Chapter 4 Key Concepts Basic ecological principles Major

Chapter 4 Key Concepts Ø Basic ecological principles Ø Major components of ecosystems Ø Matter cycles and energy flow Ø Ecosystem studies Ø Principles of Sustainability

4 -1 The Nature of Ecology is the study of connections in nature. Realm of Ecology – Studies the levels of organization of living things, from organism to biosphere, and all the connections within.

Levels of Ecological Organization

The Earth’s Life-Support Systems Ø Stratosphere Ø Hydrosphere Ø Lithosphere Ø Biosphere

4 -2 The Earth Life-Supporting Systems • The Earth is an integrated system that consists of rock, air, water, and living things that all interact with each other. • Scientists divided this system into four parts: • The Geosphere (rock) • The Atmosphere (air) • The Hydrosphere (water) • The Biosphere (living things)

The Earth as a System

• The Earth is divide into 3 layers: 1) The crust - thin and solid outermost layer of the Earth above the mantle (<1% of Earth’s mass; 5 -8 km thick under ocean, 20 -70 km under continents) 2) The mantle- layer of rock between the Earth’s crust and core; medium density (about 64% of Earth’s mass) 3) The core- central part of the Earth below the mantle; composed of the densest elements • These layers of material get progressively denser as you move toward the center of the Earth.

Earth’s Layers Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

The Earth as a System • The lithosphere is the Earth’s crust and upper mantle; contains our nonrenewable fossil fuels and minerals. • The atmosphere is the mixture of gases that makes up the air we breathe; Mostly found in the first 30 km above the Earth’s surface. (19 miles)

The Earth as a System • The hydrosphere makes up all of the water on or near the Earth’s surface; Much of this water is in the oceans, which cover nearly ¾ of the globe. • However, water is also found in the atmosphere, on land, and in the soil.

The Earth as a System • The biosphere is the part of the Earth where life exists; a thin layer at the Earth’s surface that extends from about 9 km (5. 5 miles) above the Earth’s surface down to the bottom of the ocean. • The biosphere is therefore made up of parts of the lithosphere, the atmosphere, and the hydrosphere.

Levels of Ecological Organization

Organisms • Organisms are living things that can carry out life processes independently. • You are an organism, as is an ant, ivy plant, and even each of the bacteria living in your intestines! • Every organism is a member of a species. • Species are groups of organisms that are closely related and can mate to produce fertile offspring.

Populations and Communities • Populations are groups of organisms of the same species that live in a specific geographical area and interbreed. (ie. all the field mice in a corn field make up a population of field mice) • Communities are groups of various species that live in the same habitat and interact with each other. Every population is part of a community. • Land communities are often dominated by a few species of plants. These plants then determine what other organisms can live in that community.

Ecosystems • Ecosystems are communities of organisms and their abiotic environment. • Examples are an oak forest or a coral reef. • Ecosystems do not have clear boundaries. • Things move from one ecosystem to another. Pollen can blow from a forest into a field, birds migrate from state to state). (Ex.

Biosphere • All of the Earth’s ecosystems together. • Part of the Earth where living organisms exist, however, other layers of the Earth are needed to help support life (abiotic factors)

Biotic and Abiotic Factors • Biotic factors - environmental factors that are associated with or results from the activities of living organisms which includes plants, animals, dead organisms, and the waste products of organisms. • Abiotic factors - environmental factors that are not associated with the activities of living organisms which includes air, water, rocks, and temperature.

Natural Capital: Sustaining Life of Earth Ø One-way flow of energy from Sun Ø Cycling of Crucial Elements Ø Gravity

Solar Capital: Flow of Energy to and from the Earth

The Greenhouse Effect • The greenhouse effect is the warming of the surface and lower atmosphere of Earth that occurs when carbon dioxide, water vapor, and other gases in the air absorb and reradiated infrared radiation. • Without the greenhouse effect, the Earth would be too cold for life to exist.

The Greenhouse Effect • The gases in the atmosphere that trap and radiate heat are called greenhouse gases. • The most abundant greenhouse gases are water vapor, carbon dioxide, methane, and nitrous oxide, although none exist in high concentrations. How greenhouse gases lead to global warming: by Al Gore

The Greenhouse Effect

4 -3 Ecosystem Components • In order to survive, ecosystems need five basic components: 1) energy 2) mineral nutrients 3) water 4) oxygen 5) living organisms • The main source of energy for an ecosystem comes from the SUN. • If one part of the ecosystem is destroyed or changes, the entire system will be affected.

Life Depends on the Sun • Energy from the sun enters an ecosystem through photosynthesis. (plants, algae and some bacteria use sunlight to make sugar molecules)

Energy Flow through the Biophere • Closed systems are systems that cannot exchange matter or energy with its surroundings. • Open systems are systems that can exchange both matter and energy with its surroundings. • Today, the Earth is essentially a CLOSED system with respect to matter, but an OPEN system for energy as energy travels from plant to animal which is eaten by other animals. In the process, some energy is lost as heat to the environment.

Producers and Consumers • Because plants make their own food, they are called producers. (make organic molecules from inorganic molecules) AKA autotrophs, or selffeeders. • Organisms that get their energy by eating other organisms are called consumer. (eats other organisms or organic matter instead of producing its own nutrients or obtaining nutrients from inorganic sources) AKA heterotrophs, or other-feeders.

Energy Flow in Ecosystems From Producers to Consumers • Some producers get their energy directly from the sun by absorbing it through their leaves. • Consumers get their energy indirectly by eating producers or other consumers. * ANIMATION!

• Organisms can be classified by what they eat. Types of Consumers: • Herbivores • Carnivores • Omnivores • Decomposers • Each time an organism eats another organism, an energy transfer occurs. • This transfer of energy can be traced by studying food chains, food webs, and trophic levels.

Trophic Levels • Each time energy is transferred, some of the energy is lost as heat. • Therefore, less energy is available to organisms at higher trophic levels.

4 -4 Energy Flow through an Ecosystem Primary consumer (herbivore) Secondary consumer (carnivore) Tertiary consumer Detritivores and scavengers

Trophic Levels/ Biomass More living organisms at the base of the pyramid = more biomass Showing energy loss from 1 trophic level to the next- grass stores 1, 000 times more energy thank the hawk at the top level.

Food Chains • A food chain is a sequence in which energy is transferred from one organism to the next as each organism eats another organism. • A food web shows many feeding relationships that are possible in an ecosystem.

Limits to Population Growth • Zone of tolerance. Homeostasis • Limiting factor principle – too much or too little of any abiotic factor can limit the population growth, even if all other factors are at optimum conditions. (only as strong as the weakest link!) Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Biomes are based on climate (average precipitation and temperature)

Biodiversity Ø Genetic diversity Ø Species diversity Ø Ecological diversity Ø Functional diversity

• Gross primary productivity (GPP) - the rate at which an ecosystem's producers capture and store a given amount of chemical energy as biomass in a given length of time. • Net primary production (NPP) - GPP that takes into account plant cellular respiration. NPP = GPP - respiration [by plants] Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Primary Productivity of Ecosystems Terrestrial Ecosystems Swamps and marshes Tropical rain forest Temperate forest Savanna Agricultural land Woodland shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean 800 1, 600 2, 400 3, 200 4, 000 4, 800 5, 600 6, 400 7, 200 8, 000 8, 800 Average net primary productivity (kcal/m 2/yr)

Soils Ø Origins- parent material; mixtures of eroded rock, mineral nutrients, decaying organic matter, and billons of living organisms (mostly decomposers) Ø Soil Horizons based on the type of material the horizons are composed of; these materials reflect the duration of the specific processes used in soil formation. They are described and classified by their color, size, texture, structure, consistency, root quantity, p. H, voids, boundary characteristics, or concretions. - O horizon = leaf litter, crop/animal wastes organic materials A horizon = topsoil; humus (decomposed organic matter with inorganic minerals); darker = more nutrients - B horizon = subsoil; mostly inorganic, made of broken down rock - C horizon = unweathered parent rock, bedrock

Variations with Climate and Biomes • Soil formation greatly depends on the climate, and soils from different biomes show distinctive characteristics. • Temperature and moisture affect weathering and leaching. Wind moves sand other particles, especially in arid regions where there is little plant cover. The type and amount of precipitation influence soil formation by affecting the movement of ions and particles through the soil, aiding in the development of different soil profiles. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Soil Profiles in Different Biomes Mosaic of closely packed pebbles, boulders Weak humusmineral mixture Alkaline, dark, and rich in humus Dry, brown to reddish-brown, with variable accumulations of clay, calcium carbonate, and soluble salts Desert Soil (hot, dry climate) Clay, calcium compounds Grassland Soil (semiarid climate)

Forest litter leaf mold Acidic lightcolored humus Humus-mineral mixture Light, grayishbrown, silt loam Iron and aluminum compounds mixed with clay Tropical Rain Forest Soil (humid, tropical climate) Dark brown firm clay Deciduous Forest Soil (humid, mild climate) Coniferous Forest Soil (humid, cold climate)

Soil porosity • Soil porosity refers to that part of a soil volume that is not occupied by soil particles or organic matter. Pore spaces are filled with either air, other gases, or water. Large pores (macropores) allow the ready movement of air and the drainage of water. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Matter Cycling in Ecosystems Biogeochemical cycles Ø Hydrologic cycle (H 2 O) Ø Carbon cycle Ø Nitrogen cycle Ø Phosphorus cycle Ø Sulfur cycle

The Water Cycle (Hydrologic) • Water cycle- continuous movement of water from the ocean to the atmosphere to the land back to the ocean. Consists of: – Evaporation - change of a substance from a liquid to a gas. Water continually evaporates from the Earth’s oceans, lakes, streams, and soil. – Condensation - change of state from a gas to a liquid. Water vapor forms water droplets on dust particles, to form clouds, where heavier drops then fall from the clouds as rain. – Precipitation - any form of water that falls to the Earth’s surface from the clouds, and includes rain, snow, sleet, and hail.

The Water Cycle

The Carbon Cycle • Carbon - stored in the bodies of organisms as fat, oils, carbohydrates, etc. ; Released into the soil or air when the organisms dies. • Carbon molecules form deposits of coal, oil, or natural gas, which are known as fossil fuels. • Fossil fuels store carbon left over from bodies of organisms that dies millions of years ago.

The Carbon Cycle • Carbon cycle - the movement of carbon from the nonliving environment into living things and back • Producers convert CO 2 in the atmosphere into carbohydrates during photosynthesis. • Consumers obtain C from the carbohydrates in the producers they eat. During cellular respiration, carbon is released back into the atmosphere as CO 2. • Some carbon is stored in limestone, forming one of the largest “carbon sinks” on Earth.

The Carbon Cycle

The Carbon Cycle (Marine)

The Carbon Cycle (Terrestrial)

The Nitrogen Cycle • Nitrogen cycle - the process in which nitrogen circulates among the air, soil, water, plants, and animals in an ecosystem. – Nitrogen makes up 78 percent of the gases in the atmosphere. • All organisms need nitrogen to build proteins and DNA, which are used to build new cells. However, it must be altered, or fixed, before organisms can use it. • Only some bacteria can fix atmospheric nitrogen into chemical compounds that can be used by other organisms. These bacteria are known as “nitrogen-fixing” bacteria.

The Nitrogen Cycle • Nitrogen-fixing bacteria - bacteria that convert atmospheric nitrogen (N 2) into ammonia (NH 3) • These bacteria live within the roots of plants and use sugar provided by the plant to produce nitrogen containing compounds such as nitrates (NO 3) • Nitrogen stored within the bodies of living things is returned to the nitrogen cycle once those organisms die through decomposers. • After decomposers return nitrogen to the soil, bacteria transform a small amount of the nitrogen into nitrogen gas (N 2) , which then returns to the atmosphere to complete the nitrogen cycle.

Human Activities Affect the Nitrogen Cycle • Burning fossil fuels = nitric oxide into the atmosphere » Can convert to nitric acid = acid rain • Nitrous oxide from livestock, wastes and inorganic fertilizer is a greenhouse gas. • Agricultural runoff and human sewage • Farming removes nitrogen from topsoil Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

The Nitrogen Cycle • Nitrogen-fixing bacteria - bacteria that convert atmospheric nitrogen (N 2) into ammonia (NH 3) • These bacteria live within the roots of plants and use sugar provided by the plant to produce nitrogen containing compounds such as nitrates (NO 3) • Nitrogen stored within the bodies of living things is returned to the nitrogen cycle once those organisms die through decomposers. • After decomposers return nitrogen to the soil, bacteria transform a small amount of the nitrogen into nitrogen gas (N 2) , which then returns to the atmosphere to complete the nitrogen cycle. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

The Nitrogen Cycle

The Nitrogen Cycle

The Phosphorus Cycle • Phosphorus enters soil and water when rocks erode. Small amounts of phosphorus dissolve as phosphate (PO 4 -), which moves into the soil. • Plants absorb phosphates in the soil through their roots. Phosphorus is needed to build DNA. • Many phosphate salts are not soluble in water, they sink to the bottom and accumulate as sediment. • Slower moving cycle so does not replenish itself back in to the soil = for phosphorous based fertilizers.

The Phosphorus Cycle

The Phosphorus Cycle

Nitrogen and Phosphorus Cycles Fertilizers • Fertilizers, used to stimulate and maximize plant growth, contain both N and P. • Excessive amounts of fertilizer can enter terrestrial and aquatic ecosystems through runoff. It can cause rapid growth of algae which can deplete an aquatic ecosystem of important nutrients such as oxygen.

The Sulfur Cycle • • DMS (Dimethyl Sulfide)produced by marine algae Sulfuric acid= acid rain

How Do Ecologists Learn About Ecosystems? • Field Research- observing/measuring ecosystem structure and function • Remote sensing and Geographic information systems (GIS)- new technologies that gather data fed through a computer for analysis. (ie. Computer generated maps of forest cover, coastal changes, etc) • Laboratory Research- controlled chambers such as tanks, greenhouse; control CO 2, temperature, light, humidity • Mathematical models- simulations of ecosystems that are large, complex, or difficult to study in the field/lab (ocean floor)