UNIT III

Sustainable Ecosystems

What do you Think?

1. Oceans make up the majority of Earth’s mass. Agree/disagree?

What do you think?

2. All of the particles that make up your body are being continuously replaced by new ones. Agree/disagree?

What do you think?

3. Animals need plants for food, but plants do not need animals. Agree/disagree?

What do you think?

4. All organisms are helpful in the environment. Agree/disagree?

What do you think?

5. Humans are one of the few species that do not compete with other species. Agree/disagree?

What do you think?6. Humans have been successful because

they are able to change the natural environment. Agree/Disagree?

Life on Planet Earth

• Earth is home to countless organisms and habitat types.

• Habitat = the place where an organism lives; can be terrestrial or aquatic.

• The Earth is perfectly suited for life…

The Spheres of Earth

• Earth’s atmosphere = the layer of gases extending upward for hundreds of kilometres– 78% nitrogen gas– 21% oxygen gas

– <1 % argon, water vapour, CO2…

• Moderates surface temperatures by acting as an insulator prevents excessive heating during the day and cooling during the night

• Blocks solar radiation (UV light)

• The lithosphere is the rocky outer shell of Earth rocks and minerals that make up the mountains, ocean floors, and the Earth’s solid landscape.

• The hydrosphere consists of all the water, on, above and below Earth’s surface (oceans, lakes, ice, groundwater, and clouds).

* 97% of Earth’s water is contained in the oceans.

The Biosphere

• The locations in which life can exist within the lithosphere, atmosphere, and hydrosphere

• N.B. All living things need space, water, and nutrients to survive

lithosphere

hydrosphere

atmosphere

Introducing Ecosystems

• Ecosystem = all of the living organisms that share a region and interact with each other and their non-living environment

• The living components, called biotic factors, include all organisms, their remains, and their products or wastes.

• The non-living components, or abiotic factors, include physical and chemical components such as temperature, wind, water, minerals and air.

• Ecosystems can be characterized by its particular organisms, temperature range, or water depth.

More about Abiotic Factors

• Water

• Oxygen

• Light

• Nutrients

• Soil

Table 1.2 Abiotic Characteristics of an Ecosystem

Sustainable Ecosystems

• An ecosystem that is maintained through natural processes

• Sustainability is the ability to maintain naural ecological conditions or processes without interruption, weakening, or loss of value.

• These types of ecosystems support a wide variety of organisms.

Cycling of Matter

• All life on Earth requires water and nutrients. Water provides the liquid component that makes up cells. Nutrients are a source of the building materials and chemical energy.

• All the particles that enter your body are recycled almost every 7 years!

Nutrient Cycles• *** The particles that make up matter cannot be

created or destroyed.What the heck does that mean???!!!

• All water and nutrients must be produced or obtained from chemicals that already exist in the environment.

• This happens in a series of cycles in which chemicals are continuously consumed, rearranged, stored and used.

• Because these cycles involve living (bio) organisms and occur as Earth (geo) processes, they are called biogeochemical cycles.

The Water Cycle• Liquid water evaporates, forming water vapour

that moves through the atmosphere. • Vapour condenses to form liquid water or ice

crystals returning to Earth as rain, hail or snow.

• Water that falls on land may enter the soil and groundwater or move across the surface entering lakes, rivers and oceans.

• Water is taken in by plant roots and is released from the leaves in a process called transpiration.

watercycle

The Carbon Cycle• Moves between the abiotic and biotic parts of an

ecosystem (between CO2 in the atmosphere or water and photosynthesizing plants and micro-organisms).

• Carbon Deposits: Most of Earth’s carbon is stored in deposits in the earth fossil fuels (coal, oil, natural gas). They form when decomposed organisms are compressed over millions of years.– Limestone = formed from dead marine organisms

• Carbon Sinks: large quantities or carbon are also contained in plant tissue and as dissolved carbon dioxide in the world’s oceans. Carbon can enter and leave these areas over relatively short periods of time.

The Carbon Cycle Game

Human Activities that Affect the Carbon Cycle

• When fossil fuels are burned, carbon is released into the atmosphere.

• The increased concentration of CO2 causing global climatic change this can alter critical abiotic factors such as temperature and water availability.

• Increasing temperature melting ice caps/glaciers, sea levels rise, disruption of ecosystems.

• Deforestation

The Nitrogen Cycle• Most of the nitrogen used by living things is taken from

the atmosphere by certain bacteria in a process called nitrogen fixation.

• Nitrogen gas is converted into a variety of nitrogen-containing compounds including nitrates, nitrites and ammonia. Lightning and UV light also fix small amounts of nitrogen.

• Once in the soil, the nitrogen rich compounds are available to producers where it can then be passed on up the food chain to consumers.

• Excess nitrogen consumed by animals is excreted in the form of urea or ammonia.

• Denitrifying bacteria convert nitrogen gas to its original form so that it can be released back into the atmosphere.

Tutorial 58.4 The Global Nitrogen Cycle

The Phosphorus Cycle• Phosphorus is a key element in cell membranes, in molecules that help release

chemical energy., in the making of the long molecules of DNA, and bones.

• Phosphorus tens to cycle in two ways:

A long-term cycle involving the rocks of the Earth’s Crust

A short-term cycle involving living organisms

Long-term cycle: . Phosphorus is found in bedrock . Phosphates are soluble in water and can be dissolved out of rock. When weathered on, phosphates erode from rock and are carried by water from land to rivers then to the oceans.

Short- term cycle:. In the ocean, the phosphates from rock, are absorbed by algae and other plants. . Phosphate this way, enters food chains. Animals use the phosphate to make bones and shellsWhen they die, these hard remains deposit on the ocean floor, covered with sediment, through millions of years, the deposits become rock and form the bedrock once again. The short-term cycle occurs when decomposers break down the deposits and recycle the phosphate and nutrients with other animals.

The Phosphorous Cycle

Human Activities and Nutrient Cycles• Carbon levels

increased in the atmosphere

• Decreasing water supplies

• Overuse of fertilizers/pesticides

• Run-off into aquatic ecosystems can lead to excessive algae growth eutrophication.

• HW: pp. 20, # 1-6