MAJOR BIOMES OF THE WORLD; FORESTS, DESERT, POPULATION STUDIES, ECOLOGICAL FACTORS

MAJOR BIOMES OF THE WORLD
These are seen predominantly in every nation of the earth. They include; Tropical Forest, Savanna, Desert, Shrubs, Afro- alpine, and Swamp.

TEMPERATE DECIDUOUS FOREST
This region is found in Europe, Asia, and North America- Eastern USA.

CHARACTERISTICS
1. It’s characterized by hard wood which shield their leaves in autumn
2. the number of different tree species here is far more than limited than in the tropical rain forest biome and large stands of a single specie may often be found.
3. Deer, Raccoons, Salamanders are especially characteristics of this biome.

DIFFERENCES BETWEEN THE TROPICAL RAIN FOREST AND THE TEMPERATE DECIDUOUS FOREST
1.The temperate deciduous forest has fewer number of species trees while the tropical rain forest has great varieties of tree species.
2. Most plants are deciduous in the temperate rain forest while most plants are evergreen in the temperate rain forest.
3. Epiphytes are absent in the temperate deciduous forest while Epiphytes are present in the tropical rain forest.
4. Deer, Raccoons and salamanders are animals found in the temperate deciduous forest while mammals, reptiles and birds are found in the tropical rain forest.

DESERTS
Deserts are regions of the world found on the Western side of land masses, except the Sahara which extends across Africa. The mean annul rainfall in desert vegetation is less than 25mm. The temperature is very high during the day and very low at nights. There is much evaporation of water from the soil. The dry conditions support sparse vegetation. Plants found in deserts are date palms, cactus, with leaves reduced to spines, prickly pear and sage brush. These plants have been adapted to conserve water. Animals present are apus, camels, lizards, rodents, scorpions, and antelopes. Also, these animals have developed adaptations to conserve water and also escape the scorching heat of the desert sun.

AFRO- ALPINE
Afro- alpine is found in highlands and mountains in Africa. Heat is in short supply and the vegetation is mainly grasses. The vegetation changes as one goes up the mountain, i.e, savanna temperate forest, Bamboo forest and Alpine pasture.

POPULATION STUDIES BY SAMPLING
The relative sizes of plant population may be compared by means of quadrats and transects.
A quadrat is a square frame made from thick wire for determining the population of organisms.

ECOLOGICAL FACTORS
They consist of biotic and abiotic factors.

ABIOTIC FACTORS
These consist of climatic and physiographic factors.
CLIMATIC FACTORS: They are made up of the physical and chemical factors.

PHYSICAL FACTORS:
They include wind, pressure, temperature, humidity, rainfall, and light intensity.
CHEMICAL FACTORS: They include oxygen, nitrogen, water, carbon (IV) oxide, and mineral salts.
PHYSIOGRAPHIC FACTORS: They are made up of the edaphic and topographic factors.
EDAPHIC FACTORS: These includes water content of soil, degree of acidity or alkalinity, i.e, pH, organic content of soil, available nutrient, soil profile, and texture.
TOPOGRAPHIC FACTORS: These include the nature of the soil, shape of land, altitude, drainage and erosion.

BIOTIC FACTORS
They are concerned with plant and animal relationships. thus the activities of organisms in a habitat can be described as biotic factors.

ECOLOGICAL FACTORS AFFECTING ONLY AQUATIC HABITATS
1.SALINITY: This can also be described as salt content. Sea water is highly saline while fresh water has very low salt content and so different organisms exist in each.
2. DENSITY AND VISCOSITY: These factors help in floating ability of organisms.
3. TURBIDITY: Turbidity reduces the visibility of organisms in water and the amount of light entering the water. Thus, organisms live at a greater depth in clear water than in turbid water.
4. DEPTH OF WATER: Streams or ponds are usually shallow and so sunlight can penetrate down to the bottom, unlike deep sea water. Thus, green plants can grow throughout the depth of the fresh water together with animals that feed on them.
5. Water current improves transparency, air circulations, nutrients and temperature in water for aquatic organisms.
6. Tides or Waves have similar effects as water currents.
7.pH: Organisms usually tolerate small pH variations that occur in the habitat. E.g, fresh water molluscs tend to be absent in waters with pH less than 6.
8. Dissolved Oxygen: The amount of dissolved oxygen is an important factor in all aquatic habitats since it is important in respiration.

ECOLOGICAL FACTORS AFFECTING ONLY TERRESTRIAL HABITATS
1. TOPOGRAPHY: This brings about distribution of vegetation and animals in the habitat. E.g. there is a giant forest at the bases of a mountain region in tropics but a scanty vegetation near its peak.
2. EDOPHIC: The nature of soil is important in distribution of vegetation. E.g. lateritic soil support a grassland vegetation while a loamy soil will support tropical forest. The type of vegetation will in turn determine animal distribution.

The following ecological factors are all common to all habitats and they include; Temperature, Rainfall, Light, Hydrogen ion Concentration, Wind and Pressure.

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