Unit- 5
Seeing The trees And The Forest
Earth's Natural Vegetation
1. What is natural vegetation?
Ans: We live on a beautiful Earth which is covered with many types of plants such as trees, shrubs' grasses, mosses, lichens, and algae. Most of these grow naturally while others are planted by people. The plants which grow by themselves are called natural vegetation while those which are grown by people are called cultivated vegetation.
2. How do the climatic factors of precipitation and temperature influence the distribution of natural vegetation?
Ans: The distribution of natural vegetation is influenced by climate factors such as precipitation and temperature. Precipitation influences the distribution of the main types of natural vegetation.
Although the distribution of the main types of vegetation is influenced by the variation in precipitation, it is the temperature that influences the distribution of the sub-types. If you travel from the equator to the Poles. We would observe that as the temperature decreases towards the Poles, the vegetation sub-type changes.
3. Where can we find the tropical rainforest?
Ans: The tropical rainforest is found in areas with an equatorial climate, such as in parts of Central and South America, Africa, and Southeast Asia. The Amazon Basin and the Zaire Basin are the two largest areas of tropical rainforest.
4. What are the characteristics of the tropical rainforest?
Ans: The characteristics of the tropical rainforest are -
a) The trees in the tropical rainforest are tall and grow very close together. As a result, the forest is very dense.
b) The trees in tropical forests have broad leaves with a waxy, leathery, or hairy texture. The texture of the leaves allows the rainwater to run off easily. In addition, it minimizes the loss of moisture through transpiration.
c) The trees in the tropical rainforest have shallow roots because water and nutrients are found in the top layer of the soil. This is the result of the high precipitation and temperature of the equatorial climate.
5. Where can we find the mangrove forest?
Ans: Along tropical coastal areas where the ground is muddy and water-logged, we are able to find the mangrove forest. Generally, the mangrove forest is found along sheltered, low-lying tropical coasts such as those in West Africa, Southeast Asia, and Australia.
6. What are the characteristics of the mangrove forest?
Ans: The characteristics of the mangrove forest are -
a) There is no distinct vertical layering in the mangrove forest. Most of the trees are of uniform height, about 15 m tall. They grow very close together, allowing little sunlight to reach the forest floor.
b) Nearer the coast, we find mangrove trees which grow well in salt water, while further inland we find those that are less tolerant of salt.
c) The mangrove trees have broad leaves which have drip tips that allow rainwater to flow off quickly. Most of the leaves have a leathery texture to prevent excessive loss of moisture through transpiration as well as to let the water flow quickly off the leaves.
d) Mangrove trees also have three very interesting types of roots- prop roots, buttress roots, and breathing roots.
7. Where can we find the tropical monsoon forest?
Ans: The tropical monsoon forest is found in tropical areas with a distinct dry season. Such areas may experience a tropical monsoon climate. Examples of these areas include parts of India, Bangladesh, Southeast Asia, China, South Central Africa, the West Indies, Central, and South America, and Australia.
8. What are the characteristics of the tropical monsoon forest?
Ans: The characteristics of the tropical monsoon forest are-
a) The tropical monsoon forest is made up of deciduous trees which shed all their leaves over the same period of time. In the tropical monsoon forest, the leaves are shed just before the dry season. This is an adaptation by the trees to prevent the loss of water through transpiration during the dry season.
b) Most of the trees in the tropical monsoon forest are hardwoods. Teak and rosewood are two well-known examples of tropical hardwoods.
c) The warm and wet conditions of the tropical monsoon climate allow many varieties of plants to grow. Thus, about 200 varieties of plants can be found in one hectare of the tropical monsoon forest.
d) They have waxy, leathery, or hairy broad leaves with drip tips to help the trees get rid of excessive water quickly during the wet season. However, because there is a dry season in the tropical monsoon region, the trees in the forest also have to adapt to dry conditions as well.
8. Where can we find the temperate deciduous forest?
Ans: The temperate deciduous forest is found in areas between 25⁰ and 40⁰N and S of the equator. These areas include much of Europe, China, Japan, Korea, the eastern parts of the USA, New Zealand, and the southeastern part of Australia.
9. What are the characteristics of the temperature deciduous forest?
Ans: The characteristics of the temperature deciduous forest are-
a) This forest has a three-layered structure. they are-
i) tree layer
ii) ground layer
iii) shrub layer
b) The trees in the temperate deciduous forest shed their leaves in autumn. In winter when the soil is cold, the tree roots are only able to absorb very small amounts of soil water and growth almost stops.
c) The loss of leaves considerably reduces transpiration and helps to conserve moisture.
d) The trees in the temperate deciduous forest have broad leaves to enable them to intercept the maximum amount of sunlight for photosynthesis. These trees also have thick barks which protect them from the cold winters.
e) Generally, the trees have deep roots to anchor and support them. These deep roots also allow the trees to tap the underground water during the winter months when the top layer of the soil is frozen.
10. Where can we find the temperate coniferous forest?
Ans: The temperate coniferous forest is found in the temperate latitudes in the northern hemisphere between 45⁰ and 60⁰N. This area stretches across the northern part of Europe, Asia, and North America.
11. What are the characteristics of the temperature coniferous forest?
Ans: The characteristics of the temperature coniferous forest are-
a) There is no distinct layered structure in the temperate coniferous forest.
b) The straight-trunked, come-shaped trees are of uniform height, generally about 20 m tall, and they grow close together, shutting out most of the sunlight from the forest floor.
c) The temperate coniferous forest consists of evergreen softwoods such as pine, fir, cedar, and spruce. Softwoods, as their name suggests, produce timber that is tight and soft.
d) Coniferous trees are conical in shape, an adaptation to the cold winters that bring heavy snowfall. The conical shape allows the snow to slide down the branches, preventing the snow from accumulating and breaking the branches.
e) The leaves are small, narrow, and often needle-like so that there is a small leaf area from which water can be lost through transpiration.
Q.1. What are the four layers of woodland?
Ans: A woodland is a complex ecosystem with several layers. They are-
a) Canopy:
The canopy is the top layer of tree branches and leaves. Food is constantly being made here: leaves, fruits and nuts. There are many insects feeding on the leaves. This attracts spiders, carnivorous insects and birds. Browsing mammals like the squirrel feed in this layer as do predators like the polecat, it provides good nesting sites.
b) Shrub layer:
The shrub layer is the middle layer of plants like holly, hazel and brambles. They also provide a good source of food for all the animals.
c) Field layer:
The field layer is made up of herbaceous plants like ferns, sorrel and bluebells. They provide shelter for small insects as well as a food supply.
d) Ground layer:
The ground layer includes low growing organisms like moss and fungi. It also includes the leaf litter. This is the dead and decaying remains of fallen leaves. It is a bit like a large compost heap. It contains thousands of small insects which feed on the leaves and on each other. Wild boar, bears, foxes, and wolves forage in this layer. In the soil are other animals like moles, earthworms and insect larvae.