Demographics: all about rates and more

In here, there will be mentioned several rates, such as CBR and CDR, for example.

Crude Birth Rate
The Crude Birth Rate (CBR) includes the number of births per 1000 individuals. So, the formula for this is:

CBR = (Number of births / population size) x 1000

The CBR in the world is 20.3 per 1000 per year.


Crude Death Rate
The Crude Death Rate (CDR) includes the number of death per 1000 individuals. The formula for this is:

CDR = (Numberof deaths / poplation size) x 1000

The CDR in the world is 9.6 pero 1000 pero year.


Natural Increase Rate
To know the Natural Increase Rate (NIR), it is important to know the Crude Birth Rate and the Crude Death Rate, The formula for the Natural Increase Rate is:

NIR = (CBR - CDR) / 10

It is important to say that NIR gives a percentage.


Doubling time
Last semester we saw doubling time, but we didn't saw it in a clear form. Now, we saw it in class, and with this we know that doubling time is the time in years that it takes a population to double its size. The doubling time formula is:

Doubling time = 70 / NIR

This do not considers immigration nor emigration.

Total Fertility Rate
Now, continuing with rates, we have the Total Fertility Rates (TFR) which is the average number of children that each woman has over her lifetime. This one shows the potential for population change in a country.

A Total Fertility Rate that is less than 2.0 it results in population increase. But if the Total Fertility Rate is more than 2.0 it esults in population decrease.

Factors affecting species impact
Factors affecting species impact on the environment (without counting population size) are:

• Wealth, including its distribution.
• Resource need
• Resource desire

S and J curves

S and J curves is something that we say last semester. However, we reinforced it on this semester.

S-curves

This curve, as its name says it, has a shape of an S. This is an exponential growth, but then, there is a point in which growth rate slows down when population stabilizes. This one involves density dependent limiting factors.

Furthermore, the graph involves a carrying capacity (K) which is the amount of species a system can have and maintain. The carrying capcity is asymtpotic.

The curve also shows an environmental resistance which is the area between the exponential growth curve and the s-curve. This is showed at the picture below.

J-curve

The J-curve shows a boom and bust pattern. In here population grows exponentially and then crashes. This may be called diebacks, which is when the population collapses or crashes. Furthermore, population often exceeds K before the collapse occurs, which is referred as overshift.These curves are typical from microbes, invertebrates, fish and small mammals.

References (pictures)

"Chapter 6 -- Population Dynamics ." Miami University. Department of zoology, 2002. Web. 3 Oct 2010. <http://zoology.muohio.edu/oris/Cunn06/cs6_06.htm

System population dynamics

Now, we passed to other topic in class, and this one involves the population changes among a system.

First we looked at the factors that affect the population growth and these ones are divided into two: density dependent factors and density independent factors.

Density dependent factors
These ones depend on how dense the population is. These involves biotic factors and they are mostly part of negative feedbacks. The density dependent factors are derived into externa and internal factors.

• Internal factors: this ons involves the act within a same species. This includes food supply, territory, and density dependent fertility.
• External factors: this one involves the act within a different species. This includes predation and disease.

Density independent factors
These ones do not depend on how dense a population is, in other words, it is not related to population density. It involves abiotic factors and aren't part of a feedback system. Some examples of density independent factors are: weather, climate, volcanic eruptions, floods, between other.

How do we value resources?

I was looking at my notes and I saw this title. I thought it was a good idea to post it because previously, I was talking about resources, but just in the ecological way. However, there are other ways and perspectives in which resources are valued. I think it's good to be aware of them.

• Economic: this involves money. This may include the exchange of resources viewed as just "simple items" that can be exchanged without any repercussion in other areas of study.

• Ecological: this inolves the support of the systems. This may include teh awareness that there is a whole process behind a resource and also the implications it may bring to the environment.

• Scientific: this may look really related with the one above, but this is more of the research in them.

• Intrinsic: this includes the culture we have of taking care of resources, and also, trying to belong to them, not only considering them other "item" on Earth.

What is sustainability?

On class, everyone made their definition of sustainability. My definition of sustainability was:

The process of maintaining certain things, activities, or situations by themselves (this may include a system), but in a way that it could be preserved for future generations.

Talking about sustainability, on school, we had a congress which was called EPSA (Encuentro por la sustentabilidad ambiental). This one has the task of finding sustainable solutions for the world of today. The main topic was the aiding of a community called "San Gilberto" which was affected by the hurricaine "Alex".

We had to find sustainable and realistic solutions for the problem. We worked in teams and by the end of the congress we had several solutions, and some of them were:

• The education of the community (this also included the education of teachers about sustainability so they could also teach their students)
• Reforestation
• The cleaning of the area
• Between others more

Natural Capital

Here are some of the notes taken in class concerning the economic resources topic.

Before passing to the natural capital section, it is important to know what does an economic system and resources mean.

Economic resources is a system tha produces and distributes goods and services by using natural, human, and manufactured resources.

An economic system is a system that produces, distributes, and consumes goods but also services to satisfy the people's needs and wants in an effective and efficient manner.

Resources may be also called as capital. It is important to say that when we refer to capital, we refer to the use or the production of goods and services, which this last one (capital).

There are three types of capital:

• Natural capital
• Human capital
• Manufactured capital

Natural capital and nautral income
Natural Capital
What does natural capital includes? Well, natural capital inclueds resources that have value and those which support life. Some examples of this are:

• Trees, soil, water, living organisms, ores (which are deposits were nuberaks are extracted for materials).
• But also floods and erosion protection by forests.

Furthermore, natural capital can also process photosynthesis and cycles such as water and gas.

Natural capital in economic income

Like we know, a capital yields income. Well, transferring this into ESS, natural capital yields natural income.

Did you know? The World Bank now calculates wealth or countries by including the rate of extraction of natural resources and the ecological damage caused by this.

Important fact: Sustainability often represens sources or conflict within and between political parties and counries.

Natural Income
Natural income, yields or harvests services. For example, water cycle provides fresh water and photosynthesis provides oxygen.

There are three main categories on natural income.

• Renewable: these are the resources that replace or restock themselves. They can include: water and lumber.
• Non-renewable: these are the ones that exist in finite amounts of Earth: These ones can include: minerals and fossil fuels.
• Replenishable: this category is for the resources that can be renewable but take really so long that can also be taken as non-renewable. More specific, is a mixture between both. An example of this can be grounwater.

However, we also have the fourth element, which is RECYCLABLE RESOURCES.

September 1 and 3 Notes

Here are some of the notes taken in class

Measuring changes in an ecosystem. Well first of all, it's necessary to remember some of the biotic and abiotic factors that exist.

• Abiotic: climate, soil, water, light.
• Biotic: biomass, productivity, biodiversity, NPP, GPP.

Now, EIA, stands for Environmental Impact Assesment. The name says it all, is an assesment that measures the impact, it can be beneficial or controversial, of certain project in a certain place. The EIA, may help us:

• Identify the impact
• Estimate or predict an impact
• Asseses and limits the impact

Furthermore, we saw a little bit of history on class. For example, we saw what NEPA was. NEPA stands for National Environmental Policy Act, which was an act that was of United States created in 1969, which later was adopted by others.