Consensus on the basic ecological concepts like Ecology, Eco-system, Environment, Forest system, Agro-eco-system and Ecological Constants is important for effective environmental management using the ever increasing knowledge and technology.

Ecology in its broadest sense means the science of Eco-system. At the visible level Eco-system is our earth as a household comprising of all non-living and living components. The broad categories of non-living components are different soil types, angle or degree of slopes of the land surface, water in its three stages of its existence, air as a mixture of different gases, sun light a combination of seven coloured wave lengths, heat with its variations in temperature and varying level of humidity. Among the living components are an estimated one trillion types of micro-organisms, forming the base for all the living components of our household eco-system, followed by about 3,74,000 plant species and about 8.7 million animal species and 7.8 billion humans (2020). 
    
All the living and non-living components in our Eco-system is organically inter-connected, inter-related, inter-dependent and are in a dialectical and evolutionary process at multiple levels of their existence and development as demarcated by the double edged arrows in following diagramme.
 
At the invisible level all these components in the above given diagramme are composed of chemical compounds composed of 118 elements including 30 radioactive elements as can be seen in many versions of periodic table in the Internet. 

In a periodic table the 118 elements are arranged in 18 columns and 7 rows in the progressive order of their atomic numbers 01 to 118. The radioactive elements of atomic numbers 57 to 71 and 89 to 103 in their respective two colours are shown separately in 02 rows and 15 columns. We can also notice that hydrogen occupies the first position in the table at the beginning of the first row and top of the first column while Helium occupies the last position of the first row but first position in the last column. The colour groupings signify 10 groups of elements such as metal, non-metal, alkali metal, alkaline earth metal, metalloid, transition metal, halogens, actinide, lanthanide and noble gas, signifying their chemical nature and potential for action-reaction to other elements. A careful study of the periodic table will reveal the wonderful nature of various elements and their invisible roles in the eco-system. An environmentalist cannot ignore the chemical actions and reactions of all the components shown in the Eco-system figure.  

All elements are acting and interacting to form inorganic compounds at the non-living stages and organic compounds at the living stages. Now we also know that matter exists at the subatomic levels too and already 17 of them are known to us. Science may discover further many more sub-sub atomic particles which may be the composition of the outer space, the subtle-most substance of everything in the universe (first line of Gayatri Mantra). According to Indian thought everything consists of earth, water, air, fire and akash of which Akash is the most subtle substance of matter. In the Western philosophy there is the distinction between matter and form.  Again in Indian thought there is the distinction between gross and subtle forms of matter. In science all these concepts are analogical but not absolute, leaving room for further insights. In short matter exists in an infinite range of forms. Forms are in the matter and matter is in the forms. Hence all the components of the Eco-system exist in particle of matter and form of which matter is visible and form is invisible.

All particles of matter are charged and are under various forces like gravitational force, cohesive and adhesive forces, magnetic and electric charges etc. We are all familiar with Einstein’s equation E=mc2 which means everything in the Eco-system is an expression of various forms of energy acting and interacting with each other and is in an invisible evolutionary dialectical process, some of which man is able to control and guide while others are still not. Hence management of eco-system means management of some of the visible and invisible components of the earth our eco-system. The term Eco-system therefore also refers to all the visible and invisible living and nonliving beings and their complex interactive relationships between them and Ecology means the knowledge system or science developed on these interactions of the components in the eco-system.

In any creation story or even in science humans are the last to appear in the eco-system as an end product of the millions of years of evolutionary and dialectical process under the influence of light from the sun and moon and under the gravitational forces of other planets in the solar system and several other forces.  Everything seems to have evolved towards the existence and well being of humans who are capable of guiding the destiny of everything on earth including all possibilities of life in the nearby moon and planets. 

Environment refers to the surroundings of any living being individually or in groups. Hence we refer to the environment of humans, animals, plants and microbes or all of them together. With reference to one or a group of the living beings all other living and nonliving beings constitute its or their environment. Every living being is able to influence on its environment but humans are able to influence more on his living and nonliving environment: hence the relevance of environmental studies. 

Agro-eco-system refers to that part of the Eco-system where agriculture and allied operations are done by human beings to derive all their needs for his existence and development and signifies the interactive and interdependent relationships between soil, land slope, water, air, light, heat, microbes, plants, animals and humans as in a household. Among them slope of the land is a major determining factor in the management of the agro-eco-system. 

In the ecological and environment management of any country or even globally, agro-eco-system and forest system play the most crucial roles in maintaining the ecological balance or stability of that country or the world.

Since many people are involved in the management of agro-eco-system there was the need for Ecological principles to guide his involvement of humans with everything on the earth. Environment Management follows such principles and practices to maintain equilibrium between various components in the forest system and agro-eco-system. For this we need to know the Ecological Constants or Immutable at the global level and at each nation level.

Global Ecological Constants

1. On the surface area of the earth 71 per cent is ocean and 29 per cent land, which proportion of water and land areas cannot be changed. Sea is the only source of fresh water for all living beings on land through evaporation and condensation. Sea has a key role in maintaining the seasonal climate changes, wind direction, temperature, humidity, rainfall, climate and weather variations on the land. Sea is a great source of food, minerals, renewable energy, sand and gravel. Sea plays a great role in trade, transport and tourism. Sustainable development and management of ocean resources is widely recognized by all international communities for sustained human development. The proportion of ocean area to land area (79:29) is immutable. As far as we know earth is the only planet with such an amount of water.

2. At the world level out of the estimated 13,003 million hectares of land area, only 4889 million ha (37.6%) are cultivable according to FAO. The rest 8114 million hectares are to be under perennial forest except those areas under perennial snow on the mountain tops and Polar Regions. Even the present desert areas were, once upon a time, bio-rich and should be restored to forest vegetation or agriculture land as Israel has done. Hence at the global level only 37.6% of the land area or on an average 33.3% of the land is available for human usages like agriculture, animal husbandry, non agricultural uses like cities and towns, institutional areas, transport areas, industries, mining, etc. Most developed countries maintain, on an average, two-third (66.6%) of the land area under forest and one-third for human use. 

3. Since land area for human use is limited human and domestic animal population depending on that land has to be limited: Carrying Capacity of land is limited. Hence the world population has to be regulated at a sustainable level. 
(KT Chandy was a Professor of  Agri & Environment Management,  XIM, Bhubaneswar. He can be reached at: ktchandysj@gmail.com )