Terms: pioneer species – the first organisms that live in a previously uninhabited area climax community – a stable, mature community that undergoes little or no change limiting factors – environmental factors that affect an organism’s ability to survive (food, predators, space) Bio NOTES: Succession and Population Ecology Succession - a series of predictable changes that occurs in a community over time Two types: 1. primary succession 2. secondary succession Each biome on Earth has a different type of climax community - grasslands- rainforest

Secondary SuccessionPrimary Succession occurs on surfaces where no soil exists the colonization of new sites by communities of organisms called pioneer species occurs when a disturbance of some kind changes an existing community without removing the soil takes less time than primary succession because soil is already present disturbances include wildfires, storms, deforestation, farming rocks  lichens  mosses   grasses, shrubs  trees soil  grasses, shrubs  trees

Tuesday What is a pioneer species? What is an example?

Population growth = an increase in the size of a population over time  birthrate greater than death rate  population grows  birthrate equals death rate  population stays the same  death rate greater than birthrate  population shrinks Under ideal conditions with unlimited resources, a population will grow exponentially exponential growth = as a population gets larger, it also grows faster Factors that change population size: immigration – movement of individuals into a population from another population births – causes an increase in population size emigration – movement of individuals out of a population and into another population deaths – causes a decrease in population size

Population Growth Curves “S” curve“J” curve population growth under ideal conditions unlimited resources population growth when conditions not favorable limited resources as resources become less available, the growth of the population slows or stops population grows rapidly, exponentially individuals in population reproduce at a constant rate reaches carrying capacity - the number of organisms that an environment can support carrying capacity

The human population is expected to reach carrying capacity between Two types: density-dependent density-independent Limiting factor = the factor that has the greatest effect in keeping down the population of an organism Density-dependent limiting factors - affected by the number of individuals in a given area competition and availability of food, water and space predation parasitism and disease Density-independent limiting factors - limit a population’s growth regardless of the density of the pop. unusual weather natural disasters human activities

closer What does density mean? Name the 2 types of limiting factors.

loss of land/habitat water and food shortage poor sanitation 1. Effects of Human Overpopulation: Human Impact on the Environment species extinction poverty emerging disease 4. pesticide use – using chemicals to kill and control pests - will sometimes kill non-target species - pollutes water sources - causes health problems 5. bioaccumulation/biological magnification – concentrations of a harmful substance increase in organisms at higher trophic levels in a food web 2. deforestation – loss of forests - cause soil erosion, loss of habitat, and species extinction Worldwide, about half of the area covered by forests has been cleared. 3. threaten biodiversity – the variety of organisms in an ecosystem - an imbalance can cause extinction

Global Warming Acid Rain the earth’s atmosphere keeps some heat from going out into space pollution in our atmosphere causes too much heat to stay on earth changes overall temperature/ climate raises sea level affects health of ecosystems acid rain = rain that has been made acidic by certain pollutants in the air pollutants = sulfur dioxide and nitrogen oxides from burning fossil fuels causes health problems damages forests and lakes damages buildings Human Impact on the Environment

Effects on Water Quality The runoff of silt, soil, pesticides, and fertilizers from agricultural land is the largest single source of water pollution. Eutrophication: - excess fertilizers can run off into lakes and ponds - this stimulates plant and algae overgrowth - a buildup of algae can lower the levels of dissolved oxygen in the water - this leads to the dying off of the fish population - over time, lakes and ponds slowly begin to fill in Why can’t you just clean up polluted water? - it is expensive - who pays for it? - technology not available for all types

Effects on Natural Resources Sustainability = a way of using natural resources without depleting them for future generations use renewable resources that can be “restocked” recycle and reuse products plant tree farms only cut down selected trees instead of clear-cutting follow emission standards Renewable resources - can regenerate if they are living or can be replenished by biochemical cycles if they are nonliving - ex. trees, fresh water Nonrenewable resources - cannot be replenished by natural processes - ex. fossil fuels