2.6 - biomes, zonation and succession

What is zonation?

How the ecosystem changes along a gradient

What are key factors which affect of zonation on a mountain? (5)

precipitation

insolation

soil type

species interactions

temperature

What is a biome?

A collection of ecosystems with similar abiotic conditions

What is the biosphere?

part of earth which contains life on the upper atmosphere to the deepestparts

What are key differences between zonation and succession?

• static spacial

• caused by abiotic factors

• dynamic and temporal

• caused by progressive biotic factors in the ecosystem

What happened in succession in alaska bay and different stages of zonation?

• where glaciers have retreated

• pioneer stage - fireweed are dominant

• dryas stage

• spruce stage

• alder stage

What are pioneer species?

first species to arrive after a newly created environment

what is succession?

change in an ecosystem over time

what is primary succession?

colonisation of newly created land by organisms resulting in crease of natural complexity

What is secondary succession?

occurs in developed soil which is ready to receive new seeds from the wind

what are the 5 stages of primary succession? (B,C,E,C,S,C)

• bare organic surface

• colonisation by pioneers adapted to extreme conditions and are r selcted species which are small

• Simple soil starts from windblown dust

• establishment - species diversity increases and invertebrates live in the soil with increases humus

• competition - Larger plants increase cover and provide shelter, enabling K selected species to be established

• K species outcompete r species

• stabilisation - less new species colonise

• Complex food webs develop

• climax community - exists in a steady state equilibrium

What are characteristics of r selected species (pioneer)?

• small

• rapid reproduction rate

• short life cycles

• make their own nitrogen

• spread seeds successfully over far distances

What happens to the soil a stages move forward? (2)

• soil depth incerases

• soil pH decreases

What is a seral stage?

• complete succession of plant communities which result in a climax community

What does less hostile abiotic environment lead to?

• increased biodiversity (dominant species outcompete pioneer species)

• more complex food webs

• increased niches and habitats

What does increased biodiversity lead to?

• more complex food webs

• increased biomass

what stage is biodiversity the highest?

mid succession

What is a hydrosere?

succession in water

What is the process of succession in water?

• deep freshwater no rooted plants due to lack of light

• mirco organisms like phytoplankton

• sediments get carried to the pond, and floating plants start to grow

• sediments build up

• Reeds and grasses develop around pond margin, trapping more sediment

• Marsh community builds up around the pond margins

• soil around edge dries from waterlogged like willow and alder and tree species become established

Describe changes in early, mid and late stage succession

• Low GPP and high NPP (low producers and harsh conditions)

• little increase in biomass

• GPP high

• increased photosynthesis increases as biomass from plant forms increase

• trees reach maximum size

• NPP to respirationis equal, energy used with respiration becomes equal

what is GPP and NPP?

• total energy plants capture during photosynthesis

• total energy captured after metabolic processes

When are abiotic factors most harsh?

early succession stage

What is a sub climax community?

Succession can be prevented by a particular abiotic factor

What is plagioclimax?

climax community influenced by an external factor.