temperate forests

Deciduous forest

  We’ve learnt that deciduous leaves fall off in autumn in preparation of winter to minimize the amount of water loss when transpiring. It is also known that the leaves turn brown during this period. However, you may asked one question. How do the leaves turn brown?

  It is because during the shorter days and cooler weather of autumn, green chlorophyll in the leaves begins to decompose, revealing orange, yellow, and red.  This is because the plant has limited sunlight and water thus the leaves are unable to continue producing chlorophyll. Actually, these colors were present in the leaves all year long, but had been hidden by the green pigment of the chlorophyll.  

Since there is no more chlorophyll, how do the trees survive without leaves during the winter when they cant make food?  

To prepare for winter, deciduous trees and plants become dormant. They lose their leaves and seal the places where leaves were attached with a protective covering called a leaf scar. If they kept their leaves, the water in the leaves would freeze into ice, damaging the leaves and leaving the plant vulnerable to bacteria or fungi. Plants also make a concentrated sugar solution to stop water from freezing in their stems.

How does the tree know when to start growing leaves? The longer days and warmer weather of spring signal to the trees to grow new leaves and begin photosynthesis again.

Then how does the environment have an effect on such adaptation? The trees get a lot of sunlight in summer and thus are able to get energy to make food for the plant. Some food is stored in the roots for the next spring. However, when the temperature gets lower, the tree cuts off the supply of water to the leaves and seals off the area between the leaf stem and the tree trunk. This is why trees get limited supply of water and sunlight during autumn. Finally, when the temperature get warmer, the leaves then start growing back.

We also learnt examples of tress like the Oak Tree. Leaves are big and broad to increase surface area to get as much sunlight as possible in summer. However, these leaves also losses a lot of water during transpiration making then shed their leaves in the autumn.

Knowing this, I have a question I can’t seem to find the answer to. Why do the trees have such big leaves if they lose a lot of water during the winter? Is it because they need to get a lot of sunlight during the summer? However, small leaves also can capture sunlight and make food for the plant. If this is so, why is it that the plant has big leaves instead of small leaves that will help decrease the amount of water loss during the winter? If they had small leaves, won’t they be able to make food even in the winter and don’t have to stay dormant?

Many of us have seen leaves found in temperate forests and tropical forest. There is a distinct difference in leaves for both climates. Then, what effect does climate have to the edge of the leaf?

Leaves in temperate deciduous forests mostly have toothed edges but the leaves in tropical rainforest have smooth entire edges. This is because climate and leaf margin are closely tied. The leaves of tree species native to colder climates usually have more teeth cut more deeply into the leaf; they are more dissected on their edges so they have a higher perimeter-to-area ratio. The presence of a toothed edge seems to assist in unfolding young leaves from buds so they can maximize photosynthesis when breaking winter dormancy.

The forest floor grows rapidly in summer and spring and disappears during winter. Another question I couldn’t find an answer to is, why the plants on the forest floor disappear when they can get as much sunlight as they want during autumn and winter when the leaves drop and they can get a lot of sunlight? Is it because its too cold? Is it also because of water loss?

Coniferous forest

We learnt that the coniferous forest is evergreen. They have cone shaped structures to allow snow to slide off and needle-like leaves to lessen water loss. They also have supple braches don’t break easily so the tree won’t fall off because of imbalance of weight. The leaves are evergreen because they do not lose much water during transpiration as they have small surface area. Thus the leaves always stays green and does not need to fall off.

We also know that there is only one type of plant in the coniferous forest, but why is that so? Is it because not many plants cant adapt to such a climate thus resulting in low diversity?

The soil in coniferous forests is not fertile unlike the soil in temperate deciduous forest. Why?

In the deciduous forest,it is not evergreen and the leaves drop very autumn thus resulting in very fertile soil. This is also the reason why their leave litter is so thick. Remember the trip to bukit timah? The leaf litter there, a tropical rainforest is already quite thick; but the leave litter in the deciduous forest is thicker because the leaves drop more. However in coniferous forests, it is evergreen and the leaves hardly drop thus not providing any nutrients. Thus, the soil isn’t fertile.

Bukit Timah Nature Reserve(:

Haha, this is some information about the BTNR that we're going tmrw. Yay:D Haha so cool.

 

 

Singapore, lying within the tropical zone, and blessed with high temperature and high rainfall all year round, was once covered with tropical rainforests. It has been estimated that primary rainforest once covered about 82% of the land area of Singapore, approximately 442 km² or 44,200 hectares (ha).

However, ever since people have settled on the island, more and more of the original natural vegetation has been cleared, to make way for settlements and for agriculture and plantations. Today, only 192 ha or 0.43% of the original forest cover remains. Most of the surviving primary forest is restricted to the more pristine areas of the 163ha Bukit Timah Nature Reserve (BTNR), and in scattered patches throughout the 3,043 ha Central Catchment Nature Reserve (CCNR). The remainder of these two nature reserves is occupied mostly by secondary forest.

The Bukit Timah Nature Reserve contains the largest patch of primary rainforest left in Singapore. Bukit Timah Hill, at about 163.63 metres above sea level, is the highest point in Singapore.

Importance of Tropical Rainforests in Singapore
Even though we do not possess very large areas of tropical rainforests, as compared to other countries like Malaysia, Indonesia, Congo and Brazil, our few remaining rainforests are still very important, for various reasons.

• Tropical rainforests have taken hundreds of years to develop and once cleared, they are almost impossible to replace. There are many species of plant and animal in the rainforests, most of which are found nowhere else in the world. And when they are destroyed, some species may become extinct and be lost forever. These include plants with medicinal value which have not even been identified and tested. So, rainforests in Singapore now perform the very important role of providing a place for many species to thrive and grow.
• Rainforests in Singapore also provide us with an idea of what Singapore was like at the beginning of the nineteenth century. Singapore was once covered by tropical rainforests. Hence, by looking at the rainforests now, we get a glimpse of what Singapore might have been like then.
• The rainforests form our water catchment areas. When rain falls, the rainwater is trapped by some of the leaves on the trees. The rainwater then drains slowly into the ground and may be collected in the nearby reservoirs. In this way rainforests help us 'catch' the rain and add to our water supply.
• As Singapore becomes increasingly built up, rainforests act as giant 'lungs' by absorbing large amounts of carbon dioxide and producing oxygen in exhange.
• The rainforests are beautiful and scenic, with fresh air and natural surroundings. They provide us with a peaceful alternative to the busy city, and these last bastions of wilderness are places of peace and quiet where Singaporeans can go to enjoy and appreciate nature at its best. They can also be a tourist attraction.
• The rainforests are a legacy of our natural heritage, and it is important to protect and conserve them, keeping them intact for the country's future generations to learn and appreciate the richness of our country's heritage.

Shock Absorber.

I was reading the notes about the measures to adapt and respond to earthquakes and was thinking about the part which they wrote about designing new infrastructure. A question popped up, how do the shock absorbers actually work? How exactly does the shock absorbers actually 'absorb' the tremours?
I found this on Wikipedia:

Structures
Applied to a structure such as a building or bridge it may be part of a seismic retrofit or as part of new, earthquake resistant construction. In this application it allows yet restrains motion and absorbs resonant energy, which can cause excessive motion and eventual structural failure.

After reading this, I don't really get it. What do they mean by 'yet restrain motion and absorb resonant energy'? They also mentioned that it can cause structural failure, that what is the use of it?

To sum up this whole post, it's about the some questions about the shock absorber.

Corinne & Alison.

This is the Wikipedia website: http://en.wikipedia.org/wiki/Shock_absorber

Topographic maps

A map is a way of representing two dimensional surfaces, on the other hand, a topographical map is a way of representing three dimensional surfaces by using contour lines to show the elevation change on the earth's surface.

Contour lines that are placed on the map represent lines of equal elevation. Its kind of like slicing a mountain with a perfectly flat horizontal piece of glass. The intersection of the mountain with the glass is a line of constant elevation on the surface of the mountain and could be put on a map as a contour line for the elevation of the slice.

  Every point on a contour line represents the exact same elevation. As a result of this every contour line must eventually close on itself to form an irregular circle. Contour lines can never cross one another. Each line represents a separate elevation, and you can’t have two different elevations at the same point. The only exception to this rule is if you have an overhanging cliff or cave where, if you drilled a hole straight down from the upper surface, you would intersect the earth’s surface at two elevations at the same X,Y coordinate. 

  Moving from one contour line to another always indicates a change in elevation.On a hill with a consistent slope, there are always four intermediate contours for every index contour. If there are more than four index contours it means that there has been a change of slope and one or more contour line has been duplicated. This is most common when going over the top of a hill or across a valley. Contour lines crossing a stream valley will form a "V" shape pointing in the uphill (and upstream) direction.

                                                                        The end

Nile River

-
  Can you spot the Nile river in this map? If you have spotted the Nile River, do you spot the White Nile River, the Blue Nile River and the Atbara?
  The Blue Nile and White Niles are the two main rivers that flow from the south into what is referred as the Nile proper. The White Nile is the longer of its tributaries, and the Blue Nile is the source of water and fertile soil. As for the Atbara, it flows into the Nile just north of Khartoum in the Sudan but it contributes less than one percent to total water flow.


The Blue Nile (left), White Nile (right), merge near Khartoum, Sudan


  Now back to the Nile River, its 6695km long, the major cities that are located on the edge of the Nile and White Nile are: Cairo, Gondokoro, Khartoum, Aswan, Thebes, Karnak, and the town of Alexandria lies near the Rozeta branch. 
  After seeing the map, a question popped up my mind. Why does the river flow from south to north? Its because the river just flows down hill, from the high mountains in the middle of Africa to the Nile delta (point where Nile enters the Mediterranean Sea). The picture below will show:



  Millions of people commute on the Nile river everyday. For tourism, luxury cruises and traditional Egyptian sailing boats travel on the Nile river each day. Some of these boats drop tourists off at tourist attractions and is the livelihood of many people.
  As for farming, there are hundreds of farms along the Nile, and usually farmers use boats to transport items such as rice, wheat, cattle, and hay between locations on the Nile.
  Another on which is fishing, for some fishing is a main source of income and wealth.


                                                                 the end^^

Deltas:)

DELTAS:
Deltas are the result of interacting fluvial (river) and, usually, marine systems.  However, they can form anywhere a stream flows into the sea.

The different types of Deltas...
1.  Arcuate (a fan-shaped delta) - e.g., Nile River.  Has many active, short distributaries taking sediment to their mouths.  The receiving (ambient) waters are rather shallow and have relatively even wave action arriving perpendicular to the shore with minimal longshore current.  As the sediment exits the many distributary mouths, the waves push it back, so the coastline is rather smooth.

2. Bird-foot (shaped like a bird foot) delta - e.g., Mississippi River.  Tend to have one or a very few major distributaries near their mouths.  The receiving basin has currents that carry the sediment away as it exits the distributary mouth.  There is a broad, shallow shelf that deepens abruptly, so the trend is to grow long and thin like a bird's toe.

3.  Cuspate (a tooth-shaped) delta - e.g., Tiber River of Italy.  Usually has one distributary emptying into a flat coastline with wave action hitting it head-on.  This tends to push the sediment back on both sides of the mouth, with a "tooth" growing out onto the shelf.

4.  Estuarine delta - e.g., Seine River of France.  This type of delta has a river that empties into a long, narrow estuary that eventually becomes filled with sediment (inside the coastline).

hope this will answer the question that miss jay gave us on monday:D

corinne and alison:D

Volcanoes

  We learnt that a volcano eruption is a release of pressure. Think of a bottle of coke that has been shaken before opening, not only coke come out, but gases comes out as well. Similarly, for a volcano, not only magma is released, different gases are released too. Knowing that volcanoes release gases when it erupts, one of the gases being released is carbon dioxide, a greenhouse gas. However, is the huge amount of such gases released from a single volcanic eruption, more or equivalent to the amount of greenhouse gases caused by human activities? Based on the U.S Geological Survey,the world's volcanoes, both on land and undersea, generate about 200 million tons of carbon dioxide annually, while our automotive and industrial activities cause some 24 billion tons of carbon dioxide every year world wide. From this, we can clearly state that greenhouse gases emissions from volcanoes comprise of less than one percent of those generated by human activities today.

  Volcanoes have different parts. A few of the four main parts are the crater, pipe, vent and the magma chamber. The definitions are all in the notes. A few questions struck my mind though. How is the pipe created? Why does the pipe go up? Why is the pipe narrow? How is the vent created?

  Volcanic hotspots were also mentioned. Hot spots are fixed places within the mantle or oceanic lithosphere, where rocks melt to generate magma.  When a hot spot is situated in the oceanic lithosphere a class of volcanoes known as shield volcanoes is built. The Hawaiian hot spot, for example, has been active at least 70 million years, producing a volcanic chain (o that extends 3,750 miles (6000 km) across the northwest Pacific Ocean. Where a hot spot lies beneath a continental plate the hot spot may generate enormous volumes of lava that accumulate layer upon layer. 


                                                                       ~end~    v(^o^)v

Tsunami

 The recent earthquake and tsunami in Japan has caused a lot of devastation and damage to the country. I’m very sure everyone also knows that Japan is a country that is very prone to Earthquakes. They get it so often that when an earthquake comes, they find it no big deal and would just stay very calm. However, this makes me curious as to why Japan get earthquakes, no matter big or small every year. Is it because of where their position located at? Or is it because they are just unlucky?

  

  Now back to my topic on tsunami, it is reported that “The large earthquake triggered a tsunami warning for countries all around the Pacific ocean.” It really puzzled me how and why an earthquake of such a dangerous magnitude can trigger a tsunami about 10m high. Did these two things just magically happen coincidentally? Or is it because of the impact the earthquake caused resulting in the tsunami? Then again, how are they related?

  It is said on the internet that “The Japanese archipelago is located in an area where several continental and oceanic plates meet. This is the cause of frequent earthquakes and the presence of many volcanoes and hot springs across Japan. If earthquakes occur below or close to the ocean, they may trigger tidal waves (tsunami).”

  Then this answers my question ^-^

   Because of Japan’s location, they get earthquakes very easily. And because the earthquake occurred below or close to the ocean, it triggered a tsunami.

  This picture shows how a tsunami is formed. As one plate slips below another, pressure builds after many years, resulting in a section suddenly giving way. After it gives way, it ruptures the ocean floor, resulting in a massive displacement of water. As the plate snaps back, a force pushes the water up. Oscillation develops underwater at great speed. Sea water is sucked from the shore and rushes back with force. Tsunamis are barely felt on the ocean surface. As the waves reaches the land, the tsunami becomes bigger as the water becomes shallower. 

  As I'm typing this down, another question struck my mind. Why is it that tsunamis are barely felt on the ocean floor? If the pressure that builds up after many years is what determines the impact of the tsunami, then how is more pressure formed? Is it by the number of years the pressure builds thus releasing a greater force?

                                              

                                                                      ^-^The End 

Earthquake

As i've said last week:

Transform Plate Movement A transform plate movement is one where two plates slide laterally past each other. However, movement is not smooth due to friction between the rocks of the two plates. Therefore, sometimes the two plates would get 'stuck' and lock together. But since the convection currents of the underlying magma are still dragging the plates, much tension and pressure is built up at the transform boundary. When there is sufficient buildup of pressure, rocks in the plates break and get jerked apart. This results in earthquakes.

As you may have heard, this afternoon a large quake struck Japan.

7.9 magnitude quake strikes Japan

A 7.9-magnitude earthquake has struck off Japan's northeastern coast, shaking buildings in Tokyo for several minutes and sending people out into the streets.
Japan's meteorological agency warns that a tsunami as high as 20 feet (6 meters) could strike the coast near Miyagi prefecture, closest to the epicenter.
The agency says the quake struck at 2:46 p.m. Friday at a depth of 6 miles (10 kilometers), about 80 miles (125 kilometers) off the eastern coast.
Several quakes had hit the same region in recent days, including a 7.3 magnitude one on Wednesday.

What is the link between GEOGRAPHY and the EARTHQUAKE that just happened?

Geography lesson on 4/3/11

Earth:

Crust - Solid

Mantle - Liquid

Core - Solid

 

 

 

The Plate movement:

The Plates 'floats' on the liquid mantle. As the Earth is spherical, and convection currents occur in all parts of the mantle, plates dragged away from one side will also collide on the other side. This leads to the different types of plate movements all over the Earth's surface.

 

 

Convergent Plate Movement

When two plates move towards each other, they would collide. This is called a convergent plate movement. As the plates collide, some crust is destroyed due to the impact, therefore this convergent boundary is also called a destructive boundary.

When A Continental And Oceanic Plate Collide
When a continental plate and an oceanic plate collide, subduction occurs. The oceanic plate sinks under the continental plate as it is denser. The crust carrying the ocean melts underneath at the subduction zone due to the immense friction and high heat of the magma, which is acidic with higher silican and sulphuric content.

The impact of the collision also causes cracks to form in the crust. The heat and pressure from the mantle forces the acidic magma to rise up these cracks. As the magma continues to rise up the cracks, it escapes onto the surface and solidifies, building up a volcano. Magma on the surface is now known as lava. Thus, an acid lava volcano is formed.
The converging of the oceanic and continental plate also cause deep oceanic trenches and fold mountains to form.

When Two Continental Plates Converge
When two continental plates converge, one plate will be forced only slightly under the other, but no subduction will take place. Thus, the pressing together of two plates will fold the crust and forms what we known as fold mountains.

When Two Oceanic Plates Converge
Similarly, when one oceanic plate converge, the other oceanic plate may subduct beneath the other. However, there is no head-on collision for two oceanic plates. Magma will then rise up to form volcanoes.

 

Divergent Plate Movement

A divergent plate movement occurs when two plates move away from each other. Magma from the mantle underneath the crust to rise up the surface to cool and solidify at the plate boundary. This divergent boundary is considered constructive since new crust is formed.

Divergent takes place at the boundary of the oceanic plates and forms new sea floor. This process is called sea-floor spreading.

As magma rises up to the surface, it piles up and solidifies, slowly forming a long chain of moutains on the ocean floor, called an oceanic ridge.

Volcanoes can also form undersea at these divergent boundaries, they are called submarine volcanoes and have gentle eruptions.

Transform Plate Movement

A transform plate movement is one where two plates slide laterally past each other. However, movement is not smooth due to friction between the rocks of the two plates. Therefore, sometimes the two plates would get 'stuck' and lock together. But since the convection currents of the underlying magma are still dragging the plates, much tension and pressure is built up at the transform boundary. When there is sufficient buildup of pressure, rocks in the plates break and get jerked apart. This results in earthquakes.

 

 

Earth's Layers

What are these Layer of the Earth made of?

  The outermost layer of the Earth is the crust. It is solid and comprises the continents and ocean basins. The crust has a variable thickness, being 35-70 km thick in the continents and 5-10 km thick in the ocean basins. The crust is composed mainly of alumino - silicates. 

  The mantle is liquid and composed mainly of ferro-magnesium silicates.This is where most of the internal heat of the Earth is located. Large convective cells in the mantle circulate heat and may drive plate tectonic processes.

  The outer core is liquid and is composed mainly of a nickel-iron alloy. While the solid inner core is almost entirely composed of iron. Earth's magnetic field is believed to be controlled by the liquid outer core. The outer core is 2300 km thick and the inner core is 1200 km thick.

Why is the Core Solid???

Inner core is thought to play an important role in the generation of Earth's magnetic fields by dynamo action in the liquid outer core.The existence of the inner core also changes the dynamic motions of liquid in the outer core as it grows and may help fix the magnetic field since it is expected to be a great deal more resistant to flow than the outer core liquid.

How does the Mantle Affect Us?

  Because the earth is very hot inside, a current of heat flows from the core to the crust. This is called convection current and it also takes place in the mantle. This current cools down as it comes closer to the surface of the earth. As a result, the rising of the current decreases and goes into horizontal direction along the bottom of the crust. When the current cools down more, the convection current descends again and goes to the inner earth. There the temperature increases and the current rises again. This goes on and on.

  When the current comes at a weaker part of the crust, for example at a volcano, magma comes above the earth's surface. The convection current along the bottom of the crust causes the moving of the tectonic plates. This is called plate tectonics. The movement of these plates goes very slowly. The bumping of two tectonic plates causes an earthquake.

  As I was doing my research, these three words, Asthenosphere, Mesosphere and Lithosphere came out very often so i decided to write the definition about it.

  The asthenosphere is a zone of the earth's mantle that lies beneath the lithosphere and consists of several hundred kilometers of deformable rock. It is solid rock, but  soft and flows easily (ductile).

  The lithosphere is the outer part of the earth, consisting of the crust and upper mantle, approximately 100 km (62 mi.) thick.(up to 200 km thick beneath continents, thinner beneath oceanic ridges and rift valleys), very brittle, easily fractures at low temperature.The lithosphere is comprised of both crust and part of the upper mantle.

  The mesosphere is about 2500 km thick, solid rock, but still capable of flowing.

  Also, as I was researching, these questions came out and made me really curious. Would the Earth run out of magma? If so, then what would happen and how would it affect our lives? Another question. It may sound a little unrealistic but its worth posting. What would happen if i drilled a tunnel through the center of the earth and jump into it?

                                               End of Post ^-^ 

Geography Lesson on the 18.02.11

RECAP:
We learnt about the some of characteristics of the...
- Igneous rocks
- Sedimentary rocks
- Metamorphic rocks
We did the sedimentary rocks in more detail.

Sedimentary Rocks:
- Some examples of sedimentary rocks are conglomerate, limestone and shale.
- They have very obvious layers.
- They are broken down very easily, especially limestone.
- The sedimentary rock covers of the continents of the Earth's crust is extensive, but the total contribution of sedimentary rocks is estimated to be only 5% of the total volume of the crust, much less then the igneous rocks and the metamorphic rocks.
- Sedimentary rocks are deposited in layers as strata, forming a structure called bedding.

How are the Sedimentary Rocks formed?
The sediments are deposited and they pile up in layers, with the weight of more layers piling up, the sediments will cament together and harden, forming the sedimentary rock.

I find this website diificult to understand as it is very profound. They call it a 'A Basic Sedimentary Rock Classification' but i dont understand it. But still, its about sedimentary rocks:) You can visit it if you have the time: http://csmres.jmu.edu/geollab/fichter/SedRx/sedclass.html

Some pictures of Sedimentary rocks:):)

    

11/02/11 lesson recap

What we have learnt this week:

1) Scales

Atlas -> Book of Maps -> Location -> Scales

• There are both large scales and small scales.

2)  Land Mass

World (International)   

Region                             

Continents

Countries

Cities

Towns

Community/ Village

3) Oceans

• Pacific Ocean ( America & Asia)
• Atlantic Ocean ( Africa & South America)
• Indian Ocean ( Below India)
• Southern Ocean ( Above Antarctica)
• Arctic Ocean (Above Europe)

4) Fragile Earth

 The interrelationship between physical Earth and the human environment

Human actions causes  -> Impact on environment -> Manage the impact

5) Physical Environment (Rocks)

• Rocks are small scale
• Landforms are large scale

How are they linked?

• Rocks make up massive landforms.

What are rocks?

• Rocks are solid materials on the Earth’s crust
• Made up of minerals like Quartz and Sand

                                                   End of Recap^-^

Longtitudes and Latitudes

What did we learn in the previous lesson? We learnt about the longtitudes<vertical lines> and latitudes<horizontal lines>.

Longtitude:
-Greenwich Meredian, also known as the Prime Meredian(0degree)
Latitudes:
-Arctic Center(66.5degreess N)
-Tropic of Cancer(23.5degrees N)
-Equator(0degrees)
-Tropic of Capricorn(23.5degrees S)
-Antarctic Circle(66.5degrees S)

~END OF RECAP~

Thank you. Corinne and Alison:)

Welcome:D

Welcome to our GEOGRAPHY blog(: