A2 Biology -Sucession

THE PROCESS WHERE AN ECOSYSTEM CHANGES OVER TIME 

THE BIOTIC CONDITIONS CHANGE AS THE ABIOTIC CONDITIONS CHANGE 

1. PRIMARY SUCESSION - NEWLY FORMED OR EXPOSED LAND E.G. SEA LEVEL DROP 
2. SECONDARY SUCESSION - WHEN LAND HAS BEEN CLEARED OF ALL THE PLANTS E.G DEFORESTATION 

STARTS WHEN SPECIES COLONISE A NEW LAND SURFACE - PIONEERS SPECIES 

PIONEERS SPECIES HAVE ADAPTIONS WHICH HELP THEM IN HOSTILE CONDITIONS 

• THE ABILITY TO PHOTOSYNTHESISE AS FOOD WILL BE SCARCE 
• THE ABILITY TO FIX NITROGEN FROM THE AIR 
• DEEP ROOTS TO COLLECT WATER WHEN IT IS SCARCE 

PIONEERS SPECIES CHANGE ABIOTIC CONDITIONS - THEY DIE - MICROORGANISMS DECOMPOSE THE MATERIAL AND MAKE SOIL 

MAKING CONDIITONS LESS HOSTILE MEANING MORE LIFE CAN GROW IN THE AREA - E.G. SOIL HELP RETAIN WATER 

EACH STAGE OF SUCESSION IS CALLED A SERAL STAGE 

AT EACH STAGE, DIFFERENT PLANT AND ANIMALS THAT ARE BETTER ADAPTED FOR THE IMPROVED CONDITIONS MOVE IN , OUT COMPETE THE PIONEER SPECIES AND BECOME THE DOMINANT SPECIES 

SPECIES DIVERISTY AS IT MOVES UP STAGES BECAUSE THE ECOSYSTEM BECOMES MORE COMPLEX

FINAL SERAL STAGE IS CALLED CLIMAX COMMUNITY ECOSYSTEM IS SUPPORTING THE LARGEST AND MOST COMPLEX COMMUNITY IT CAN 

HAPPENS IN THE SAME WAY AS PRIMARY SUCESSION, BUT BECAUSE THERE I ALREADY A SOIL LAYER SUCCESSION STARTS AT A LATER SERAL STAGE 

PIONEER SPECIES WILL BE SHRUBS FOR EXAMPLE 

COONSERVATION IS THE MANAGEMENT OF THE EARTHS NATURAL RESOURCES IN SUCH A WAY THAT MAXIMISES USE OF THEM IN THE FUTURE.

INVOLVES ACTIVE INTERVENTION BY HUMANS TO MAINTAIN BIODIVERSITY AND ECOSYSTEMS 

MAIN REASONS FOR CONSERVATION ARE 

• ETHICAL 
• ECONOMIC - LIVING THINGS CONTAIN LOTS OF GENES WHICH CAN BE USED TO MAKE SUBSTANCES TO SELL
• CULTURAL AND AESTHETIC - INSPIRES WRITERS , ARTISTS ETC. 

HUMAN ACTIVITIES CAN PREVENT SUCCESSION E.G. MOWING THE LAWN 

CONSERVATION SOEMTIMES INVOLVES PREVENTING SUCCESSION IN ORDER TO PRESERVE AN ECOSYSTEM IN ITS CURRENT SERAL STAGE.

E.G. IN SCOTLAND LARGE AREAS OF MOORLAND PROVDIE HABITATS FOR ORGANISMS - IF SUCCESSION OCCURED IT WOULD LEAD TO A CLIMAX COMMUNITY OF TREES SO THE HABITAT IS LOST.

WAYS OF CONSERVING - ANIMALS GRAZING (MOWING) , MANAGED FIRES