Elements of Geography

8/12/2019 Elements of Geography

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Elements of Geography

The Natural Vegetation of the arth

Submitted by: Miraluna D. Saltones

Submitted to: Mrs. Jenny Belmonte- Orbegoso

TOPIC: The Natural Vegetation of the Earth

I. Introduction


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INTRODUCTION:

Climate leads to a study of the earths natural vegetation considering that plants are

greatly affected by the climate, especially in their distribution over the earths surface.

Plants have their climatic controls in terms of moisture, temperature, sunlight and winds.

Likewise, plants are controlled by topographic (landform), edaphic (soil) and biotic

factors.

Geography is interested only in distribution of earth phenomena and their areal

differentiation. Plants show certain general groupings based on size, height, leaves,

density, branching character and other factors. They exhibit certain associations or

groupings called communities, namely, forests, scrublands or woodlands, grasslands

and deserts. The groupings are primarily due to the amount of precipitation in certain

regions; hence the emphasis in the present description of vegetation is on the bio

climatological aspects of vegetation. In fact, this is the preoccupation of the branch of

the geographic discipline called phytogeography.


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The Ecology of Vegetation

1. Plant communities

Ecosystem - which is a set of biotic and abiotic elements so related that together

they form a complex whole.

Plant community - is an assemblage of plant species in an area, existing in a

systematic interaction with one another and with the animal life in the area.

- Objective of Ecology

Is the study of life communities and their interrelationships with one another and

with the other components of the abiotic environment

- Plant species in a community or plant association do not usually compete forenergy and moisture because each species has its own special niche or level in

the community with its own energy and moisture requirements.

Steady state or stable ecosystem - in the process of arriving this state, should

two species compete for essential sustenance in the same niche in a plant

community.

2. Biotic succession

- Are specifically called plant succession

- Is a gradual sequence of changes of phases in biotic communities in a certain

area over a period of time, even if climate remains unchanged.


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- One plant community appears and then gives way to another until a series of

replacements a stable community predominates and there is no further

alternation in its composition

Pioneer community - a plant community (grass) that started the succession which

is able to colonize and inhabit a bare surface

Climax community

- the end product in the succession (oaky-hickory forest)

- Most complex type of community which a particular natural environment

will support

- Stable and able to maintain itself over a long period of time

- It is also the efficient user of solar energy and soil nutrients in the area

The general trend in plant succession

Taller plants

More density

Greater stability

Two (2) kinds of vegetative succession

Primary succession- occurs in places that have not previously supportedlife

Secondary succession- Takes place on areas where the original climax

vegetation has been destroyed or disturbed but where the soil has been

retained

3. Formation types

- Another way of describing plant communities over the earths surface is to

characterize them in terms of the form elements of their assemblage.

The classification elements

a. Plant type - such as trees, shrubs, herbs and grasses


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b. Sizesuch as tall or short trees and grasses

c. Leaf shapesuch as broadleaf or needle leaf

d. Branching character such as high- branching (like many trees) or low-

branching (like shrubs)

e. Leaf behavior such as evergreen (with leaves throughout the year) or

deciduous (with leaves falling off during dry period)

f. Horizontal densitysuch as closely spaced or widely spaced

g. Vertical alignment such as canopy- producing tree crowns, or a second-

story growth below the tree crown, or undergrowth (on the ground)

Factors Affecting the Distribution of Vegetation

1. Climatic factors

- Is the most important environmental element influencing the distribution of

plant communities over the earths surface

Precipitationmoisture is again the most important influence in the distributed ofvegetation

The three great formations of natural vegetation

Forests

Grassland

Desert

- Copious rainfall often gives rise to forests

- Moderate rainfall or summer season rainfall to grassland

- Scanty rainfall to desert plants

Osmosisa process where water is taken is mainly by plants at the roots


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High temperature and low humidityfavor rapid loss of plant moisture

Low temperature and high humidityinhibit its loss

Plants are distinguish by their ability to respond to variations in the amount of

precipitation of certain area receives

Xerophytes(greek xeros = dry, phytos = plant)

- Plants that is structurally adapted to very limited moisture budgets

Hydrophytes( greek hydro = water)

- Vegetation that are adapted to very humid environmental and have rarely

any defense against evaporation and moisture insufficiency

Mesophytesplant types that have intermediate needs and tolerances for water

Halophytes(greek halos = salt)

- Plants that have adapted to salty water conditions, such as beach and

mangrove vegetation

Temperature - ranks next to precipitation in importance as an influencing factor in

vegetative growth

Three (3) critical temperatures

1. Minimum or lower temperaturebelow which it will die

2. Maximum or upper temperatureabove which it will likely wilt or die

3. Optimum temperatureat which it thrives best

Species that survived prolonged low temperatures periods through seed carryover


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Annuals complete their life cycle during warm season and their vegetative

structure perishes completely during the cold season

Biennials species that need more than one year to complete their cycle

Perennialssurvive through contrasting temperature regimes year after year

Temperature fall below 20 degrees Celsius throughout the year

- All of the above plants cannot survived

Solar energyplays a major role in the regulation of the life cycle of plants

2. Topographic factors (landform)

- Specifically in terms of elevation and slope, also affect the growth and

distribution of plant communities

3. Edaphic factors (soil)

- Do not have much influence as climate in influencing regional plant

distribution but they may be significant locally

4. Biotic factors

- Lower forms of organisms have a profound and pervasive effect on

vegetative communities

Elements of Geography

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