Biology, a mother science concerns everything related to life. It considers both plant and animal kingdom and also the world that we can’t see but abounded with minute life. Considering the aspects of living beings, this science sometimes needs to go beyond the living world to understand the correlation between the biotic and abiotic entities. Today we are going to understand such a branch of biology known as ecology and ecosystem with reference to the brief design of the earth both interior and outer.
So, what is ecology?
Schienen and Willig (2008) gave the definition of ecology as such,
‘Ecology is the study of the spatial and temporal patterns of the distribution and abundance of organisms including causes and consequences.’
In nature, there are interactions among the communities of organisms and their abiotic surroundings. There are both structural and functional reciprocal relationship. This type of relationship is very important to understand the distribution and abundance of organisms all around the globe. For example, relationship with the abiotic saline enviroment and the salinity tolerant plants are studied in ecology. The xeric environment and the plants that grow there are studied here as well. So this science particularly studies the relationship with organisms and environment, not separately but together.
- Ecology is similar to the terms ‘Biogenocenosis’ and ‘Microcosm’.
- Ecosystem is delimited by more or less uniform sections of the biosphere (where life exists).
- Community of organisms plus environmental conditions.
- Each ecosystem has a certain spatial extent. So, different ecosystems form a diverse mosaic in the biosphere. The principles by which all this ecosystems operate whole equally well for the biosphere and for the natural and artificial systems (e.g.. Kaptai lake, aquarium, rice field) are:
(Two characteristics of ecosystem)
- Inertia: Prevent change.
- Resilience: Shift to previous condition if change occurs upto the threshold level.
State of Equilibrium
We know that the net transfer of energy in a chain always proceeds in one direction- from the sun, through the primary producer to the decomposers. Unlike unidirectional flow of energy, matter is cycled. Each cycling of elements take place at three distinct levels.
- In the plant
- In the ecosystem
- In the biosphere
Ecosystem possesses intrinsic (internal) mechanism for self regulation. It is based on the ability of individual organism, population and communities to adopt and on the properties of the producers. If the supply of energy is sufficient and recycling of the matter undisturbed a state of equilibrium is obtained and the state is maintained without notable changes.
In addition to the food chain, there are other kinds of interdependence and interaction relationships among the organisms and in an ecosystem. It may either benefit and hamper the individuals like any other organisms.
For example: pollination, symbiosis, allelopathy, parasitism etc..
(Like any other organisms, man is an environment dependent member of the living community. Man is also an environmental factor with respect to the member of the ecosystem. He is a conscious and purposeful shaper of the nature. Because he intervenes with the natural process and creates habitat to his own living.)
Vertical Structure of the World
Biosphere is that part of the earth surface where life exists. In vertical section it extends from the deepest part of the ocean floor (Mariana Trench: 11,000 m below the sea level to at least 10,000 m above the sea level). In this region, bacteria and fungi can be found. Actually this region is very narrow possibly less than 200 m from the sea level.
The radius of the earth is approximately 6,370 km or around 4,000 miles. The vertical structure of the earth atmospheric surface and interior is illustrated in figure 1 and 2.
- Continental crust
- Oceanic crust
- It is around 20-70 km (average 30 km).
- Granite (AlSiOx), metamorphic rock.
- Relatively low density (2.7 gm/cc).
- 125 km above sea level (?).
- Old (upto 3.8 billion years).
- Forms the deep sea floor.
- 5 to 10 km (average 7 km).
- Basalt rocks (Fe, Mg, Al. Na, Ca, SiOx), Igneous rocks.
- Relatively densed (approximately 3 gm/cc).
- Negatively buoyant.
- Surface: 4 km below the sea level.
- Young (less than or equal to 160 to 190 million years).
- Covers 71% of the total earth surface.
- Crust + solid outer mantle.
- 70-250 km thick.
- Thicker under continent and thinner under oceans.
- Broken into many plates known as lithospheric plate.
- Plates float on soft aethosnosphere.
Surface area of the earth:
Water storage in hydrosphere
|Storage||Volume (1000 km3)|
|Average in stream channel||1|
|Vapor and cloud in the atmosphere||13|
|Soil water (above water table)||67|
|Saline lakes and inland seas||104|
|Fresh water lakes||125|
|Ice crops and glaciers||29200|
- 1 km3 = 264 billion gallons
Composition of sea water: (Only elements that are more than 1000 MT/km3 in quantity)
- Sequestration: Carbon capture and store.
The earth’s atmosphere is the reason why nature flourished in this planet. It is somewhere rough, somewhere very convenient and many times good and sometimes scary. The earth’s atmosphere is a great puzzle for the geologists as it can shift its temper anytime and anywhere with or without any symptoms. And we all are affected by it. However, to understand this creation of mother earth the weather scientists divided this vertical unseen covering around the globe into some layers based on the temperature that prevails.
Variation of atmospheric temperature with height:
- The terms tropopause, mesopause and stratopause apply to those boundaries where the temperature is constant with height.
- Within each regions temperature changes with height.
- Lives essentially occur in the troposphere.
- The height of the Mount Everest is approximately 9 Km.
This article is the beginning of a series on Physiological ecology that will further focus on the things that we have discussed here. So more is coming.