2 Ecological Succession Process by which communities in a particular area change over timeEarly communities modify the environment causing change to occurThis affects biological community as wellHow?
3 Each successive (new) community is more favorable for new species Changes in stages until a climax community is established
4 Composition of the community changes with time PastCommunityFutureCommunityPresentCommunitySome species in thepast community wereout-competed, and/ordid not tolerate alteredabiotic conditionsModifies such abioticfactors as:Light intensityWind speedAir TemperatureSoil compositionLight qualityWind directionSoil waterHumidityChanges allow newspecies to becomeestablished.
5 Primary Succession Regions with no existing community Bare rock Receded glaciersVolcanic regionsKrakatoa, Glacier BayClimaxCommunityLichens, bryophytesAnd annual herbsSlower growingbroadleaf speciesGrasses andSmall shrubsFast growingtreesBare Rockyears
6 Pioneer SpeciesFirst organisms to live in a new community. Usually brought in by wind or animals
7 Secondary Succession Takes place after a land clearance Fire, landslide, forest clearingSoil is already thereMore rapid than primaryClimaxCommunityOpen pioneercommunity(annual grasses)Maturewoodlandmainly oakPrimarybare earthGrasses andlow growingperennialsScrub: shrubsand small treesYoung broad-leavedwoodland150+1-2 years3-5 years16-30 years31-150
8 Gap Succession In a forested area with a thick canopy Reduced light on soilWhen a tree falls sunlight fills forest floorNew communities are formed
9 Wetland Ecological Succession In open body of water, aquatic plants are introducedIncrease in aquatic plants causes sedimentationSwamps may occur and in warmer months may dry offMay lead to EUTROPHICATIONMore production (photosynthesis)Lead to reduced oxygen and fish killsNatural and anthropogenicType of pollution
10 Aerial view of Lake 227 in Note the bright green colour caused by algae stimulated by the experimental addition of phosphorus for the 26th consecutive year. Lake 305 in the background is unfertilized.