Human Transformation of Land Resources

1
Human Transformation of Land Resources

• Discussion 16
• (modified from Prof. S. Kung)

2
Impact of Human on Land Use, Soils, and
Environmental QualityA. IntroductionB.
Agricultural Revolution C. Industrialization
3

• History of Human Population
• From 150,000 to 10,000 years ago, while hunting
  and gathering were the dominant life style, human
  population followed the rule that governed the
  populations of all species and fluctuated around
  a natural mean (5 millions).

4

• Archaeological evidence indicates that, about
  10,000 years ago, humans learned to farm and
  started to settle in different parts of the
  earth.
• This was the result of (1) domesticating certain
  plants and animals and (2) domesticating certain
  animals as power source and (3) inventing
  shelters, wheels, and tools such as plows for
  tillage.
• Since then, human population has been steadily
  increasing.

5
Evidence of Domestication of Plants Animals
6
Major Domesticated Plants

• Time (1000Y) Location Plant
• 10.7 - 9.8 Mexico squash,
  pumpkin, gourd
• 10 - 9.3 Jericho/Syria wheat, two-row
  barley
• 9.8 - 8.6 Fertile Crescent wheat, bean,
  pea, oat
• 8.0 - 7.0 north China millet, gourd,
  soybean
• 8.0 - 7.0 central China rice
• 9.4 - 9.2 Andes pepper, bean,
  potato, cotton
• 10 - 3.5 Africa millet, dry rice, melon
• 4.5 Indus Valley cotton

7
In natural ecosystems, food sources are scattered
and diversified. Therefore, the hunting and
gathering life-style naturally provides a
balanced diet and encourages dispersion and
migration.  In contrast, because of farming,
people in agricultural systems tend to congregate
into communities. People living under
agricultural systems have a more limited variety
of foods. Trading becomes essential to maintain a
balanced diet and enhances the development of
society.
8
Small tribal governing bodies were initially
established to regulate the survival/stability of
society. Concentrated power from organized
labor enabled humans to expand territory, conquer
lands, and convert more natural ecosystems into
agricultural systems.  More stable food
supplies from agriculture increased human
population.  Larger populations required larger
kingdoms and governments.  Strengthened by this
positive feedback loop, humans gradually became
de-coupled from the natural ecosystem in terms of
food supplies.
9

• After agricultural revolution, human population
  was no longer governed by the natural balance
  within a food-chain of an ecosystem.
• The limiting factors hindering human population
  growth were competing species such as
  weeds/microbial/insects/rodents/ carnivores,
  major drought events, wars, diseases, limited
  labor, and soils natural productivity (i.e.,
  capacity to hold nutrients
• and water).

10
(No Transcript)
11

• From 4000 BC to 1650 AD, it was estimated that
  the worlds cultivated lands increased from 93 to
  265 million hectares.
• Animal-based power systems and biomass-based
  fueling system were the main limiting factors for
  humans to convert natural ecosystems into
  agroecosystems.

12

• It was estimated that the human population
  increased approximately from around 5 million in
  8,000 BC to 250 million in 0 BC and to 500
  million in 1650 AD.

13

• Since industrial revolution, energy resources
  have evolved from animal- and biomass-based, to
  wind- and hydraulic-based, to coal-based, to
  fossil fuel-based, to nuclear fission-based
  systems.
• The average annual energy consumption of an adult
  human is 4 GJ from food.  The average annual
  energy consumption per capita in U.S. in 2000 was
  400 GJ.

14
Energy consumption per capita for selected
countries Consumption in 2005 (106
tonnes) USA 945 (1st) China 327 (2nd)
Japan 244 (3rd) India 116 UK 83
Source BP, 2006
15
With more energy resources, humans have became
more able to mine and refine other natural
mineral resources for food production, habitat
expansion, and technological advancement. With
mechanized power, the world cultivated lands
increased from 265 million hectares in 1700  to
1750 million hectares in 1990. Since 1930,
medical science and technology has significantly
suppressed the human death rate caused by
diseases. The development of irrigation and
fertilization systems from extra  energy
resources further alleviated the water and
nutrient shortages as limiting factors in food
production.
16
1950 1991 2005 Oil production (million
b/d) 10 590 811 Natural gas production (trillion
ft3) 7 77 97 Cultivated Cropland (million
ha) 1170 1750 Irrigated area (million
ha) 94 235 278 Fertilizer use (million
tones) 14 136 145 Pesticide use (million
pounds) 50 750 Grain production (million
tones) 630 1700 1821 Soybean production (million
tones) 18 106 190 Meat production (million
tones) 46 173 242 Fish catch (million
tones) 22 97 95 Human Population
(million) 2565 5409 6400
Sources BP, Earth Policy Inst., WorldWatch
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
The rate of human population increase was
greatest during the 40-year period from 1950 to
1990, when synthesized pesticides (e.g.,
Herbicides, Fungicides, Insecticides, Acaricides,
Nematicides, Molluscides, Rodenticides ) were
introduced to suppress all other species
competing for food in agricultural systems. 
During this period, human population had
increased from 2,565 millions to 5,409 millions
(approximately 1.9/yr increase) and cultivated
crop land increased from 1,170 million hectares
to 1,750 million hectares.
21
Top 12 Pesticides Used in US For Corn Production
in 1991 (pounds) COMPOUND Applied COMPOUND
Applied ATRAZINE 53,796,206
METOLACHLOR 41,546,112 CYANAZINE 26,569,313 ACETOC
HLOR 23,841,035 ALACHLOR 13,902,747 EPTC 9,102,
979 BUTYLATE 7,648,802 DICAMBA 6,907,941 CHLORPYR
IFOS 6,710,506 TERBUFOS 6,497,298 2 4
D 4,550,447 PENDIMETHALIN 3,957,004 Total 230,
274,593
22
As a result of industrial revolution, the human
population exploded from 550 million in 1700 to
6400 million in 2005 (approximately 0.77/yr
increase).
23
(No Transcript)
24

• The current rate of global human population
  increase and habitat expansion is unparalleled in
  the earth's 4.6 billion years history.  (Even
  dinosaurs, which prospered and dominated the
  Jurassic period for over 100 million years,
  depended completely on the natural ecosystems to
  survive.)  
• What is the long-term impact of 10,000 yr
  history of human de-coupling from natural
  ecosystems on its own survival?

25

• Lessons Learned from Old Civilizations
• Is there any lesson to be learned from the
  burst/bust of several old civilizations?

26

• Sumerians settled and cultivated the fertile
  lands along the lower valley of the Euphrates and
  Tigris Rivers in the Mesopotamia around 3,500 BC.
  
• They invented wedge-shaped writing language
  called cuneiform.  Their remarkable
  ingenuity/accomplishments included wheeled
  vehicle, yoke, plow, sailboat, potter's rotary
  motion, waterwheel.
•   They were the first generation who had much
  more energy resources than their ancestors and
  neighbors.  As a result, they suddenly increased
  their population and developed one of the first
  human culture as well as an empire dominating the
  Two-River regions.

27

• Sumerians were completely replaced by Akkadians,
  who built a larger empire in the upper valley of
  the Eupharates and Tigris Rivers. However, the
  Akkadian kingdom was not long-lived either.
• It is unclear exactly why these early empires
  tumbled. Generally, it is believed that they
  developed intensive farming systems for food
  production and systematically destroyed
  surrounding forests for building materials,
  weapons, and metallurgical purposes. 
• As a result, soil erosion and salinity of both
  water and soil quickly deteriorated soils and
  environmental quality of their habitats along the
  Two-River valley. 

28

• Because both Sumerians and Akkadians completely
  de-coupled themselves from natural ecosystems and
  depended exclusively on agricultural systems for
  their food supply, the population collapsed when
  soil quality quickly deteriorated. 
• Similar stories occurred in other old
  civilizations in other parts of the world.

29
The Incas were the rulers of the largest native
empire of the Americas. The empire controlled an
estimated 12 million people in much of what is
now Peru ,Colombia, and Ecuador as well as in
large parts of Chile, Bolivia, and Argentina. The
Cuzco valley was the capital of the empire. At
its height in the fifteenth century, the empire
thrived by developing an economy based on an
intensive terracing of mountain slopes and
irrigation. The empire ended abruptly in
1500's.
30
Cuzco Valley, SA
31

• In ancient times, people could always move
  around to find new fertile lands, to settle and
  repeat the burst/bust cycle of civilization. This
  occurred as long as the agricultural systems and
  human habitats were only a very small fraction of
  the total global land surface.
• However, we now have reached a point where more
  than a third of the total global land has been
  significantly altered by human activities. Humans
  have now cultivated about half of the total
  arable land of the earth.
• In other words, there is not much fertile virgin
  land left for humans to continue the
  experimentation of the burst/bust cycle.

32

• Earth with the most diversified ecosystems, the
  most diversified species within an ecosystem, and
  the most diversified genetic pools with a species
  ensures (1) multiple pathways for the maximum
  cycling of energy and elements to support life
  and (2) large varieties/forms of life for the
  optimum capacity to cope with changes and
  stresses. In short, bio-diversity favors the
  ultimate safety for the collective survival of
  all living organisms.

33
According to Vitousek et al. (1986), about 40 of
all global terrestrial primary production of
photosynthesis have been appropriated by humans.
Top Five Major Crops Occupy About 90 of the
Global Agricultural Fields. Crop million
ton wheat 563.65 corn 526.42 rice
525.48 potato 268.49 barley 160.13 What
would happen if certain pathogens cause the total
collapse of these crops?
34
Before Ind Rev
Today
35
Time Scale of Earth History4.6 x 109 y Earth
Formation 365 days3.5 x 109 y Primitive Life
278 days550 x 106 y Complex Life in sea 44
days245 x 106 y Permian-Triassic boundary 19
days 20 x 106 y Six major Ecosystems 1.6
days 2 x 106 y Ecosystems Matured 3.8 hours
100,000 y Modern Human Appeared 10
minutes10,000 y Agricultural Revolution 69
seconds300 y Industrial Revolution 2
seconds
36
Conclusions