Communities

Question 1

Community

Answer 1

All populations of organisms in a particular habitat

Question 2

Ecosystem

Answer 2

habitat and its associated community and the interactions within and between them

Question 3

Succession

Answer 3

Progressive change in species composition of a community over a period of time

Question 4

Primary succession

Answer 4

Previously uncolonised substrate

e.g. volcano deposit lava
glacier retreating deposit rock

Question 5

How do pioneer species colonise

Answer 5

Usually r-strategists specialised in dispersal and colonisation

Dominate new communities and modifies abiotic environment

Question 6

How do stages of succession occur

Answer 6

When pioneer modify env it results in change in community

This new community further alters the env making it more favourable for the establishment of new species - process continues in seres

Question 7

Final Sere

Answer 7

Climax Community

relatively stable and is in dynamic equilibrium with the environment

Question 8

Climatic Climax

Answer 8

if composition of climax community determined by the climate

Question 9

Biotic Climax

Answer 9

some succession do not reach potential climax due to interference by a biotic factor

e.g. grazing

Question 10

Trends Evident as Succession Proceed

Answer 10

•soil develops - incr depth and organic content

•height and biomass of veg increase
-these provide greater variety of microhabitats and ecological niches

•incr complex plant community and wider variety of niches support greater no. animal species

•Species diversity increases

•Number of food chains increases - more complex food webs develop

•Community becomes more stable and dominated by K strategists

Question 11

Secondary Succession

Answer 11

Occurs aftrr an existing ecosystem has been disturbed - fire or flood

Happens more quickly - does not involve loss of soil and some veg remains present