The Ecology - Eco-Systems

What is Ecology?

Photo courtesy of Indian Institute of ScienceOpens in new window

Ecology helps us to understand how the world works. It provides useful evidence on the interdependence between people and the natural world and, as well the consequences of human activity on the environment.

The discipline of ecology emerged from the natural sciences in the late 19th century. Ecology is not synonymous with environment, environmentalism, or environmental science.

Ecology is closely related to the disciplines of physiology, evolution, genetics and behavior. It has a tremendous scope, but with certain limitation.

It does not take into account the formation of cells (A fundamental unit of organisms or life) and the Protoplasm, but deals with the behavior of the organisms in individual, population and community level. Thus, by now, it has expanded its frontiers from that of simple environmental biology to the stage of exobiology.

Since ecology refers to any form of biodiversityOpens in new window, ecologists research everything from tiny bacteria’s role in nutrient recycling to the effects of tropical rain forest on the Earth’s atmosphere.

There are many practical applications of ecology in Conservation Biology, wetland management, natural resource management (agriculture, forestry, and fisheries), city planning (urban Ecology), community health, economics, basic & applied science and it provides a conceptual framework for understanding and researching human social interaction.

Conservation biology is often referred to as a “Discipline with a deadline”. And which is concerned with phenomena that affect the maintenance, loss, and restoration of biodiversity and the science of sustaining evolutionary processes that engender species, and ecosystem diversity.

Conservation biologists research and educate on the trends and process of biodiversity loss, species extinction, and the negative effect these are having on our capabilities to sustain the well-being of human society.

Species are broadly categorized as Autotroph (or primary producers), Heterotroph or consumers, and Detritroves or decomposers.

• Autotrophy are organisms that produce their own food (production is greater than respiration) by photosynthesis or chemosynthesis.
• Heterotrophy are organisms that must feed on others for nourishment and energy (respiration exceeds production).

Heterotrophs can be further sub-divided into different functional groups, including primary consumers, (strict herbivores), secondary consumers (carnivores) predators that feed exclusively on herbivores), and tertiary consumers (predators that feed on a mix of herbivores and predators).

Omnivores do not fit neatly into a functional category because they eat both plant and animal tissues. It has been suggested that omnivores have a greater functional influence as predators, because compared to herbivores; they are relatively inefficient at grazing.

Branches of Ecology

Early ecologists have recognized two major subdivisions of ecology in particular reference to animals or to plants, hence animal ecology and plant ecology. But when it was found that in the ecosystems plants and animals are very closely associated and interrelated, then, both of these major ecological subdivisions became vague.

However, when animals and plants are given equal emphasis, the term biocenology is used. Further, ecology is often broadly divided into AutecologyOpens in new window and SynecologyOpens in new window. Thus, an audiologist may study the life history, population dynamics, behavior, home range and so on, of a single species, such as the Mexican free-tailed bat, Indian bull frog, or maize-borer.

Thus, a synecologist might study deserts, or caves or tropical forests. S/he is interested in describing the overall energy and material flow through the system rather than in concentrating on the finer details of a particular organism. In the words of Herreid II:

The synecologist paints with a broad brush the outline of the picture and autecologist stroking in the finer details. Herreid II (1977)

According to the kind of habitat, ecology is subdivided into marine ecology (oceanography), estuarine ecology, fresh water ecology (limnology), and terrestrial ecology. The terrestrial ecology in its turn is classified into forest ecology, cropland ecology, grassland ecology, desert ecology, etc., according to the kinds od study of its different habitats.

Habitat Ecology

Habitat ecology focuses on how the living organisms (animal and plants) react to biotic and biotic factors in their environment; physiology, morphology and behavior. Physiological ecology on animal focuses on the whole-animal function and alteration to ever-changing environments. These alterations have a tendency to maximize the fitness of animals (their capacity to survive and reproduce successfully). The physiological processes studied are temperature regulation, nutrition, water and metabolism on energy and energetic and response to environmental stresses. These environmental factors may include nutrition, disease, climate variation and toxic exposure.

For instance, animal’s heat and mass balances are affected by the climate thus these changes affect how bodies regulate temperatures. On the other hand, physiological ecology on plants emphasizes on understanding how plants deals with environmental variation at the physiological intensity, and on the pressure of resource limitation growth, metabolism and reproduction of individuals. They also deal with plants populations, gradients and different communities and ecosystems.

Community Ecology

This deals with the interactions between organisms that is, the feeding relationships among species, or who helps who, who competes with whom and for what resources and how those interactions affect community structure (the organization of a biological community with respect to ecological interactions).

Community ecologist investigates the factors influencing community structure, biodiversity, and the distribution and abundance of species. These factors include the interrelations with the non living world and different collectiosn of interrelations that take between species. The primary focus of community ecology is on predation, herbivory, competition and parasitism and mutualism.

Population Ecology (Demecology)

This deals with studies of structure and dynamics of populations. That is; factors that affect population and how and why a population varies over time. A population ecologist studies the interrelations of organisms with their environments by gauging properties of populations rather than the behavior of the individual organisms.

Among the properties of population studied is population size, population density, patterns of dispersion, demographics, dynamics, population growth and restraints on growth. This ecology is vital in upkeep of biology, particularly in the progress of PVA (population viability analysis) which allows the forecasting of long-term possibility of a species persevering in a particular locale such as a national park.

Ecological energetic is one branch of ecology that deals with energy conservation and its flow in the organisms within the ecosystem. In it thermodynamics has its significant contribution.

Physiological ecology (Ecophysiology)

The factors of environment have a direct bearing on the functional aspects of organisms. The ecophysiology deals with the survival of populations as a result of functional adjustments of organisms with different ecological conditions.

• Chemical ecology deals with the adaptations of animals of preferences of particular organisms like insects to particular chemical substances.
• Ecological genetics (gynecology) — An ecologist recognized kind of genetic spasticity in the case of every organism. In any environment only those organisms that are favored by the environment can survive. Thus, genecology deals with the study of variations of species based upon their genetic potentialities.
• Palaecoecology ecology is the study of environmental conditions, and life of the past ages, to which radioactive dating methods have made significant contribution.
• Space ecology is a modern subdivision of ecology which is concerned with the development of partially or completely regenerating ecosystems for supporting life of man during long space flights or during extended exploration of extra-terrestrial environments.
• Pedology ecology is a branch of terrestrial ecology and it deals with the study of soils, in particular their acidity, alkalinity, humus contents, mineral contents, soil types, ect., and their influence on the organisms.
• Radiation ecology deals with the study of gross effects of radiations and radioactive substances over the environment and living organisms.
• Socioecology is the study of ecology and ethology of mankind.
• Systems ecology is the modern branch of ecology which is particularly concerned with the analysis and understanding of the function and structure of ecosystem by the use of applied mathematics, such as advanced statistical techniques, mathematical models, characteristics of computer sciences.
• Evolutionary ecology deals with the problems of niche segregation.
• Taxonomic ecology is concerned with the ecology of different taxonomic groups of living organisms and eventually includes following divisions of ecology: microbial ecology, mammalian ecology, avian ecology, insect ecology, parasitological, human ecology and so on.

Contrasting Brown and Green Priorities

Both green and brown proponents have reason to criticize many existing approaches to urban environmental managementOpens in new window, even if their priorities differ. At a superficial level, the brown and green agendas are in direct opposition to each other.

For example, the brown agenda would seem to call for more water use, more sewage connections, more waste collection, more urban residential land and more fossil fuel use (to replace smoky biofuels).

By ways of contrast, the green agenda would seem to call for water conservation, less water-borne sewerage, less waste generation, less urban expansion and less fossil fuel use.

While these potential contradictions should not be ignored, a review of existing policy problems indicates that the trade-offs need not be as sharp as such generalizations seem to imply.

Water

Urban water supply planning has been preoccupied historically with how to increase supplies to meet growing demand, given the physical and financial constraints of the city. By and large, demand has been assumed to be beyond the influence of water sector policies.

For those households and businesses connected to piped water systems, water is generally provided far below its full cost. For example, there is little incentive for users to conserve or encouragement to the industries that are the largest water users to recycle waste water or seek less water-intensive systems of production.

In some of the wealthier cities, subsidized water supply systems have brought major benefits to most of their populations, including a high proportion of their lower income populations.

For instance, there has been a considerable expansion in the proportion of the population with piped water supplies in many of the wealthier Latin American cities. In cities such as Sao Paulo, Belo Horizonte, Curtiba and Porto Alegre, most of the population receives piped water supplies to their homes (Jacobi, 1994; Mueller, 1995).

However, the proponents of the green agenda can rightly point to the serious consequences this often brings. The emphasis on increasing supply and keeping the price of water ‘affordable’ has resulted in major cities throughout Africa, Asia and Latin America overexploiting local water resources. For instance, in many coastal cities local aquifers have been overpumped, resulting in saltwater intrusion.

Overexploitation of underground water has also caused serious problems of subsidence for many buildings and sewage and drainage pipes in many cities (Damian, 1992; Postel, 1992). As local ground and surface water sources are overused (or polluted), meeting rising city demands generally means having to draw on ever more distant and expensive water resources.

This can be to the detriment of the populations (and often ecosystems) in the areas from which the water is drawn and with the higher water costs rarely reflected in higher prices for the largest city water users.

Proponents of the brown agenda often share this green agenda concern for unrealistically low water prices.

They can point to how the discrepancy between water utilities’ costs and revenues (from water sales and public subsidies) often inhibit expansion to low income areas and help to ensure that high proportions of the population in most cities remain unconnected to piped water systems.

Indeed, a combination of price controls and very limited public funds is a recipe for intragenerational inequities, with the subsidies that do exist flowing, along with the water, to those who least need them. Even for those low income groups who have access to connections, water supplies are often irregular or of poor quality or difficult to access – for instance, as dozens of households share each standpipe.

At least 300 million urban dwellers in Africa, Asia and Latin America remain without piped water supplies (WHO/UNICEF 1993) and tens of millions of those whose governments include in their statistics as having access to piped supplies still face inadequate, irregular or unsafe supplies which are often difficult to obtain (Satterthwaite, 1995; WHO, 1996).

While the water-related priorities of the green and brown agendas are different, their goals are not inherently incompatible. The often unmet minimum daily needs for health (about 30 litres per capita) amounts to about two flushes of a conventional toilet or one slowly dripping faucet.

The international standard of 150 litres per capita per day is only a small fraction of the typical usage in affluent cities in the North. Providing sufficient water for health needs is not the reason that many cities are overtaxing their water supplies.

Indeed, in many cities programmes encouraging water conservation and ensuring the better management and repair of piped water systems can often free up sufficient new supplies to allow regular piped water supplies to be extended to unserved households with no overall increase in water use. Intragenerational water inequities need not be solved by creating intergenerational or transboundary water inequities or vice versa.

It is politics and policy instruments, not physical imperatives, that create a stark trade-off between environmental health and ecological sustainability. Moreover, for most cities it is relatively clear whether environmental health or ecological sustainability ought to be the more pressing concern.

Sanitation

Proponents of the green and brown agendas can also point to problems in provision for sanitation, although, as in water supplies, they emphasize different problems. Here the conventional approach has been to promote water-borne sanitation systems, or steps in that direction, with the ultimate aim of providing all households with a flush toilet connected to a sewer.

Again, households obtaining connections receive considerable benefits, often at subsidized prices. But in most urban centres, sewage systems are characterized by significant inequities, relevant to both the brown and green agendas.

There are some cities in Latin America, Asia and parts of Africa where most of the population is adequately served by sewers. These are also generally the cities with low infant mortality rates and high life expectancies. However, the (generally) high unit costs of such systems also means that these cities are in the minority and very few cities have sewerage systems that serve most of their residents.

In many cities, sewers only serve a small proportion of the population (generally those in the more centrally located and wealthier areas). Most small urban centres have no sewer systems at all.

Estimates suggest that close to one-half the urban population of Africa, Asia and Latin America lack adequate provision for sanitation. Tens of millions of urban dwellers have no access to any form of sanitation or have only such poor quality, overcroweded public facilities that they have to resort to defecation in the open.

Proponents of the green agenda point to the environmental costs that conventional sewer systems can bring, especially the large volumes of water used to flush toilets and the problem of disposing of large volumes of sewage.

In Latin America, Asia and Africa only a small proportion of sewage is treated before disposal (WHO/UNICEF, 1993; WHO, 1996; Bartone et al, 1994). Untreated sewage is a major contributor to highly polluted water bodies in most cities, although it is generally difficult to determine its contribution relative to that of untreated industrial wastes and storm and surface run-off.

Fisheries are often damaged or destroyed by liquid effluents arising from cities. Thousands of people may lose their livelihood as a result as some of the largest cities are close to some of the world’s most productive fishing grounds.

Sewage systems also require large volumes of water to function and, as such, help to build into city sanitation systems high water demands. And although there are many examples of cities where some of the sewage is used for crop or fish production, the proportion of sewage used in such a way is limited by the sheer volume of such wastes and the difficulties (and costs) of transporting them to areas where they can be used productively.

Proponents of the green agenda often point to alternative sanitation systems that do not require sewers. These include many that bring ecological advantages such as requiring no water at all and some that are designed to allow the conversion of human wastes into safe fertilizers, allowing the recycling of nutrients in the food system.

These limit water demand and remove the problem of sewage disposal. Simple sewerless sanitation systems are also generally much cheaper than sewered systems, especially when account is taken of the cost of sewage treatment.

But here there is a serious potential conflict between the brown and the green agenda. Proponents of the brown agenda can point to the hundreds of millions of urban dwellers who currently rely on sanitation systems that do not use water—for instance, pit latrines—which bring serious health risks and often contaminate groundwater.

They often contaminate piped water supplies too, as inadequate maintenance of the piped water network means many cracks and leaks and water pressure is not constant (many city water supply systems have irregular supplies, with water available in many districts for only a few hours a day), so sewage seeps into the pipes.

Pit latrinesOpens in new window can be particularly hazardous in areas that regularly face floods as the pits become flooded and spread human excreta everywhere. There is also the problem in many cities of the lack of services to empty them (or the high price that has to be paid for doing so), while space constraints inhibit provision for solutions which limit this problem — for instance, twin vault systems or larger pits.

There is also the question of cost; in many cities, even a good quality pit latrine within their home (or plot) is an unattainable luxury for many low income households. This includes the large proportion of low income groups who rent accommodation and for whom there is no rented accommodation that they can afford with adequate provision for sanitation.

A stress on sewerless latrines may mean that the importance of adequate water supplies are forgotten (the latrines may need no water, but the households who use them certainly do, including the water needed for washing and personal hygiene).

A stress on dry latrines may also mean that the problem of removing waste water is forgotten; one of the key advantages of a sewer system is that it also conveniently and hygienically removes waste water other than sewerage after its use for cooking, laundry or washing.

Brown agenda proponents can also point to instances where the unit cost of installing sewers was brought down to the point where they no longer far beyond the price that low income households could pay (Orangi, 1995) and to community level sewer systems that do not require high levels of water use and with local treatment which greatly reduceds the ecological impact of the effluents on water bodies.

In assuming that all waterborne sanitation systems have unacceptable ecological impacts, there is a danger of promoting alternative sanitation systems that bring inconvenience, higher maintenance costs and greater environmental risks to the users, or of simply producing latrines that the population do not use.

In short, an excessive reliance on conventional water-borne sewerage intensifies the discrepancies between the brown and green agenda: as a tool of urban environmental management it can reduce intragenerational inequities, but typically at the cost of transboundary and intergenerational inequities.

Undoubtedly there are many instances where extending water-borne sewerage systems is justified, especially in high-density residential areas. There are also the measures that can be taken to reduce greatly the ecological disadvantages of such systems, as noted above.

However, proponents of both the brown and the green agendas can take issue with measures that subsidize sewerage systems for relatively affluent urban dwellers, diverting public funds from low income dwellers and imposing environmental costs on those living downstream and even future generations.