Species and habitat change through ecological succession

Question 1

Examples of natural peturbations

Answer 1

Weather
Fire
Wave action
Disease
Volcanoes
Landslips`

Question 2

What are annual plants?

Answer 2

Life cycle is complete in a year

Question 3

What are perennial plants?

Answer 3

life cycle lasts more than two years

Question 4

What is climax vegetation?

Answer 4

Community in equilibrium, no progressive change

Question 5

What is a seral community?

Answer 5

Intermediate stage of succession as the habitat moves towards climax

Question 6

What is does edaphic mean?

Answer 6

Influenced by or related to soil

Question 7

What is an ecotone?

Answer 7

edge or transitional areas where vegetation patches merge

Question 8

What is a succession?

Answer 8

(the process in which an area becomes vegetated), the changing composition of a community resulting from changes in species type and diversity

Question 9

What is a R and K strategy?

Answer 9

R = Many offspring
K = Little offspring

Question 10

What is primary succession?

Answer 10

• Usually classified by type of surface (substrate) that is being vegetated
• Can also be classified by major limiting factor (like water) and environmental gradients from the pioneer to climax communities

Question 11

What is a secondary succession?

Answer 11

• Occurs after pioneer plants have established soil
• Usually faster turnover than primary succession due to availability of soil, increasing seed density and increasing nutrient availability
• Autogenic succession: Driven by internal forces
• Allogenic succession: Driven by external forces

Question 12

What is Clement’s succession theory? (1916)

Answer 12

• Seral stages forming orderly sequece from pioneer species to a stable climax end point.
• One type of end point: monoclimax
• Stable monoclimax vegetation varies with location (related to climate)

Question 13

What is Clements 5 stages to succession model? (1916)

Answer 13

• 5 stages to succession model:

1. Nudation – creation of bare surfaces
2. Immigration – arrival of pioneer species
3. Ecesis – establishment of pioneer species
4. Reaction – interactions between plants forming seral stages
5. Stabilisation – creation of equilibrium communities – climatic climax

Question 14

What is Tansley’s succession theory? (1939)

Answer 14

• Occurs in seral stages
• Succession would end in Polyclimax rather than Monoclimax
• Difference in end point vegetation is result of more than climatic zones – soils, altered microhabitats, variable fire regimes
• Succession can be ‘arrested’ by environmental conditions – soil conditions (edaphic climax), topographical conditions (topographical climax), animal/human disturbance (biotic climax)

Question 15

What is Whittaker’s succession theory? (1958)

Answer 15

• Modified Tansley’s theory to create ‘mosiac’ or ‘climate pattern’ hypothesis
• Succession generates a polyclimax mosaic of patches repeated across the landscape
• Devised the term ‘ecotone’ for the transitional areas where vegetation parches merge
• Model 1: Facilitation
Plants in one stage (sere) modify conditions and facilitate the arrival of species with a less colonising ability
• Model 2: Tolerance
Plants in one stage neither help nor hinder other species; succession occurs as the dominance of pioneers gives way to dominance by climax species owing to their longer life-span
• Model 3: Inhibition
Plants in one stage out-compete or otherwise inhibit other species