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

BIOMASS!

 WHAT IS IT?

Biomass is the term that refers to the total amount of living material in  certain area. Biomass is regarded as an important indicator of ecological and management processes in an ecosystem.

WHY TO MEASURE IT?

The university of Idaho established that some important reasons to measure biomass is because:

• Plants that dominate a site, in terms of biomass, are a reflection of the plants that are controlling the nutrient, water, and solar resources on the site.  Therefore, biomass is often measured to assess the ecological status of a site.

• Measures of standing crop also reflect the amount of energy stored in the vegetation, which can indicate the potential productivity at the site. Therefore, estimates of biomass are used in assessing rangeland condition.

• Estimates of biomass and residual biomass also strongly influence the hydrologic properties of the site including infiltration, runoff, and erosion.

HOW TO MEASURE IT?

The ideal way to measure biomass would be grouping all the organisms of certain population and take their weight. But since this feat is almost imposible, specially in large ecosystems, there are some methods to aproximate it:

Estadistically:

The transect method consists in selecting an imaginary line across the ecosystem, and counting the organisms that are in the area limited by this transect. That data can then be estimated using the proportion of the transect  to the rest of the ecosystem.

The quadrats metod uses a rectangular area and biomass is counted in that specific place.

These methods must consider that the selected area share almost the same conditions as the entire ecosystem in general; also, since they are estatisitics, as more times the measures are taken, most accurate will be the result of biomass.

Technologically:

Satelite monitoring is also used to measure biomass: Images generated are analyzed to determine total biomass productivity. but this method is only used with producers. An example of this technology is the MODIS Rapid Response System, developed to provide daily satellite images of the Earth's landmasses in near real time. It uses the MODIS Enhanced Vegetation Index (EVI) to shows the density of plant all over the entire globe. 

Also, in controlled ecosystems, there can be applied the Global Navigation Satellite Systems (GNSS), which is an animal tracking system which uses devices which send a signal to plot the position of an individuo of certain specie in their actual location.

ADVANTAGES AND DISADVANTAGES. 

So  to large ecosystems is better to use estatistic approaches because of their relative simpleness compared with the animal tracking system, but of course the second one will give an almost exact index of biomass of certain population. This method have also the disadventage that there can exist an organism missed and do not count in the actual register.

Some methods have the adventage of being used to both producers and consumers, such as the estatistical ones, but others are speciallized such as the satelite monitoring (focused on producers) or the animal tracking system (used mostly in consumers ).

BIOMASS IN THE ESTUARY:

After biomass is collected at different trophic levels, a biomass pyramid can be made. Here's an example of an estuary, more specifically, Chesapeake Bay. Taking the following food chain:

phytoplankton -> clams -> blue crabs -> sandbar sharks

Firstly, the units will be measured in kg per cubic kilometer, since it is a aquatic ecosystem. We can calculate the amount of each species in the food chain, and we get the following information:

There are 31,333,333 units of phytoplankton in 2320 cubic km of water in Chesapeake Bay.

There are 9,200,000 clams in that same area.

There are 278,666 blue crabs.

There is one sandbar shark.

Then, considering the weight of each specie and the area, we can calculate biomass, which then can be shown in what is known as a biomass pyramid.

Phytoplankton:78200000kg/2923km^3

Clams:7820000kg/2923km^3

Blue Crab:189100kg/2923km^3

Sandbar Shark: 59kg/2923km^3

"Why Biomass?." Principles of Vegetation Measurement and Assessment . University of Idaho, 2004. Web. 27 Aug 2010. <http://www.cnr.uidaho.edu/veg_measure/Modules/Lessons/Module%206/6_2_Why%20Measure%20Biomass.htm>.

"Measuring Biomass." Global Greenhouse Warming. N.p., n.d. Web. 27 Aug 2010. <http://www.global-greenhouse-warming.com/measuring-biomass.html>.

Biodiversity

"Biological diversity" or Biodiversity is the amount of the different species, plants and animals, that can be found within an ecosystem, biome or the entire Earth. 

As time passes by, different biodiversity indices have been created. The completest one might be the Simpsons' one. It covers dominance, diversity and evenness.

Why to measure biodiversity?

It can be a reflect of the health of an ecosystem, because is clear that an ecosystem that has a wide biodiversity have favorable conditions for life to grow, but there are some "healthy" ecosystems with a narrow biodiversity, and that's why not always biodiversity is used to measure this.

As an index, biodiversity can state the natural capital that have certain ecosystem, in terms of species living inside, which is a reflect of the synergy between biotic and abiotic factors which allow a "fertile" and suddenly stable ecosystem. Taking this, biodiversity allow humans to put a value in the natural resources provided by the ecosystem, justifying the measurement of biodiversity as a way to determine "how rich" an ecosystem is.

Biomes with major biodiversity:

Classification of living organisms.

Before enter in the classification methods themselves, we ca understand a little bit of the past and nature of classifications.

The Editorial Medica Panamericana defines classifications as "hypotheses that biologists continually test through their work, using a classification system for naming and grouping the known species in a logical, objective, consistent and not redundant manner".


Of course the base of this classifications are the characteristics that living organisms have, but... Why to organize them?


Since there are millions of living organisms, the scientists have had to group them to make easier their study: 

•  Aristotle's Classification . He consider no more than a few hundreds of species: he classify them in Animals Kingdom and Plants Kingdom; also he made a division in the first kingdom, differentiating the ones who have red blood and the ones who haven't.
• Linné's Classification. He was a Swedish botanist from the 18th century. He established a hierarchy of groups named "taxa". Each "superior taxon" involves one or more "inferior taxons".

And this is the origin of the most recognized and standardized classification of organisms nowadays: The scientific classification. It consider 8 taxons which are (from bigger to smaller):

1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus 
8. Species

It also proposes, as Linné, the binomial nomenclature, to name the organisms, which consist in call a living organism with its genus name and its specie name.

This classification of course involve a detailed observation not only phisical characteristics of organisms but also genetic characteristics, turning it in a very specific, but exclusive-scientific classification.

Turning back to the nature of classifications, some ways to group living organisms have to do with the easily identifiable characteristics that display: biped or quadruped; oviparous or viviparous; herbivore or carnivore, and those are commonly used in practical cases, unless are not as specific as the scientific classification. 

Basic Information

I understand that the course of ESS can be divided into 3 parts: one directed to explain the nature of the environment; the second one in which we study the basic activity of humans in the environment; and the third one and most important for me: the way we are linked to the environment considering the correlations between humans and nature.

In order to go to the third part, we must remember some basic information that has to do with the nature of the environment:

• A system is a set of biotic and abiotic factors that are interrelated between them. It is important to emphasize that the system also includes the relations between all those factors. 
• Some examples of ecosystems are the tundra, taiga, rainforest, desert, estuary, etc. Here in our city we have a lot of ecosystems: 

Decidious forest in Chipinque

Aquatic ecosystem of Presa de la Boca

The steppe in the northern side of the city (García, N.L.) 

• Inside an ecosystems, the biotic factors (which involve all animals, plants, bacterias and microorganisms) can be arranged in trophic levels, which are the position that an organism (representing the entire population of that same organism) occupies inside a food chain. So for example, in the ecosystem of the steppe of García N.L. there are population of short bushes, roadrunners and coyotes. Since the coyotes eat roadrunners, and the roadrunners feed from the bushes, we can state that each population occupies a different trophic level: the bushes represent the first trophic level (producers); the roadrunners represent the second trophic level (herbivores) and the coyotes represent the third trophic level (carnivores).

• Another characteristic of an ecosystem, as it was stated previously, it includes the interrelation between the factors that form it. Two of the most important interrelations are the energy and mass flow: 

In the savanna, the trophic level from a population of sequoias represent the producers organisms because they through photosynthesis can assimilate the energy from the sun light and store it to be available to the next trophic level; the same happens with the mass, as well as the energy, it is transfer from the fist trophic levels to the last one. One interesting issue is that, as the second law of thermodynamics state, only the 10% of the energy from one trophic level will be used by the upper trophic level, and it is reflected in the mass of an organism of the upper trophic levels must eat in order to get all the energy it need: since there is less energy available, an upper trophic level eat more amount of mass. So in this specific ecosystem, the savanna, a large population of producers feed a medium population of giraffes, which are eaten by just a few lions, which, at the top of the food chain, store a large amount of mass, but a small amount of energy.