Ecology is the science of relationship between living organisms and their environment . Human ecology is about relationships between people and their environment. In Human ecology the environment is perceived as an ecosystem. An ecosystem is everything in a specified area- the air, soil, water, living organisms and physical structures, including everything built by humans. The living parts of an ecosystem – microorganisms, plants and animals (including humans ) are its biological community.

Ecosystem can be anysize. A small pond in a forest is an ecosystem and the entire forest is an ecosystem. A single farm is an ecosystem and a rural landscape is an ecosystem. Villages , towns and large cities are ecosystems. A region of thousands of square kilometers is an ecosystem.Although humans are part of the ecosystem, it is useful to think of human – environment interaction between the human social system and the rest of the ecosystem.Every material object contains energy, most conspicuous in foods and fuels and every object contains information in the way ecosystems to social systems independent of materials. Material , Energy and information move from social system to ecosystem as a consequence of human activities that impact the ecosystem.

1)People affect ecosystems when they use resources such as water, fish, timber and livestock grazing land.
2) After using materials from ecosystems, people return the materials to ecosystems as waste.
3)People intentionally modify or reorganize existing ecosystems, or create new ones, to better serve their needs.

Many forests have disappeared in recent years because people have cut so many trees and bushes for cooking fuel. Now there are not enough trees and bushes for cooking fuel. Now there are not enough trees and bushes to provide all the fuel that people need. People have responded to this ‘energy crisis’ by having their children search for anything that can be burned , such as twigs, crop residue(bits of plants left in farm fields after the harvest) and cowdung. Fuel collection makes children even more valuable to their families , so parents have more children. The resulting increase in population leads to more demand for fuel.

Intensive collection of cooking fuel has a number of serious effects in the ecosystem. Using cowdung as fuel reduces the quantity of dung available for use as manure on farm fields and food production declines. In addition, the flow of water from the hills to irrigate farm fields during the dry season is less when the hills are no longer forested and the quality of the water is worse because deforested hills no longer have trees to protect the ground from heavy rain , so soil erosion is greater and the irrigation water contains large quantities of mud that settles in irrigation canals and clogs the canals. This decline in the quantity and quality of irrigation water resources food production even further. The result is poor nutrition and health for people.

This chain of effects involving human population growth, deforestation, fuel storage and lower food production is a vicious cycle that is difficult to escape. However, biogas generators are a new technology that can help to improve the situation. A biogas generator is a large tank in which people place human waste, animal dung and plant residues to rot. The rotting process creates a large quantity of methane gas, which can be used as fuel to cook food. When the rotting is finished, the plant and animal wastes in the tank can be removed and put on farm fields as fertilizer.

poor people – poor farmers who own very little , if any , land , if people must pay a high price for biogas generators, only wealthy families can afford to buy them. Poor people , who donot have biogas generators , will earn money by gathering cow dung to sell to wealthy people for their biogas generators . Poor people may not care much about the ecological benefits from biogas generators because a better supply of irrigation water offers the greatest benefits to wealthy farmers who have more lands.

As a consequences , the benefits from biogas generators could go mainly to the wealthy, widening, the gap between the wealthy and poor. Poor farmers , who see few benefits for themselves , might continue to destroy the forests and the community as a whole might receive little benefit from the new technology. To improve the situation , it is important to make sure that everyone can obtain a biogas generator. Then everyone will enjoy the benefits and the vicious cycle of fuel scarcity and deforestation will be broken.

There is a close connection between the sustainability of human ecosystem interaction and the intensity of demands that people place on ecosystems. We all depend on ecosystems for material and energy resources .Some resources such as mineral deposits and fossil fuels are non- renewable, other resources such as food, water and forest products are renewable. People use these resources and return them to the ecosystem as waste, such as sewage, garbage or industrial effluent.

In general, greater demands on ecosystems in the form of more intense resource use are less sustainable. Intense use of non- renewable resources exhausts that supply more quickly . Intense use of renewable resources can damage the ability of ecosystems to provide the resources . Sustainable interaction with ecosystems is only possible if demands are kept within bounds. This has not been the case in recent decades as human population growth, aswellas industrial and economic growth and burgeoning material consumption , have dramatically increased the scale of natural resource use. As environmental awareness has increased, there have been changes in the social system to reduce the intensity of demands on ecosystems. There has been a shift in recent years from technologies that are wasteful of resources toward technologies that use resources more efficiently and reduce pollution.

“I am from Bangladesh! International Coordinator of Green Youth Generation, IYC- Rio Selected for Bangladesh Chapters and somany Sustainable Groups- IHRC, Ex-GreenWorldOne to RioNing!” -Mahfuja