Ecosystem ,Safety

7/30/2019 Ecosystem ,Safety

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Types Of EcosystemIn a marvelous way all the living, non living and climatic conditions of a place are interconnected and a

geographical area along with this interconnected network is termed as an Ecosystem. Ecosystems differ in

flora, fauna and weather but all of them support some kind of life. Therefore, it is very important to understand

the features of the ecosystem before entering it and trying to make changes. It was lack of this understanding inearly days that led to exploitation of the natural habitats and extinction of many rare species along with

destruction of some beautiful landscapes. There are many important energy and matter transformation cycles

that run through these ecosystems. Human beings are known to act in manners which disrupt these cycles and

disrupt the natural flow of things in an ecosystem. This leads to major problems in the ecosystems as links of

cycles get detached and stability of the system is lost. To prevent this from happening we need to understand

what type of ecosystem we are dealing with. This is just a brief introduction to a subject which requires in

depth study.

Different Kinds Of Ecosystem

There are basically two types of ecosystems; Terrestrial and Aquatic. All other sub-ecosystems fall under these

two.

Terrestrial ecosystems

Terrestrial ecosystems are found everywhere apart from water bodies. They are broadly classified into:

The Forest Ecosystem

These are the ecosystems where abundance of flora (plants) is seen and they have a large number of organisms

living in relatively small areas. Therefore, the density of life in forest ecosystems is very high. Any small

change in the ecosystem can affect the whole balance and collapse the ecosystem. You can see wonderful

diversity in the fauna of these ecosystems too. They are again divided into few types.

Tropical evergreen forest: Tropical forests which receive an average rainfall of 80 to 400 inches ina year. These forests are marked by dense vegetation comprising of tall trees with different levels.

Each level gives shelter to different kinds of animals.

Tropical deciduous forest: Dense bushes and shrubs rule here along with broad levels of trees. Thistype of forests is found in many parts of the world and large variety of flora and fauna are found

here.

Temperate evergreen forest: These have very few number of trees but ferns and mosses make upfro them. Trees have spiked leaves to minimize transpiration.

Temperate deciduous forest: This forest is found in the moist temperate regions with sufficientrainfall. Winters and summers are well defined and with trees shedding their leaves during winter.

Taiga: Situated just south of the arctic regions, Taiga is distinguished by evergreen conifers. Whilethe temperature is subzero for almost six months, the rest of the year it is buzzing with insects and

migratory birds.

The Desert Ecosystem

Desert ecosystems are found in regions receiving an annual rainfall of less than 25cm. They occupy around 17

percent of all land on the planet. Due to very high temperature, intense sunlight and low water availability,

flora and fauna are very poorly developed and scarce. Vegetation is mainly bushes, shrubs, few grasses and

rarely trees. Leaves and stems of these plants are modified to conserve water. The best known desert plants are

the succulents like spiny leaved cacti. Animal life includes insects, reptiles, birds, camels all of whom are

adapted to the xeric (desert) conditions.


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The Grassland Ecosystem

Grasslands are found in both temperate and tropical regions of the world but the ecosystems are slightly

varying. This area mainly comprises of grasses with very little amount of shrubs and trees. Main vegetation is

grasses, legumes and plants belonging to composite family. Many grazing animals, herbivores and insectivores

are found in grasslands. Two main types of grasslands ecosystems are:

1. Savanna: These tropical grasslands are seasonally dry with few individual trees. They support large number

of grazers and predators.

2. Prairies: This is temperate grassland. It is completely devoid of trees and large shrubs. Prairies can be

categorized as tall grass, mixed grass and short grass prairie.

The Mountain Ecosystem

Mountain lands provide a scattered but diverse array of habitats in which a large range of plants and

animals are found. At higher altitudes harsh environmental conditions generally prevail, and only

treeless alpine vegetation is found. The animals living here have thick fur coats fro prevention from cold

and hibernate in winter months. Lower slopes commonly are covered by coniferous forests.

AquaticEcosystems

An aquatic ecosystem is an ecosystem located in a body of water. It comprises aquatic fauna, flora and the

properties of water too. There are two types of aquatic ecosystems, Marine and freshwater.

The Marine Ecosystem

Marine ecosystems are the largest ecosystems with coverage of nearly 71% of the Earth's surface and

containing 97% of the planet's water. The water in Marine ecosystems has salts and minerals dissolved in them

in high amounts. Different divisions of marine ecosystems are:

Oceanic: The relatively shallow part of the ocean that lies over the continental shelf. Profundal: Bottom or deep water. Benthic Bottom substrates. Inter-tidal: The area between high and low tides. Estuaries Salt marshes Coral reefs Hydrothermal vents-where chemosynthetic bacteria form the food base.

Many types of organisms are found in marine ecosystems including brown algae, dinoflagellates, corals,

cephalopods, echinoderms, and sharks.


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The Freshwater Ecosystem

In contrast to the Marine ecosystem, freshwater ecosystems only cover 0.8% of the Earth's surface and contain

0.009% of its total water. There are three basic types of freshwater ecosystems:

Lentic: Still or slow-moving water like pools, ponds, and lakes. Lotic: Fast-moving water like streams and rivers. Wetlands: Places where the soil is saturated or inundated for at least some time.

These ecosystems are home to amphibians, reptiles and almost 41% of worlds fish species. Faster moving

turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater

biodiversity than the slow moving water of pools

HYDROLOGIC CYCLE

The movement of water on the earth's surface and through the atmosphere is known as

the hydrologic cycle. Water is taken up by the atmosphere from the earth's surface in vapourform through evaporation. It may then be moved from place to place by the wind until it is

condensed back to its liquid phase to form clouds. Water then returns to the surface of theearth in the form of either liquid (rain) or solid (snow, sleet, etc.) precipitation. Watertransport can also take place on or below the earth's surface by flow.

The hydrologic cycle is used to model the storage and movement of water between the

biosphere, atmosphere, lithosphere and hydrosphere. Water is stored in the followingreservoirs: atmosphere, oceans, lakes, rivers, glaciers, soils, snowfields, and groundwater. It

moves from one reservoir to another by processes like: evaporation, condensation,

precipitation, deposition, runoff, infiltration, sublimation, transpiration, and groundwaterflow.

Water is stored in the atmosphere in all three states of matter. Water vapour in the

atmosphere is commonly referred to as humidity. If liquid and solid forms of water can

overcome atmospheric updrafts they can fall to the Earth's surface as precipitation. Theformation of ice crystals and water droplets occurs when the atmosphere is cooled to a

temperature that causes condensation or deposition. Four processes that can cause

atmospheric cooling are: orographic uplift; convectional uplift; air mass convergence; and

radiative energy loss.Precipitation can be defined as any aqueous deposit, in liquid or solid form, that

develops in a saturated atmospheric environment and generally falls from clouds. A number

of different precipitation types have been classified by meteorologists including rain, freezingrain, snow, ice pellets, snow pellets, and hail. Fog represents the saturation of air near the

ground surface. Classification of fog types is accomplished by the identification of the

mechanism that caused the air to become saturated.

The distribution of precipitation on the Earth's surface is generally controlled by theabsence or presence of mechanisms that lift air masses to cause saturation. It is also

controlled by the amount of water vapour held in the air, which is a function of air

temperature.In certain locations on the Earth, acid pollutants from the atmosphere are being

deposited in dry and wet forms to the Earths surface. Scientists generally call thisprocess

acid deposition. If the deposit is wet it can also be called acid precipitation. Normally, rain isslightly acidic. Acid precipitation, however, can have a pH as low as 2.3. Evaporation and


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transpiration are the two processes that move water from the Earths surface to its

atmosphere. Evaporation is movement of free water to the atmosphere as a gas. It requires

large amounts of energy. Transpiration is the movement of water through a plant to theatmosphere. Scientists use the term evapotranspiration to describe both processes.

In general, the following four factors control the amount of water entering the

atmosphere via these two processes: energy availability; the humidity gradient away from theevaporating surface; the wind speed immediately above the surface; and water availability.Agricultural scientists sometimes refer to two types of evapotranspiration: Actual

Evapotranspiration and Potential Evapotranspiration. The growth of crops is a function of

water supply. If crops experience drought, yields are reduced. Irrigation can supply cropswith supplemental water. By determining both actual evapotranspiration and potential

evapotranspiration a farmer can calculate the irrigation water needs of their crops.

The distribution of precipitation falling on the ground surface can be modified by the

presence of vegetation. Vegetation in general, changes this distribution because of the factthat it intercepts some the falling rain. How much is intercepted is a function of the branching

structure and leaf density of the vegetation. Some of the water that is intercepted never makes

it to the ground surface. Instead, it evaporates from the vegetation surface directly back to theatmosphere. A portion of the intercepted water can travel from the leaves to the branches and

then flow down to the ground via the plants stem. This phenomenon is called stem flow.

Another portion of the precipitation may flow along the edge of the plant canopy to causecanopy drip. Both of the processes described above can increase the concentration of the

water added to the soil at the base of the stem and around the edge of the plants canopy. Rain

that falls through the vegetation, without being intercepted, is called through fall.Infiltration is the movement of water from precipitation into the soil layer. Infiltration

varies both spatially and temporally due to a number of environmental factors. After a rain,

infiltration can create a condition where the soil is completely full of water. This condition is,

however, only short-lived as a portion of this water quickly drains (gravitational water) viathe force exerted on the water by gravity. The portion that remains is called the field capacity.

In the soil, field capacity represents a film of water coating all individual soil particles to a

thickness of 0.06 mm. The soil water from 0.0002 to 0.06 mm (known as capillary water) canbe removed from the soil through the processes of evaporation and transpiration. Both of

these processes operate at the surface. Capillary action moves water from one area in the soil

to replace losses in another area (biggest losses tend to be at the surface because of plantconsumption and evaporation). This movement of water by capillary action generally creates

a homogeneous concentration of water throughout the soil profile. Losses of water stop when

the film of water around soil particles reaches 0.0002 mm. Water held from the surface of the

soil particles to 0.0002 mm is essentially immobile and can only be completely removed withhigh temperatures (greater than 100 degrees Celsius). Within the soil system, several different

forces influence the storage of water.

Runoff is the surface flow of water to areas of lower elevation. On the microscale, runoff

can be seen as a series of related events. At the global scale runoff flows from the landmassesto the oceans. The Earths continents experience runoff because of the imbalance between

precipitation and evaporation.

Through flow is the horizontal subsurface movement of water on continents. Rates ofthrough flow vary with soil type, slope gradient, and the concentration of water in the soil.


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Groundwater is the zone in the ground that is permanently saturated with water. The top of

groundwater is known as the water table. Groundwater also flows because of gravity to

surface basins of water (oceans) located at lower elevations.The flow of water through a stream channel is commonly called stream flow or stream

discharge. On many streams humans gauge stream flow because of the hazards that can result

from too little or too much flow. Mechanical gauging devices record this information on agraph known as a hydrograph. In the online notes there is a representation of a hydrographshowing some of its typical features.

Oceans cover most of the Earth's surface. On average, the depth of the world's oceans is

about 3.9 kilometers. However, maximum depths can be greater than 11 kilometers. Thedistribution of land and ocean surfaces on the Earth is not homogeneous. In the Southern

Hemisphere there is 4 times more ocean than land. Ratio between land and ocean is almost

equal in the Northern Hemisphere.

The water found in the ocean is primarily a by product of the lithospheric solidificationof rock that occurred early in the Earth's history. A second source of water is volcanic

eruptions. The dissolved constituents found in the ocean come from the transport of terrestrial

salts in weathered sediments by leaching and stream runoff. Seawater is a mixture of waterand various salts. Chlorine, sodium, magnesium, calcium, potassium, and sulfur account for

99 % of the salts in seawater. The presence of salt in seawater allows ice to float on top of it.

Seawater also contains small quantities of dissolved gases including: carbon dioxide, oxygen,

and nitrogen. These gases enter the ocean from the atmosphere and from a variety of organicprocesses. Seawater changes its density with variations in temperature, salinity, and ocean

depth. Seawater is least dense when it is frozen at the ocean surface and contains no salts.

Highest seawater densities occur at the ocean floor.Atmospheric circulation drives the movement of ocean currents. Within each of the

ocean, the patterns of these currents are very similar. In each basin, the ocean currents form

several closed circulation patterns known as gyres. A large gyre develops at the subtropics

centered at about 30 degrees of latitude in the Southern and Northern Hemisphere. In theNorthern Hemisphere, several smaller gyres develop with a center of rotation at 50 degrees.

Similar patterns do not develop in the middle latitudes of the Southern Hemisphere. In this

area, ocean currents are not bound by continental masses. Ocean currents differ from eachother by direction of flow, by speed of flow, and by relative temperature.


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Nutrient Cycles

Carbon Cycle* Carbon EXISTS in abiotic environment as:

1. Carbon dioxide [CO2 (gas)] in the atmospheredissolves in H2O to form HCO3-

2. Carbonate rocks (limestone & coral = CaCO3)3. Deposits of coal, petroleum, and natural gas

derived from once living things

4. Dead organic matter (humus in the soil)

* Carbon ENTERS biotic environment through:1. Photosynthesis: changes light energy to chemical energy

* Carbon RETURNS to atmosphere by:

1. Respiration CO22. Decomposition / Decay

3. Burning* Carbon Cycle and Humans:1. Removal of photosynthesizing plants

2. Combustion of fossil fuels

Nitrogen Cycle* ~79% of air is N2 gas* N is essential to plants and animals

* Plants and animals cant use N2 gas

* Usable N: ammonia (NH3) or nitrate (NO3-)

* Conversion of atmospheric N2 to NH3 and NO3-:Nitrogen fixation1. Aquatic ecosystems: blue-green algae2. Terrestrial ecosystems: bacteria on root nodules of legumes (peas, beans,

alfalfa, clover)

3. Lightening* Nitrogen RETURNS to soil by:

1. decomposition of once living thingsammonifying bacteria + fungi

2. exists in soil as nitrate (NO3-), nitrite (NO2-), and ammonia (NH3)

* Nitrogen returns to atmosphere by:

1. denitrifying bacteria

Nitrogen Cycle and Humans:

1. Nitrogen required for genetic materials (DNA, RNA, amino acids)


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Phosphorus Cycle

* Major environmental reservoir: rocks

1. Leaching: water dissolves phosphates in rocks and carries to

lake, stream, etc.2. Dissolved phosphate: used by plants and passed through food

chain

3. Animals return phosphorus to environment by:

* excretion

* death and decay

Phosphorus Cycle and Humans:

1. Phosphates mined for fertilizers returns P to soil2. Erosion: P in soil and rocks washed away into water systems
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Ecosystem ,Safety