Food Soil and Pest Management

Outline Issues involved in the imbalanced food supply.

Population Pyramids

What do it tell us:
*Population distribution
*Population changes

Types of pyramid shapes: (in stages)

Population growth and food shortages

Two main theories arose in this aspect: 


MALTHUS (who says that the population is growing geometrically while the food supply increases aritmethically, which lead in the fact that it will be a moment in which population will pass the amount of food available, causing the disappearance of extra-individuals) (very related with a J-curve)


vs 




BOSERUP (states that while the population keeps growing it will develop the technology needed to meed the food demand.) (it can be seen as a extension strategy of marketing, in order to keep population "in the market" :D) 


It is important to emphasize that in those cases, the food supply acts as the caring capacity of the population.

About human population....

As we said in the last post, the human population is now around six billion people, and growing.
This is a graph of how the population has been (with an interesting little note), and how it seems to be in the future:

(I took this image from the page of Gerald G. Marten: if you have the chance look at it: it have very intersting graphs about population growth, specially human population.)


But looking again to the graph it can be stated that the human population follows a J-curve growing.


We must take into account that human population is very diverse, and certainly in measuring it (specially in qualitative measures) we must consider a lot of factors before interpreting or using this data.



The Human Development Index is an index (duuh) adopted by the UN Development Programme as a measure of the well-being of a country. It combines factors such as: Education, Life expectance, Standards of living, Income, Gross Domestic Product (GDP) per capita, access to health services between others.


By taking this classification, countries can be divided in MEDCs (more economical developed countries) and LEDCs (less economical developed countries) 

Population Dynamics

A simulation of the human population dynamics is in this webpage: www.breathingearth.net
It calculates 6,859,548,511 people at the time i entered.


Not only ours, but any population change over time due to many different factors that, in this course of ESS, are known as limiting factors:

• Density dependent factors: the impact these factors have depends on how many individuals are in the population. These are usually biotic factors.
• Density independent factors: those that affect a population regardless of its size. These are usually abiotic factors. 

(in this PDF of the Canadian Province Manitoba, are a list of many examples of limiting factors, and an interesting case)

Growth curvesA visual representation of the growth rate are the growth curves, that show a different type of population growth:  

• J-curve

It display an exponential growth that suddenly it will have what is known as a dieback, or a radical decrease, as a result of the fact the population have overpass the carrying capacity (K), which is the maximum amount of individuals an ecosystem can support without being affected. 

• S-curve

S-curves shown also a exponential growth, but in a middle point the rate of growth decrease as the population reaches its carrying capacity (K). This growth rate is consistent with density dependent factors. 


Measuring population changes: 


The main factors that affect the size of a population are: Birth rate, Death rate, Immigration and Emigration


The Crude Birth Rate (CBR) is the number of births per one thousand individuals in a population per year. It is calculating by dividing the number of births by the total population size and multiplying by 1000.

CBR=[(Number of Births)/(Population Size)]*1000
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The  Crude Death Rate (CDR) is the number of deaths per 1000 individuals. It is calculated the same as the CBR.

CDR=[(Number of Deaths)/(Population Size)]*100
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Doubling Time is the time in years it takes for a population to double its size.

Doubling Time= 70/NIR
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Natural Increase Rate is the rate of population that doesn’t consider immigration and emigration.

NIR = (CBR - CDR) / 10
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Total Fertility Rate (TFR)  is the average number of births that each woman has over her life time. It shows the potential of population change.

• A TFR > 2.0 results in a population increase
• A TFR < 2.0 results in a population decrease
• A TFR = 2.0 results in a stable population

Sustainable Yield

I liked a lot the notes taken from Ada's Blog "The first law of Ecology" in which the information about sustainable yield is summarized as the following:

...

"Sustainable Yield (SY) refers to the increase in natural capital. It is the natural income that can be exploited each year without depleting the original stock or affecting its potential for replenishment.

* MSY means the maximum sustainable yield, and it is the one that is of interest commercially speaking.

Some important aspects to consider when calculating sustainable yield are:

• carrying capacity
• population size
• total biomass or energy at a given time
• Rates of change of population, biomass, and energy.

However, there is a convenient formula for calculating Sustainable Yield:

SY= Annual Growth and Recruitment - Annual Death and Emigration
Basically, what this calculates is how many organisms are there at a given point in time. It considers new individuals that came in, and individuals that died or left. 

Sustainable Yield can also be calculated by 

SY= (Total Biomass or energy at a Time T)+1 - (Total Biomass or energy at a Time T)

defining... Sustainability

This is one of the most important activities that we have done in the ESS class:
to define a term have never been such funny, dynamic, holistic and accurate as it was in the classroom:

First of all, we need to do a brief brainstorming to give ideas of what does sustainability means for everyone;

After that, magic began: using a flash based software named Wordle (www.wordle.net)  (things that just Mendez and God can find in my opinion), the following was created:

And this is what is called a cloud: it represents the more repeated words in larger font size so we can have a "visual idea" of what does the brainstorm was about:

With this cloud, is easy to define sustainability taking the more highlighted words as:

The ability of maintain the balance between the environmental system and our activities in order to have the less possible impact,  taking in account our needs, the resources of the ecosystem and the future generations.

A VVV: very visual and valid interpretation just emerge.

capital capital capital

Taking the example of an economic system, the term capital is related to everything we give vaule for its roll in the exchange of goods and services that involves this system

As well as this, we must consider that environmental systems (natural systems) have their own natural capital, which include all natural resources that have value, and the most important, resources that support life.

Natural capital might be classified, depending its availability and time of renewal, in:

1. Renewable
2. Non-renewable
3. Replenishable
4. Recyclable