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1 THE
GEOGRAPHY AS SPATIAL SCIENCE?
1.1 Geography
unit or diversity?
2 THE
CHARACTERS OF THE GEOGRAPHICAL SPACE.
2.1 The
characters of the geographical space.
2.2 A
changeable space that is described.
2.2.2 Homogeneity
of the geographical spaces.
2.2.3 The notion
of scale applied to the geographical space.
2.3 The space
and the geographical system.
2.3.1 The types
of arrangement of the same natural landscape.
2.4 The notion
of natural resources.
2.5 The notion
of natural obstacle.
2.6.1 The
influence of the man in the way.
2.7 The man
and the modified way.
2.8 The
geographical space is a space perceived and felt.
2.9 The
meaning of the densities.
2.9.1 Different
densities in a few similar means.
2.9.2 The same
densities and different meanings.
2.10 The
optimum of population: overpopulation and subpopulation.
2.11 Rural
space and urban space.
2.12.1 The
aspects of the urban space.
2.12.2 The
influence of the cities on its environment.
2.12.2.1 Relations
country - city.
2.12.3 Urban
functions and life of relation.
2.12.4 The
relations’ city - country according to the level of development.
2.12.4.1 In the
developed countries.
2.12.4.2 In the
industrial countries.
2.12.6 The
region, extension area of a landscape.
2.12.7 The
assignment of the cities in the formation of regions.
2.12.8 The
evolution of the region.
2.13 The
organization of the space in the industrial countries.
3 ZONES
OF VEGETATION AND CLIMATE
3.1.2 Vegetation
and environment.
3.1.3 Ecosystems
or biogeocenos.
3.1.4 Climatic
zones of the Earth.
3.2 ZONE OF
TROPICAL rainforest ALWAYS GREEN.
3.2.1 Tropical
rainforest always green.
3.2.1.1 Climate
and microclimate.
3.2.1.2 Soils and
cycles of the matter.
3.2.1.3 Structure
of the cap of the trees.
3.2.1.4 Other
forms of life: lianas and epiphytes.
3.2.2 Levels of
the tropical mountains.
3.3 VEGETATION
Of THE TROPICAL ZONE WITH SUMMER RAINS.
3.3.3 Sheets
determined by the climate. Grass and woody species as antagonists.
3.3.4 Plains of
the Orinoco and closed Fields.
3.3.5 Tropical
meadow on soil of changeable dampness and in area of flood.
3.3.7 Swamps and
formations of the beaches.
3.4.1 Water
supply of the arid zones plants.
3.4.2 Ecological
adjustments of the plants of arid zones (xerophytes).
3.4.3 Arid
subtropical zones of the different floral kingdoms.
3.4.4 Types of
arid landscapes.
3.5 ESCLEROFILA
VEGETATION OF THE ZONES WITH WINTER RAINS.
3.5.1 Mediterranean esclerofila region.
3.5.2 Altitudinal
Mediterranean levels.
3.5.3 Mediterranean
steppe of the plateaus.
3.5.4 Esclerofila
Vegetation with winter rains of California.
3.5.5 Chilean esclerófila Zone.
3.5.6 Vegetation
of the South Africa winter rains zone.
3.5.7 Vegetation
of the zones with winter rains of Australia.
3.6 ZONE OF
WARM TEMPERED VEGETATION.
3.6.1 Zone of
warm forest tempered of the oriental coasts of the continents.
3.6.2 Hot-tempered
New Zealand Forests.
3.7 NEMORAL
ZONE OR ZONE Of FOREST GREEN PLANIFOLIO IN SUMMER Of TEMPERED CLIMATE.
3.7.1 Distribution
of the forests caducifolios tempered.
3.7.2 Atlantic
regions of the moorlands.
3.7.3 Planifolio
forest as ecosystem or biogeocenos.
3.8 ARID ZONES
OF VEGETATION OF THE MODERATE ZONE.
3.8.1 Wooded
Steppe with zone of semiarid transition.
3.8.2 Soils of
the wooded zone of Eastern Europe.
3.8.3 Steppes of
meadows on black deep land.
3.8.5 Steppes of
grass of the south hemisphere.
3.8.6 Deserts of
Central Asia with cold winters.
3.8.7 Deserts of
Oriental Asia.
3.8.8 Cold
deserts of high mountains of Asia.
3.9 BOREAL
ZONE OF FOREST ACICULIFOLIO.
3.9.1 Climate
and aciculifolias species of the boreal zone.
3.9.2 Types of
forest of the nemoral boreal European zone.
3.9.3 Floors of
acicufolo forest of the Central European mountains and the limit of the trees.
3.10 ARCTIC
ZONE OF THE TUNDRA
3.10.2 Climate
and vegetation of the tundra.
3.10.3 Antarctica
and subArctic islands.
3.11 ALPINE
VEGETATION OF THE MOUNTAINS.
3.11.1 Diverse
types of limits of forests.
3.11.2 Climatic
conditions of the Alpine floor.
3.11.3 Ecological
determining of the Alps over limit of the trees.
4.1 DEFINITION
AND CLAFICACIÓN
4.2.3 Traditional
intensive systems.
We can to answer without ant doubt tha diversity. There exist aspects
that have lasted during long time:
- The fundamental aim of the geography was the spatial differentiation (posibilism).
- The landscape: natural and cultural.
- Relation environment-man.
- The fundamental aim is the space.
Characterization of the geographical space.
- Evolution of the external reality.
- Theoretical reflection of the Geography.
- The space is analysed by other sciences.
What is not the geographical space?
It is not a simple frame where a series of facts are given. It is not
totally abstract.
The space is objective and extensive, has a reality beyond the personal
reflection
It is something independent of us. He is an attaché of physical elements
and human elements. It is something heterogeneous, limited by a series of zones
of transition. It is a produced and organized space. It is never chance. He is
not organized of a random way.
It reflects the internal contradictions of the society.
It is material, tangible, endowed with an expression and cartographical.
It is constituted by a series of physic fact.
It can be submitted to abstractions and theoretical models. They are an
attempt of simplifying the reality.
It is a space produced by the society. It is a social product. This
organization answers to a few interests and values. This order is a reflex of
the values and contradictions of the society. It answers to an internal logic.
From this we can to deduce that if any space is organized we can look for laws
that explain this organization. The task of the geographer would be to seek
that one for order and to explain it, to rationalize it.
If the space is produced by the society, it is an object of consumption.
It takes a price, a value as goods. Big benefits can be obtained from its
occupation and consumption It is an integrated space of interrelationships. The
facts do not appear isolated, but interrelated across a few movements or flows,
visible or material, invisible and not tangible.
The geographical space is a functional space. This functionality gives
place to a spatial hierarchal structuring, establishing a few relations of
authority of a few areas over others.
The geographical space it is a dynamical space. The geographer must
analyse the processes of change of the spatial units.
Questions that must be made and the geographer answers.
- Where? He analyses the spatial distribution of the phenomena.
- Why? It looks for the explanatory reasons.
- Who? He analyses who are the spatial agents who organize the space.
- How? Of what form and by means of what mechanisms is organized the
space.
- For what and for whom? Depending on what interests organizes the
space. Consequences of this organization for the groups of the society.
- When? Reconstruction of the processes that have given place to the
spatial situation.
The space is considered as a ecosystem (spatial system).
Structure of the Geography.
If the Geography is considered like a spatial system every of its
elements are considered as subsystems.
Divisions:
- Regional geography and general (systematic) Geography.
The general Geography studies spatial subsystems. Inside this
conception, it might define to the region as a constant space of changeable
extension characterized by a dispersion of physical and human elements.
The regional space appears constructed by the relations that are
supported between his elements and his territories. It is a opened,
hierarchical space, in continuous dynamism.
The general Geography will analyse the systems of activities in the
totality of the terrestrial surface. It is necessary to distinguish the
physical elements of the human beings.
Each of these fields has been divided according to the elements and
resultant spaces:
Physical geography:
- Geomorphology.
- Climatology.
- Biogeography.
- Hydrology.
Geography Humanizes:
- Subsystems of activity.
- Spatial subsystems to global scale.
Inside the first case, (subsystems of activity) we can to differ:
- Economic geography. Its aim is to analyse the relations among the
economic fact and the territory.
- Social geography. Relation of the social structures and the spatial
ones.
- Political geography. Influence of political power in the organization
and modification of the territory. Influence of the space on political actions.
- Historical geography. It establishes processes of evolution.
Ecosystem
Factors that intervene in the modification of the ecosystem:
Solar radiation, tectonic movements that act on the atmospheric mass,
which will give place to the atmospheric dynamics. The tectonic movements that
act on the litology will give place to sets morfoestructurales.
Between(among) the elements of the ecosystem there take place(are
produced) a few interactions that will give place to the formation of the
geosistema.
Elements of the system
- The climate. It is the principal. It is going to act on the litology
and it is going to be the person in charge of the different types of soil.
It is going to shape the relief Acting on the geological structures
(erosion).
The forms of relief are interrelated with the vegetation.
The climate will influence the hydrographic net according to the rain
and snow regime.
Solar radiation.
Engine that puts in functioning the atmospheric dynamics and the
distribution of climates. The Sun emits radiations of which the land intercepts
a very small part. It has a constant value (solar constant). Its value is of 2
calories per minute and for cm2 (2 Langley per minute). The unit of
measurement is the Langley. It will not come to all zones of the land of the
same way.
1) Distribution of the solar energy.
The solar radiation is not equal in the time. It changes along a few cycles
(Cycles of the solar spots: 11 years of duration).
2) Modification in the space.
It is different in the different zones of the Earth. It depends on two
factors:
- Height of the Sun.
- Duration of the day
a) Height of the Sun. It is the angle that they form the solar beams
with the horizontal of the terrestrial surface. As higher, the radiation will
be bigger.
In the zones of lower latitude, it better received the radiation.
The solar radiation changes according to the station of the year, being
major in the summer of the corresponding hemisphere.
b) Duration of the day. Due to the movement of the Sun, there is a
different duration of the day in both hemispheres.
Since consequence in both inter-tropical zones, there are no differences
between the hours of sun and the temperatures. There are no thermal stations.
When the latitude increases, the contrasts between the stations increase
too.
The first losses happen on having crossed the ozonosphere (15-35km).
The second obstacle is the presence of clouds. Part gets lost also to
the being absorbed by the water steam.
The different caps of the atmosphere also stop to the radiation.
This does not happen in the same way in all the zones. The cap of ozone
is denser in the polar caps.
There exist three bands of major cloudiness:
- Ecuador.
- Intermediate zones between the north and the south.
Four bands of minor cloudiness:
- 2 polar Caps.
- 2 Tropics.
Part of the energy that comes to the Earth is going to happen to be
reflected depending on the part where it comes: Albedo.
It is related to the heat. The zones of perpetual snow have a very
strong albedo (80-90 %), the white sands (50-60 %), the lakes (18-20 %) and the
forests (2-3 %).
In the zones of fort albedo there takes place warming of the low caps.
There are strong changes of temperature.
This thermal balance (balance between the zones that have major
radiation that irradiation) is different depending on the zones. There exist
zones that have a positive balance (warm and moderate zones) and zones with
negative balance (poles and cold zones).
This balance be altered by diverse factors:
- Airs movements in the atmosphere.
- Waters movements.
They produce mechanisms of heat interchange between the different zones.
They are the surfaces factors.
Close to these, it is necessary to mention:
- Contrasts among the continents and the oceans.
The continents are cooled and warm up more rapidly than the oceans. They
carry the heat of different way. In order that the interior of a continent
reaches a low temperature, it is necessary that in exterior beech a temperature
lower than if it was an ocean.
The oceans have a few much softer thermal contrasts. The thermal extent
is very much major inside the continents that in the littorals.
- The topography.
It will influence on one hand making diminish the temperature, as we
ascend, in a gradient of 6 º for kilometre. In the middle and high latitudes,
the altitude establishes the dissymmetry between two slopes. The Sun affects
more in one that in other one.
Thermal investment. There is more cold in low zones that in the high
ones.
3) Factors that determine the distribution of the temperatures.
- Latitude.
1) Hot inter-tropical zone. The temperature is the most superior to 18
º. It does not exist winter. The growth of the plants is not interrupted.
In July, it moves towards the north and in winter towards the south.
2) Moderate zones. Climates where in winter there are temperatures to 18
º. Summers of +20 in the hottest month.
3) Zones below the 10 º. No month reaches the average of the 10 º.
Thermal summer does not exist. Difficulty of development for the vegetation.
4) Authority of the permafrost.
- Marine currents. Hot or cold. In the low latitudes, the western coasts
of the continents have a few temperatures colder than the oriental ones. The
opposite happens in the average and high latitudes.
They tend to balance the thermal balance of the land. They continues a
path Ecuador - pole and vice versa. Due to the rotation, (Coriolis's effect)
the currents turn aside to the left side or to the right (hemispheres South and
North respectively).
The currents of compensation descends from the poles (cold drop).
Currents.
The Atlantic Ocean North. Of the Gulf or Gulf Stream.
Equatorial zone. From the Caribbean Sea
to Europe.
The Cold Current of Canaries.
Current of the Labrador, of compensation, bathes the northeastern coasts
of America.
In the Atlantic Ocean South.
Current of the Brazil. Hot.
Benguela's current. Cold.Coast western South of Africa.
- Current of the Malvinas. Of compensation. Cold. Similar to the
Labrador.
Pacific Ocean.
Kuroshivo. Hot.
Oya Shivo. Cold
Both are in the north of Japan.
The cold currents produce dryness, coastal deserts.
The hot currents provoke strong rainfalls.
The decrease of the temperatures supposes an increase of the relative
dampness and an increase of the temperatures provokes a decrease of the
relative dampness.
If the air mass has a relative dampness of 100 %, it is saturated and if
it continues being cooled, there is produced the condensation (step of the
gaseous state to the liquid). It is necessary that exists in the atmosphere a
few particles (nuclei of condensation) that absorb the water, and that are in
the air. They can have different origins: smoke, crystals of ice, remains of
pollution, etc...
The reason of the cooling can have different reasons:
- For contact with a cold surface.
- Adiabatic cooling (internal cooling of the airs masses).
In the first case, the cooling takes place in touch with a cold surface.
The low caps cool and give place to the condensation. On no having been
increase of height (of the air mass), it will take place to evenness of the
soil, for what it will not provoke rains, but fogs, hoar-frosts and dew.
In the second case, the cooling takes place inside the mass. The whole
mass that ascends is experiencing changes of pressure, volume and temperature.
It loses pressure (8 mb every 100 meters), increases of volume and diminishes
the temperature (adiabatic cooling). It is produced with a gradient of 1 º/100
meters. This cooling changes when the level of condensation is reached since on
having changed its state it detaches heat (latent heat of condensation). For
this heat the adiabatic gradient diminishes from the level of condensation and
stays in 0 ' 6 º/100 meters (pseudo-adiabatic gradient).
Forms of condensation.
a) Hydrometeors of type stratiform (gradient least than 0 ' 5 º/100
meters)
1. -Formation of fogs.
a) Radioactive (fog and smog).
b) Fogs of advection.
2. -Form of the clouds. Level of the base
a) Low stratus ....................... Less than 9000 meters.
b) Nimbus stratus........................ 900-2500 meters.
c) Altostratus ......................... 2500-5500 meters.
3.-Rainfall.
a) Drizzles and thin rains.
b) Powder of snow.
b) Hydrometeors of type convective limited. They are formed when the
gradients are unstable or unstable between 0 ' 5-1 º), in a limited thickness
and them they are produced in the most top part of the cloud.
1.-Scarcely they give fogs.
2.-Types of clouds Level of the base.
a) Stratum cumulus ............................. 300-2500 meters.
b) Altocumulus .................................. 2500-5500 meters.
c) Cirrocumulus ................................. more than 5500 meters.
3.-Rainfalls.
a) Light downpours.
b) Light snowfalls.
c) Hydrometeors of type convective unlimited. The forms of condensation
of this type are produced when the atmosphere is the sufficiently unstable in
order the vertical convection penetrates in height.
1.-Scarcely there are fogs.
2.-Forms of the clouds. Level
of the base.
a) Cumulus .................................... 1000-3000 meters.
b) Cumulonimbus ............................... 1000-3000 meters(metro).
c) Cirrus ..................................... 6000-12000
meters(metro).
3.-Rainfall.
a. Moderated or forts of frontal or organic character.
b. Moderate strong downpours or and snow.
Classes of rains.
Orographical. The mass finds an obstacle.
Convective.
Of convergence.
Frontals.
Convective. An air mass warms up to the contact with a warm surface and
rises. In the moment of the condensation, it forms clouds of the group of the
cumulus. If the ascent continues the Nimbus-cumulus are formed and rainfalls are
produced. They take place in the inter-tropical zones and are a reason of the
"summer storms".
Of convergence. Meeting of two airs masses of the same characteristics.
In the equatorial zone takes place a shock between two masses of hot air. An
ascent is produced, they converge and the rainfall takes place.
Frontals. Shock of two airs masses of different characteristics. When the cold air enters in contact with the
hot, the cold mass, which is more weighed, penetrates in the hot mass in touch
with the soil. There takes place an ascent of hot air until disappears. It
takes place in average latitudes. The Polar front is the zone of contact
between the air masses. It is divided in several sectors.
- Where the hot mass exercises bigger pressure. Hot front.
- Cold front. The opposite thing happens.
As it is made deeper, a tempest is formed.
When a hot mass of air is introduced in cold turbulences, several
consequences are given:
1) Cold air. Dry weather, without rains.
2) Soft and lasting rain. It takes place due to the push of the hot
front.
3) Stratographycs clouds. Light rains.
When the hot front passes, it stops raining and they raise the
temperatures.
The cold front originates intense rainfalls with storms, but slightly
intense. When the cold front passes, it stops raining and the temperatures
fall.
In the equatorial zone, the rains are caused by convergence and
convection.
In the temperate zones, they are frontal and convective.
In the zones of cold currents, a great aridity takes place. In the zones
of hot currents, take place big rains.
In the western zones of the average latitudes, the rains are more
abundant than in the oriental ones. In the low latitudes in the western ones
they are minor.
If a hot current exists the air mass becomes overheated in its base and
rises, turbulences take place are produced and forms clouds. If a cold current
exists, the air remains compressed, fogs are formed and aridity will be
produced).
Atmospheric dynamic.
The atmosphere is constituted by airs masses in constant movement. They
are not homogeneous; they are unbalanced. The air column that exists on
different points of the globe is not the same, which produces movement.
The pressure is in inverse relation to the volume that occupies the air
mass. The air can be compressed and the airs caps that are more compressed are
denser. As the air mass rises, the pressure diminishes. The normal pressure is
of 760 mm or 1013 mb.
There are zones with bigger pressure and many molecules for m2,
and vice versa.
The pressure is measured in cartography by the isobars.
The high pressures are represented with a letter A and the falls with
one B. They are the centres of action atmospheric. The air in surface moves
from the centres of high pressures to the low pressures (barometric gradient).
In the globe, there exists a belt of high pressures and other one of low
that are distributed according to the latitude.
In the equatorial zone there exists a zone of low pressures where takes
place the convergence of winds of low pressures.
On the tropics, we have zones of high pressures. In surface, the zones
of high pressures are of difference.
In the average latitudes, there exist zones of low pressures. Zones of
wind convergence.
In the Poles we find zones of high pressures.
The Coriolis’s effect does that the winds turn to the left side in the
south hemisphere and towards the right in the hemisphere north.
Close to the coordinates and their latitude, the emplacement and the
position constitute a point of reference for the location of a place in to
land. Therefore, it is possible to say that the geographical space is cartographible.
Another question that it is necessary to know is the differentiation,
facet that we find in any space: we will never find spatial elements or similar
landscape neither in another part of the world or in another moment.
We can fall down in the mistake of to find incompatible this
differentiation with the notion of homogeneity. We will see that the
homogeneity is the result of the repetition of certain number of forms that are
given of similar form, though not identical.
Because of it, and due to the differentiations that are produced in the
bosom of the families of forms, it is difficult to do rapid comparisons and
schemes.
The geographer, nevertheless, tries to show the elements of comparison
that allow regrouping the forms in big families. He emphasizes a series of
combinations that facilitate the classification and explanation of the forms,
necessary for the comparisons.
The modification of the Earth is demonstrated; modification that leaves
its fingerprint in any landscape and that is easily verifiable. It is this
landscape, physiognomy, as was named by VIDAL OF THE BLANCHE, which is
described.
The description is, together with the explanation, one of the principal
occupations of the geographer.
It values, classifies and arranges the elements of the landscape. It
allows to raise problems.
As example, we can mention a description of the Central French Clump:
Its high plateaus, raised, waved, are replete of small valleys of humid
bottoms. Their horizontality is owed to tertiary surface of erosion. The
tectonic movements of the second half of the Tertiary raised these surfaces of
erosion and gave place to the cut of the throats.
The plateaus are formed by granites, crystalline schist, material resistant
to the erosion. In the plateaus, the hydrographical net is inserted giving
place to narrow valleys.
The description of an urban landscape allows knowing its history, the
process of development produced from its origins up to the current moment.
A great part of the European cities they have a similar scheme:
First, we meet an enclosure walled of the medieval epoch, inside which
all buildings, streets, etc ... were situated around the cathedral or the
church.
Beyond this walled belt, more recent neighbourhoods were located.
In addition, there exist cities that preserve vestiges of the step of
the Romans. In the study of the landscape, it is necessary to grant great
importance to the interactions between the endogenous forces and the exogenous
ones, since all the reliefs are products of them. Anyhow it is necessary to
emphasize that the transformations have not taken place in all the forms to the
same time, but they depend on other factors (volume, climate etc...).
This is easily verifiable comparing to genesis of an islandsis (great
continental glacier) with that of an Alpine glacier. Its great volume will give
place to climatic modifications that will leave its fingerprint in the
glacier’s margins. The time of formation of an islandsis is of several dozens
of millions of years.
In the Alpine glacier all the phenomena happen in a space of shorter
time, so if in case of the islandsis the climatic change was accused after
several centuries, in case of the glacier the consequences will be able to see
in a short period.
Any change takes place from a given situation, and it is fed from
inheritances.
In a beginning the bottom of the valley is covered with a cap of
pebbles, when the change of climate takes place the relations change wealth -
load (of the river); the river does an incision in the alluvial caps and the
terraces appear. The river in its flows displeases pebbles came from the
alluvial formations deposited in previous times.
These displacements are not constant, but there exist big periods of
stagnation, of "silence".
The displacement is characterized by the system diversity of erosion
that, and for the transformations that each of them produces in the fragments.
- Displacement of a rocky fragment.
- Accumulation in a cone of erosions.
- Because of a climatic change it is caught by a glacier and is
converted in a part of a moraine, the edges are smoothed.
- The waters of merger turn it into a boulder and later into sand.
- Finally, it can end in state of sandstone.
It is necessary to say that these phases are symmetrical neither in its
effects, nor in the time.
A clear example is the "sahel" or frontier region with the
desert.
If takes place a wider duration of the dry years and if the human action
provokes the destruction of the trees, the desert would advance and occupy what
previously was a steppe.
The threshold for the step of steppe to desert is easier crossed that
the threshold desert - steppe.
The study of these elements is important to know and to understand the
phenomena that help to modify the natural landscape, as well as those who rule
the societies that occupy the space, so when threshold is penetrated place
takes a process and other one disappears.
" A homogeneous space is a constant space. Each of its parts
presents a few characteristics as similar as those of the set ". (J.R
BOUDEVILLE).
The external homogeneity exists:
- It corresponds to the area of a landscape.
And in the internal:
- It is a system governed by an internal cohesion (LEVI-STRAUSS).
Likewise we canto consider:
- A space constitutes any state in which its citizens obey the same
laws.
The scale is a very important factor for the analysis of any
geographical environment.
The scale is necessary to not to fall down in mistakes of magnitude.
For example, we cannot to compare the population and his distribution of
Brazil and Costa Rica, though both belong to Latin America. In addition, we
must realize that if the scale changes, change the nature and magnitude of the
phenomena. It is not the same a city of a million of inhabitants that 20 of
fifty thousand, in spite of being equivalent numerically speaking. The
comparisons have to be done between similar forms, to verify the analogies and
to follow its evolution. For this reason to do comparisons and classifications
have to be used scales of equal value.
Diverse forms of classification have been presented:
- CAILLEAUX and TRICART. Classification of the mountains.
It’s based on the surface.
- The first order. Big mountain chains of the west of America. They have
15000 extensions kilometres and go from Alaska to Earth of Fire; the
alpine-Himalayan group.
- The second order. A subdivision of the previous one: the Alps.
- Third order. An inferior stratum of previous orders: Sierra Nevada and
the Coast Range.
It is advanced towards the inferior scales, coming to the seventh order,
where we find a plait, and the eighth one is a flank of this plait of a few
kilometres.
With regard to the climates, we can classify them of similar form,
beginning for the big climatic zones and ending for the microclimates.
Likewise, we can divide the space by the levels of development; developed
countries and underdeveloped countries, between which we can do a gradation (or
degradation). We find, on the developed big countries differences between Italy
and Sweden, and in the opposite pole (underdeveloped countries) between
Venezuela and Colombia.
BRUNET does a division that is related with the
previously mentioned of CAILLEAUX and TRICART.
I. Zone ........….…1st Order ..………107 Km2……scale
1/10.000-.000
II. Authority ....... 2nd order ..……... 106 Km2....…scale
1/1.000.000 to 1/500.000
IIIa). Province .... 3rd Order ..…….... 105 Km2… scale 1/500.000
IIIb). Region .….. 4th order ...…….... 104 Km2..… scale
1/200.000 to 1/100.000
IV. Region ........... 5th order ……....... 500/1000 km2….…1/50.000
to 1/20.000
V. District ..…...... 6th and 7th order .... 5 to
50 km2…….... 1/10.000-20.000
VI. Apple..... hectometric forms…. .... 1ha-1km2..………. 1/2.000-1.000
VII. Plot .... 7th and 8th order
.....…….... 1a-1 has ...……….. 1/500-100
This division has the method of joining in the same order all the
necessary elements, so of the environment as the human system, for the organization
and evolution of the space.
The man turns the natural system into geographical system, but he is
doing it for a little time (6500-7000) years, after the appearance of the
agriculture.
The types of landscapes have qualified in three, basing in the
modalities of human intervention in the way:
- Natural landscape. It has not experienced any transformation by the
man, at least in a recent epoch. They are not suitable for the agriculture or
cattle: high mountain, deserts, and tropical marshes. Nevertheless, these zones
are used frequently for the base installation of scientific character or
strategic-military.
Due to the climatic inclemency, the presence of the man is very scanty
and by no means it helps to modify the general character of the set.
- Modified landscape. The attitude of groups of recollectors and
hunters, though they practise neither the cattle nor the agriculture, can
modify the landscape: utilization of the fire to hunt. This measurement of to
burn the boundaries of the jungles in search of animals could have been the
reason of the appearance of the sheets, which origin had been looked long ago
in reasons foreign for the man.
The exercise of the cattle provokes likewise a visible modification in the
way.
On the other hand, and in the relating thing to the nourishment of the
animals it is necessary to say that due to the selection of plants on the part
of goats, lambs and oxen, there takes place a transformation of the existing
vegetable carpet.
Man contributes to this modification, because his action is usually
destructive. The abandon of zones on the part of the man is another reason of
landscapes. As example, we can mention the current jungles of the Yucatan,
cradle of to former and flourishing Mayan culture.
- The arranged landscapes. They are a product of several factors.
A conscious, pondered action. It is tried to extract to the way. The
space is organized depending on a few economic, social schemes and the allowed
technologies.
A compound action. A society directs its efforts towards diverse aims.
Depending on the capacity of the individuals’ tasks and obligations are
distributed to each of them.
An action continues. It is consequence of the previous two. The action
must be constant, though it is realized depending on a future more or less
distant.
Of the same way, we can extract diverse landscapes depending on his
utilization. We choose as example a virgin jungle.
- Virgin, primary jungle, which has not suffered the step of the man.
- Itinerant culture. Plowing of small chunks and sowing in the skylights
up to the depletion of the soil. Abandon of the same and appearance of the
secondary jungle. After fifteen or twenty years, take place the whole process
with the plowing and burns of the felling. They are crops of subsistence that
scarcely allow covering the basic needs of the man. They are used very
rudimentary tools. The density of population is very scanty.
- The jungle can be plowed and replaced by a bush crops: coffee, cocoa
etc... There exist surpluses that will be used in the national or international
transactions.
- Pastures for animals replace the jungle.
This differentiation does not mean that the diverse uses given to the
jungle cannot be one near others, as happens in any Latin-American countries.
Their value is determined by the society, the production technologies
and the epoch. For example the uranium was not possessing the same value one
century ago that now.
The same resource can be used of different form depending of epochs and
the technologies. A river makes move the wheels of a mill, provides water for
the systems of irrigation.
It depends on the technologies and the epochs. It serves as example the
terraces made from a slope.
If it is cultivated by a peasant who alone uses the force of his hands
it will not have differences with the plots that are in the plain. Even when it
is necessary to have animals transport the surpluses the difficulty and the
cost will be minimal, thanks to the of horse-shoe ways, to the wheel etc...
This situation changes when the mechanization appears. The access to the
terraces will be more difficult, with a major cost, on having had to use more
specializing machines.
There exists also the problem of the composition of the soil, often
porous, that is easier to work to hand that with machines, since it spoils the
machinery.
It takes place of diverse forms.
It can be realized across the climate: adjustment of societies in
extreme climates (Eskimo of the Arctic one, the nomads of the Saharan desert
etc ...).
This adjustment is helped by the physiological development of several
parts of the body (cap of protective fat…).
There are regions characterized for being an area of diseases and with a
negative influence on the accession of stable communities (tropical zones).
Paradoxically, many of the tropical regions (South-East of Asia, Java) figure
between the most populated with the world, done that only can be understood due
to the reorganization that it has been effected in those zones.
Together with the already studied transformations of the way on the part
of the man, we have to do support in the consequences that the same man
provokes in the way for him created.
Climate, noise, pollution, tensions of the daily life (stress), shortage
of the physical exercise, help to change the pathology of the inhabitants of
the city, being the fatigue and the weariness one of their principal
characteristics.
Also the historical situation contributes to the adjustment of the man
to the way. One of the multiple examples that reflect it is the Christian
collectivities expelled by the Turks to the mountains, till then an unknown
way. The big Turkish landowners occupied the plain, unhealthier.
Other times, nevertheless, does not exist adjustment to the natural way.
This is the case of the inhabitants of the Punjab (India) that leave fallow the
fields in epoch of rains, when they would obtain bigger benefits that
cultivating them on the dry station. In this case, it has given more priority
to the cultural tradition than the climatic pressure.
The geographical space has diverse ways of being perceived, depending on
his type (of the geographical space), the time and the place where it is placed
and the human group that lives it.
This is what has happened in the big mountains the residence of the gods
(the Greek Olympus and the Anapurna of the Nepal). The water, sacred element,
is seen as a symbol of purity, cleanliness. The Californian Indians had the
very clear things with regard to "its" territory, in which they were
hunting, were going fishing and gathering. Everything what there was in it
belonged them.
This way of understanding the space was broken when were joined in the
same set pieces of different territories (African settling).
This problem arises from the average densities. 11 to 12
habitantes/km2. This
could be read in the statistics of Peru in the year 1970. Nevertheless, to local
scale these numbers do not agree with the reality, which is very different. So,
we meet regions that are real human deserts and with others that overcome the
500 h/km2.
There are, nevertheless, zones of the same region or country that have
the same density but whose meaning is not similar. We can find cases of this
kind in the French regions of Brittany and Alsace. The first case represents a
population who, though it has not lost the agricultural character, has its more
important expectations in the industry. In the second one, on the contrary, we
meet a population exclusively dedicated to the agriculture; and as easy of to
suppose the farmers do not have the same mentality that the industrial workers.
Even in case the communities of two populations have similar activities
and an equal density, there can be given marked differences (Condado
Venosino and oases near to Lima, Peru). Both have in the horticultural
culture his mean way of life, and both possess similar densities (+ 100h/km2),
but the income per capita is very unequal: In the Condado Venosino 75000
annual pesetas, whereas in the oases they do not come to 20000.
The population’s optimum only can exist by means of a static balance
between inhabitants' number and the resources that these they arrange during a
certain space of time (PIERRE GEORGE).
If it does not come near or this ideal one is exceeded the productivity
is diminished.
The concept of overpopulation was defined by MALTHAUS as the
increase of a population that resides in a limited surface and whose resources
cannot increase.
This situation goes:
- Demographic dynamism.
- Technical stagnation.
- Social inflexibility.
- Inability to innovate.
This period is accompanied of scarcities, famines and epidemics, which
contributes to an increase of the mortality and a decrease of the population.
They are regulatory mechanisms that they would support the population near of
the average.
It breaks the balance, and overpopulation can exist in scantily
populated regions.
We suppose a group of hunters, a small group that lives in
"harmony" with the animals. If hunters' number increases, the animals
will be more harassed, will diminish of number and hunger and scarcity will
appear for the hunters.
It is a fruit of a decrease of population that does not allow to a
society to work according his rules, getting down the level of life.
We find subpopulation when a population tries to change his authority
into the space, and is incapable to do it due to his scanty density.
Returning to the notion of ideally of population, we have to concentrate
on his staticity, since there is not demographic dynamism; even take place
innovations directed to a bigger production with the maximum benefits. Across
the history, it has been present at diverse modifications of the densities and
in the professional composition of the population.
The industrialization is a sample of it. It is possible to consider her
as the engine of the urbanization. He needs numerous hand of work, which will
come from the foreigner or from the field, provoking in the latter marked
enough depopulation (Spanish field in the years 60).
It is the area of the pastoral and agricultural activities: the field.
The rural space has other meaning, as the playtime, rest and residence
for a population who works in the sectors before mentioned.
It can be said that the rural space is to mercy of the climatic
conditions, since they determine and make change its physiognomy.
On the other hand, the man contributes to the modification of the soil.
This modification will be accused depending on the quality of soil and on
fertilizer’s technology and worked applied.
There exist several organizations of the rural space.
-Lump. Space cultivated by an agricultural collectivity. Is
characterized by the form of the fields, its disposition….
- Fields and "bocages". The first ones are open groupings or
regions of open fields, where the big sets of meadows, forests are well
distributed. The "bocages" is surrounded fields and exists a mutual
understanding between the field and the meadow. It used to be accompanied by a
dispersion of the community, grouped in remote hamlets far ones from others.
In the same way, they can appear, disappear or transform, as happened in
the west of France.
His appearance was due to diverse factors according to regions and
epochs.
- Juridical factor (limit of the property).
- Technical factor (protection of the field of cattle by means of
hedges)
- Climatic factor (protection against the winds of the west).
- Ethnic factor (Celtic individualism).
Together with the agricultural functions, of leisure and of rest, we
find that the rural space has been used to be supportive of process of
communication (railroad, highways), that allow the inter-city relations.
The rural society is better professionally differentiated that the urban
environment, its level of life is minor that that of the city, which gives
homogeneity that does not know the city.
It is characterized by the presence of urban nuclei that include:
built-up surface, urban road net work, industrial and transport companies, gardens,
accessible areas of leisure to the citizen.
The city is related to agglomeration, convergence of nets, solid and
constructed well structure.
During enough time there was tried to give a definition of city that
which was satisfying to the whole world, something that seemed to achieve in
1966.
" The urban population is formed by a set of persons that reside in
a group of compact housings, in number of 2000, with the condition that in the
nuclei of less than 10.000 the cash that lives of the work of the land does not
exceed 25 %. Over this quantity, (10.000 inhabitants) any grouping will be
considered urban.
This definition is not very exact, because in spite of include the whole
Western Europe, it includes likewise populations of Nigeria and India of more
than 50000 inhabitants, whose population is in the main agricultural. It
excludes, besides, the new American constructions composed of a central nucleus
of services separated from the residential zone constituted by houses with
gardens, meadows, forests, fields of tillage and enclosed desert.
Therefore also they can be given, basing us on certain number of
information, other different definitions:
- Concentration in a limited surface of the habitat.
- Equipped, expensively, with great density of facilities space. There
is a competition for its utilization. It appears an exaggerate speculation.
Though the population grows of an enormous form, the limited surfaces
are still intact. For this reason and on not having had the sufficient
resources to survive they depend on other regions’ supplies. This supply is
done by means of the big nets of route of communication that have as central
axis the most important cities.
In the cities, there get together the tertiary activities, the industry,
and the administration. The cities have, therefore, a socio-economic power more
important than the rural way. This fact is typical in the whole world, we can
to compare countries of Africa with Asia, and Europe and we will see that this
phenomenon takes place in each and every of the chosen countries.
The position and the emplacement are, apart from mentioned in the
previous paragraph, two factors necessary for the definition of city.
- Situation or position. It is studied in maps of medium or small scale.
" It is the location of a city in relation with natural facts " (PIERRE
GEORGE). " The position of a city in relation with the regions and
process of communication " (DERRAU).
- Emplacement. It is studied in the maps of great scale. "
Emplacement is the seat of the city, the location of the space constructed in
its relations with the local topography (DERRAU). " The emplacement
is defined by the topographic frame in which it has established the city, at
least in its origins " (P. GEORGE).
The value of the emplacement can change depending of the epoch. The
hills that have given place to many cities turn out to be an obstacle for the
current ways of transport.
Many cities were born depending on a few needs and a privilege (to be
coastal, as Rouen) that now when the tonnage of the ships to grow and have
difficulties in to mend the estuaries already it is not such.
There are cities placed on several topographic sets: mountain and plain.
An element inside the city (a river) can change function with the
passage of time. The same river could be used as way of transport for after be
a basic element in the water supply of the city.
There are great typologies of cities, which are in an important variety
of geographical and historical sets.
City is as a small Spanish city (Alicante), as a Japanese agglomeration
(Tokyo), though it is necessary to treat both in very different scale.
We suppose that Tokyo has 12.000.000 and Alicante only 120.000. The form
of life in each of them, the problems, even the level of life is different,
given the difference between them.
The urban system is a work of man and therefore we can to say without
fear of us mistaking that reflects much more faithfully than the rural space
the physiognomy of the society of which it is an expression.
There has existed a trend to place the decision-making centres and of
bigger importance in the centre. It has given place to high prices of the area,
congestion, difficulties of access, especially for cars. As consequence of it
and for a few years, a search of areas has been initiated where to place the
trades, companies of assurances...
Another problem is the industries. Their placement depends on several
factors:
- Process of communication.
- Facility of provisioning.
- Available areas.
These areas must be far from the cities due to the harmful effects of
the factories: smokes, gases, and noises...
In any city exists neighbourhoods, zones or districts in which there
resides a group of men whose race, customs, or economic power (or scarcity)
they are similar. Sometimes they form a sub city preserving in many cases the
customs of land (emigration for work).
Even in the same zone of the city, different manners of living exist. For
example the centre of the big cities of United State is populated in the
daytime by bankers, economists, important people, whereas in the night a
wretched population is an owner of them.
The cities have depended on an important way of the field, especially in
the moment of their birth and development, especially on the agricultural
surpluses what allowed the birth of the cities. Nowadays country provides hand
of work, lands to feed to the urban population and space of leisure and rest.
From the demographic point of view two types of relations exist: country-
city and city -country:
- In the first case, people leave country to establish in the city. It
is the rural exodus.
- The inverse case, the citizen who moves to the country to rest
(pendulous movements of urban workers).
We can say that a great part of these relations are effected by
displacements.
- Another type of relation exists, anyway, due to the appropriation of
the agricultural lands on the part of the inhabitants of the city.
One of the principal functions of the city is to offer a series of
services, not only to their inhabitants, but also to the places around.
In any city, there are a hierarchy of services determined by the volume
and characteristics of a clientele to that it is necessary to attend.
The city is a receptor of the excess of rural population, which provides
a mediocre and unstable employment.
It works as a magnet that attracts the earnings of the country by means
of the territorial, commercial and financial rent
It is the intermediary between the developed countries and the rural
space.
It can present as area of modernity and development, but at all farther
of the reality: shanties, degradation, poverty, are usual in any city.
It’s appreciated homogeneity of the forms of life in the country and in
the city. Complementariness exists between both: the city provides services and
employments and the country place of rest and distractions. An urbanization of
the country has been initiated due to the progressive introduction of residential
neighbourhoods, companies and commercial surfaces, and with the access of the
villagers to the services that before were being destined only the inhabitants
of the city.
A Natural region.
It is a notion based on the basic role that they grant to the physical elements in the organization of the space.
" It is a part of the terrestrial space which unit is born exclusively of the intervention of physical elements rivers, mountains... (A. CHOLLEY). The scale does not make sense for her, since it can include big extensions of area (Sahara) as few dozens of kilometres.
A The historical region.
Territory inhabited by a group of people during several generations and that has not lost its cultural, political characteristics and its customs.
Also we can to consider as a historical region all what stays of a
territory that could not be converted into nation or state and was absorbed by
a political unit of bigger entity. In case of the historical region, the political
aspect has more importance than the physicist.
" The region corresponds to the extension area of a landscape
" (MAX SORRE). The geographical landscape takes place thanks to the
repetition of elements on the surface. These elements can be physicists or
human beings born by the meeting between a natural way and a human community.
It has been often criticized, and sometimes of wrong form, the notions
of region previously described (native and historical).
Some of these critiques are done because the historical region, due to
the modern ordination of the territory has lost her usefulness.
The analysis of the conditions that presided its formation is an
indispensable element for the knowledge of the region and its possible
definition.
The cities have a great importance in the organization of the inhabited
space. The regions are formed from the cities, and thanks to the birth of bows
of complementariness established between the cities and the field, and to the
relations that establish among the cities belonging to the same urban net.
The region can be considered as a biological being: it is born, develops
and dies.
The region suffers along in its "life" diverse changes that or
they affect directly its limits, or are internal changes that referred to its
structure. The weakness, the reinforcement, the displacement of borders is
causes of modifications in the cities and in the close regions.
There are clear and diaphanous interregional limits, another are
indeterminate, though sometimes it is at the mercy of the contentious ones
between the groups of influence.
The processes of communication are indispensable elements for the
organization of the space.
There are a sequence of relations between the diverse sectors, for what
a decision can affect several of them at the same time: a strike in a motive
industry can block the whole chain of productions and commercial operations.
The space is conceived in different ways by the inhabitant and by the citizens.
For this one the lower step is the neighbourhood of residence and of
work, and the highest those of distraction and vacations.
The peasant resides in the rural neighbourhood defined by the landscape,
a disposition of the fields and a habitat. In the villages, there are the more
elementary thing and the basic services.
Part of the activities they are organized with the regional and
provincial capital.
The relations of the space in an industrial country are not submitted to
a great hierarchy, which is only one of the factors on their favour.
The evolution of the vegetable kingdom has given place to different
groups (or kingdoms) floral:
- Holartic. North America, Eurasia and Greenland.
- Neotropic. South America.
- Paleontropic. Africa, Arabia, Monsoon Asia.
- Antarctic Ocean. South of South America, Antarctica.
- Australian. Australia.
- Capense. South-occidental extreme of Africa.
These demarcations are not excessively rigorous, since we found elements
of a kingdom mixed with them of different other one.
The vegetation is determined by the climate and the soil. The main rock
influences in the soil, and the flora the vegetation.
The factors that determine the growth and the development of the plants
are divided in:
- Thermal conditions.
- Water conditions
- Light intensity and duration of the day.
- Chemical factors.
- Mechanical factors.
A) Thermal conditions.
Between them, it is necessary to emphasize the temperature to which they
take place the vital processes of the protoplasm. In animal organisms, they are
distinguished:
- Species of cold blood (porquilotermas). Their temperature depends on
the exterior, for example the plants.
- Species of warm blood (homothermous). They possess own temperature.
3) The factor of the competence and the vegetable communities.
It is erroneous to think that the distribution of the vegetable species
is ruled by the ecological conditions, since this only happens in certain
occasions. The distributions limits of a species take place when diminished the
favourable environmental conditions up to the point of which their capacity of
competence is displeased by other species.
When the ideal ecological does not coincide with the ideal physiological
one (favourable conditions in the laboratory), we do not can recognize his
physiological needs basing us on the distribution, as well as knowing the
physiological needs after investigations in the laboratory we do not can to
guess his distribution.
We speak about competence when the growth of a species is determined by
the presence of others. Inside this we distinguish:
Inter-specific. It favours the survival of stronger.
Intra-specific. A species displeases to the others. The competition
gives place to the appearance of the vegetable communities. The balance that
exists between the species and the way takes place thanks to:
- Competition among the species.
- Dependence of a species of the existence of others.
- Presence of complementary species (in the time or in the space).
Variations take place in the ecological residence; will change the
combination of species and another vegetable community is formed: it is what is
named succession. Primary because of natural reasons and Secondary, a work of
the man.
An ecosystem is formed by animal organisms, the inorganic world and the
plants. It includes a delimited and homogeneous community it is called
biogecenos. We can to differentiate those who are in relation with the man of
whom they are with the nature.
- Equatorial zone. 10 º N-S. The thermal daily oscillations are major
that the annual ones of the daily average (25-27 º). High rainfalls, especially
in the equinoxes. There are arid regions.
- Tropical zone. Valuable variation of the daily average of the
temperature. Maximum of rain in the epoch of more height of the Sun.
- Subtropical zone. Scanty rainfalls and high daily temperatures. In
winter inferior to 0 º. Deserts.
- Zone of transition with winter rains. Summer inside the zones of high
pressures. Winter rains. It is the climate of the Mediterranean region. Summer
drought.
- Tempered typical climate. Cold winter, fresh (continental) summer.
- Tempered warm. Winter slightly cold. Humid summers.
- Tempered arid. There are big differences between summers and winters.
Scanty rainfalls.
- Boreal or tempered cold. Fresh and humid summers and cold winters that
last half a year.
- Arctic zone. Scanty rainfalls. Humid summers, without nights. Long and
dark winters.
Because of important inequalities, this classification is not valid.
- Asymmetric conditions on both sides of the Ecuador. The bigger
quantity of water in the south hemisphere cools the climate.
- The trade winds determine diversions in this classification.
- The mountainous chains. The hillsides of lee are more arid than those
of windward. (Föenh Effect)
It is a very humid zone, in which the rains fall down in the evening.
The radiations of the Sun are very intense. The leaves directly exposed
to the radiation experience high temperatures and are submitted to a great
drought.
Inside the rainforest, there are not big oscillations and the air is
saturated of steam.
They are poor soils, though its exuberant vegetation looks like to
contradict it; and very ancient (of the Tertiary)
The reserve of nourishing substances of the forest is contained in the
air fitomass. The erosion eliminate the soil up to the underlying mother rock,
can be generated another jungle, initiating a succession of the first one.
The cap of the trees reaches in some occasions 55-60 meters. They are in
three levels, though not always they are distinguished: inferior, half and
Superior.
They have slender trunks, with thin bark. They have elongated and
relatively small tops. The roots scarcely have depth; according with the humid
soil where they are.
The leaves of the trees are bigger as the more humid and warm it is the
climate. The stretching of the branches is not constant and often the branches
more young hang weakly.
With regard to the leaves, sometimes falls down the former before the
new ones go out, so that the tree could stay without leaves during not very long
time a period. They do not bloom all the branches simultaneously either; it is
the called autonomous periodicity. It is possible to say that in the rain
forest there does not exist a general flowering epoch.
Trees compose the 70 % of the rain forest. It is difficult to separate
the cap of shrubs of the herbaceous one. We find, likewise, species as
bindweeds and epiphytes, of great interest.
The bindweeds use the trees as support for their stem. For the lianas, the
branches of the trees they use as support. They have several systems of
fixation:
- They intermingle with the system of branches.
- They take roots in the cracks of the trunks.
- Sometimes they grow at the same time as the tree.
The branches growing, in spite of the good supply of light, impedes the
water supply, for what the quantity, more than the frequency, of fallen water,
is of great importance for them. They must store water in their organs. This
absorption takes place thanks to the air roots.
The hemi epiphytes occupy an intermediate place between the lianas and
epiphytes. Some grows in the trunk as lianas, after having germinated in the
soil. The " strangling trees " germinate like epiphytes; form a long
root that grows downwards. When it comes to the soil, the stem begins to grow,
at the same time as engrossing the roots and prevent the growth of the tree.
The forests of mountain are rich in epiphytes, on having eliminated in
the mountains the drought that takes place in the plains.
The temperatures descend up to reaching the level of the clouds. It is
not situated to a certain height. The mosses hang as curtains; there are great
quantities of ferns. The palms or the bamboos characterize the most humid
level.
After the level of clouds, they get down the rainfalls. The coniferous
Podocarpus appears, the lichens substitutes the mosses and finally it passes to
the zone of bushes, zone less higher in the tropics that in the subtropics.
They are the "high plateaus". It is humid, cloudy,
inhospitable and cold. The changes of temperature do not affect to the plants,
since they take place in the epoch of flowering.
The soil is always humid, still on dry station. Besides the plants that
grow near the soil, high plants appear.
The duration of the dry station increases the top level of trees remains
formed for deciduous. The rainfalls diminish the rainfalls the species(kinds)
lose the leaves(sheets). They diminish below 500 mm/año the vegetation
it(he,she) happens(passes) to depend on the soil. In the clayey soil the sheet,
in the rocky soil the thorny bushes. They are not soils adapted for the
agriculture (Africa).
The trees are more time without leaves due to the stretching of the dry
station. They take a yellowish colour before falling down. Nevertheless, this
station does not suppose a period of rest for the deciduous forests, since some
of them begin to bloom at the end of the same one.
Sheet: herbaceous and homogeneous surface with woody plants in regular
dispersion. The grass and the woody species are antagonists and they exclude
themselves. This antagonism comes given for:
1. Radicle system. That of the grass is branched out with a great number
of roots; whereas that of the woody species is extensive.
2. Water economy. The grass perspires intensely when the water supply is
favourable. When the dry station is initiated, it continues the perspiration
and the plants dry off. The woody species possess a water-balanced system,
reducing very much the perspiration. They need to absorb water of the soil and
when they do not obtain it die.
Rainfalls of 1300 mm for what it had to wait for deciduous forests, that
only appear in small formations. Grasses cover the rest of the surface with
small trees dispersed. The presence of these small trees is due to the
conditions of the soil.
It has been said that it is a sheet originated by a fire. The fire has
helped to form the sheet.
-
Central
part of the Plains. In an epoch in which the level of the phreatic water was
very high, a crust was formed cemented with monoxide of iron: the reef
Eastward the reef is not so hard,
but the roots of the trees cannot cross it.
a) Between the Indian Ocean and the Atlantic Ocean, named dambo.
There are ecological typical residences of changeable dampness. When the
declivity is big, the river is observed, the grasses disappear and the forest comes
to the river.
b) Meadows in depressions with black soil (mbuga).
The black coloration comes given by complex humus’s - clays of the same
colour. Hawthorns and acacia flute.
c) Meadow flooded by the rivers on having been near lakes.
If termites inhabit them, trees will populate the left constructions and
the sheet of termites is formed.
The high rainfalls and the small evaporation produce big surpluses of
water. It is a carpet of grasses, formed by stems of grass.
The swamps grow in the zones of tides in salty water. They do not have a
zone distribution, finding in distant points some of others.
There are coastal swamps, there grow on flat coasts without water
contribution of the interior, swamps of river mouth, in deltas of the rivers
and swamps of reef.
The water supply remains approximately equally in arid and humid zones
(100-1500 mm/year).
The plants reduce increasingly their surface, but they reduce
increasingly intensely their root system.
According to their ecological behaviour, we can to divide them in:
- Malacofitos. Semiarid
zones. Soft leaves that fade
up during the dry station.
- Esclerofilos. Small and hard leaves. Zones of long summer drought. Olive tree.
- Estenohidros. Their leaves get yellow and later they fall
down. Plants of extreme deserts.
The level of rainfalls has an importance only indirect for the plants of
arid regions. More decisive it is the water quantity of the soil, which they
can have. The clayey soils are the driest ecological residences; the sandy ones
provide better supply of water. The rocky cracked soils are the most humid
ecological residences.
a) Holartic.
Saharan –Arabic Desert.. Grass and dwarf bushes xerophytes.
b) Pale tropical. Southern Sahara. Grass with less hard leaves(sheets).
More numerous shrubs. – Exterior Namibia. Salt desert, without rains.
- Interior Namibia. Summer rains. Trees in dry valleys.
- Karroo. Two stations of rains. Dwarf bushes. Woody plants in dry
valleys.
- Tropical region of Oriental Africa. Succulent and baobabs.
c) Neotropical. Desert of Sonorous. Semi desert. Cacti candelabra, ferns.
- Larrea's desert. Bushes of creosote.
- Desert Coastal Peruvian - Chilean. Nebulous. Very humid soil.
Herbaceous carpet. There is a lack of woody plants. Cacti.
- Equatorial zone of South America. Semi desert of cacti and thorny
material.
d) Australian.
The principal species of the centre of Australia is the mulga.
4-6 meters height. Lack of succulent
species.
a) Desert of stone.
Under the stones there can exist a stratum of hydrophobic land, in which
is not possible the vegetable growth.
b) Desert of pebble.
It is formed with conglomerates. Under the cap of pebbles, a hard cap
can exist compacted for plaster.
c) Desert of sand.
d) Wades. Dry riverbeds of rivers.
e) Boilers.
f) Oasis. Places of desert full of dense vegetation.
I hibernate the cyclones bring rains in winter and in summer the anticyclone
of the Azores determines the presence of dry and warm time. Sometimes the
frosts appear.
The zone vegetation consists in a esclerofilo forest always green with
quercus ilex (oak), blockhead, olive tree, carob-tree and European palm.
a) Humid sequence of floors. The esclerofilo level is followed by a
level of subMediterranean planifolio deciduous forest, above we find beeches
and firs.
In the Alps, we meet the Alpine sublevel of picáceas.
b) Arid sequence of floors. The level of planifolio forest lacks. To the
level esclerófilo they follow(continue) levels of aciculifolios.
Anatolia. Included in the zone of the winter rains. The mountains prevent
the step to the winter rainfalls. Rainfalls below 350 mm. Strong summer
drought. Winter months very cold (up to -25 º). The pine gives step to steppe
vegetation.
Centre and south of California, only zone of esclerofilas. In the north
zone esclerofilas always green oaks appear and in south dominates the
chaparral.
The flora is different to the previously described. The esclerofila zone
includes only the centre of Chile. Forests of 10-15 meters of xerophytes
species.
It includes a total floral kingdom, geld. Wealth of species is
extraordinary (2000 in 2000 has). The vegetation, called fynbos, is a bush.
Only a tree exists: the silver tree. There exist also geophytes, diverse
herbaceous species and dwarf shrubs.
In the SW Australian dominate the arboreal forms. The protaceas forms
the stratum of bushes. The ericaceous is replaced by the peicridaceas.
For the climate corresponding to the Mediterranean dominates the
eucalyptus marginata.
The zone of "wandoo", drier, is characterized by the
eucalyptus redunca. Below 500 mm, the eucalyptus grows of denser way.
They are exposed to trade winds or monsoon, and for this reason the
maximum of rains is received on the dry station. Forests always green. The size
of the leaves diminishes. They are frequent the arborescence ferns. The
conditions are favourable for the development of nemoral vegetation.
In New Zealand, no native species of eucalyptus or acacia exists. Even
the protaceas has only three species. The coniferous have great importance, and
the Antarctic element, represented by 5 species.
They avoid the maritime extreme zones and continental extreme it is the
nemoral zone. We find this zone in the oriental part of North America, Western
Asia and in Eastern and Western Europe.
The moorlands are a product of the degradation of planifolios forests.
The soils, poor and acids only can support vegetation of bushes.
The moorland existed before like oak woods undergrowth. After the
destruction of the forest, the moorland conquered the whole surface. In the
maritime extreme region, the tubers of coverage also occupy an out-standing
role.
It is a vegetable stratified community. It consists of one or two
arboreal caps, a cap of bushes and of an herbaceous cap. Inside this, we find
hemicriptofitos, but also many geophytes. There lacks, nevertheless a stratum
formed by mosses.
The structure of the forests comes given by the type of exploitation.
The beech wood only presents an arboreal stratum. The oak woods are mixed
formations.
A planifolio forest consumes the whole water of the rainfalls.
It increases the extent of temperatures; the annual average diminishes.
The rainfalls diminish.
This steppe is a macro mosaic of forests and steppes. We find forests on
small elevations in hillsides of fluvial valleys.
In the humid region, we find typical soils of podsol and grey soils. In
the arid zone, from black lands to dun lands.
Annual development: after the merger of the snow the soil is humid, they
increase the temperatures and a rich spring flora develops. In the middle of
May they sprout the grass, at the beginning of June, the most multicoloured
state is reached. From middle of July, the plants start drying and in August,
the steppe appears dries.
To the south of the steppes of meadow, dominant the species of steppe
and the grass move back.
The zones of vegetation, meadow of high grass, mixed meadow and meadow
of short grass passed one to other from East to West in direction of increasing
aridity. In every zone, a floral direction exists in direction N-S.
The increasing aridity towards the west demonstrates in the
accumulations of lime in the profile of the soil.
In comparison with those of the north hemisphere, the steppes of the
south hemisphere occupy a relatively small surface. The major region in this
regard is the Argentine oriental pampas. Between 1000 mm - 500mm. Also very
high temperatures appear (16ºC). It is a kind of a meadow without trees due to
the fires provoked by the man in the previous nemoral vegetation. It is an arid
climate as that of the wooded steppe.
The meadow of Patagonian Tussock is similar to the Otago of New Zealand.
- Desert of ephemeral. Soils of type loess free of salt. Annual species
and geophytes.
- Desert of plaster. Rocky on altiplanoes of tubular mountains.
Terofitos and plants of plaster. Some halophytes.
- Deserts of halophytes. Soils with phreatic slightly deep water.
- Deserts of sand. Summer grasses and bushes.
- Ordos.. Wide surface of sand and dunes.
- Alachan. Sandy surface with barjanes. Bushes mesofilos and above
forest aciculifolios
- Beichan. Continuation of the previous one. Low bushes and some
halophytes.
- Tarim Basin with the Takla Makan. The most arid part of Oriental Asia;
though it is rich in phreatic water. Without vegetation.
- Tsaidam. Saline desert lacking in vegetation.
- Gobi. Saline soils and plastered. The central part lacks vegetation.
In the rest, the vegetable coverage also is scanty.
Tibet, the bigger plateau of the Earth. With an average altitude of
4200-4800 m. The merger of snow they form swampy surfaces. Furthermore, there
exist salty lakes and dunes of sands. The central part is characterized by its
extreme climate (average of-5ºC). Very poor flora; dwarf shrubs.
The boreal zone is recognized in the climatic graphs because the duration
of the daily averages over 10ºC is minor to 120 days, and the cold station
lasts more than six months.
Due to the extent of the zone, an oceanic cold climate has to be
distinguished with a small extent of oscillation of the temperatures and a continental
climate in which the difference carries to extremes can come to 100ºC. With
regard to the forests, it is necessary to say that the number is very big in
North America and Oriental Asia, but very small in the Euro-Asian region.
The forest of red firs (taiga), which grows in soils of podsol. Wild
pine, common heather, birch, tremulous poplar.
In the top floor of beech wood there grows the white fir, below which it
begins the floor of the red firs. In the inferior floors we find wild pine.
The nemoral floor of the central Alps is formed by the European larch
and the cembro. Over the forest, we find black pine, which is displeased by the
green alder-tree.
Between the nemoral zone boreal and the tundra without trees exists a
zone of transition in which the forest and the tundra form a macro mosaic.
In the wooded tundra exist spots of mosses and lichens. The surfaces
without trees are colonized for dwarf shrubs.
Only they exist between 55 and 188 days a year with more of 0ºC of
temperature. In the oceanic region, the winters are enough soft, but in the
continental region they are extremely cold.
Scanty rainfalls (less than 200 mm) but due to little evaporation the
climate is humid. The snow and the ice recover an important role for the
vegetation. Birches and dwarf willows, tundra of lichens. On the humid soils
moss grow.
Only mosses have been fanerogamas, and lichens. It’s limited to points
transitorily without snow of the coast
and to rocky abrupt walls.
- A theoretical climatic limit of the forest. It coincides with a
certain level of height.
- Potential limit. The level to would come without the intervention of
the man.
- Current limit. 100-200 m below the potential due to the felling and
the shepherding.
The climate is different depending on the zones. In the Alpine floor,
the rainfalls descend with the height, unlike the tropical climate.
The climatic conditions disable to treat the Alpine vegetation of
similar way to that of other mountains.
Vegetative short period. The radiation increases with the height. The
permafrost is not of great importance. The important thing for the plants is
the relief, the direction of the wind and the exhibition.
- Climatic limit of the forest.
- Alpine inferior floor: deformed trees, creeping shrubs and dwarf
bushes.
- Average floor. Alpine meadows compacted with grasses.
- Top floor. With stains of Alpine meadow.
- Climatic limit of the snow.
- Inferior floor. Fragments of Alpine meadow, plants of ink pad, spots
with moss and lichens.
- Average floor(flat). Mosses and lichens.
- Top floor. Isolated Fanerogamas, mosses and lichens.
The agrarian systems are the set of natural and human resources that
enter interaction to obtain products. The economic value acquires then a great
importance.
Inside the classifications, we can to observe several types:
1) - Traditional Systems = auto subsistence.
- Modern systems = Look for
the obtaining benefit.
2) - Climatic Aspects
- Socio-economic aspects.
- Systems of cultures.
3) - Traditional; extensive and intensive.
- Evolved.
Now we will pass to explain and to describe the traditional and evolved
systems.
It is an extensive system of low productivity. It possesses a few very
rudimentary technologies. It is a system of subsistence destined to the
self-consumption. The used energy is animal or humanizes. . It develops in an
unfavourable way. Lack of investments, low productivity. It depends on the way,
and mix periods of great productivity big famines with scarcities.
An example of this system would be the itinerant system of cleared
grounds that takes place in the equatorial Africa or in Indonesia and Malaysia.
It consists of dividing the area in a series of part (stubble). The
first one of these cleared grounds is cleaned of trees and vegetation, later it
is burned and on the ashes is cultivated. When the productivity of this cleared
ground has exhausted, it passes to other one, continuing even the last one.
Traditionally, the scanty tools gave them to the possibility of regeneration of
every cleared ground, since it past enough time from the culture of the first
one to the culture of the last one. Nowadays the demographic pressure of these
countries has given place to the use of new technologies that accelerate the
process and do not give time to the regeneration of the area, producing grave
demographic imbalances. The cattle corresponding system is the nomadic cattle.
Mediterranean dryness. High temperatures with irregular rainfalls.
Discontinuity of the relief. Three zones:
- Steppe. Few cultures.
- Mountain. Cultures up to certain heights.
- Plain. It is where the cultures centre. Trilogy of cultures: Vine.
Except the cereals are scantily mechanized. Regulated by the community politics
(P.A.C).
The cattle system is the transhumance. Between sedentary and nomadic. Of
the mountain to the valley or of North to South, moving for the glens. In
Castile his importance has descended notably.
They take place due to the demographic pressure. Lands of irrigation
compose them. Two types:
- Traditional: Culture of garden. Citrus fruits, fruit trees. The
rudimentary technologies have been begun to substitute for water-sprinklers).
Likewise, has begun to regulate the use of the water.
- For drip or exudation.
1) To small scale. Community Europe. His agrarian structure has two
problems:
- His historical past.
- A more recent development to which it must be moulded. The P.A.C
establishes an only market where the last discrepancies want to be eliminated
between countries. It wants to become detached of the American influence. From
1985 several reforms have taken place:
- Medium exploitation.
- To foment the system of cooperative societies.
- Formation of the peasants.
- Regional involution.
2) To great scale. In USA. Cultures of maize, ovine cattle. They
cultivate a series of products and use of part of the excess to feed to the cattle, in the moment in which the
benefits are minor. Involution of the cattle industry.
Extensive, American cereal, plantations. System of plot town-city.
Plantations. Destined to a monoculture. Monopolized by the developed
countries, influenced by the ecological and market instability.
In regression. In the USSR from the Russian Revolution. Two systems:
Sovjos: Farms pilots specialized in monocultures. They are in hands of
the state and their production is destined to the international market.
Koljos: Cooperative societies. Their destiny is supplying the local
market.
Both base on a planned system; is produced what is going to demand.
