Presentation on theme: "Section 2: Plant Succession"— Presentation transcript:
1 Section 2: Plant Succession Plant communities develop through a succession of changes.Key Ideas:Seral StagesClimatic Climax VegetationPlagioclimax VegetationCase study : Psammoseres (sand dunes) e.g. Murlough Nature Reserve outside Newcastle
2 Biogeography: The study of the distribution of plants and animals over the earth’s surface. ‘Nature abhors a vacuum’i.e. if plants die something will always replace them. When new land is created, e.g. a lava flow, new species will move into that area and take over.Algae & lichen will colonize rock and break it down (weather it) to form soil.The formation of soil then allows other plants to take over.01
3 What is vegetation succession? PRISERE is the term for vegetation succession. It is the complete chain of successive seres beginning with a pioneer community and ending with a climax vegetation.Vegetation succession occurs because the environmental conditions change. This happens gradually for lots of plants to develop.Each stage is called a SERAL STAGE.Each stage sees the development of species which cause the micro environment to change which in turn lets new species move in and become dominant.
4 The MONOCLIMAX CONCEPT F.E. Clements (1916) said that for each climatic zone only one type of climax vegetation could evolve.He called this the climatic climax vegetation. It is now more commonly known as the monoclimax concept.This occurs when the vegetation is in harmony with the local environment.As seral stages develop the number of species and height of the plants increase.Each sere tends to be named after the dominant species ( the largest or most numerous species).The Monoclimax ConceptPioneer CommunitySeral stages:temporaryconditions whichdevelop over time(plant succession)prisereClimatic climax(natural vegetation)
6 Britain’s Climate Cool temperate due to our island position Cool summers (winds off Atlantic cooling influence– water slower to heat up than land)Mild winters (winds off Atlantic warming influence – water holds its heat for longer & warm ocean current North Atlantic Drift)Rain in all seasonsHOW DOES THIS INFLUENCE VEGETATION?
7 Britain’s VegetationOur natural Climatic Climax Vegetation is broad leaved deciduous forest.The dominant vegetation is influenced by soil type, rock type and climate if people do not interfere.So why is Britain not covered in woodland?Human activities have cut down many trees (farming & urban growth).Trees do not exist on mountains – relief, soils & climatic factors.Coniferous trees (fast growing) are planted which are not native.
8 Britain’s Vegetation: The vegetation cover in much of Britain is a PLAGIOCLIMAX VEGETATION.This is a deflected climax vegetation that occurs when people have damaged the natural climatic climax so much that regeneration is not possible.In the UK you now have grassland instead of woodland.
9 Possible interruptions: Natural interruptionsHuman interruptionsTectonic activitye.g. volcanic eruptionse.g. deforestationPlagioclimax Vegetation(if permanent)Temporary climaticchanges e.g. drought,colder conditions
10 The Polyclimax TheoryThe monoclimax concept has been replaced by the polyclimax theory.This theory acknowledges the importance not only of climate, but of several (poly) local factors including :- drainage- parent rock- relief- microclimate- human activity
12 abandoned farmland due to shifting cultivation in New or previouslysterile land surface,or in waterLand on which previousmanagement has beendiscontinued e.g.abandoned farmland dueto shifting cultivation inthe tropical rainforestPrimary SuccessionSecondary Succession
13 Ecosystem Evolution Bare surface Subclimax Relic Ecosystem Ecosystem X DeflectedSuccession e.g.relief restrictsdevelopmentDeflectedSuccession e.g.severe disturbancefire, hurricaneSubclimaxEcosystemRelicEcosystemXsuccessionPrimarySudden displacement e.g.loggingSecondary succession e.g.natural regrowthClimatic ClimaxEcosystemPartial displacement e.g.grazingSecondary succession e.g.development of afarmed ecosystemPlagio ClimaxEcosystem