Key question 11. The biotic and abiotic factors, which control the distribution of the

world’s major biomes.

Key factors that determine an areas climate are incoming solar energy, the earth’s rotation, global patterns of air and water movement, gases in the atmosphere, and the earth’s surface features. These differences in long-term average annual precipitation and temperature lead to the formation of tropical, temperate, and cold deserts, grasslands, and forests as well as largely determine their location.

2. A survey of the global system followed by a study of the distribution of the following biomes:

a) tropical rainforest:abiotic factors: Tropical rain forests have warm climates and are very humid. Mean monthly temperatures exceed 18 °C during all months of the year. It is wet and moist year round as the rainfall is frequent and typically heavy. There is no dry season. All months have an average rate of precipitation of at least 60 mm. The soil is often poor because the heavy rainfall results in the leaching of soluble nutrients in the ground. Tropical rain forests rarely extend more than 10 degrees north or south of the equator. Tropical rain forests are divided into layers (from top to bottom): the emergent layer, the canopy, the understory, and the forest floor.biotic factors: Tropical rain forests are full of life with approximately 15 million different species of plants and animals. Plants like bamboo and tropical fruit trees provide oxygen and food for the animals. Fruit eating animals, like birds and bats, help pollinate plants and spread seeds. Carnivores like jaguars and snakes eat smaller animals. Insects, fungi, and bacteria break down dead materials and return nutrients to the soil. 

b) Monsoon Rain Forest: The tropical monsoon climate experiences abundant rainfall like that of the

tropical rain forest climate, but it is concentrated in the high-sun season.Being located near the equator, the tropical monsoon climate experiences warm temperatures throughout the year.

The monsoon climate lies beyond the equatorial region both north and south of the equator. The countries are along the coastal regions of southwest India, Sri Lanka, Bangladesh, Myanmar, Southwestern Africa, French Guiana, and northeast and southeastern Brazil.

The major controlling factor over the monsoon climate is its relationship to the monsoon circulation. The Monsoon is a seasonal change in wind direction.The “classic” monsoon circulation of Asia exhibits an onshore flow of air (air moving from ocean towards land) during the summer or high-sun season, and offshore airflow during the winter or low-sun season. The change in direction is due to the difference in the way water and land heat.

c) Tropical savannah: Also known as the savanna, this tropical grassland contains widely

scattered clumps of trees such as acacia, which are covered with thorns that keep herbivores away. Savanna plants, like those in deserts, are adapted to

survive drought and extreme heat; many have deep roots that can tap into groundwater.

This biome usually has warm temperatures year-round and alternating dry and wet seasons.

Tropical savannas in East Africa are home to grazing and browsing hoofed animals such as wildebeests, gazelles, zebras, giraffes, and antelopes as well as their predators. These predators include lions, hyenas, and even humans. Herds of these grazing animals migrate in search of water and food in response to seasonal variations in rainfall and food scarcity.

e) Temperate deciduous:These forests grow in areas with moderate average temperatures that

change significantly with the seasons. These areas have long, warm summers, cold but not severe winters, and abundant precipitation spread evenly throughout the year.

This biome is dominated by a few species of broadleaf deciduous trees such as oak, hickory, maple, polar, and beech. They survive cold winters by dropping their leaves in the fall and becoming dormant through the winter. Each spring, they grow new leaves whose colors change in the fall into an array of reds and ranges and then drop.

Because they have cooler temperatures, and fewer decomposers, these forests have a slower rate of decomposition than tropical forests have. This results in a thick layer of decaying leaf litter on the forest floor, which acts as a storehouse for much of the biome’s nutrients.

f) High latitude tundraThese biomes lie south of the arctic polar ice cap. These treeless plains are

cold, swept by frigid winds and covered with ice and snow. Winters are long with short days, and the precipitation it does get falls as snow.

Underneath the snow lie low-growing plants such as grasses, mosses, lichens, and dwarf shrubs. Trees and other tall plants are unable to survive in the cold and windy tundra as they lose too much heat. The majority of the tundra’s annual plant growth occurs during the 7-8 week summer when the sun shines almost around the clock.

The tundra soil is nutrient poor and the short growing season means that growth and recovery is very slow. One key characteristic of the tundra is permafrost. This is underground soil in which captured water stays frozen for more than 2 years at a time. This permafrost prevents melted ice and snow from draining into the soil during the brief summers, resulting in the formation of small lakes, marshes, bogs, ponds, and other season wetlands.

Hordes of mosquitos, black flies, and other insects thrive in these environments. They are in turn, a food source for many insect-eating birds that return to the south to breed. Animals in this biome survive with the help of adaptations such as thick coats of fur, and feathers and living underground. d) desert: 

abiotic factors: Deserts are hot, barren areas of land where little precipitation occurs and very little moisture is in the air. Mean annual temperatures range from 20-25 °C. Maximum temperatures ranges from 43-49 °C. Minimum temperatures, usually during the night, sometimes drop to -18 °C. Deserts generally receive less than 25 cm of precipitation a year. Deserts are also described as areas where more water is lost by evapotranspiration than falls as precipitation. Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks, which consequently break in pieces. Deserts typically contain a lot of sand, which is broken down rock.

biotic factors: The biodiversity of deserts are very low compared to other biomes because the harsh living conditions are hostile for plant and animal life. Plants and animals living in the desert need special adaptations to survive in the harsh environment. Types of plants include various forms of cacti, tumbleweeds, and poppies. The lack of vegetation exposes the unprotected surface of the ground to the processes of erosion and denudation. They typically can retain water for long dry periods. Types of animals include rabbits, lizards, snakes, and coyotes. Most animals are only active at night when the hot sun has set. 

3. The two contrasting case studies should be chosen from these. Whilst a biome can be considered a global scale ecosystem, ecosystems occur on a variety of scales within broad vegetation zones. 

Tropical rain forests and deserts have some similarities, but are generally very different. Rain forests have poor soil that is low in nutrients because the rain beats down on it, but deserts only have sand which contains no nutrients. Rain forests and deserts are both warm, but deserts are on average hotter. Rainforests get 60 mm of average precipitation while deserts get 25 cm of precipitation a year. Rainforests have very high biomass and biodiversity because it supports 15 million different species of plants and animals, while deserts have very low biomass and biodiversity because the harsh environment is hostile to plants and animals. Rainforests have a net primary product of 9000 kilocalories/ square meter/ year, while deserts have less than 200 kilocalories/ square meter/ year.

4. Photosynthesisa) Photosynthesis is a process used by plants and other organisms to convert

light energy, normally from the Sun, into chemical energy that can be later released to fuel the organisms' activities. The requirements are carbon dioxide, water, light and chlorophyll.

b) Visible light ranges from low blue to far-red light and is described as the wavelengths between 380 nm and 750 nm. The region between 400 nm and 700 nm is what plants use to drive photosynthesis and is typically referred to as Photosynthetically Active Radiation (PAR). There is an inverse relationship between wavelength and quantum energy, the higher the wavelength the lower quantum energy and vice versa. Plants use wavelengths outside of PAR for the phenomenon known as photomorphogenesis, which is light regulated changes in development, morphology, biochemistry and cell structure and function. Plants also use multiple variants of chlorophyll, as well as accessory pigments such as carotenoids to tune themselves to absorbing different wavelengths of light. That makes it impossible to assign a single wavelength of best absorption for all plants. All plants, however, has chlorophyll a, which absorbs most strongly at approx. 450 nm, or a bright blue color. This wavelength is strong in natural sunlight, and somewhat present in incandescent lights, but is very weak in traditional fluorescent lights. Special plant lights increase the amount of light of this wavelength that they produce. But a 400-500 nm wavelength bulb wouldn't be enough, since many plants take cues for germination, flowering, and growth from the presence of red light as well. Good plant lights produce

red light as well; giving plants all the wavelengths of light they need for proper growth.

c) At low light intensities, as light intensity increases, the rate of the light-dependent reaction, and therefore photosynthesis generally, increases proportionately (straight line relationship). The more photons of light that fall on a leaf, the greater the number of chlorophyll molecules that are ionized. At a very high light intensity, chlorophyll may be damaged and the rate drops steeply. Although the light dependent reactions of photosynthesis are not affected by changes in temperature, the light independent reactions of photosynthesis are dependent on temperature. The amount of light will affect the rate of photosynthesis. If there is no light, there will be no photosynthesis. As light intensity increases, the rate of photosynthesis will increase as long as other factors are in adequate supply. As the rate increases, eventually another factor will come into short supply.

KQ1b. What are the main components and characteristics of ecosystems and how are they structured?

b. Monsoon Rain Forest:a. Fertile Soil, typically waterloggedb. Monthly mean temperature of 18 Cc. Average Low: 60 mm of rain/ Average High: 100 mm of raind. Canopy receives large amounts of sunshine however lower levels of forest

receives little to no sunshine due to the amount of cover they receivee. 2200 Mean Net Primary Productionf. Plants hold all the nutrients, not the soil, therefore, succession relies on plant

lifeg. 140 tC/hah. 4200 known plant species that live in Monsoon Rain Forests, 400 known

animal species that live in Monsoon Rain Forests

i.

j. Various habitats and niches due to the forests microclimates places with a variety of temperatures, shady and summer areas, moister and drier areas, and son. The trees provide habitats from climbers, vines, insects, and arboreal animals. The forest growth cycle provides yet more habitats – differing sizes of gaps in the forest, variations in the forest canopy cover, differing fruit cycle, and on and on.

c. Tropical Savannaha. Soil is more fertile near south-east sector of savannas while in the north-west

there are infertile deep sandy soilsb. Average temperature is around 75 F to 80 Fc. Average rainfall is between 30- 50 inches per yeard. Lots of photosynthesis due to little tree cover in savannahse. 900 Mean Net Primary Productionf. In the savannah, primary succession would most likely occur in the event of a

major volcanic eruptiong. 326 tC/ha

h. 400 known species of plant species live in savannah/ 300 known animal species live in savannah

i.

j. Since savannah’s are for the most part, grasslands and so most animals stay under the shade of the few trees or live underground

e. Temperate Deciduousa. As leaves decompose, the nutrients contained in the leaves are absorbed

by the soil. For this reason the soil of this biome tend to be very fertile. Growing season tends to be 5 to 6 months long

b. 50 F averagec. 30- 60 inches per year on averaged. Canopy receives large amounts of sunshine however lower levels of

forest receives little to no sunshine due to the amount of cover they receive

e. 6000 Mean Net Primary Productivityf. Lichens have the ability to give off acid which will degrade rock to form

soil creating lifeg. 325 tC/hah. Over 500 species of plants/ over 400 species of animals

i.

j. Some habitats include the trees where insects as well as birds live, the forest floor where larger mammals such as bears live, and the soil where insects and bacteria live.

Tropical Rain Forest

A) Most tropical rainforest soils relatively poor in nutrients. Millions of years of weathering and torrential rains have washed most of the nutrients out of the soil, and it has less organic matter than temperate forests.

B) The temperature in a rain forest rarely gets higher than 93 °F (34 °C) or drops below 68 °F (20 °C)

C) An average of 50 to 260 inches (125 to 660 cm.) of rain falls yearly.D) The billions of leaves of the canopy, acting as miniature solar panels, provide the

source of power for the forest by converting sunlight to energy through photosynthesis.

E) 9000 Kilocalories/ square meter/year F) Primary: flooding happens quite often from the profuse rain. This strips the

topsoil, so the environment must create new. Secondary: Farmers in the rainforest cut down large areas of trees to grow their crops and after a few years the soil becomes infertile. After the farmer moves, secondary succession sets in, fertilizing the soil and growing small plants and trees again until the forest, after hundreds of years, has grown back.

G) Woody tissues of trees account for about 80 percent, another 15 percent of the organic matter occurs in soil and litter and 5 percent foliage.

H) No one knows exactly how many species live in the world's tropical rainforests — estimates range from 3 to 50 million species — rainforests are the undisputed champions of biodiversity among the world's ecosystems, containing far higher numbers of species on a per-area basis relative to sub-tropical, temperate, and boreal ecosystems.

I)

J) Above the canopy, in the top canopy, in the understory, in the lower part of the forest, or on the ground. Of course, there are horizontal niches as well, and there are many other niches in rivers and lakes, in flooded, cloud,

Desert

A) Most desert soils are called Aridisols (dry soil). However, in really dry regions of the Sahara and Australian outback, the soil orders are called Entisols. Entisols are new soils, like sand dunes, which are too dry for any major soil horizon development.

B) The average daytime temperature is 100°F, while at night the average temperature is 25°F.

C) Less than 10 inches, or 25 centimeters, of precipitation a year.D) CAM photosynthesis or Crassulacean-Acid metabolism is the type of

photosynthesis that is most common in desert plants where water is at a premium. In CAM photosynthesis, CO2 is taken up only at night and is stored in vacuoles.

E) < 200 Kilocalories/ square meter/yearF) Primary: could occur on a sand dune or a fresh lava flow. Bacteria or seeds of

colonizing species find a foothold where a microclimate offers a pocket of

increased moisture and protection. These original colonizers form biofilms and put down roots that stabilize the upper layer of soil and break down rocks. The improved soil can hold more moisture and support other plants, which crowd out the original colonizers. Eventually the ecosystem may be able to support grasses and finally woody shrubs, if there is enough water. Secondary: fire, flash flood scouring or land clearing can disturb Desert ecosystems. After disturbance, succession is set back, but the soil has already been developed. Secondary succession in deserts is relatively quick compared to primary succession, but it takes much longer to establish a desert community than it does in less arid regions.

G) Desert ecosystems have the lowest biomass on Earth, but that does not mean that deserts have zero biomass. On the contrary, desert biomass includes unique organisms often found nowhere else on earth.

H) Desert species diversity is very much dependent on rainfall and vegetative cover, with the fewest plant and animal species in the driest deserts.

I)

J) Some desert habitats are short-lived—springing up to brighten the landscape only when the rains come.

High Latitude Tundra

A) The tundra is a very unique landscape, with freezing and thawing creating unique patterns in the ground. During the summer, water can accumulate underground, then freeze, which drives the soil upward into a small hill call a Pingo.

B) The average winter temperature is -34° C (-30° F), but the average summer temperature is 3-12° C (37-54° F) which enables this biome to sustain life.

C) Rainfall may vary in different regions of the arctic. Yearly precipitation, including melting snow, is 15 to 25 cm (6 to 10 inches).

D) Vascular plants are generally assumed to have no photosynthetic activity under the snow because of the severity of the subnivean environment. In the arctic tundra, snow cover persists into the spring after air temperatures and light increase to levels suitable for photosynthesis of vascular plants in the absence of snow cover. We found significant photosynthetic activity in four arctic evergreen species under springtime snow.

E) 600 Kilocalories/ square meter/yearF) When glaciers started to melt, they left behind rocky land with no fertile soil.

Over time, lichen started to grow on the rocks, slowly breaking them down and allowing more plants to grow. Ecological Succession Secondary Succession: Because the tundra is so dry, when lightning strikes, wildfires have been known to start. Over time, new plants and mosses grow over the ashes of the previous inhabitants.

G) The amount of native tundra biomass depends more on the local temperature than the amount of precipitation.

H) In the tundra, very few plants grow due to the lack of nutrients and because the ground is frozen beneath the top layer of soil. The only vegetation that grows there are shrubs, sedges, mosses, lichens, grasses, and a couple of birch trees and willow trees. There are 48 different species of land mammals in the tundra. These consist of hares, rodents, wolves, bears, foxes, and deer. There are also carabou, oxen, polar bears, and wolverines. Some of the insects in the tundra include black flies, deer flies, and mosquitoes. The mosquitoes have adapted to the cold environment by replacing the water in their bodies with glycerol to keep themselves from freezing.

I)

J) The animals of the Arctic live through freezing weather and manage to find shelter, food and safety, and carve out breeding periods, all in an area where many creatures would surely freeze to death.

2. The Interaction of these components to be illustrated through relative size of the flows and stores of nutrients between vegetation, litter, and soilA) Tropical Rainforest

B) Monsoon Rainforest

C) Tropical Savannah

D) Desert High rates of decomp and High amount of bio mass info litter

E) Temperate Deciduous

F) High latitude Tundra