Succession + Energy transfer

Ecosystem

characteristic community of interdependent species + their habitat

Sucession

change in structure and species composition of community over timeq

Where does primary succession occur?

habitat that hasn’t previously supported a community e.g bare rock after volcanic erruption

What is the first species that colonise + their role?

• pioneer species like lichens which are well adapted to survive + reproduce in harsh environments

• can secrete acids to extract minerals from rock to erode it + begin soil formation

What happens after pioneer species has been established?

• change abiotic conditions e.g when they die they add organic matter to soil

• allows others species to colonise e.g mosses blown in wind - they outcompete pioneer species as have advantage

• process continues → as one community changed abiotic factors new species migrate and outcompete them as soil has developed

• grasses → plants → shrubs establish until climax community reached

What are the different stages in succession called?

seral stages

Climax community

final stage in ecological successionsucc

What is secondary succession?

species recolonise a habitat where there had been a community before e.g deforestation7

• more rapid process as soil is already developed

gross primary productivity

rate of production of chemical energy in organic molecules by photosynthesis

net primary productivity

energy available in plant's biomass available to primary consumers

How to calculate NPP

NPP = GPP - energy lost in respiration

Factors affecting succession

• immigration → new seeds + animals in habitat = increases species diversity

• interspecific competition → better adapted outcompete others

• facilitation → pioneer species facilitate to make better resources for other species

how is energy lost at trophic levels

heat loss

-respiration

-movement

-faeces + urine

-indigestible