EGE 312: People and the Earth's Ecosystem PDF

EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM M1 LESSON 1: ENVIRONMENTAL CHALLENGES WE 2. in highly developed nations, individual demands FACE on natural resources are far greater than the...

EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM M1 LESSON 1: ENVIRONMENTAL CHALLENGES WE 2. in highly developed nations, individual demands FACE on natural resources are far greater than the requirements for mere survival. Rich countries Human Impacts on the Environment deplete resources and degrade the global Earth’s central environmental problem, which links all environment through increased consumption of others together, is that there are many people, and the nonessential items such as televisions, jet skis, number continues to grow. On a global level, nearly one and gadgets. in four people lives in extreme poverty. Two types of resources Poverty Nonrenewable resources - are natural a condition in which people are unable to meet their basic resources that are present in limited supplies and needs for food, clothing, shelter, education, or health. are depleted as they are used. These include Poverty is tied to the effects of population pressures on minerals and fossil fuels. natural resources and the environment. Renewable resources – are resources that are replaced by natural processes and that can be Rich and Poor Countries used forever, provided they are not overexploited Countries are divided into rich (the “haves”) and poor in the short term. Examples are trees, fishes and (the “have-nots”). Rich countries are known as highly fresh water. Rapid population growth can cause developed countries, examples are Norway, renewable resources to be overexploited. For Switzerland, Qatar, USA, Canada and Japan. example, poor people must grow crops on land— Highly developed countries - there are such as mountain slopes or tropical rain forests— countries with complex industrialized bases, low that is poorly suited for farming. rates of population growth, and high per person incomes. The effects of population growth on natural resources are Poor countries, in which about 82% of the world’s particularly critical in developing countries. population live, fall into two subcategories: moderately Economic growth of developing countries: developed and less developed. o People and the Earth’s Ecosystems Moderately developed countries – are o exploitation of their natural resources countries with medium levels of industrialization o resources for export to highly developed and per person incomes lower than those of countries highly developed countries. Example of countries Developing countries dilemma: are Turkey, South Africa, Thailand and Mexico. exploiting natural resources to provide for their Fewer opportunities to: income; education; and expanding populations in the short term; or health care. conserving those resources for future Less developed countries - are countries with generations. low levels of industrialization; very high rates of population growth; very high infant mortality Population Size and Resource Consumption rates; and; very low per person incomes. A country is overpopulated if the level of demand on its Examples are the Philippines, Bangladesh, resource base results in damage to the environment. Haiti and Laos. People overpopulation – is a situation in which there are too many people in a given geographic Population, Resources and the Environment area. People of the highly developed countries consume many Consumption overpopulation – is a situation in more resources per person than do citizens of developing which each individual in a population consumes countries. This high rate of resource use impacts the too large a share of resources. ecosystem at least as much as the population boom that is happening in other areas of the world. We may make Fact: Highly developed nations represent less than 20% two important generalizations about the relationship of the world’s population, yet they consume significantly between population growth, natural resource use and more than half of its resources. These countries also environmental degradation. generate 75% of the world’s pollution and waste. 1. the quantity of resources vital to an individual’s survival is small, but rapid population growth Ecological footprint (often found in developing countries) tends to is an amount of productive land, fresh water, and ocean overwhelm and deplete a country’s soils, forests, required on a continuous basis to supply each person with and other natural resources. 1  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM food, wood, energy, water, housing, clothing, interacting and interdependent components transportation, and waste disposal. forming a unified whole. Biosystem - a system that constitutes living Human impacts on the environment are difficult to assess. (biotic) and nonliving (abiotic) components; in One way to estimate them is to use the 3 factors most the diagram, this is ranging from genetic systems important in determining environmental impact (I): to ecological systems. 1 The number of people (P). 2 The affluence per person, which is a measure of the consumption, or amount of resources used per person (A). 3 The environmental effects (resources needed and wastes produced) of the technologies used to obtain and consume the resources (T). This method of assessment is usually referred to as the IPAT equation: I = P × A × T The three factors in the IPAT equation are always changing in relation to each other. For example, consumption of a particular resource may increase, but technological advances may decrease the environmental impact of the increased consumption. Sustainability and the Environment Sustainability ensures that the ecosystem can work indefinitely without slipping behind the burden that human activities put on natural systems. Environmental Sustainability the ability to meet humanity’s current needs without compromising the ability of future generations to meet their needs. LESSON 2: HOW ECOSYSTEM WORKS Ecology derived from the Greek word oikos (“household”) and logos (“study”). It literally means the study of household. This is the study of “life at home” with emphasis on “the totality or pattern of relations between organisms and their environment.” More scientific definition is the study of environmental house that includes all organisms in it and all the functional processes that make the house habitable. Ecology is largely concerned with the system Attributes of a Natural Ecosystem levels beyond that of the organisms. Concept of ecosystem Biotic (living) organisms and abiotic (nonliving) Basic Principles and Concepts of Ecology environment are inseparably interrelated and interact with Levels-of-Organization Hierarchy each other. Ecological system or ecosystem is any unit Levels of organization - is a hierarchical that includes biotic community (all organisms) in a given arrangement of order ranging from the ecosphere area interacting with the physical environment so that a (or beyond) to cells (or beyond) illustrating how flow of energy leads to clearly defines biotic structures each level manifests emergent properties that are and cycling of materials between living and nonliving best explained at a particular level of components. The ecosystem is the first in the ecological organization. hierarchy that is complete with all the components Hierarchy - the arrangement into a graded important for survival. series, while a system consists of regularly 2  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM organic compounds that link biotic and abiotic components (ex. Protein, carbohydrates, lipids and humic substances); air, water and substrate environment, including the climate regime and other physical factors; producers (autotrophic organisms) in which mostly green plants that can manufacture food from simple inorganic substances; phagotrophs, heterotrophic organisms (animals), they ingest other organisms or particulate organic matter; and Energy also flows out of the system in the form of heat saprotrophs, decomposers (mainly bacteria and and in other transformed or processed forms, such as fungi), these are heterotrophic organisms that organic matter (food and waste products) and pollutants. obtain their energy by breaking down dead Water, air and nutrients necessary for life, along with all tissues or by absorbing dissolved organic matter kinds of other materials, constantly enter and leave the (DOM) from plants and animals. ecosystem; and organisms and their propagules (seed or spores) and other reproductive stages enter Examples of Ecosystems (immigrate) or leave (emigrate). Abiotic substance - includes inorganic and organic compounds, such as water, carbon dioxide, O2, Ca, N, S, and P salts, amino and humic acids, and others. Producer organism Consumer organisms Decomposer organisms Fundamental Concepts Related to Energy Energy is defined as the ability to do work. The behavior of energy is described by the following laws. 1. The first law of thermodynamics, or the law of conservation of energy, states that the energy may be transformed from one form to another but is neither created nor destroyed. 2. The second law of thermodynamics, or the law of entropy, may be stated as: no process Trophic Structure of the Ecosystem involving an energy transformation will spontaneously occur unless there is a Two layers of ecosystem degradation of energy from a concentrated form 1. autotrophic stratum (upper) or the “green into a dispersed form. belt” of chlorophyll-containing plants in which the fixation of light energy, the utilization of simple Energy Partitioning in Food Chains and Food Webs organic substances, and the buildup of complex organic substances predominate; 2. heterotrophic stratum (lower) or the “brown belt” of soils and sediments, decaying matter, roots, etc. in which the utilization, rearrangement, and decomposition of complex materials predominate. Components constituting an ecosystem are: organic substances that involved in material cycles (ex. C, N, CO2 and H2O); 3  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM Food Web for Terrestrial Ecosystem Cycling of Sulfur Three natural biogeochemical processes release sulfur to the atmosphere: the formation of the volatile compound dimethylsulfide (DMS) (by enzymatic breakdown of an abundant compound in phytoplankton dimethylsulfonioproprionate); anaerobic respiration by sulfate-reducing bacteria; and volcanic activity. Cycling of Carbon There is a chance that this carbon atom will become part Biogeochemical Cycles of the skeleton of the plankton, or component of the bones The chemical elements, including all the essential of the larger animal that consumes it, and then part of the elements of life, tend to circulate in the atmosphere in sedimentary rock when the organisms die and only the characteristic pathways from environment to organisms skeletons are left behind. and back to the environment. These more or less circular pathways are known as biogeochemical cycles. Cycling of Nitrogen For nitrogen to be usable to generate proteins, DNA, and other compounds of biological significance, it must first be transformed into a different chemical type. The method of transforming N2 into nitrogen, which is naturally available is called nitrogen fixation. The Hydrologic Cycle The main source of water is the oceans; energy from the sun makes water evaporate into the atmosphere, winds distribute it over the surface of the Earth, and precipitation brings it down to earth in a form of rain, snow, or hailstorm where it may be stored temporarily in soils, lakes and Cycling of Phosphorus icefields. Main supplies of phosphorus are present in surface water, rivers, lakes and seas, and in rocks and ocean sediments. 4  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM Niche Light - places organisms on the horns of While there are few environments on earth dilemma: direct exposure of protoplasm to light without life, no single species can tolerate the full range of causes death, yet sunlight is the ultimate source earth’s environments. The niche summarizes the of energy, without which life could not exist. Light environmental factors that influence the growth, survival, is not only a vital factor but a limiting one, at both and reproduction of a species. A species’ niche consists the maximum and minimum levels. of all the factors necessary for its existence— Water - Water, a physiological necessity for all approximately when, where, and how a species makes its life, is from the ecological viewpoint chiefly a living. limiting factor in land environments and in water This ecological principle is called the limiting environments where the amount can fluctuate factor principle: Too much or too little of any abiotic greatly or where high salinity fosters water loss factor can limit or prevent growth of a population, even if from organisms by osmosis. Rainfall, humidity, all other factors are at or near the optimal range of the evaporating power of the air, and the available tolerance. This principle describes one way in which supply of surface water are the principal factors population control—a scientific principle of sustainability measured. is achieved. Types of interaction between two species Limits of tolerance concept 1. organisms may have a wide range of tolerance for one factor and a narrow range for another; 2. organisms with wide ranges of tolerance for limiting factors are likely to be most widely distributed; 3. when conditions are not optimal for a species with respect to one ecological factor, the limits of tolerance may be reduced for another ecological factors; 4. frequently, organisms in nature are not actually living at the optimum range of a particular physical factor; and 5. reproduction is usually a critical period when environmental factors are most likely to be limiting. The concept of limiting factors is valuable because it gives the ecologists an “entering wedge” into the study of complex ecosystems. Regulatory Factors Soil - nutrients are regenerated and recycled during the decomposition in the soil before they become available for the primary producers, the soil can be considered a chief organizing center for land ecosystem. Fire - major factor in shaping the history of vegetation in most of the terrestrial environment of the world. As climate pulses between wet and dry periods, so does fire in the environment. LESSON 3: THE ECOSYSTEMS Temperature - temperature fluctuating between 10°C and 20°C and averaging 15°C does not Biome necessarily have the same effect on organisms A large, relatively distinct terrestrial region with similar as a constant temperature of 15°C. Organisms climate, soil, plants, and animals, regardless of where it that are normally subjected to variable occurs in the world temperatures in nature tend to be depressed, inhibited, or slowed down by constant Types of Biomes temperatures. Terrestrial Biomes - A terrestrial biome is a land- based community of organisms and 5  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM the interactions of biotic and abiotic components Standing-water Ecosystem in a given area. They are as follows: tundra, A body of fresh water surrounded by land and whose forest (temperate; tropical; boreal) grassland, water does not flow; a lake or a pond. Zonation is savanna, desert characteristic of standing-water ecosystems. 3 zones of a large lake: the littoral, limnetic, and profundal zones Aquatic Biomes - Aquatic ecosystems are ecosystems present in a body of water. These can be further divided into two types, namely: freshwater, saltwater Flowing-water Ecosystems Factors Affecting The Distribution Of Organisms are highly variable; the surrounding environment Salinity - The concentration of dissolved salts changes greatly between a river’s source and its (such as sodium chloride) in a body of mouth. Certain parts of the stream’s course are shaded water. Different organisms are adapted to by forest, while other parts are exposed to direct sunlight. different salinity levels Dissolved Oxygen - This is the amount of Freshwater Wetlands oxygen gas present in the water. Most aquatic Lands that shallow freshwater covers for at least part of organisms need oxygen to breathe and survive. the year; wetlands have a characteristic soil and water- Nutrient Minerals - These are essential tolerant vegetation substance like nitrates and phosphates that aquatic plants and algae need to grow. They Freshwater Swamps form the base of the food web. More nutrients are inland areas covered by water and dominated by often mean more plants and algae, which support trees, such as baldcypress more animals. Seawater Ecosystem Three Main Ecological Categories Of Organisms The seawater ecosystem includes seas and oceans. 1. Planktons - usually small or microscopic organisms; tend to drift or swim feebly, so, Brackish Ecosystems: Estuaries for the most part, they are carried about at A coastal body of water, partly surrounded by land, with the mercy of currents and waves. access to the open ocean and a large supply of fresh 2. Nektons - larger, more strongly swimming water from a river. organisms such as fishes, turtles, and whales. Major Ocean Life Zones 3. Benthos - bottom-dwelling organisms that fix themselves to one spot (sponges and oysters), burrow into the sand (worms and clams), or simply walk about on the bottom (crawfish and aquatic insect larvae). Freshwater Ecosystems include lakes and ponds (standingwater ecosystems), rivers and streams (flowing-water ecosystems), and marshes and swamps (freshwater wetlands); about 2% of Earth’s surface. 6  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM M2 LESSON 1: HUMAN POPULATION CHANGE THE Carrying Capacity ENVIRONMENT The largest population a particular environment can support sustainably (long term), if there are no changes Population in that environment. individuals of a given species are part of a larger organization called a population. Thomas Malthus - One of the first people to recognize that the human population can’t increase indefinitely was Population Ecology pointed out that human population growth is not always. Branch of biology that deals with the number of individuals of a particular species found in an area and Projecting Future Population Numbers why those numbers increase or decrease over time. Zero Population Growth - The state in which the population remains the same size because the birth rate Dispersal equals the death rate; estimates vary depending on movement from one region or country to another. fertility changes. 1. Immigration (i) - individuals enter a population and increase its size. Demographics of Countries 2. Emmigration (e) - individuals leave a population Demographics - The applied branch of sociology and decrease its size. that deals with population statistics. Infant Mortality Rate - The number of deaths of Maximum Population Growth infants under age 1 per 1000 live births. Biotic Potential - The maximum rate at which a Per person GNI PPP - a country’s gross national population could increase under ideal conditions. Factors income (GNI) in purchasing power parity (PPP) that influence the biotic potential of a species: divided by its population. It indicates the amount the age at which reproduction begins of goods and services an average citizen of that the fraction of the life span during which an particular country could buy in the United States individual can reproduce the number of reproductive periods per lifetime the number of offspring produced during each period of reproduction. Factors That Interact To Change Population Size Replacement-Level Fertility - The number of children a couple must produce to “replace” themselves. Total Fertility Rate (TFR) -The average number of children born to each woman. Age Structure of Countries Age Structure - The number and proportion of people at each age in a population. Exponential Population Growth Age Structure Diagram - presents the number The accelerating population growth that occurs when of males and the number of females at each age, optimal conditions allow a constant reproductive rate. from birth to death. Environmental Resistance Population and Urbanization organisms don’t reproduce indefinitely at their biotic Urbanization - A process whereby people move potential because the environment sets limits (e.g., from rural areas to densely populated cities. limited food, water, shelter, and other essential resources, as well as increased disease and The City as a Dynamic Ecosystem predation) The Environment Controls Population Size As the population increases, so does environmental resistance, which limits population growth. 7  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM Environmental Problems of Urban Areas Factors contributing to food shortage: civil wars Suburban sprawl that encroaches into former and military actions, HIV/AIDS, floods, droughts, forest, wetland, desert, or agricultural land and soil erosion from hilly, marginal farmlands. destroys or fragments wildlife habitat. Economic development - An expansion in a Brownfields - areas of abandoned, vacant government’s economy, viewed by many as the factories, warehouses, and residential sites that best way to raise the standard of living. may be contaminated from past uses. Air pollution Poverty and Food Water flow is affected because they cover the Poverty - main cause of undernutrition rainfall absorbing soil with buildings and paved Infants, children, and the elderly are most roads susceptible to poverty and chronic hunger Contaminated runoff world’s poorest people—those living in developing countries in Asia, Africa, and Latin Environmental Benefits of Urbanization America—do not own land on which to grow food Well-planned city actually benefits the and do not have sufficient money to purchase environment by reducing pollution and preserving food. rural areas. Compact development - Design of cities in The 2 Principal Types of Agriculture which tall, multiple-unit residential buildings are 1. Industrialized agriculture - Modern agricultural close to shopping and jobs, and all are connected methods that require large capital inputs and less by public transportation. land and labor than traditional methods. It relies on large inputs of capital and energy (in the form Challenges Faced By Developing Countries of fossil fuels) to make and run machinery, substandard housing (slums and squatter purchase seed, irrigate crops, and produce settlements); poverty; exceptionally high agrochemicals such as commercial inorganic unemployment; heavy pollution; and inadequate fertilizers and pesticides or non-existent water, sewage, and waste 2. Subsistence Agriculture - Traditional disposal (left figure). agricultural methods that are dependent on labor Rapid urban growth also strains school, medical, and a large amount of land to produce enough and transportation systems. food to feed oneself and one’s family. LESSON 2: PEOPLE AND AGRICULTURE Other Types of Agriculture Shifting Cultivation - A form of subsistence World Food Problems agriculture in which short periods of average adult human must consume enough food to get cultivation are followed by longer periods of approximately 2600 calories, per day fallow (land being left uncultivated), during Undernutrition - a type of malnutrition in which which the land reverts to forest. there is an underconsumption of calories or Slash-and-burn agriculture - A type of shifting nutrients that leaves the body weakened and cultivation that involves clearing small patches of susceptible to disease tropical forest to plant crops. Farmers must move Overnutrition - a type of malnutrition in which from one area of forest to another every 3 years there is an overconsumption of calories that or so. leaves the body susceptible to disease. Nomadic herding - which livestock is supported Kwashiorkor - caused by severe protein by land too arid for successful crop growth, is a deficiency. Note the characteristic swollen belly, similarly land-intensive form of subsistence which results from fluid retention agriculture. Nomadic herders must continually Marasmus - is progressive emaciation caused by move their livestock to find adequate food for the a diet low in both total calories and protein. animals. Symptoms include a pronounced slowing of Intercropping - A form of intensive subsistence growth and extreme wasting of muscles. agriculture that involves growing a variety of plants on the same field simultaneously. When Population and World Hunger certain crops are grown together, they produce Food Insecurity - The condition in which people higher yields than when they are grown as live with chronic hunger and malnutrition. monocultures. 8  EGE 312: PEOPLE AND THE EARTH’S ECOSYSTEM Monoculture - is the cultivation of only one type water erosion polluting nearby waterways and of plant over a large area. damaging aquatic habitats Polyculture - is a type of intercropping in which depletion of the groundwater several kinds of plants that mature at different times are planted together. Acid Mine Drainage Pollution caused when sulphuric acid and dangerous Challenges of Agriculture dissolved materials such as lead, arsenic, and cadmium Prime Farmland - land that has the soil type, growing wash from mines into nearby lakes and streams. conditions, and available water to produce food, forage, fiber, and oilseed crops. Tailings Loss of Agricultural Land usually left in giant piles on the ground or in ponds near Global Decline in Domesticated Plant and Animal the processing plants; contain toxic materials such as Varieties cyanide, mercury, and sulfuric acid; contaminate the air, Increasing Crop Yields soil, and water. The Green Revolution Critics of Green Revolution Restoration of Mining Lands Increasing Livestock Yields When a mine is no longer profitable to operate, the land can be reclaimed, or restored to a Environmental Impacts seminatural condition (e.g Copper Basin in Tennessee) Air pollution Reclamation prevents further degradation and Water pollution erosion of the land, eliminates or neutralizes local Pesticide runoff sources of toxic pollutants, and makes the land Degradation (of land) productive for purposes other than mining Habitat fragmentation Restoration also makes such areas visually attractive Solutions to Agricultural Problems Sustainable Agriculture Crop rotation Organic agriculture Integrated Pest Management (IPM) Second Green Revolution Genetic Engineering The manipulation of genes (for example, taking a specific gene from one species and placing it into an unrelated species) to produce a particular trait. Pros: has the potential to produce more nutritious food plants that contain all the essential amino acids; has been used to develop more productive farm animals, including rapidly growing hogs and fishes. Cons: inserted genes could spread from GM crops to weeds or wild relatives of crop plants and possibly harm natural ecosystems in the process; some consumers might develop food allergies to GM foods LESSON 3: MINING AND ENVIRONMENT Effects of Mining disturbs large areas of land destroys existing vegetation mined land is particularly prone to erosion wind erosion causing air pollution 9