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									Lecture 39
There are dramatically apposing attitudes
towards the tropics, both anti- and pro-
tropic sentiments:

 Salubrious and balmy vs. Hot and steamy
Cruise ships, waving palms vs. Poisonous snakes & crocs
Resorts & retirement havens vs. Slums & shacks
Birth of civilization vs. Uncivilized
Green and bountiful vs. Starvation & malnutrition
Rich in flora vs. Monotonously green
Beverage Crops


    Coffee       Tea
          Fruits and Nuts

Avocado       Citrus        Banana & Plantain

Date          Papaya              Pineapple
          Starchy vegetables
Cassava                          Sweetpotato

  Taro                         Yam
Industrial Crops

   Rubber tree     Coconut

Rice             Sugarcane

Cinnamon   Nutmeg

   Clove    Vanilla   Ginger   Pepper

Orchids         Plumeria        Poinsettia

 Streletzia   Philodendron   Bougenvillia
Celestial Mechanics
Revolution is the movement of the earth in an elliptical
  orbit around the sun whose average distance is 93
  million miles away. The time to travel 1 orbit = 1
  year. During this time there are 365.25 rotations of
  the earth.

Theory of the
Symbol Major climate     Chief characteristic   Subclimates (incomplete)
A       Tropical rainy   Coolest month          Af, tropical rainforest
                         above 18°C (64.4°F)    Am, monsoon rainforest
                                                Aw, tropical savannah
B       Dry              Evaporation            BS, steppe
                         exceeds                   BSh, tropical and subtropical steppe
                         precipitation             BSk, middle latitude steppe
                                                BW, desert
                                                   BWh, tropical and subtropical desert
C       Humid, mild-     Coldest month          Cs, Mediterranean (dry-summer subtropical)
        winter           between 18°C               Csa, hot-summer Mediterranean
        temperate        (64.4°F) and 0°C           Csb, cool-summer Mediterranean
                         (32°F)                 Ca, humid subtropical (warm summer)
                                                    Caw, with dry winter
                                                    Caf, with no dry season
                                                Cb, Cc, marine west coast (cool summer)
D       Humid,           Coldest month      Da, humid continental, warm summer
        severe-winter    below 0°C (32°F);     Daw, with dry winter
        temperate        warmest above 10°C    Daf, with no dry season
                         (50°F)             Db, humid continental, cool summer
                                            Dc, Dd, subarctic
E       Polar            Warmest month          ET, tundra
                         below 10°C (50°F)      EF, icecap
Forests are stratified, typically 3 layers or strata.

Clays are the “life blood” of the soil due to the active
  exchange mechanism of bases.

Clays differ in tropics and temperate climates
  Temperate clays: Montmorillonite (2:1 layer)
  Tropical clays:       Kaolinite (1:1 layer)
Nutrient Recycling
 Net Photosynthesis as a Percent of Af Climate

                                  Ca        D
                         Cs      (Mild    (Severe
Time           Af   Aw (Medit) temperate) winter)
Entire Year   100   105  117      91        68
8 months
              100   106   127      123      101
4 months      100   109   136      133      152
Agriculture in Tropical Systems
Upland rice clearing in forest for rice, Maranhao
Cerrado Burning, Brazil
Themes in Tropical Agriculture
  Norman E. Borlaug, 1970 recipient of the
 Nobel Prize for Peace, working with hybrid
wheats at the CIMMYT Toluca station, Mexico.
Lodging susceptible and resistant rice
Cacao fruit and dry beans
Through fermentation
and drying, the cacao
pod’s pulp-surrounded
seeds are converted into
nibs ready for roasting
and grinding into
chocolate liquor.
Rice paddy near Bandung, West Java, Indonesia
Sugar Mill, Ponte Nova, Brazil, 1963
Oil palm, Elaeis guineensis
  Originates to west and
  central Africa
  An unbranched
  moneocious palm; 40–50
  leaves (24/year), 10–11m
  at 25 to 35 years.
  A drupe with fleshy
  mesocarp and hard
  endocarp which surround
  1, usually 2, and
  occasionally 3 seeds.
Flower Type
The flower type shows a relationship to fruit shape.

       I         II      III      IV        V

              Papaya flowers, Hawaii
Valencia Orange, Israel
Nucellar polyembryony in Citrus
Avocado varieties, Israel
Bird of Paradise
Anthurium, Hawaii
Elephant pod
Double Poinsettia

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