Lesson 3 Ecology & Comparing Ecosystems November 17, 2010

Why do we need pests? Imagine a world without pests! Summer without mosquitos, a garden without weeds… that sounds great?! BUT, how would other organisms be affected?

No Pests! Some fish and amphibians rely on mosquito larvae for food Adult mosquitoes are important food source for swallows, robins and other small birds Most plants rely on insects for pollination Some insects help decompose tissues of dead plants and animals- returning nutrients to the soil Many insects dig around roots of plants allowing more oxygen to get to their roots Garden weeds are important source of food for many animals- grazing animals would become extinct Roots of these weeds pump more nutrients into soil’s surface Some weeds even anchor soil, preventing erosion

Organisms Interact within Ecosystems Eco- Greek word oikos, meaning place where one lives Logy- Greek word logos, meaning study of Ecology- study of how organisms interact with each other.

Ecological studies can begin at the level of a single organism They determine how the individual interacts with its environment and how factors in the environment affect its growth, feeding habits and reproduction. There are 2 types of factors in an ecosystem- biotic and abiotic Biotic- factors caused by the presence and roles of other living things Abiotic- non-living factors or influences on organisms (ie. Sunlight, temperature, strength and direction of wind)

Organisms do not live in isolation-they usually group with others of the same species Population- all of the members of the same species living in the same ecosystem or habitat There is usually more than one species in an ecosystem, there is more than one population. Community- collection of all the populations of all the species in an ecosystem or habitat ( in a lake there may be populations of pike, perch, tadpoles, mosquito larvae, and algae)

What do ecologists study in a community? They study how the biotic factors affect each population An ecologist studying a forest community might look at interactions between different types of plants and animals

And if they want to study more? The can extend their study to include the physical environment The ecologist studying the forest community might examine how much sunlight reaches the forest floor and what affect that has on the plants and animals

Ecotones and Biodiversity Ecosystems do not have distinctive boundaries Organisms can move back and forth from one to another There is usually a grey area between ecosystems where organisms from each ecosystem interact with each other This transition area is called and ecotone

Ecotones guard against extinction If an organism has only one source of food in its ecosystem, its own existence is linked to the survival of that species Ecotones have more species, giving the organism an alternative food source

Comparing Ecosystems What are some artificial ecosystems in your area? Artificial ecosystem- planned or maintained by humans What are natural ecosystems in your area? Natural ecosystems- living community is free to interact with the physical and chemical environment (not maintained or planned by humans, but may not be untouched by humans)

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