Changes in Ecosystems (succession)

the changes in an ecosystem over time when the starting point was nothing e.g. volcanic islands

mosses and lichens attach to hard substrate grass starts to grow flowering plants and shrubs tree (climax community) plants go through life cycle, start to decay and form soil, allows more complex species to thrive

pioneer species

succession on rock

1) weathering of exposed rock 2) growth of lichen 3) moss outcompetes lichen 4) grasses and small herbs colonise 5) small shrubs colonise the surface 6) pioneer trees outcompete shrubs 7) legumes make nitrogen - increasing soil fertility 8) larger trees colonise, casting shade and killing off smaller species 9) climax community forms - deciduous woodlamd

succession when the starting point is water

1) rooted plants can’t survive in water 2) sediment builds up - water gets shallower 3) emergent species grow partly in the water 4) submerged plants (pondweed) establish on the surface 5) a swamp forms 6) death and decay of plants increases sediment 7) species adapted to very wet conditions die out 8) transpiration of plants dries the soil - ferns thrive 9) small flowering plants are established 10) decay and aerobic decomposition adds nutrients to soil 11) oak and ash develop with flora 12) climax community reach (deciduous woodland)

succession on sand

1) mobile dunes accumulate sand 2) hardy species (marram grass) colonise the area 3) vegetation develops and dunes are stabilised 4) wild thyme, plantains and buckthorn accumulate 5) moisture loving plants colonise - followed by heath and woodland 6) climax community reached - deciduous woodland

occurs when succession/climax community is impacted by a disturbance (natural or human) may take succession back to earlier stages

primary = starting point is nothing secondary = soil is present and happens much faster

biodiversity soil depth/richness complexity of plants size of plants shade on forest floor amount of niches

an area or habitat that has been prevented form carrying on natural succession deflected or halted succession

Lowland heathland and upland moorland = grazing and controlled burning chalk grassland and water meadows = grazing hay meadows = harvesting coppiced woodland = coppicing garden lawn = mowing/weeding

Volcanic island in Iceland formed by volcanic eruptions, 1963-1967 provides the world with a natural laboratory 1965 = first vascular plants 89 species of bird and 355 species on invertebrates