To be able to make environmentally sound decisions, we need to understand some basic ecological principles…. <ul><li>Interrelationships and interactions in nature </li></ul><ul><li>Biogeochemical cycles </li></ul><ul><li>Energy flows through ecosystems </li></ul><ul><li>Food chains and food webs </li></ul><ul><li>Populations grow until their resources are limited (carrying capacity) </li></ul>
Ecology is the study of the relationships among organisms (living things) and between living things and their environment. <ul><li>2) The Biotic Environment- everything that is or was recently alive </li></ul><ul><li>1) The Abiotic Environment- all the non-living surroundings of the Biotic environment- (soils, weather, solar radiation, gravity, atmosphere, water, rocks and other non-living material) </li></ul>Our Earth is also called the Biosphere- It is that part of the Earth that supports life and contains the following two elements.
To fully understand an ecosystem, we must factor in all of the biotic and abiotic components…
Abiotic elements influence organism survival. Organisms have specific physiological ranges: if the temperature or moisture isn’t suitable for example, then organisms cannot survive in that habitat
In terms of biotic elements…All ecosystems contain three types of living organisms, which fulfill ecological niches… Saprovores (or detritivores) are organisms that decay ( to deteriorate, rot or decompose ) substances of dead organisms. Producers are organisms that contain chlorophyll and synthesize organic compounds with sun energy
Consumers are organisms that cannot produce their own food (animals, humans- any living thing that does not have chlorophyll) and therefore must eat other organisms (plants and/or animals) to get their energy and food. Consumers can be further classified as herbivores, carnivores, or omnivores (based on diet) or they can be classified as primary, secondary, tertiary, etc. (based on where they eat in a food chain)
Food chains are limited in length, though, because the amount of available energy in an ecosystem decreases as one goes up higher levels in a food chain. The amount of biomass decreases too.
Energy flows through successive levels of an ecosystem and then is ultimately “lost” as heat. The sun provides the energy to sustain life.
Unlike energy, some materials cycle within ecosystems Major nutrients, such as carbon, phosphorous, water, and nitrogen flow through ecosystems, and may be in various organic and inorganic forms…
The cycling of many materials is due to the nature of the feeding relationships (the food web) within an ecosystem…
Some of the relationships among organisms are obvious… Some are not so obvious
So energy flows through earth ecosystems and nutrients cycle within ecosystems… What happens when there is environmental change? The Hubbard Brook study has shown the important role that living things have on the balance and cycling of nutrients through ecosystems
We must better understand how these materials move through ecosystems so that we can better understand environmental consequences, e.g., global warming
There is another important ecological issue… populations grow. Populations are groups of members of the same species in the same area Populations in turn are going to be interacting with the environment and with other populations
Populations of organisms interact in nature, which tends to keep populations from growing too large. The maximum number of individuals an environment can support is known as the carrying capacity
Populations grow until something limits them. It could be a lack of resources, damage to the environment caused by the population, or other populations which grow in response to a growing population All populations have growth limits
Human population growth is of special concern because of its potential impact on our biosphere
Local Growth <ul><li>Louisville, KY’s Population in: </li></ul><ul><li>1800: 359 </li></ul><ul><li>2006: 701,500+ </li></ul>
“ This we know - the Earth does not belong to man - man belongs to the Earth. This we know. All things are connected like the blood which unites one family. All things are connected. Whatever befalls the Earth - befalls the sons of the Earth. Man did not weave the web of life - he is merely a strand in it. Whatever he does to the web, he does to himself.” Chief Seattle 1854 The key to understanding ecology? All things are connected…
Ultimately, we must try to understand the interactions in nature so that we can predict impacts of environmental change, understand human population growth impacts We attempt to develop models of ecosystems in order to predict environmental impacts of “changing just one thing…”
Even though we need a global perspective to address many environmental issues, and indeed many issues cannot be addressed unless we think about “whole earth” approaches, some issues are more local in nature. That is why we are taking a Kentucky AND global focus in this class.