Resource use and pollution management

Carrying capacity: Maximum number of a species or “load” that can be sustainably supported by an environment.

Populations remain stable if DR and BR are equal.

There have been numerous examples of resource failure and the concecuences of human activity.

Human population size is not the only factor responsible for the impact on resources and on the environment.

Also to consider: Wealth, desires, needs, uses.

Population impact models work on the assumptions that all individuals (or similar populations) have the same needs and thus a similar impact.

Individual / population resource use is a dynamic principle.

Resources use varies with time/space.

Different resources use

• MEDCs vs LEDCs
• Urban vs Rural
• Young communities vs Old communities

Impacts will vary in scale, type and severity.

Pollution

Adding substance or agent to the environment by human activity at a rate greater than that at which it can be rendered harmless by the environment.

Major sources

• Combustion
• Domestic waste
• Industrial waste
• Agricultural waste

Pollution management

Sources

• Point source
• Non point source

Detection and monitoring

• Directly
• Indirectly
• Pollution indicators

BOD – amount of dissolved oxygen required to break down the organic material in a water volume through anaerobic or aerobic activity.

Indicator species (biotic index 1-10) through invertebrates, etc.

Three-level model of pollution management

Replace, regulate, restore

Waste management

• Minimize waste: reduce, reuse, recycle
• Disposal
• Landfills
• Incinerators

Organic waste management

Initiatives and agreement

Sources of Energy

The main


1) Fossil fuels: By far the most exploited energy resource but not for much longer. Oil, coal, gas.

2) Nuclear energy: Highly productive but has hazardous issues.

3) Hydroelectric energy: Harnesses the kinetic energy of flowing water.

4) Solar energy: Renewable because the sun will be around for a few billion years more. Very expensive.

Others

Wind

Geothermal

Tidal

Hydrogen fuel cells

Biofuels

Biomass

MEDCs and LEDCs: Food Distribution

In many MEDCs, the cost of staple food items is relatively cheap, and most people make purchases based in taste and preference. Produce seasonality has mostly disappeared due to globalization, and this has allowed for greater international variety in most supermarkets.

In LEDCs, staple food may not be always affordable as prices fluctuate. People tend to make purchases based on nutritional need and affordability. Political and economic agendas can affect food production: cash croppingEven if food crops are not used as cash crops, food production is still impacted since arable land is being occupied all the same.

In MEDCs the average caloric content per capita per day of food is 3314 calories. In the USA specifically, this number is 3374 calories.

In LEDCs the average caloric content per capita per day of food is 2666 calories. In Eritrea this number is 1512 calories.

What does the following table tell you about your diet?

                                              MEDC       LEDC
Meat                                      12.9           7.3
Fish and seafood                        1.4            0.9
Cereals                                   37.3          56.1
Vegetables, fruits, fats               48.4          35.7

Think globally
The American Association for the Advancement of Science suggests that there is an average of 2790 calories available each day for every human on the planet. That is enough to feed everyone. If food production has kept up with population growth, why are there still so many problems with famine, hunger and malnutrition?

Factors to consider
Distribution: If countries like Canada, USA and Australia have an excess of food, can that be shipped to Bangladesh, Ethiopia, or Sudan? Who will pay for it? Do they even want that kind of food?
Politics: If excess food is not paid for, is the receiving country now in the debt of the donating country or the donating corporation?

So far, food supply has kept pace with human population growth, seemingly refuting Malthus, however recently some are doubting this can continue.
As we adapt an increasing amount of global NPP to human needs. use and degrade more land, eat more meat, contaminate more water, we are getting closer to the planet's K... we just don't know that this is yet.
There are 1.1 billion people living in poverty... They are increasing and growing hungrier.
Annual grain yields per hectare have slowed their rate of increase since the Green Revolution (1990-2000 had the lowest increase since before the 1950s).

Types of farming systems
1) Subsistence: Food for farmers and their community, little or no surplus, little technology.
2) Commercial: Lar profit generating scale, yields are maximized, monocultures, high levels of technology, energy and medical input.

Farming can also be
1) Extensive - More land with lower density of animals.
2) Intensive - Intense use of land, higher inputs and outputs.
Also as pastoral, arable or mixed

(Worksheet) Food, Nutrition and Production.

Food Security is the situation in which people in a determinate area has daily access to enough nutritious food to have a healthy life. Food security also depends on reducing (at least slightly) the harmful environment effects of agriculture at local, national and global levels. 

In order to maintain good health, the human body needs macronutrients, micronutrients and minerals. People suffer from chronic undernutrition or hunger when they cannot grow or buy enough food to meet their basic needs, and children who suffer from this condition often live in developing countries. The consequences of undernutrition are mental retardation, stunted growth and death caused by infectious diseases, such as measles and diarrhea.

Malnutrition results from deficiencies of protein, calories and other key nutrients. This is because many of the world’s poor can afford only to live on a low-protein, high-carbohydrate, vegetarian diet. Overnutrition occurs when food energy intake exceeds energy use and causes excess body fat.

One of every three people has a deficiency of one or more vitamins and minerals, especially vitamin A, iron and iodine, the three of which are very important for keeping a good health.  Iron is a component of the hemoglobin that transports oxygen in the blood, so it's vital to be renewed in nutrition. If people don't consume iron in sufficient quantities, they might then suffer from anemia.  The lack of iron also may cause fatigue, make infection more likely and increase a woman’s chances of dying from hemorrhage in childbirth.

A famine  is a severe shortage of food in an area accompanied by mass starvation, many deaths, economic chaos, and social disruption. Famines often lead to mass migration of starving people to other areas or to refugee camps in their need for food, water, and medical attention from sickness and diseases that may appear from the lack of nutrition. Famines are usually caused by crop failures from drought, flooding, war and other catastrophic events.

There are three main systems which provide almost all of the world’s food:

• Croplands: Provides 77% if the world’s food using 11% of the world’s land area. These mostly produce grains.
• Rangelands and pastures: Provide about 16% of the world’s food using about 29% the world’s land area. These areas produce meat, mostly from grazing livestock.
• Oceanic fisheries: Supply about 7% of the world’s food from fishing activities.

Traditional agriculture consists of two main types which together are practiced by the 42% of the world’s people and provides one-fifth of the world’s food supply:

• Traditional Subsistence Agriculture: Uses mostly human labor and draft animals to produce only enough crops or livestock for a farm’s family survival.
• Traditional Intensive Agriculture: Farmers increase their inputs of human and draft-animal labor, fertilizer and water to obtain a higher yield per area of cultivated land. They produce enough food to feed their families and to sell.

Demographic Transition Model

DTM describes the pattern of decline in mortality and natality (fertility) of a country due to social and economic development. Cal be described as a 5 stage model:

• Pre-industrial
• LEDC
• Wealthier LEDC
• MEDC - stable
• MEDC - population decline

Population Pyramids

Also called age-sex pyramids, they show how many individuals are alive in different age groups (called cohorts) in a country or region for any given year. They also show the male-female ratio. Population numbers are on the x-axis and age groups are on the y-axis.

Types of pyramids:

• Stage 1: Expanding - High CBR, rapid fall in each upward age group due to high CDR, short life expectancy.
• Stage 2: Expanding - High CBR, fall in CDR as more individuals live to middle age, slightly longer life expectancy.
• Stage 3: Stationary - Declining CBR, low CDR, More individuals live to old age.
• Stage 4: Contracting - Low CBR, low CDR, higher dependency ratio (those that cannot work), longer life expectancy
• LEDCs tend to be in stage 1 or 2
• MEDCs tend to be in stage 3 or 4

Ways to reduce family size

There are several ways of reducing family size rather than imposing legislation as it's done in China:

• Provide education
• Promote alternative "family methods"
• Make contraception available
• Improve health availability
• Improve standards of living
• Improve economic conditions
• Provide nutrition
• Have a wider resource distribution

Some of these methods might be difficult to achieve in general but are the ways in which MEDCs have managed to reduce family size considerably. LEDCs should take these considerations in their development route.

Population size impact and changes

Impact
Population size is not the only factor that determines our species impact on the environment.

• Resource use and pollution
• Amount of wealth
• Resource desire
• Resource need

Many environmental impact models are based on the assumption that all individuals in a population have the same resource use and waste profile and thus impact the environment equally.


Changes
4 main factors for population changes:

• Birth rate
• Death rate
• Inmigration
• Emigration

The measures of population change are:

• Crude birth rate or CBR = (Number of births)/(Total population) * 1000
• Crude death rate or CDR = (Number of births)/(Total population) * 1000
• Natural increase rate or NIR = (CBR-CDR)/10
• Doubling rate = 70/NIR
• Total fertility rate: The number of children every woman is having in a determined area. The total fertility rate in the world is 3, 1.7 in MEDCs and between 3 and 6 in LEDCs
• Also important to note: Population density = (Total population)/(Total area)

MEDCs and LEDCs

Countries are classified economically based on industrial development and GDP (in the map, dark blue are developed, cyan are in transition, orange are less developed and red are least developed).

MEDCs - Most economically developed countries

(Tokyo, in Japan, one of the MEDCs)

• MEDCs are industrialized nations with high GDPs
• Relatively rich population and starvation is unlikely
• High level of resources per capita
• Relatively low population growth rates
• Shown in the map in blue (North America, Northern and Western Europe, Japan, South Korea, Australia and New Zealand)

LEDCs - Least economically developed countries

(Port Au Prince, in Haiti, one of the LEDCs)

• Less industrialized or have no industries at all.
• Low GDPs and high poverty rates
• May have plenty of natural resources, but these are exported to MEDCs
• High population growth rates
• There are risks of starvation
• Shown in the map in red (Eastern and Western Africa, some parts of Asia)

Population - Limiting factors and growth curves

Limiting factors

Populations can change over time due to many factors or variables. These can be classified as:

• Density dependent factors
• Density independent factors

Density dependent factors are biotic

• They act as negative feedback
• Regulate and stabilize populations
• Internal factors act within the species (such as limited food supply)
• External factors act between different species (such as predation)

Density independent factors are abiotic

• They represent no feedback system
• Acts over all the ecosystem no matter the species that are present or the density
• Weather, climate, floods, storms.

Population curves

S-curve

• Starts with exponential growth
• Growth rate stabilizes
• Stabilize at carrying capacity (K)
• The area between the exponential growth curve and the S curve is called environmental resistance.
• lag / exponential / deceleration / stationary

J-curve

• Shows a boom and bust pattern
• Grows exponentially and then crashes
• Collapses are called diebacks
• Exceeds K (overshoot)
• Typical of microbes and invertebrates.

Sustainability and the sustainable yield

Sustainability means:

• Living  with the means of nature, on the "interest" or sustainable natural income generated by natural capital.
• However, economists and environmentalists may have very different views on what is sustainable.
• Any society that supports itself in part by depleting essential forms of natural capital is unsustainable.

Sustainable yield is the increase in natural capital. Natural income that can be exploited. It's important to know some factors:

• Carrying capacity
• Population size
• Total biomass or energy at a given time
• Rates of change of population, biomass and energy

Two formulas for calculating sustainable yield are

• (total biomass or energy at time t+1) - (total biomass or energy at time t)
• (Annual growth and recruitment) - (Annual deaths and emigration).

Resources - What to know about them.

Economic resources 

• An economic system produces and distributes goods and services by using natural, human and manufactured resources.
• An economic system consumes goods and services to satisfy people's needs and wants in the most efficient and effective way.

Resources

• May be known as capital
• Capital used as it is or to produce goods and services.
• There are three main types:


• Natural capital
• Human capital
• Manufactured capital

Natural capital and natural income

• Natural capital includes natural resources that have a value and those that support life.


• Trees, soil, water, living organisms, ores, etc.
• Flood and erosion protected by forests, etc.



• Natural capital can also be processes


• Photosynthesis
• Water and gas cycles

Natural capital in economic systems

• Capital yields income
• Natural capital yields natural income
• The World Bank now calculates wealth of countries by including the rate of extraction of natural resources and the ecological damage caused by this. Least developed countries might have a large amount of natural resources and natural capital, but these are exported to more developed countries for manufacture.
• Sustainability often represents sources of conflict within and between political parties and countries.

Natural income

• Yield or harvest of services
• Water cycle provides fresh water
• Photosynthesis provides oxygen

Resource categories

• Renewable: Can be replaced continuously as it is used by humans. For example, agriculture products.
• Non-renewable: Finite amounts of a resource, which are used as a short term solution. They might be replaced by other resource when depleted completely. For example, fossil fuels.
• Replenishable: Middle ground between renewable and nonrenewable, a resource that can be replaced but at slower rates than renewable resources. For example, groundwater.
• Recyclable: Resources that have been used and can be processed to be used again in another form. For example, paper glass and plastic.

Measuring Changes in an Ecosystem

The changes in an ecosystem may be:

• Biotic
• Abiotic
• Human impact

To evaluate these changes, an EIA might be used. EIA stands for Environmental Impact Assessment.

Biomass numbers in the taiga

In a previous investigation project, some classmates and I developed a biomass pyramid for the taiga. This serves as a good example for the previous post on measuring and estimating biomass.

Measuring and estimating biomass.

First of all, biomass is the total weight of living matter, measured in dry weight. The importance of biomass comes from the fact that it includes all the organic matter in an ecosystem, and that's why it's important to have it measured or estimated. To do this, there are some methods:


One of the methods is simply counting the number of organisms of a single species in the ecosystems and then measuring the dry weight of a single organism. This method may be very long, and can be inaccurate if the area is not covered correctly.


Another method is monitoring soil with electronic devices. These devices can be left unattended while they collect data, and can be left away from laboratory conditions.


In the case of insects, they can be collected with methods like hand held sweep nets, sticky traps and light traps. These insects can then be monitored with the use of radars. This method can be very destructive so it has been replaced by other methods.


One of these newer methods is satellite monitoring. The MODIS Rapid Response System was developed to provide daily satellite images of the Earth's landmasses in near real time. Here's a very simple example of how biomass can be estimated with satellite monitoring:

This MODIS Enhanced Vegetation Index (EVI) map above shows the density of plant growth over the entire globe. Very low values of EVI (white and brown areas) correspond to barren areas of rock, sand, or snow. Moderate values (light greens) represent shrub and grassland, while high values indicate temperate and tropical rainforests (dark greens).

Satellite systems can also be used in animal tracking. This new method allows the animal's location to be plotted against a map or chart and localizing an entire population to be measured.

These are only a few ways for estimating biomass. Equations and other methods can also determine biomass density in an area.

Biodiversity indices...

Now this is a completely new concept for me. What's a biodiversity index? A diversity index is a mathematical measure of species diversity in a community. Diversity indices provide more information about community composition than simply the number of species; they also take the relative amount of different species into account. There are several biodiversity indexes:
Species richness is simply the number of species present in a sample, community, or taxonomic group. Species richness is one component of the concept of species diversity, which also includes the relative abundance of species. Species diversity is one component of the concept of biodiversity. Patterns of species richness can be observed at a variety of levels. The causes of these patterns remain active areas of research in ecology, biogeography, and evolutionary biology.
Simpson's Index measures the probability that two individuals randomly selected from a sample will belong to the same species (or some category other than species).

n = the total number of organisms of a particular species
N = the total number of organisms of all species
Shannon diversity index is another index that is commonly used to characterize species diversity in a community. Like Simpson's Index, Shannon's index accounts for both abundance and evenness of the species present.

where p_i is the fraction of individuals belonging to the i-th species.

I guess it's clear... It'd gonna take me some time to understand it completely, though. I hope we continue to work with this topic. :)

Mass and energy flow in the taiga

Particularly, the taiga is my favorite biome because of its weather, trees and fauna. It's also the world's largest biome and it's the one I researched about in my first semester of environmental systems and societies. As my team did a LARGE poster about the taiga, I can clearly describe an example of biomass and energy flow that occurs in this biome.

As we all know, these flows are related to the trophic levels. It all starts with grass (in this case) creating biomass as it obtains energy from the sun and changes chemical energy into an organic source of energy that can be transferred. The whole amount of energy produced by the grass in the ecosystem is known as gross primary productivity. However, plants required some of that energy to grow and carry out respiration processes, so the amount of energy that they pass to the next level, known as net primary productivity, is lower.

Then, let's imagine that white-tailed deer eat this grass. All the amount of energy they get from the grass they eat is called gross secondary productivity. However, as these deer have much more processes and activity than grass, they're going to require lots of energy from what they ate, so the amount of energy they pass to the next level, net secondary productivity, is much lower.

When a wolf, which is a second level consumer, eats the white-tailed deer, they're going to receive very low amounts from the original energy, so they will have the need to eat in more quantities to receive enough energy.

This is a single food chain, but this happens in every food chain in the taiga and all other ecosystems. The concept's known as entropy.

Trophic levels

Organisms occupy hierarchical positions in an ecosystem related to the way they obtain energy. It's important to note that every trophic level receives less energy than the level below it, so they need to eat more in order to get enough energy.

The trophic levels mainly go as follows:

Producers

Plants such as grass, and some plankton, are producers, the first trophic level. They create organic food molecules by using inorganic molecules from the surroundings and energy from the sun. Turn chemical energy into energy usable by other organisms. Also called autotrophs or "self-feeders" because they don't need to eat any organism.

First level consumers (herbivores)

First level consumers, such as moose, fish and cows, eat the producers. Along with other consumers, they're called heterotrophs because they eat other organisms. The energy they get from the plants is less than the original energy produced by them.

Second and third level consumers (carnivores)

Second and third level consumers eat other consumers. As they're a high trophic level, they get a very small amount of the original energy that their prey obtained from producers, so they need to have more food. Also called heterotrophs.

Decomposers or saprobes

Decomposers, such as bacteria or fungi, break down dead or decaying organisms in a process called decomposition. In this process, nutrients are returned to the soil to be used by producers, so the cycle completes.

So... What is an ecosystem?

There are many terms that have to be defined before stating what an ecosystem is. A particular group of organisms that are capable of interbreeding is known as species, and form a population when they live together. Several populations living in a single area are known as a community. Then, an ecosystem appears when this community interacts with the physical environment of matter and energy in which they live. Organisms are the biotic factors and non-living objects and conditions are the abiotic factors that make up the ecosystem. Several ecosystems with similar climatic characteristics and populations are known as biomes.

Here I show some examples of ecosystems:

Tropical rain forest

This is one of the most productive ecosystems because of its warm temperatures and high amount of precipitation (abiotic factors). Tall trees have enough resources to grow there, as well as populations of bushes. Animals include monkeys, elephants, snakes and insects.

Tundra

As opposed to the tropical rain forest, the tundra is the least productive ecosystem because of its low amount of precipitation and harsh cold temperatures. The plant populations limit to moss and lichens, which can endure the freezing conditions. Animals are highly adapted as well and include polar bears, caribou, and some ducks and geese.

Coral reef

Coral reefs are a type of marine ecosystem and contain an enormous diversity of organism ranging from corals to anemones to sponges to several species of fish.

Urban ecosystem

These are artificial ecosystems created and populated by humans. We share these environments with many other species of plants and animals. As an example, New York City, which can be considered one of the world's most urbanized areas, incorporates Central Park in which there is a higher concentration of other populations. All urban ecosystems are shared between us and other species.

These are just a few examples of strikingly different ecosystems. Around the globe there are many similar ecosystems (which I previously defined as biomes) but it's best to know that every single ecosystem has its own mix of biotic and abiotic factors that make it unique.

What is a system?

Before entering this course, it would have been very difficult for me to answer this question, as there were lots of ambiguous definitions I would have used for "system". Now I can define a system as  a set of components that function and interact in a predictable manner. The components in a system are inputs, outputs, flows, sources, storages and sinks. In an ecosystem, for example, the sun is a source of energy. This energy flows to plants, which are a storage, and then flows again to herbivores. When herbivores die, the energy flows to the ground, which is a sink. Making some change in the ecosystem, such as introducing a new species, becomes an input, and the result of this change is known as the output and affects the whole ecosystem, such as less food available for the other species in the area. A system can be classified as open, closed or isolated. Open systems can transfer matter and energy in and out of their boundaries, while closed systems can only transfer energy. We can think of a forest as an open system and a greenhouse as a closed system. Isolated systems don't transfer energy or matter through boundaries, which is only a term because this can't happen. The universe is the only example of an isolated system because there's no other system to transfer matter or energy. It's good to finally have the question answered. :)

Introduction

Welcome to EnviroSys&So, the blog I've created to share with you everything I've learned in the Environmental Systems and Societies course (hence the name, obviously). In this entry I want to explain the theme of the blog, which has the purpose of both contrasting and linking nature and human society. The title banner mixes elements of nature, such as animals and plants, with elements created by us such as computers and cities. The wallpaper shows two sides of our planet. The day half shows its natural side, as it looks almost unaltered by human society, while the night half shows the society side, as those small lights among the darkness come from the cities we've built. I hope to learn a lot and update this blog regularly so that I can keep track of the topics of the course. Thanks for reading! :)