Bio-geography

Notes to remember
When soil water freezes and tends to form ice layers parallel with the ground surface then it heaves the soil upward in an uneven manner.
Soil particles present in a loamy soils are sand particles, clay particles and silt particles.
Soil water is available to plants is maximum in clayey soil.
Capillaries are most effective in loamy soil.
Salinisation occurs when the irrigation water accumulated in the soil evaporates, leaving behind salts and minerals. The effect of salinisation on the irrigated land is that it makes some soils impermeable.
Gram and other pulses have nitrogen fixing capacity.
The plants growing in water are called hydrophytes.
Xerophytes are plants which can withstand extreme aridity.
The smallest distinctive division of the soil of a given area is pedon.
Plants growing in areas of high temperature are called megatherms.
Minor climatic variations in the environment lead to modifications in the plant bodies.
Thorns in cacti are modified leaves.
Climate, soil and vegetation are all interrelated.
Biochore is an area of vegetation having uniformity of life form.
In Savanna biochore, the structure of vegetation is significantly determined and maintained by periodic fires.
A large unit of vegetation having uniformity of not only the life form but also of adaptation of environment is called a biome.
An ecological niche is the smallest unit of vegetation having internal homogeneity and adaptation to its environment.
The nature of vegetation in the world changes according to the latitude, climate and nature of soil.
Going from poles to the equator, the variety of plants increases.
The term deciduous implies plants shedding leaves during dry season.
Coniferous trees are so named on the basis of the shape of the leaf.
Temperate forests are known for having pure stands of single species of trees.
The term 'Taiga' means coniferous trees.
The typical structure of a tropical forest is three tier.
Before the climatic climax vegetation evolves, there are some stages of short term equilibrium between the plants and the environment. Such a short term climax is called an edaphic climax.
The Savanna is a tropical mixed vegetation dominated by grasses.
The characteristic of evergreen forest is, all the trees do not shed their leaves simultaneously.
Evergreen forests indicate a climate with year round adequate rainfall.
The broad leaf trees are most common in hot and humid areas.
The leaf size of vegetation is a function of temperature and moisture both.
In dry regions, the leaf size becomes smaller due to reducing transpiration.
Tropical rain forest regions are characterised by little undergrowth, trees of several layers.
Time is considered as a passive soil former.
Soil that owes its colour to oxides of iron is laterite.
In the hot and humid regions of the tropics, the characteristic soils are laterites.
Pedalfer soil is formed in the regions of ample rainfall and is characterised by abundance of aluminium and iron.
In Tundra region, jaegers, geese, shorebird, songbird are found.
A system is in dynamic equilibrium, when it is neither growing nor getting smaller but continues to be in complete operation.
Plant succession in which vegetation change is brought about by some external environmental factor, such as disease, is called pathogenic succession.
Impermeable rock layer that resides the infiltration of ground water, consists of tightly packed or interlocking particles such as in shale is called aquiclude.
Alfisol order of the CSCS is supported to be the most fertile soil in natural conditions.
CO2 are directly involved in chemical reactions affecting clay minerals and carbonate minerals in the soil.
Clay layers are poor aquifers because the inter-particle space of clay minerals is the least.
When the soils are related to the topography of a hill side, Catena represents a sequence of soil type down a slope.
Solonetz soils is the product of intense alkanisation and is characterised by the presence of sodium carbonate.
The most suitable measure for the soil conservation is afforestation.
The zonal soil type of peninsular India belongs to red soils.
Laterite soils are formed due to removal of silicates, lime and organic matter.
Lithosol is an azonal soil.
The dominant Mediterranean scrub vegetation in Southern California is chaparral.
In tropical Savanna regions, water availability determines the tree growth and trees exhibit various adaptations to fire.
The alluvial soils of the Gangetic valley are described as azonal.
Ephemerals have short life cycle and may form a fairly dense stand after rainfall.
CSCS is based on a hierarchy of six categories or levels.
Laterisation processes occurs in humid tropics where heavy rain and uninterrupted warmth give rise to deeply weathered layer.
Black soil of steppe is black in colour due to tettaniferrous mineral.
An epipedon is a horizon that forms in the sub soil portion.
C-horizon is usually the parent material rock.
V. V. Dokuchaiev is considered as a pioneer in the study of soil genesis and soil classification.
V. V. Dokuchaiev proposed the first scientific classification of soils in 1886 and classified soils into:
1) normal (upland)
2) transitional (meadow, calcareous, alkali)
3) abnormal (organic, alluvial, aeolian).
The normal class was further divided into '7 zones' based upon climate and 'soil types' based upon soil colour.
C. F. Marbut translated Glinka's work into English, borrowed and modified the Russian pedologic views and finally prepared a comprehensive system of soil classification for the United States.
The substance of the soil exists in solid, liquid and gaseous state.
The smallest distinctive division of the soil of a given area to which a unique single set of properties apply is called as polypedon.
Soil consists of liquid, solid and gaseous states.
Gases present in the open pores of the soil consist not only of the atmospheric gases, but also of gases liberated by biological activity and chemical reactions within the soil.
The soil column, which represents the dynamic and distinctive layers of soil, comprises A and B horizons.
C-horizon lies below the level of root activity.

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