M P bio 2 succession Flashcards
what is succession?
the process by which a community changes over time, due to environmental change, due to species present
what is a pioneer species?
the organisms that first colonise an area (e.g. marram grass in sand dune ecoosystem)
what is a climax community?
the final stage of ecological succession. it is stable and changed very little. same species present for long periods of time and abiotic factors are constant and population sizes stable
what is a climatic climax?
the species that make up the climax community depend on the climate of the ecosystem so is the climax community for a particular climate
what is hostility?
abiotic factors are unfavourable, few species adapted to survive in these conditions
what is diversity?
the relationship between the no. of individual organisms and the no. of species within a community. diverse community= wider range of species and greater no. of individuals of each species present
give a brief overview of the process of succession
-pioneers
-alter environment (make conditions less harsh
-allow more diff species to become established
-more habitats and increased biodiversity
-climax community
give a detailed overview of the process of the 1st stage of succession (pioneer species)
pioneer species establish in an area and change abiotic factors. they die and are decomposed by microorganisms into dead material (humus). make abiotic factors less hostile. humus retains water + nutrients allowing for better adapted plants to outcompete them
describe the 2nd stage of succession after the pioneer species are beginning to be outcompeted
nitrogen fixing bacteria form ammonia from the N2 in the air, then they form ammonium ions which then form nitrates
describe the 3rd stage of succession
some new species make the environment less suitable for previous species e.g. water availability and nutrient availability
describe the final stage of succession
the dominant species are the ones that cause most change to the abiotic environment.
stable community (succession has ended)
same species present
abiotic factors constant
population size constant
what different factors increase as succession occurs?
-stability
-abiotic factors hostility less harsh
-niches
-biodiversity
-complexity of food webs
what is secondary succession?
occurs after a forest fire or clearance of agricultural land as spores, seeds and vegetative organs may remain viable in soil + influx of animals and plants through dispersal + migration from the surrounding area. so doesnt begin with pioneer species so time taken to reach climax community decreased
what is it called when succession is stopped (often associated with human activity) and doesnt reach the climax community?
deflected succession
what are the 4 ways deflected succession can occur?
grazing, fertilisers, use of herbicides, mowing/burning
