understory
- this forest gets more light on the floor than the floor of rain forest does

Question 26

What is the soil of the temperate deciduous forest like?

Answer 26

contains more organic matter and nutrients than soil in a tropical rainforest