Climate Limits to Vegetation

Geog403

Ecosystem: a linkage of plants (or animals) to their environment in an open system as far as energy is concerned (solar energy is absorbed and chemical and heat energy are lost).

Example: Sunlight phytoplankton carbohydrates (food substance; these food producing plants are called autotrophies) small larvae and other tiny life forms in the pond called zooplankton small fish large fish

Meanwhile plants and animals die in pond and decay, releasing chemicals back into water to be used by autotrophiesEcological efficiency: 15% of food produced by autotrophies are consumed by the next participants in the food chain, and less in a higher trophic level (loss of chemical food energy)

In Africa, Savanna, the autotrophies are grasses and other plants, next is herbivores, then carnivoresFor entire ecosystem, desert ecosystems have the lowest efficiency of all, less than 0.1%; Swamp in tropical areas have the highest 4%.

Plant successions1. Linear autogenic succession: plants themselves initiate changes in the

land surface that consequently cause vegetational changes (the order is not repeated) (example: growth of vegetation in an area that have been a lake)

2. Cyclic autogenic succession: one kind of vegetation is replaced by another, which is in turn replaced by the first or possibly the original vegetation follows a series of two or three others. (example: Tundra vegetation of grasses, sedges and bare ground willow scrubs and spruce trees developed after permafrost melt in summer; Then a layer of litters insulates ground and permafrost rebuilt)

3. Allogenic succession: outside environmental force causes vegetation change. (nuclear radiation, epidemic disease, climate change)

Final stage: climax community of vegetation: vegetation and ecosystem are in complete harmony with the soil, climate and other parts of the environment; stable amount of accumulated energy, constant stored energy of the biomass.

Vegetation distribution

Two major factors: climate and terrain

Climate factors:

1. atmosphere and its circulation system (moisture)

2. Solar radiation (energy)

Terrain factors:

1. distribution of landmass and ocean basins

2. the topography of the continents

Figure 27-1. Global distribution of the principal terrestrial biomass

Tropical rainforest: tall, closely spaced evergreen trees, great diversity in species and forms (40 species trees per hectare-2.5 acres)

Tropical savanna: transitional environmental between rainforest and desert. Tropical grassland with widely spaced trees. Bulbous plants, thorn forests characterize by dense, spiny, low trees. Deciduous, lost leaves in dry season.

Desert Biomes: (1) emphemerals, completing their entire life cycle in a single growing season. (2) Perennial-cactuses and euphorbias (spurges); Succulents: plants with fleshy water-storing leaves or stems.

Temperate grassland biomes: occurs over large continental interiors, perennial and sod-forming grasses. Corn belt, livestock farming

Temperate forest:1. Deciduous forest biomes: eastern US, Europe and

eastern China, oak, beech, birch, walnut, maple, elm, ash, and chestnuts. Agricultural activities

2. Evergreen forest biomes: western coasts in temperate latitudes where abundant precipitation js the norm.

Mediterranean scrub: shores of the Mediterranean sea, coast of California, central Chile, in south Africa’s cape province, in southern and southwestern Austria. Widely spaced evergreen or deciduous trees (pine and oak) and dense, hard-leaf evergreen scrub, thick waxy leaves are adopted to long, hot, dry summers. (Chaparral or maquis in S. Europe, or Mattoral in Chile, or Fynbos in S. Africa). Vine yards, olive groves.

Northern coniferous forest (boreal forest, snow forest or taiga: spruce, hemlock, fir and pine withstand drought resulting from long periods of freezing conditions

Tundra: most continuous of all the biomes it occurs almost unbroken along the poleward margins of the northern continents. Mosses, lichens, sedges, and sometimes dwarf trees.

30N

60N

Rainforest

desert savannarainforest

desert

Mediterranean shrub

grassland

Deciduous forest

Evergreen forest

Northern coniferous forest

Tundra

0N

90N

Climate limits for CropsWheat: grow almost anywhere due

to large varieties of species. Annual precipitation ranges from

15-45 inches, most extensively on where P not exceeds 30 inches. In humid regions, the diseases (rust, scab, mildew and leave spots) affect crop, or difficult in preparing the ground in seeding and in harvesting and caring for crops due to excessive growth and lodging.

Most cultivation in regions where frost-free period is 100 days or higher, mean summer month’s temperature at or above 57F.

A: oats;B: Barley;C: wheatD: rye

Why wheat gained its popularity?

(1) Its carbohydrates and proteins are well-balanced

(2) Produced economically with nearly complete mechanization

(3) Can be grown in a wide variety of climates throughout the world

Climate limits-rice

Rice: is of tropical origin, varieties are adopted to a wide range of climatic situations (tropical to temperate climate).

At least 4 month of mean temperature of 20°C, cannot survive freezing.

Largest rice growing area is on monsoon climate regimes; with bi-modal rainfall distribution patterns, the double cropping is practical.

For germination, needs a minimum temperature of 52-54F, for flowering, 72-73F, and grain formation 69-70F, mature days range from 120-140 days.

Climate limits-maize• Maize: cultivated second largest

areas (after wheat) among cereals. Of American origin, optimum temperature is 25°C, temperature range for growth is 15°-45°C, cannot grow where mean summer temperature is less than 66°F or mean temperature during 3 summer month falls below 55°F.

• Water requirement is 500-600mm during growth season period; P varies from 10 to 200 inches.

• Mature days range from 90-190 days.

Climate limits-othersPotatoes: favor in moist, cool

temperature and a deep friable soil. Decreases in tube production at constant temperature above 68°F and complete inhibition at 84°F, Freezing point temperature is 29°F.

Rye: more resistant to low temperature and grow further north than any other cereal.

Barley: more drought and cold resistant than wheat (survive with annual rainfall of 8 inches)

Climate limits (continue)Oats: more resistant to disease than other small

grains.Sorghum: native to tropical but is adopted to temperate

regimes. similar T range as maize but can support higher maximum temperatures; It requires frost free day of 130-140 days and long-time mean July temperature of 70F. water requirement is 400mm during growth period. It grows where is too hot and too dry for corns, but cannot produce grains without any summer rainfall.

Millet: same temperature range as sorghum, water requirement is 300-350mm during growth period.

Tapioca: originate from dry tropic and drought resistant. Adopted to a wide range of environment from swamp forest to semi-desert regions. Cultivations are occurred in relatively humid region of tropic compared with other grains.

Vegetable categoriesA. Cool-region crops that prefer 60 to

65°F and are intolerant of high summer temperature (monthly mean above 70-75F)

1. Very hardy crops that normally may encounter freezing weather without injury: (a) Cabbage and related plants: cabbage, Brussels sprouts, kale, turnips, rutabagas, kohlrabi, collards, sprouting broccoli, horseradish. (b) Spinach and beets; (c) parsnips.

2. Cool-season crops usually damages by freezing weather: (a) cauliflower and heading broccoli; (b) lettuce; (c) carrots and celery; (d) peas; (e) potatoes

Vegetables (continue)

B. Crops adapted to a wide range of temperature but not tolerant to freezing

1. Crops adapted to monthly means of 55 to 75°F and tolerant to frost under certain conditions: Onions, garlic, leeks, shallots

2. Crops adapted to monthly means of 65 to 80°F but not tolerant to frost or prolonged exposure near freezing: (a) Muskmelons, cucumbers, squash, pumpkins; (b) beans, all kinds; (c) tomatoes, peppers (some varieties); (d) sweet corn

Vegetables (continue)

C. Distinctly warm-region, long-season crops that are intolerant of cool weather (will not thrive below a mean of about 70°F).

1. Watermelons2. Sweet potatoes3. Eggplant, peppers (some

varieties)4. OkraD. Perennial crops: Asparagus,

globe artichoke, rhubarb

Fruits and nutsTemperature is the most important climatic factor

for fruit and nut crops. There are three groups based on their climatic requirements

1. Strictly tropical fruits and nuts. Fail to withstand freezing temperatures and injured by prolonged exposure to T many degrees above freezing. Examples: bananas (only adopted to above 50°F), breadfruit, mangoes, papayas, durians, animas, sapotes, and mongosteens; coconuts, Brazil nuts, and cashews. (coffee and cacao, pineapples adopted slightly cooler conditions)

Fruit and nuts (continue)

2. The subtropical fruits: endure temperatures slightly below freezing without injury; require some cool weather for proper development (do not grow well in strictly tropical climates).

Oranges, grapefruit, lemons, limes, kumquats, cherimoyas, avocados, litchis, jaboticabas, olives, figs, and dates.

Fruits and nuts (continue)3. The hardy fruits: produced on

deciduous trees or bushes that during the dormant season go into a rest period, which it takes a period of cold weather to break. They are unadapted to tropical climates because of their requirement of a period of cold. Apples, peaches, pears, cherries, plums, and prunes, grapes, apricots, blackberries, and raspberries (strawberries are evergreen plants, only semi hardy).

Agricultural revolution and domesticationWhen (b.c.) Where What

10,000 Southwest Asia Wheat, barley, sheep, goats domesticated

8000 Mexico Chiles and squash domesticated

8000 Peru Lima beans domesticated

7000 Southwest Asia Bread wheat developed; flax for fabric

7000 Southwest Asia and New Guinea

Pigs domesticated

6000 Northern China (first agriculture in China)

Millet domesticated

6000 Middle East Apples cultivated

6000-4000 Southwest Asia (modern Armenia)

Grapes cultivated for wine

5000-6000 Southwest Asia Cattle, chickpeas, lentils domesticated

5000 Yangtze River delta, China; Central India

Rice domesticated

4000 Southwest Asia Olives domesticated

3000 Southwest Asia Cities, irrigation, wheel, plow, sail

2686-2181 Egypt Pyramid building

2500 China Water buffalo domesticated

Food Categories

Based on Bangladesh, there are five food categories

A. Strength giving foods: general refer to rich protein food or vitamin and nutritious food. Examples: butter, milk, big fish and fish heads, young chicken, sheep’s head, etc. Sometimes, rice depending on how it is prepared (not eat alone). Also, almonds, cashews, pistachios, currants, and raisins are considered as strength giving food.

B. Blood producing foods: the food that has ability to replenish blood supply in the body. These include certain types of fishes that can stay alive a few days in a small amount of water after caught (because they have visible evidence of blood in their body). Examples are Shing, Magur, koi (Bangladesh naming).

Food Categories (continue)C. Hot and Cold foods: It is believed that the balance of

forces within an individual is essential for the physical and mental health of a person, and the imbalance caused through overheating or over-cooling of the body resulting from eating of “hot” and “cold” foods may result in illnesses or aggravate the existing imbalance. Cold foods include chicken, mutton, citrus fruits, mango, lentils, yoghurt, etc. Hot foods include beef, duck, jackfruit, lichees, shrimp, milk. In general hot foods are considered to be hard to digest and more harmful than cold food. Contrary to Bangladesh, hot foods in Mexico are believed to be more digestible.

D. Fault and disease free foods: hot or cold exist in balanced proportions (so neither hot nor cold). They include most vegetables except pumpkins, eggplants, and a few others.

E. Bitter foods: the local medicines. Old saying “eating of bitter-tasting foods prevents diseases and cleanses the blood”. They include bitter tasting vegetables like karolla (bitter melon) and uste (varieties of bitter gourds). They are believed to prevent illness especially during summer time.

Why its cool to like it hot

Hot comes from Wasabi root, fresh ginger, horse radish, mustard seed or grinded pepper, chilly pepper

Hot and spice are two different sensation:Hot is physical reaction in the mouth that causes burning feeling

Spicy is sensed in the nose

Why hot is good?1) “burn” created by capsaicin (an ingredient in chilly pepper) activates pain

receptors in the mouth, which causes the brain to release endorphins (‘feel good’) chemicals that may produce a brief high.

2) Capsaicin also can turn on appetite-suppressing brain cell (people tend to consume less calories)

3) Hot dish may temporary boost adrenaline to temporary speed up metabolism and stimulate the breakdown of the fats

4) Capsaicin helps us sweat by activating the body’s natural cooling system.

(Parade Magzine, Nov 16,2003, p22)