Vegetation Print Handout

7/28/2019 Vegetation Print Handout

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Ecosystems fall into 2 major categories:

Aquatic & TerrestrialTerrestrial ecosystems which are dominated by land plants spread widely over upland surfaces of the

continents.

The terrestrial ecosystems are directly influenced by climate and man and they interact with the

soil.

Within terrestrial ecosystems, the largest recognizable subdivision is the biome.

Biome: total assemblage of plant and animal life interacting within the life layer.There are 5 principal biomes:Forest Biome

Savanna Biome

Grassland Biome

Desert Biome

Tundra Biome

Forest Biome -------- Tropical RainforestGrassland Biome ---------- Tropical & Temperate GrasslandsTundra Biome ---------- Northern Coniferous Forests

TROPICAL RAINFORESTS

These constitute part of the forest biome.They are found in equatorial and tropical latitude zones that extend polewards (lat. 10o to 25o N).They consist of tall closely set trees and crowns form a continuous canopy of foliage and provide denseshade for ground and lower layers.

One of the major characteristics of tropical forests is their distinct seasonality: winter is absent, and onlytwo seasons are present (rainy and dry).

Rainforests develop in a climate that is continually warm, frost-free and has abundant precipitation in allmonths of the year.

The length of daylight is 12 hours and varies little.Rainforests are definedas you would expectby rainfall, and in fact they are literally created by it.


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They can be found where rain exceeds 80 inches per year.Tropical rainforests often have from 160 to 400 inches of rain a year. (~400mm/month).But just as important as the amount of rain in shaping the unique character of rainforests is the constanthumidity and high average temperature.

In the Amazon basin you can expect at least 130 days of rain a year and, in many places, up to 250 days.The relative humidity never falls below 80%, and temperatures vary little between daytime averages of 31degrees Centigrade (88 Fahrenheit) and night-time lows of 22 degrees C (72 F).

Because of the wet and hot climate that predominates the tropical rainforests the trees are very tall, lushand of a great variety of species.

The hot, humid climate is ideal for plant growth and the plants are aseasonal and deciduous sheddingtheir leaves throughout the year.

A multilayered structure is characteristic of tropical rainforests.

The highest layer consists of scattered, Emergent trees that protrude from the closed canopy below, oftenrising to 40m (130ft).

Some emergent species develop with wide buttress roots, which aid in their physical support.Soils of the typical lowland rainforest are often shallow. In much of Amazonia, theres only a few inches ofsoil above reddish clay. Many roots stretch out over the surface, rather than burrowing underground. Here

many trees use wooden buttresses (like the buttresses which support the giant Gothic cathedrals of

Europe), organic flanges which grow out from the base of the tree on all sides to balance it. Some biologists

say this shape also allows the tree to gather nutrients from a greater surface area of soil since lots of small

rootlets extend down from the bottom of the buttresses.

In other places, so-called prop or stilt roots emerge like slanting rods from the main trunk 1 to 2meters above the ground to help support the trunk. This particular kind of root is often found in flooded or

mangrove forests, where it also protects the tree against waves and currents.

Below the layer of emergents is second layer called the Canopy.The canopy is formed from the large trees whose crowns form a tight, continuous layer above the ground(15 to 30m/50 to 100ft high).


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The canopy is home to 90% of organisms found in the rainforest!In the wild, most animals spend their entire lives in the canopy, never touching the ground.A third, lower layer consists of small, slender trees 5 to 15m (15-50ft) high with narrow crowns.

The Understory/Undercanopy tends to be dark and relatively open, and contains smaller trees andshrubs.

The forest floor receives only what little sunlight escapes through both the canopy and the understory, sonot many plants grow here.

The ones that do are well adapted to a very low level of light.Rainforest leaves also have distinctive features. Many have drip tipsa pointed shape which helps drainexcess water from the leaf and reduces vulnerability to mold and predation. Researchers often speak of how

different plants try to prevent herbivorythe eating away of vegetation by insects or other parasites

and minimizing moisture with drip tips is one such strategy. When it fails, leaves become a lacy net of holes

and fibers.

Typical of rainforests are thick, woody lianas supported by the trunks and branches of trees.Some are slender, like ropes while others reach thicknesses of up to 20cm (8 inches).They climb high into trees to the upper canopy where light is available and develop numerous branches oftheir own.

Epiphytes are also common.These plants attach themselves to the trunk, branches or foliage of trees and lianas.

Their host is used solely as a means of physical support.

Epiphytes include plants of many different types-ferns, orchids, mosses and lichens

The Shrub layer is where trees and heavy wood and stems grow.A rainforest with a very thick canopy and understory might have a very small shrub layer.A rainforest with a very open canopy will probably have a very large shrub layer.Lastly there is the forest floor which is often covered with rotting leaves and little or no grass.Soils: the soils of these areas are usually heavily leached and ferralitic (latosols), with accumulations ofresidual insoluble minerals containing, iron, aluminium and manganese.

The hot humid environment speeds up chemical weathering and decay of organic matter.The soils are well developed, but have been weathered for a long time so they are ultimately lacking innutrients.

They are inherently infertile.


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Tropical rainforests have long been home to indigenous peoples who have shaped civilizations andcultures based on the environment in which they live.

Great civilizations like the Mayas, Incas, and Aztecs developed complex societies and made greatcontributions to science.

Currently hundreds of indigenous tribes currently reside in the AmazonLiving from nature and lacking the technology to dominate their environment, native peoples havelearned to watch their surroundings and understand the intricacies of the rainforest.

Over generations these people have learned the importance of living within their environment and have

come to rely on the countless renewable benefits that forests can provide.

Destructive Humans:Conservationists are alarmed over the fast depletion of world's tropical rainforests over the past fewdecades. If the destruction of the rainforests continues at the current pace, the rainforest animals and all

other related entities will find it difficult to survive.

That is, if the area of rainforests goes down, the number of related species like rainforest animals also godown.

The immediate causes of rainforest destruction are clear.The main causes of total clearance are agriculture and in drier areas, fuelwood collection.The main cause of forest degradation is logging.Mining, industrial development and large dams also have a serious impact.Tourism is becoming a larger threat to the forests.

IMPORTANCE OF TRFSFood, Water ,Diversity of plants and animals, Carbon sink ,Medicinal purposes ,Shelter, TimberGrasslands

Grassland biomes are large, rolling terrains of grasses, flowers and herbs.

Latitude, soil and local climates for the most part determine what kinds of plants grow in a particular

grassland.

A grassland is a region where the average annual precipitation is great enough to support grasses, and insome areas a few trees

Grasslands go by many names. In the U.S. Midwest, they're known as prairies. In South America, they're

called pampas. Central Eurasian grasslands are referred to as steppes, while in Africa they're named

savannas.

What they all have in common is grass as their naturally dominant vegetation.


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In fact, most grasslands are located between forests and deserts.

About one quarter of the Earth's land is covered with grasslands, but many of these lands have been turned

into farms.

Grasslands are generally open and fairly flat, and they exist on every continent except Antarctica.

Most lie in the drier portions of a continent's interior.

Temperate grasslands are characterized as having grasses as the dominant vegetation. Trees and large shrubs are absent. Climate is semi-arid. These areas have two seasons: a growing season and a dormant season. During the dormant season, no grass can grow because it is too cold. Temperate Grasslands are found throughout the globe, generally in the interiors of the continents and northor south of the tropic of cancer/capricorn. The following are the major regional expressions of grasslands

recognized around the globe.

Veldts of South Africa Puszta of Hungary Pampas of Argentina/Uruguay Steppes of Russia / China Plains and Prairies of North America Minor Expressions: There are smaller local expressions of grasslands as well. These include the following: Australian Outback Minnesota Cedar Creek Region Precipitation in the temperate grasslands usually occurs in the late spring and early summer. There is an average of 20 35 inches of rainfall a year. The amount of rainfall however determines the height of grasses in the grassland. For North America, this rainfall gradient helps to divide the temperate grasslands into tall grass prairies (in

wetter areas) and short grass steppes (in drier habitats).

The temperature range is very large over the course of the year. Summer temperatures can be well over 38C (100 degrees Fahrenheit), while winter temperatures can be as low as -40 C (-40 degrees Fahrenheit).

The soil of the temperate grasslands is deep and dark, with fertile upper layers. It is nutrient-rich from the growth and decay of deep, many-branched grass roots.


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The rotted roots hold the soil together and provide a food source for living plants. Each different species of grass grows best in a particular grassland environment (determined by

temperature, rainfall, and soil conditions).

The soil has a good crumb structure and is relatively alkaline ,thus suitable for agriculture. The thickly matted root system reduces the risk of erosion. Mollisols develop under grassland vegetation, these soils are well-known for their dark brown to black

organic rich surface layers. Mollisols are high in nutrients and rich in calcium soils among the most fertile

soils on the earth. Mollisols are found in the drier portions of the humid continental climate through the

steppe climate.

Temperate Grasslands are dominated by one or a few species of grasses while there are several hundredother types of grasses and non-woody flowering plants that while less abundant make up a vital part of the

species composition.

There are many types of grass species that are dominant species in their own region. Each species of grass grows better with varying temperatures / rainfall / and soil conditions. Grasses are

dominant (instead of trees) because of fire, drought and grazing by large herbivores.

The most common grasses include blue gamma grass, buffalo grass, Johnson grass, and various sorts ofwheat and burley. Common flowers include types of asters, coneflowers, Solidagos (goldenrods), vetches,

Indian blankets and sweet clovers.

As mentioned before, Temperate grasslands can be further subdivided. Prairies are grasslands with tall grasses while steppes are grasslands with short grasses.

Steppes are dry areas of grassland with hot summers and cold winters. They receive 25.4-50.8 cm (10-20

inches) of rainfall a year. Steppes occur in the interiors of North America and Europe. Plants growing in

steppes are usually greater than 1 foot tall. They include blue grama and buffalo grass, cacti, sagebrush,

speargrass, and small relatives of the sunflower. Today, people use steppes to graze livestock and to grow

wheat and other crops. Overgrazing, plowing, and excess salts left behind by irrigation waters have harmed

some steppes. Strong winds blow loose soil from the ground after plowing, especially during droughts. This

causes the dust storms of the Great Plains of the U.S.

There is a great concern for remaining grasslands in temperate regions. Because the soil in these areas is incredibly rich and the land is flat and treeless, most of this biome has been

turned into farms or ranches.

The result of this overuse and consumption of the grassland by agricultural practices is a fragmentation of

once large tracks of grassland

Fragmentation decreases biodiversity.


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Plowing of grasslands, combined with wind has lead to huge dust storms, such as those which created theGreat Dust Bowl in the American Depression of the mid 1920s.

Finally, in dryer areas, overgrazing and salt build-up from irrigation of the land have turned these areas into

near-wastelands

Savannas are areas of tropical grasslands that can occur with or without trees and shrubs All are characterized by a continuous cover of grass. They cover about of the worlds land surface and are found between the tropical rainforests and the

subtropical high pressure belts that produce the worlds great desert.

Savannas of one sort or another cover almost half the surface of Africa (about five million square miles,generally central Africa) and large areas of Australia, South America, and India.

TROPICAL GRASSLANDS

Climate is the most important factor in creating a savanna. Savannas are always found in warm or hot climates (tropical wet-dry climate) where the annual rainfall is

from about 50.8 to 127 cm (20-50 inches) per year.

It is crucial that the rainfall is concentrated in six or eight months of the year, followed by a long period ofdrought when fires can occur.

If the rain were well distributed throughout the year, many such areas would become tropical forest. Temperatures remain high throughout the year ranging between 23-28oC. High temperatures cause high evapotranspiration rates and the seasonal nature if the rainfall cause a two-

fold division of the year into seasons:

Water surplus (wet season) Water deficiency (dry season) Savannas which result from climatic conditions are called climatic savannas The link between soil and climate in the savanna could hardly be closer. Soils in the savanna are commonly leached ferruginous soils. During the wet season, the excess of precipitation over evaporation means that leaching of soluble minerals

and soil particles will take place down through the soil.

By contrast in the dry season, silica and iron compounds are carried up through the soil and are deposited

close to the surface

Geomorphology plays an important role in soil formation too. Some areas, notably the base and slopes of valleys are enriched by clay, minerals and organic matter

deposited there.


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By contrast, plateaus, plains and slope tops may ne nutrient-depleted by erosion. The local variation in soils leads to variations in vegetation-edaphic control. Different savannas support different grasses due to disparities in rainfall and soil conditions.

Because the savanna supports such a large number of species competing for living space, usually only one ora few kinds of grass are more successful than the others in a particular area.

For example, in drier savannas such as those on the Serengeti plains or Kenya's Laikipia plateau, thedominant grasses on well-drained soils are Rhodes grass and red oat grass; throughout the East African

savannas, star grasses are dominant; the lemon grasses are common in many western Uganda savannas.

Deciduous trees and shrubs are scattered across the open landscape. One type of savanna common in southwestern Kenya, Tanzania, and Uganda, known as grouped-tree

grassland, has trees growing only on termite mounds the intervening soil being too thin or poorly drained

to support the growth of trees at all.

All savanna vegetation however are xerophytic (adapted to drought) and pyrophytic (adapted to fire). Adaptations to drought include deep tap roots, partial or total loss of leaves and sunken stomata to reduce

moisture loss.

Trees survive a fire by retaining some moisture in all their above-ground parts throughout the dry season.Sometimes they have a corky bark or semi succulent trunk covered with smooth resinous bark, both being

fire resistant.

Savannas has a NPP of about 900g/m2/year. The warm, wet summers allow much photosynthesis and NPP can reach as high as 1500g/m2/year. Seasonal fires (some caused by humans) play a vital role in the savanna's biodiversity. Fire is prevalent

around January, at the height of the dry season. The fires do not devastate the community. Most of the

animals killed by the fires are insects with short life spans. A fire is a feast for some animals, such as birds

that come to sites of fires to eat grasshoppers, beetles, mice, and lizards that are killed or driven out by the

fire. Underground holes and crevices provide a safe refuge for small creatures. Although the dry stems and

leaves of grasses are consumed by fire, the grasses' deep roots remain unharmed. These roots, with all their

starch reserves, are ready to send up new growth when the soil becomes more moist. The scattered shrubs

can also subsist on food reserves in their roots while they await the time to venture above the soil again.

During March, violent thunderstorms occur again, this time heralding the rainy season. When the rainscome, savanna bunch grasses grow vigorously. Some of the larger grasses grow an inch or more in 24 hours.

The savannas experiences a surge of new life at this time.

Humans and grasslands

Quality and quantity of grasslands are based on the ecosystem, climate and vegetation features, soilconditions, formation and development of grasslands and fire management.


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Because there is drought cycles, dehydration, fires, and the human population in areas where grasslandenvironments exist they can survive in almost all climates and all weathers, either developing into

something new or surviving on the old.

If one was to travel or live in a grassland environment there are some things to be understood. Through the ecosystem it has been stated that many different reasons how grassland environment was left

vulnerable and weak, yet through slight changes many grasslands have been saved.

It is said that through the one hundred to one hundred thirty-year drought in the Northern planes of UnitedStates grass productivity declined and evaporated, however, irrigation was yet introduced.

Formation and development of grasslands change more so because as the climates and the formationschange the grasslands change into new breeds.

Grasslands have expanded, some have decreased all in all they continue to change and develop into newbeginnings.

Humans can adapt to all settings as long as they have some knowledge or experience in such atmospheres. For e.g. In the Central Himalayan region of India, many humans have adapted to the grassland way of life,

however, due to their over populating community they are slowly declining. As forests are evaporating and

food is becoming harder to find, soon the Indian grassland may disappear.

NORTHERN CONIFEROUS FORESTS

The northern coniferous forest of the Subarctic climate, also known as the boreal forest, is dominated by

coniferous trees, with hardy deciduous trees or pines and firs.

To the south lies the temperate forest and the north the tundra. An ecotone is found between northern

coniferous forest and tundra vegetation called the taiga.

Taiga is a more open form of boreal forest with low growing conifers. Boreal forests, or taiga, represent the

largest terrestial biome.

Occur between 50 and 600 north latitude, boreal forests can be found in the broad belt of Eurasia and North

America: two-thirds in Siberia with the rest in Scandinavia, Alaska, and Canada.

Seasons are divided into short, moist, and moderately warm summers and long, cold, and dry winters.

The typical climate is referred to as cold continental. Rainfall is concentrated in the short summer when it is most useful; precipitation is as snow in winter. Annual rainfall averages just about 250mm. Temperatures are very low. Summers are short, lasting maybe 50 to 100 days without frost. Flora consist mostly of cold-tolerant evergreen conifers with needle-like leaves, such as pine, fir, and spruce. The needle-shaped leaves reduce transpiration and are designed to conserve moisture.


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The length of the growing season in boreal forests is 130 days and trees have to make full use of the shortgrowing summer.

Hence they are evergreen so the leaves are ready to begin growth as soon as the temperature rises. Growth, however, is very slow and the summer is not long enough for flowers to be produced and pollinated

and seeds dispersed in the same season.

Coniferous trees are therefore pollinated in one season and the seeds dispersed in the next. Trees in the northern coniferous forest primarily possess pine needles instead of broad leaves like those of

the temperate forests to the south.

Needles are an important adaptation to the extreme conditions present in the climate of the boreal forest. The needle-shaped leaves reduce transpiration and are designed to reduce moisture: Water loss is further reduced by the thick waxy coating common to pine needles. Water is "shut off" from the tree when the ground completely freezes. Under these circumstances the

stomata close-up to prevent loss of water from the tree.

Being dark in color they absorb what little light falls on their surfaces. The sloping sides of the conical canopy helps catch the low angle sun rays typical of high latitude locations. Usually there is only one tree layer creating a shading effect that precludes the growth of any lower tree

layers.

Most trees have a conical shape, which reduces wind rocking and prevents extensive snow accumulation onthe Branches

The main soils are podzols: thin, nutrient-poor, and acidic. Rapid leaching of these soils occur in the spring because of snow-melt. Coniferous forest vegetation release humic acids called chelating agents. These allow the leaching of iron

and aluminum to the B horizon and the accumulation of silica in the E horizon which has a characteristic

ash-grey, bleached color. The upper O and A horizons are black due to the presence of humus (raw, acidic-

mor). A hard iron pan (deposited iron) creates an impermeable layer within the soil. The C horizon takes

on the color of the underlying bedrock. Podzols are very distinct soils because their acidic nature limits the

presence of earthworms, one of the most important agents in mixing soil horizons.


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Fauna: Taigas are relatively low in animal diversity because of the harsh winters. They have fewer animal species than tropical or temperate deciduous forests. Some taiga animals cope with the cold winter environment, but many migrate south to warmer climates

during the winter.

Others hibernate until warmer temperatures return. Fur-bearing predators like the lynx and members of the weasel family (e.g. wolverine, fisher, pine martin,

mink, ermine, and sable) live in taigas.

They prey on herbivores like snowshoe or varying hares, red squirrels, lemmings, and voles.

The gray wolf is a top predator in the taiga of North America. Humans have moved in and eliminated

wolves as predators that threaten livestock. The rare Siberian tiger is found in the taiga of northern Russia

and China. It has been hunted for its striking fur.

Large herbivores graze in the taiga on deciduous trees and shrubs. These herbivores include elk and moose. The beaver, the basis for the early North American fur trade, also thrive when deciduous trees and shrubs

are plentiful.

One of the issues that affect the health of the taiga is human development, which reduces habitat for theplants and animals that live there.

Humans kills predators that threaten livestock. We build roads and power lines, and explore for minerals. The natural succession of the forest is disrupted when forest fires are suppressed to protect human

dwellings.

Many of the taigas of the world are what is called old growth forests. Their large trees are desirable for the lumber industry.


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Old growth forests have virtually disappeared in Norway, Sweden, Finland, and Russia; few are left in NorthAmerica.

The removal of all the large trees affects the natural rate of succession. Waste products from mining and development may pollute the land and water. Industrial contaminants from around the world have accumulated in taiga food webs.

These contaminants along with naturally occurring substances, such as some metals and radioactive

material, are transported in by wind and rain

Climate change is also an issue. Scientists continue to track and compare temperature data to determine whether it has affected taiga. Warming temperatures can affect habitats, by melting permafrost areas, raising lake levels, and changing

vegetation growth patterns.

In addition, the maximum and minimum temperatures might be higher and the precipitation patterns mightchange.

Worldwide, precipitation has increased in high latitude areas where the taiga is located. There is not enough data to determine whether changes have occurred.

Biomes established by altitude

Temperature is the major influence on the biomes discussed above. Because temperatures decline withaltitude as well as latitude, similar biomes exist on mountains even when they are at low latitudes. As a rule

of thumb, a climb of 1000 feet is equivalent in changed flora and fauna to a trip northward of some 600

miles.

Thus, plants occurring at higher elevations generally experience cooler temperatures and shorter growingperiods than low-elevation plants.

Variation in thetemperature gradientcan be caused by differences in slope, aspect, radiation input, clouds,and air drainage patterns.

The precipitation gradient in most mountains is the reverse of the temperature gradient: precipitationincreases with altitude.

General changes in vegetation with increases in altitude include reduction in plant size, slower growth rates,lower production, communities composed of fewer species, and less interspecific competition.

However, many regional exceptions to these trends exist.
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Established by rock type

The effect of bedrock geology on vegetation is not always direct. Some times it involves many interrelated factors, for example soils and climate which affect the vegetation

and its spectral properties.

But on a regional scale, and even sometimes on a local scale, close relationships have been identified. The underlying bedrock will directly affect the soil type that results. This type of soil is then characteristic of the existing Biome, where its a TRF, Desert or Savanna. E.g. Podzols These are formed under Coniferous Forest Regions. Podzols form from parent material that is high is quartz, such as sandstone and granite.

They have a characteristic subsurface layer known as the spodic horizonmade up of accumulated humusand metal oxides, usually iron and aluminum.

Above the spodic horizon there is often a bleached-out layer from which clay and iron oxides have beenleached, leaving a layer of coarse-textured material containingprimary mineralsand little organic matter.

Because of this type of soil resulting from the quartz-rich parent, material, the rock type has affected theresulting vegetation.

Conifers are the dominant vegetation is this area, because they have adapted to the soil (acidic) which hasresulted from the underlying bedrock.

Established by Slope angle

Attributes such as slope angle and aspect are important variables for spatial analysis and distribution ofvegetation.

Slope angle affects the angle of the sun and variations in slope will affect the degree of sunlight vegetation isexposed to.

Biomes established by drainage: vegetation distribution is influenced by local drainage and drainage

patterns. deserts.
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