Shaping an Ecosystem

Shaping an Ecosystem

C-4-2

Ecosystems are influenced by a combination of biotic (living organisms) and abiotic (physical) factors.

The area in which an org. lives is a habitat - this includes both factors.

Niche - all conditions in which an org. lives and how it uses those conditions

~ type of food eaten

~ place in the food web

~ temp. in which they survive

~ reproduction style

No two species will share the same niche in the same habitat!

However, there are many different ways species can interact with each other within their communities...

1.) Competition - species have similar needs and compete for survival

* Competitive exclusion principle  no 2 species can occupy the same niche in the same habitat at the same time

~ this would result in the elimination of one of the species

2.) Predation - one org. eats another

3.) Symbiosis - relat. where 2 species live closely together.

3 types:

a.) Mutualism - both species benefit

ex: flowers and insects

b.) Commensalism - one benefits, the other is neither helped or harmed

ex: barnacles on a whale

c.) Parasitism - one org. lives on another and the host is harmed

ex: tapeworms in mammals

Ecosystems are constantly changing

* human interference

* natural disturbances

As these changes occur, old species die out and are replaced by new.

~ called ecological succession

Primary succession= occurs on surfaces where no soil exists

ex: bare rock eventually gets covered by vegetation

~ pioneer species are the first ones to populate the area - usually lichen

Secondary succession = the rebound of an ecosystem after a disturbance

ex: forest fire or clearing land by humans

~ eventually, the plants will re-grow and restore the land

Extension - EXTRA CREDIT!!!

Read through section 3 of chapter 4. Pick any biome and make a travel brochure that makes me want to go there!

~ worth 20 bonus points!

~ see me for guidelines!

Limits to growth

C-5-2

Populations can grow exponentially if not kept in check.

~ for instance: one bacteria will become 2, then 4 then 8,then 64, then 512,then at the end of one day, there will be 4.72 x1021

* Called Exponential Growth!

However, this only happens when populations have every offspring survive to reproduce.

As resources become less available, offspring don't live as well. This stops population growth.

~ This happens when the population has reached carrying capacity. - max # org. an ecosystem can support

There are several limiting factors that keep pop's in check...

1.) Competition - more org. = less resources

2.) Predation - predator-prey relationships keep each other in balance

3.) Parasitism and Disease - keeps pops. down by killing host

4.) Drought / Climate extremes - extreme heat or cold, lack of or too much water...all can kill

5.) Human disturbances - changing the ecosystem ~ deforestation, waste dumping, killing off predators

1-3 are density-dependent factors, 4-5 are density-independent

DDF - only become limiting when the pop. density reaches a certain level

DIF - affect all pops. similarly regardless of pop. size

Through a combination of all of these factors, populations can vary from being in balance, to being way out of balance.

The most influential? US!!

Biodiversity

C-6-3

Biodiversity - the sum of all genetically based org. in the biosphere

Along with this, there are several other types of diversity...

~ Ecosystem diversity - includes habitats, communities, and processes

~ Species diversity - # of dif. species in biosphere

~ Genetic diversity - all dif. forms of genetic info for all life forms on the planet!

We benefit from this diversity in many ways:

* food

* medicine - pain killers, antibiotics, heart drugs, anticancer drugs etc.

* industrial products

However, there are many threats to biodiversity:

~ We are the # 1 threat!

1.) Habitat alteration

* land development splits habitats and destroys others

*this makes the species that live there more fragile and open to harm from further change

2.) Demand for wildlife products

* hunting has made some species extinct!

* fur, meat, body parts thought to have medicinal qualities

* most endangered species are now protected from hunting - but poaching continues to be huge problem

3.)Pollution - major factor is toxic compound accumulation - Biological magnification - fig. 6-16

4.) Invasive species -non-native species that reproduce rapidly due to lack of predators.

~ often overcrowd native species and overtake the habitat thus destroying or changing the ecosystem

ex: zebra mussles - in Lake Erie - have pushed some species to near extinction!

So how do we make sure the biosphere is maintained?

Conservation!

Strategies:

*captive breeding programs at zoos

*set aside land to protect certain ecosystems - parks/reserves

* limiting hunting and fishing to certain seasons

* imposing stricter laws against pollution

and mining for natural resources

Challenges... implementing these strategies may infringe on some ways of life but it must be done!

ex: fishing industry - loss of habitat = loss of jobs

Charting a Course for the Future!

C-6-4

Before we can make a plan, we need research and evidence to help us come up with a strategy.

2 biggest problems for our future...

1.) Depletion of the ozone layer

2.) Global climate system

Ozone depletion:

* Ozone layer resides bet. 20-50km above earth

* absorbs UV rays - like sunscreen!

* without it, we receive too much UV which can lead to tissue damage in plants and animals

* holes are over the poles and thought to be caused by CFCs - we have since banned use of CFCs in aerosol cans and refrigerators -holes should shrink in about 50 years

Global climate change:

~ there is strong evidence that the climate is changing!

ex: from 1980, the avg. world temp has increased approx. .3o Celsius and about .6o C over the last 100 years

~ the ice caps on both poles are significantly smaller from what they were 30 years ago

~ thought to be due to possible natural fluctuations in the earth's climate change along with our influence of burning fossil fuels magnifying the greenhouse effect

*greenhouse effect is like this:

Possible effects:

1.) Avg. global temps.likely to increase by between 1.4 and 5.8 degrees Celsius (2.5 and 10.4 degrees Fahrenheit) by the year 2100.

2.) Sea levels may rise enough to flood coastal areas

3.) More severe weather - storms, drought

4.) Ecosystems may not be able to adapt fast enough leading to extinction or take over where they once did not live

Do your part to conserve Ohio and the world's ecosystems!