| Trophic
Levels
Introduction
Land
Use
As
the population of the world increases, there will be ever more pressure
on our environment to produce food. One issue that will begin to
garner a lot of attention will be land use. As stated in the book,
the amount of energy available at trophic level of the ecosystem
decreases as one moves from herbivores to carnivores. This decrease
in the amount of energy corresponds to a greater amount of land
that needs to be used in order to create the food at each trophic
level. As a general rule, the amount of plant material that can
be grown on a piece of land is about ten times the amount of meat
in weight that can be raised on the same amount of land. While meat
is somewhat higher in energy density than plant material, it still
means that the number of calories per acre of land is about 5 times
more for things like grain than for meat. A good estimate for meat
is about 1,200 calories per acre per day while about 6000 calories
of grain can be produced per acre per day. Thus, if a person were
to consume a diet of 1000 calories of meat and 1500 calories of
grain each day, they would need approximately 1.1acres of land on
which to grow their food; someone that consumes 500 calories of
meat and 2000 calories of grain each day only requires .75 acres
for the same amount of energy.
Grain
Versus Beef
These examples exhibit one of the differences between eating a diet
with a larger proportion of meat and one with a larger proportion
plant matter. Historically, third world countries, which contain
the largest percentage of the world's population, have subsisted
on a diet that derives very little of its calories from meat products.
While there are other factors for this, one of the prime reasons
is the lack of available land on which to grow enough meat. In the
U.S., we do not have this land problem, and our diet reflects this.
About one third of the calories in our diet come from animal sources.
If the population continues to increase, this situation may have
to change in the future.
Of course, there are other differences between meat-based and plant-based
diets besides just the amount of land that is required to produce
them. Questions regarding the healthiness of these two types of
diets have raged for years. Proponents for both vegan and omnivorous
diets claim that their diets provide for a healthier lifestyle than
the other. Some of the links below go to websites that discuss these
pros and cons, as well as providing nutrition data about what a
healthy should be like.
Dietary Information
USDA Nutrient Data
Lab
FDA
Food Label
Pro-Vegetarian
Veganation
Meat.org
Vegan.com
Vegan.org
Pro-Meat
People Eating Tasty Animals
Beef.org
National
Meat Association
National Pork
Board
After reading through these and any other sites that you might find,
answer the following questions
- Reviewing what you have consumed over the last several days,
about how many calories are you averaging per day? Is this normal
for you?
- About what percentage of your dietary intake comes from animal
sources?
- Some people state that a vegetarian diet is unsafe since it
does not provide all of the nutrients necessary for a healthy
individual. Is this true? If it is not true, are there special
measures that a vegetarian would have to take in order to insure
that they got the proper nutrients? If it is true, what harm will
befall vegetarians for following their diet?
On
your next trip to the grocery store, check out the nutrition labels
from several manufacturers on food products that you buy. Take
note of the serving size, as well as the caloric, fat, protein,
and carbohydrate content of the food. Be sure to look for varieties
of food that have special labels such as "Lite", "Healthy",
"Lean", "Reduced", etc.
- Is
there a big difference in the caloric content of the food from
different manufacturers? What about the fat, carbohydrate, and
protein content?
- Is
there a difference between the foods with special labels and those
that do not have these labels? If so, how do they differ?
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