Influences on Population Dynamics

MEDC vs. LEDC over Food Supply

More Economically Developed Countries

• In many MEDCs the cost of staple food items is relatively cheap.
• Most people make purchases based on taste and preference.
• Produce seasonality has mostly disappeared due to globalization.
• This has also allowed for a greater international variety in most supermarkets.
• The average caloric content per capita per day of food is 3314 calories. In the USA specifically, this number is 3774 calories.
  
  

Less Economically Developed Countries

• In LEDCs, staple food items 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: e.g. cash cropping
• Even if food crops are not used as cash crops, food production is still impacted since aable land is being occupied all the same.
• The average content caloric content per capita per day of food is 2666 calories. In Eritrea this number is 1512 calories.

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.

Factors to Consider

• Distribution
• Politics

In Summary...

• So far, food supplu has kept peace with human population growth, seemingly refuting Malthus... however recently some are doubting if 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 waters, we are getting closer to our planet's K... we just don't know what that 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)

Food

Food Security is the term that refers to the situation in which every person in a given area has daily access to enough nutritious food to have an active and healthy life. Developing countries do not produce enough food for feeding their people and are too poor to import enough food to provide national food security. Food security also depends on gently reducing the harmful environment effects of agriculture, not only at local, but also at national and global levels.

In order to maintain good health, the human body needs macronutrients, micronutrients and minerals. When people cannot grow or buy enough food to meet their basic needs, they suffer from chronic undernutrition or hunger. Children who suffer undernutrition often live in developing countries. The consequences of this 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. Too many calories, too many exercise or both can cause overnutrition.

One of every three people has a deficiency of one or more vitamins and minerals, especially vitamin A, iron and iodine. Iron, is a component of the hemoglobin that transports oxygen in the blood. Too little iron, may cause fatigue, makes infection more likely and increases a woman’s chances of dying from hemorrhage in childbirth. It also causes anemia.

A famine occurs when there 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 a frantic search food, water and medical help. Famines are usually caused by crop failures from drought, flooding, war and other catastrophic events.

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

o Croplands: Mostly produce grains, and provides 77% if the world’s food using 11% of the world’s land area.

o Rangelands and pastures: produce meat, mostly from grazing livestock and supply about 16% of the world’s food using about 29% the world’s land area.

o Oceanic fisheries: Supply about 7% of the world’s food.

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:

o Traditional Subsistence Agriculture: Uses mostly human labor and draft animals to produce only enough crops or livestock for a farm’s family survival.

o 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.

Measuring Changes in a (Eco)System

- Abiotic (climate, soil water, light, ecological contingencies, ...)

- Biotic (biomass, biodiversity, NPP, GPP, ...)

- Human impact

EIAs [Environmental Impact Assessment]

Measuring Biomass

Measuring biomass: Biomass refers to living and recently dead biological material and excludes organic material which has been transformed by geological processes into substances such as coal or petroleum. It is usually measured by dry weight, and is the total mass of living matter.

The effects of climate change on plants, animals and biomass generally are quite difficult to measure, but potentially dramatic (see also biodiversity ). Many plant and animal species inhabit precisely bounded ecological niches, and even small changes in climate may cause fundamental disruptions in habitat or food availability. In the past, animals found it easier to respond to climate pressures by moving from one place to another. However, land development and many other human uses of the environment has constrained and fragmented ranges and travel routes, making species migration in response to climate change much more difficult.

The purpose of the climate change detection and monitoring activity is to identify variability and trends in the climate system. In understanding these changes we are able to identify specific causative factors, whether natural or human-induced.

Soil Monitoring

Long-term monitoring of soil has become routine in the past twenty years as dataloggers and electronic monitoring equipment become widespread. These types of automated electronic monitoring systems have distinct advantages as they can be automated to collect data unattended. They can also collect numerous measurements each day, and do not require laboratory conditions to provide results



Insects

Historical record of insects and disease infested areas can be collected with yearly aerial surveys. Hand held sweep nets are often used for insects such as lygus bugs, some aphids, and beneficial insects, as they are often very mobile, and hard to monitor any other way. Insects are also caught and monitored by using various insect traps including sticky traps, light traps, pitfall traps and pheromone traps. Radar has also been successfully used for over twenty years to study the flight behaviour of a variety of migrant insects. Observation satellites are now used to collect imagery on forests which can map the devastation caused by insect infestations (e.g. Mountain Pine Beetle ).

Satellite Monitoring

The MODIS Rapid Response System was developed to provide daily satellite images of the Earth's landmasses in near real time. True-colour, photo-like imagery and false-colour imagery are available within a few hours of being collected, making the system a valuable resource for organisations like the U.S. Forest Service and the international fire monitoring community, who use the images to track fires. As the climate changes and some areas prone to experiencing less rainfall, fire activity will increase and measuring biomass in this way is extremely important to fire fighting authorities.

Here is a the NASA site, where you can view the locations of the fires detected by MODIS on board the Terra and Aqua satellites over a 10-day period.

The geographic ranges of plant species are affected by climatic change. Surface sampling and instrumentation can provide very detailed data records at a particular ground location, but time series satellite images provide information on changes to vegetation cover and density at a regional level.

Satellite images can pick up dust blown from the land surface, a process of degradation and often desertification. These fine-grained minerals are critical to vegetation growth, and also create potentially hazardous air quality to humans on a local and regional scale, and adversely affecting climate on a regional and world-wide scale.

Animal Tracking

The use of Global Navigation Satellite Systems (GNSS) in animal tracking has become widespread since the commercial development of the first units in 1991. The recorded location data can be stored within the tracking unit or may be transmitted to a centrally located data store, or internet-connected computer, using an embedded cellular (GPRS), radio, or satellite modem. This allows the animal's location to be plotted against a map or chart either in real-time or when analyzing the track later using a GIS package or custom software.

The NOAAs turtle study is a pioneer in showing the value of combining animal movements and oceanographic data from satellite remote sensing. Tracking animals is useful within a climate context as it provides information on movement and range than can be compared in later studies to better understand the changing environment.

Experiments in Controlled Environments

In 1999, Dr. Carl Baugh patented a small "Hyperbaric Biosphere". This unique chamber, designed to emulate the conditions thought to exist on the early earth, is located in Glen Rose, Texas. It provides double atmospheric pressure, enhanced oxygen, and protection from ultraviolet radiation, while magnetic coils attempt to make up for earth's reduced magnetic field. Initial results from ongoing tests with fruit flies, poisonous snakes, and other organisms point to some dramatic differences in creatures living in this environment compared to a control group; for example, the lifespan of fruit flies has been tripled, and the toxicity level of copperhead snake venom has been lowered.

A much larger (62-foot) hyperbaric biosphere is currently under construction in the same location, and is one of many devices that could be used to study climate change.

Biomass and Ecosystem

Biomass, a renewable energy source, is biological material from living, or recently living organisms, such as wood, waste, (hydrogen) gas, and alcohol fuels. Biomass is commonly plant matter grown to generate electricity or produce heat. In this sense, living biomass can also be included, as plants can also generate electricity while still alive. The most conventional way on how biomass is used however, still relies on direct incineration. Forest residues for example (such as dead trees, branches and tree stumps), yard clippings, wood chips and garbage are often used for this. However, biomass also includes plant or animal matter used for production of fibers or chemicals. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic materials such as fossil fuels which have been transformed by geological processes into substances such as coal or petroleum.

Savanna

Biodiversity

Biodiversity is defined as the variety of all forms of life, from genes to species, through to the broad scale of ecosystems.

Biological diversity can be quantified in many different ways. The two main factors taken into account when measuring diversity are richness and evenness. Richness is a measure of the number of different kinds of organisms present in a particular area. For example, species richness is the number of different species present. However, diversity depends not only on richness, but also on evenness. Evenness compares the similarity of the population size of each of the species present.

A diversity index is a statistic intended to measure the differences among members of an ecosystem consisting of various types of objects. There are different types of diversity indexes such as:

• Simpson's Diversity Index: measures the probability that two individuals randomly selected from a sample will belong to the same species. It is measured by the following formula:

When apllying the formula, the value that we can obtain starts with 1, representing a community of only one specie. The higher the value obtained, represent greater diversity.

To calculate Simpson's Index for a particular area, the area must first be sampled. The number of individuals of each species present in the samples must be noted.

• Shannon's Diversity Index: Is another diversity index used for characterize diversity in a community. It accounts for both abundance and evenness of the species present. The formula for applying this index is: