Niger Delta Ecosystems: the ERA Handbook/What is the Environment?

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  • Defining Ecology and the Environment in Terms of the Human Landscape
  • Analysing the Landscape
  • The Human Landscape: Economic Activity and Society
  • Landscapes are Alive
  • Ecosystems
  • Terms used in the Description of Ecosystems
  • Plants and Animals in Ecosystems
  • The Dynamics of Ecosystems and Viability
  • Real Ecology: Human Society


The world in which we live has been shaped by mankind. It is a human landscape. Thus an understanding of our world depends upon an understanding of ecology. After all:

#The Human Landscape is a Physical Manifestation of Humanity's Ecological Relationship With Its Environment.

If you have a basic knowledge of geography and biology you will have no trouble in understanding ecology. It is not a difficult or inaccessible science and anyone who takes an interest in their surroundings and tries to understand it, is an Ecologist. A good forester, farmer or planter is an Ecologist. Nonetheless there are a number of definitions and concepts which are central to the ecological debate: they are easy to understand and we all have to know their common names for ease of communication. These will be discussed below.

Ecology is a young science which has developed out of natural history as a result of the need to understand, explain and solve the problems of mankind's increasingly damaging impact on the environment. In essence:

#Ecology is the study of relationships between living phenomena in thier environment.

But this begs the question: what is the Environment, which everyone talks so much about?

#The Natural Environment is the result of the dynamic relationship between climate, soils, microbes, plants, water, and animals.

That is, of course, the Environment without people, where vegetation is able to reach its state of climax for a given climate. This could be rain-forests on the West African coast, pine forests on the Siberian plain or the lime forest in much of Southern England.

But people have to be brought into the environmental equation. Our unnatural technology significantly influences the development of the climax vegetation or else destroys it altogether. The influence is clear in urban and agricultural landscapes, less obvious in inaccessible forests, which seem to be entirely natural. But even here, mankind has had a significant impact.

However, it is only possible to understand the human impact on the environment if we understand that:

#The Natural Environment is what the Environment would be like without people

Only then can we understand how the environment influences the way people live, and how mankind influences the landscape: only then can we understand the dynamic relationship between the two.


Looking at any landscape and trying to understand it means analysing its components and understanding why they are there and what they are. Why is that forest there and why does it have special characteristics? Why is that farmland as it is? Why is that town in that position? What is the relationship between the forest and the farms? What will the landscape look like in six months, or in ten, twenty and a hundred year's time?

Analysing a landscape is best approached in eight steps, each being necessary to an understanding of the next.


This includes altitude, and the global and continental position of a landscape.

In the case of the Niger Delta it is important to realise that it is flat and at sea level. It is made up of sand and silt brought down by the Niger/Benue river system to the Bight of Benin on the West African coast, which is in the tropics. Much of the sand is spread along the continental shelf and thrown back onto the shore by ocean currents to form the characteristic barrier islands.


This depends on latitude, continental position and altitude, and on both local and regional topography, such as nearby mountains. A knowledge of the climate is essential to an understanding of the Niger Delta, as a Tropical Rainy Climate.

A Tropical Rainy Climate occurs within 5-10 degrees of the equator and at altitudes below 1000 m. Throughout the year, the mid-day sun is more or less overhead and there is little variation in the hours of daylight. High humidity and large amounts of cloud keep the temperature below the levels of the drier outer tropics, so that throughout the year the mean monthly temperatures remain around 26-27 degrees Celsius. Annual rainfall is high and the rapid uplifting of moisture caused by the high equatorial temperatures can result in dramatic storms in the late afternoon.


Natural hydrological characteristics are a function of geology, topography and climate. Thus in any given place at any given time, water may arise either locally, as stored ground water or rain, or from outside as upstream water or downstream tidal pressure. There are the daily tidal variations, in addition to seasonal change: also there are the subtle relationships between fresh and salt-water.

However, the activities of mankind can have a profound influence on the hydrology of an area. For instance a natural forest ecosystem tends to act as a sponge, soaking up water in wet weather and releasing it slowly in dry thus moderating the water supply to a river systems. Where natural forest is removed or substantially transformed this sponge function of the forest—effectively a natural reservoir—is lost so that flooding becomes more frequent in wet weather and river failure in dry. The same process may apply to lakes and to ground water systems.

3.2.4 SOILS

Soil forming processes are a function of geology, topography, climate and hydrology and it is important to stress that soils are the unique expression of these predetermining factors.

Thus, for instance, a soil formed on the tropical coast, on alluvial deposits, will have quite different characteristics from a soil formed on the same latitude, with the same rainfall patterns, on a hillside at an altitude of 500m. Moreover, it will have different characteristics from a coastal soil formed on alluvial deposits in the temperate zone.

A soil map of the Niger Delta would show a complex series of soils, the common feature being that they are all the result of a tropical rainy climate. This ensures that they tend to be either highly leached and eroded (where there is free drainage), or arising from rapid rates of deposition and subject to water-logging (for instance the peat swamp soils and the mangrove soils). Moreover in certain conditions—river terraces for instance—soil formation is subject to a dynamic combination of both these activities.

Within this general climatic condition soils are differentiated both regionally and locally by geology and by topographical features.

It is important to remember that soils are alive so that their characteristic are as dependent on microbiotic life forms, such as fungi and bacteria, as they are upon water, mineral particles and humus.


Natural vegetation climaxes are determined by soil conditions.

If the soil conditions are themselves understood in terms of their relationship to geology, topography, climate and hydrology, then there is no need to go beyond soil conditions in order to understand vegetation climaxes. This must be stressed, because too often vegetation is described purely in terms of "Latitude, Altitude and Climate." This is not sufficient for ecological purposes: the soil must be understood first.

#Thus the natural vegetation climaxes are as varied as the soils that determine them.

In terms of plant diversity, the general rule is that the warmer and wetter the climate, the greater the diversity. It is not surprising, therefore, that the Niger Delta has international significance in terms of its importance to the maintenance of global biodiversity.


Within a given climate, vegetation and hydrology/water quality define animal habitats which in turn determine animal communities. Thus a consideration of animal communities involves an understanding of their habitats, both aquatic and terrestrial (and many animals, it must be remembered, inhabit both).

For the same reason as plants, animal diversity is high in the Niger Delta.


Prokaryotae - single celled bacteria, which are important in breaking down dead matter, and in fixing atmospheric nitrogen;

Protoctista – multi-celled organisms which photosynthesise (see 4.5.3) and absorb nutrients from water, such as slimes, sea-weeds and the green algae that grows on stagnant water;

Fungi - which absorb their nutrients from dead matter (saprophytic fungi) or living organisms (the parasitic fungi);

Plantae – the higher plants; and

Animalia - animals.


Soils and climate determine vegetation, but clearly, also, vegetation influences the soil: change the vegetation from forest to plantation and you will thereby change the nature of the soil. The climate, hydrology and vegetation are able to determine what sort of aquatic and terrestrial animal communities live in an area.

Animals also influence vegetation by their eating habits. They influence the soil by the deposition of their waste products on to it, by burrowing into it and, at death, by becoming part of it.

Thus the relationship between soils, vegetation and animals is a complex of cycles. This relationship is particularly obvious in the mangrove forests where we can see soils and communities of plants and animals evolving together on new land.

Vegetation also affects climate. For example rain rolls into the interior of Borneo, the world's third largest island, because it is taken up by the forest vegetation which then releases the water again by evapo-transpiration. This same water falls again further and further inland. Take away the forest and the interior will be much drier.

3.2.8 PEOPLE

The impact of people and of their societies upon the landscape is so pervasive that often, in urban and agricultural landscapes, we forget about the other components altogether. Conversely, when we are in the "bush" (which may seem to city eyes seem wild and natural), we fail to see that the landscape is often as influenced by man as any city or plantation. This very is true of the Niger Delta, where mankind's exploitation of the landscape has influenced most areas. The mangrove forests are perhaps the least cultured part of the landscape, but even they have been influenced by mankind for thousands of years.


Most landscapes, even those that seem to be entirely natural, are a manifestation of human ecosystems which have arisen out of mankind's dynamic relationship with natural ecosystems. This relationship can also be understood as economic activity because:


And mankind's ability to exploit minerals further expands the equation:


The way that mankind organises itself in order to maximise the efficiency of economic activity is manifested in human society because:


When we look at a landscape as a picture we see land-uses (e.g. roads, villages, cassava farms, plantations and processing plants) and ecological resources (e.g. rivers, forests, and soil). The picture is not an accident but the result of mankind's economic exploitation of the natural ecosystems for the resources that we need, and the social structure that has developed as a result of this exploitation.

The landscape represents human society's impact upon the environment. An impact which today is potentially more damaging to the ability of ecosystems to continue to provide the resources required of them, because of fast-growing human populations and inappropriate technology.

This is not academic theorising but a reality which must be grasped, especially in terms of efficient integrated, landuse planning which must work with human ecological, economic and social realities, not against them. Thus the present state of the ecological resources and land-uses of any country or region are best understood in terms of:

  • the natural ecosystems;
  • human economic impact;
  • society; and
  • the resulting human landscape.


Ecology recognises that landscapes are alive. There is a dynamic relationship between their components, so that the landscape is always changing: not for one minute does it stay the same. Thus in ecology, landscapes are classified not just in terms of the components we have described, but in terms of life. The definitions below all refer to life: 'bios' is the ancient Greek for life.


That part of the earth in which life occurs: from the bottom of the deepest ocean trench to the heights where the strongest bird can fly.


These divide the Biosphere into regions of distinct and characteristic combinations of plants and animals across a gradation of climates. They tend to be divided by oceans, deserts and massive mountain ranges. Ecologists differ on the specific definition of the Biogeographical regions but a useful classification defines eight:

  • the Nearctic region - North America;
  • the Neotropical region - South America;
  • the Palearctic region - Eurasia and N. Africa;
  • the Afrotropical region;
  • the Oriental region - India and South East Asia;
  • the Australasian region;
  • the Oceanic region; and
  • the Antarctic.


These define the biogeographical regions in more specific terms and are more closely related to geographic factors such as climate and relative isolation. The Niger Delta is in the West African sub-region, which also includes the Congo river basin and the more humid (southerly) part of the Niger/Benue river basin, as well as all the West African coast the mouth of the Congo.

3.4.4 BIOMES

These are large areas containing characteristic communities of plants and animals. Thus the West African biogeographical sub-region contains both Tropical Rain Forest and savannah biomes.


Ecosystems are what ecologists are really interested in: they describe the mechanics of the landscape.

Technically an Ecosystem is an area within a biome which can be given a physical boundary for convenient ecological study.

#Ecosystems tend to be defined in three ways

  • as places which can be recognised within their general surroundings, such as the levee forest at Okoroba or a shrine forest at Botam-Tai;
  • as places which are defined by the predominance of one plant species, such as the Rhizophora mangrove forests of Akassa Creek; or
  • as places which are defined by the territory of one animal, such as the Chimpanzees of Okoroba. #But Ecosystems can be Sub-Divided again and again

Thus, for instance, within the Ecosystem of a forest, one can define sub-Ecosystems according to soils and drainage, and so on to the sub-Ecosystems of individual trees or even of individual leaves.

As with the landscapes they describe, Ecosystems change. They are the dynamic workshops where plant and animal species co-evolve.


Now here is some necessary terminology with which you will have to become familiar for a further exploration of ecology.


An Ecosystem largely determined by the natural environment (e.g. a mangrove creek), as opposed to one that is largely determined by mankind (e.g. an oil-palm plantation), and within which there is a dynamic relationship between living things and the rest of their environment.


An area within a biome that has characteristic Ecosystems, such as the alluvial tropical rainforests of the Niger Delta.


One of the parts into which an ecozone can be broken for the purposes of study, such as a ridge-top cultured forest on Akassa Island.


The transitional zone between one Ecosystem and another, such as the banks of a river.


All the plant or animal individuals which can successfully reproduce with each other.


The number of individuals of a species found in a given area.


The number of species in a given area.


Another word for species diversity.


The divergence and extinction of species through natural selection.

3.6.10 A NICHE

The home of an organism in all its dimensions, or how it fits into and makes a living in its ecosystem.

3.6.11 A HABITAT

The viable Ecosystem that is required to sustain a species.


The wise use of resources and the management of the environment so that all species, including mankind, can survive in a viable Ecosystem.


Ecosystems can be described in terms of plants or of animals but because plants do not move, their relationship to the environment is different from that of animals.

The components of an environment which determine plant characteristics, species diversity and populations are water, temperature, mineral nutrition, and competition with other plants and animals.

Plant species create microclimates for themselves, for other plant species, and for animals. This is how life initially colonises hostile environments. A good example is the colonisation of beach ridges by Casuarina trees.


Because of the small surface area of their leaves, Casuarina trees are well suited to growing in exposed positions. They are one of the few non-legume trees able to fix Nitrogen, and in well-drained conditions their roots are able to explore large volumes of soil enabling them to anchor themselves into poorly structured soil. Thus without competition the trees grow fast in the sandy beach ridge soils. Because the leaves have a small surface area, when they drop they are not blown away and soon form a mat under the tree. This decomposes to form a very thin but humus-rich soil, hardly more than a scab on the sandy surface. Initially other casuarina trees germinate beneath the first tree so that a clump of trees is formed. Together with the new soil, this creates a protective microclimate for the development of what J.C. Okafor calls Strand Vegetation:—

The total width of this vegetation varies from a few metres to about 100 m. Perhaps because of its small extent and simplicity Nigerian strand vegetation has been infrequently described. This also places it in great danger of being totally eliminated by oil pollution which is now pervasive along the coastline. The extent to which strand vegetation contributes to stabilising beaches against erosion in Nigeria is not known, but could be significant. (Nigeria's Threatened Environment — A National Profile, Nigerian Environmental Study/Action team, 1991.)

In contrast to plants, an animal can change its environment quickly by moving location, and it may even move between aquatic and terrestrial environments. This may be because of physical parameters such as temperature or humidity change, or because of a search for resources such a food, shelter, or a mate.

Similarly, an animal can move to escape a competitor or a predator. Plants do not have this option but have evolved other mechanisms of protection. For instance a plant cannot run away from the animal which wants to eat it. But, it survives by having thorns which stop the animal completely finishing it; it may taste nasty; or it can store energy in its roots and grow new parts above ground later, when the animal has finished its meal.

Aquatic and terrestrial animals have different requirements in terms of what components of the physical environment are the most important to them. For aquatic animals, water is their medium; without it they die. However the condition of the water is also important: dissolved salts and oxygen, currents and levels of light may be critical. Aquatic animals evolve to suit specific hydrological conditions: if these conditions change the animals may die.

Terrestrial animals need water just as much as aquatic animals—without it they also die. However, for terrestrial animals climatic conditions are especially important, and particularly temperature. The great annual migrations of birds, for instance, between Europe and Africa, are the result of seasonal climatic changes.


Whilst Ecosystems can be described simply in terms of just plants (a mangrove forest) or just animals (the Andoni elephants), plants and animals have a dynamic ecological relationship.

However it is a relationship where animals are particularly dependent upon plants, and nowhere is this more obvious than in obtaining and using energy. All living things need energy and all energy comes from the sun; but only plants are able to convert the sun's energy into carbohydrates, which can be stored and used as energy. To obtain energy animals must consume plants or eat other animals which have already done so.


Autotrophs are Primary Producers, being the photosynthesising (see 4.5.3) plants and plankton which convert water, the sun's energy and inorganic substances into the living matter upon which heterotrophs depend.

Heterotrophs are Consumers and include:

  • Herbivores, animals which eat only plants;
  • Carnivores, animals which only eat other animals;
  • Omnivores, animals which eat both plants and animals; and
  • Decomposers, animals and plants that live on dead and decaying material (Detritus). This group includes the:
  • Primary Decomposers, those organisms (such as bacteria and fungi) that mineralise detritus thus releasing nutrients into the soil.

In the African savannah, grass converts the sun's energy into carbohydrates, antelopes eat grass to get their energy and lions eat antelopes to get theirs. It is a dynamic system: just thinking about the relationship of soils and vegetation and animals, and of grass and antelopes and lions, indicates the complexity and dynamics of Ecosystems in general.

Energy is vital to an Ecosystem being the only component which comes from outside the biosphere: all others are recycled. Looking at the forest edge again, the herbage grows because it receives energy from the sun, but also because it gets water from the rain and nutrients from the soil. The nutrients arise from inorganic sources released in solution in the water, and from the decay of organic matter that is either the wastes of animals (such as urine) or matter that was once alive and has died (Detritus).

Detritus is broken down by the decomposers (e.g. termites and vultures) which eat it, and by the primary decomposers (the micro-organisms, such as bacteria) which mineralise it, so that it become nutrients for plants again, which can be eaten by animals.

The Ecosystem of a tree is a more contained example: at its simplest, leaves fall to ground and decay with the help of the primary decomposers; the minerals so formed dissolve in the soil water to be taken up by the tree's roots and to become leaves again. If larger animals eat the leaves the cycle is enlarged and nutrients do not reach the tree again until they have been passed out as animal waste and/or the animal dies.

This is the nutrient cycle, one of the many ecological cycles, into which the dynamics of whole Ecosystems can be broken down. Within the nutrient cycle, the movement of carbon or nitrogen can then be described in their own cycles. Energy from the sun may be stored and transferred but some is lost at every stage and must be replaced from outside the ecosystem.

It is difficult to analyse natural Ecosystems as total and self-contained entities, in order to understand the dynamics of the natural relationships that are the subject matter of ecology. In reality Ecosystems consist of many inter-related cycles that link one with another, so that in the end there is only one Ecosystem, and that is the Biosphere. However the description of a hypothetical island serves to illustrate ecological dynamics: thus, Eco Island.


Eco Island is isolated in a tropical ocean thousands of miles away from any other land. The Eco Island Aphid Eater is a small bird that lives on the island. It is a poor flyer, spending all its life on the island. Its diet consists exclusively of the aphids that suck the sap out of the young green stems of the only type of tree which grows on the island: the Eco Tree.

A fungus grows on the leaves of the Eco Trees because of the honeydew that drips onto them from the aphids while they are sucking the sap from the stems. The aphids are cared for by ants which milk them for the honeydew, and carrying it to their nests at the foot of the trees.

The Eco Tree can only grow in very special conditions which include: the climate of Eco Island, the aeration at its roots created by the ants' nests, and the high levels of phosphate in the soil that comes from the guano or faeces of the Aphid Eater. However if the population of aphids gets too large the Eco Tree is weakened and likely to die because too much sap is sucked from it and because the fungus on the leaves grows so thick that they cannot photosynthesise. Moreover, the aphids are unable to move much on their own and depend on the ants to move them around the tree. If the aphids are not moved populations become locally so high that they suffocate.

But on Eco Island all life thrives: the Aphid Eaters are never hungry, the aphids never suffocate, the Ants are as happy as ants can be and the Eco Trees are healthy despite the aphids that live on them and despite spots of fungus on their leaves.

Thus an Ecosystem is the sum of nine conceptual components, listed below.


The Aphids need the Eco Tree and the ants; the Eco Tree depends on the Aphid Eater birds to ensure that the Aphids do not become too populous, and it depends on the ants to give it the right soil conditions; the Ants need the Aphids for the honeydew. And there are many other less obvious and less direct dependency relationships. All living things depend on others to survive: to give them immediate sustenance and to create for them the right environment.


The habitats of the ants, the aphids and the Aphid Eaters do not overlap: each has its own Niche. However, each individual competes with members of its own species for resources, for mates and for living room.


The Eco Tree gets is energy by photosynthesis (4.3.5); the aphids get their energy by sucking sap from the Eco Tree; and the Aphid Eater gets its energy by eating the aphids. Thus energy enters the Ecosystem from the sun and is lost only as heat generated by the activities of all the animals and during decomposition of detritus by the decomposers.


Biomass is the total mass of life on Eco Island at any one time: it is both the result of productivity and an indicator, in terms of mass per unit area, of the productivity of the island.


The Eco Tree is a Primary Producer, converting solar energy and inorganic material into living matter. The aphids, the ants and the Aphid Eater are Secondary Producers, depending upon the primary producer and each other to live. The productivity of Eco Island depends on its inorganic resources such as water and soil nutrients, while production itself is activated by energy.


Like the energy flow, the Eco Tree takes its nutrition from the soil, the aphids from the Eco Tree, and the Aphid Eater from the aphids. But, unlike the energy flow, this is a cycle because all nutrients are returned to the soil by the decomposition of detritus (animal wastes and dead material) for recycling.


Bioactivity is the combination of energy flow, productivity, biomass and the resource cycles, measured by the speed of the resource cycles.


The Eco Tree eventually decays and is recycled through the system as new production. Therefore, Decomposition balances Production.


In summary, Eco Island as a Natural Ecosystem is a system of component inter-acting cycles that defines the community of life on the island. A Natural Ecosystem that is productive in a balanced way is called a Viable Ecosystem.

#A Viable Ecosystem is like a healthy body, able to withstand and recover from massive shocks such as volcanic eruptions, floods, droughts and hurricanes.

And even, although it takes time, oil spills. Even the recent ice ages did not result in a diminution of species.

The Biosphere of our earth is Eco Island on a global scale, made up of an almost infinite number of sub-systems: as a natural ecosystem, the Biosphere is a Viable Ecosystem.


The Natural Ecosystem defines the natural environment; that is, the described environment without human society. But in reality, as we have already made clear, human society has to be added to the ecological equation.

Human society may be defined as the human species plus human technology. These influence the Biosphere so that its viability is undermined to such an extent that it is less able to withstand shocks.

Mankind's activities have affected the environment ever since we evolved as a tool-using animal, capable of reason, thought and speech. Most of the world's landscapes have been modified by mankind, but not to the extent that the Ecosystems have become non-viable. It is only in the last hundred years (a little longer in Western Europe) that the scale of human activity, the pressure of human numbers and the propensity to manufacture unnatural substances (that the Ecosystem cannot absorb without being poisoned) have made mankind a threat to the viability of the Biosphere. And only in the last thirty years have obvious manifestations of Ecosystem collapse become evident.

It is not just mankind's increasing population that threatens the viability of Ecosystems. It is our high consumption of the earth's resources and our desire to exploit these resources for the highest and quickest financial return, regardless of the economic cost (and damage to Ecosystems is a real economic cost that can be valued) that threatens the viability of the Biosphere.

Thus in mankind's relationship to the environment three types of human society can be distinguished. They exist in both historic and contemporary spatial terms.


Where mankind's habitat demands are in a stable balance with the Ecosystem in which they live. Pre-agricultural hunter/gatherer societies are examples. It is unlikely that any truly natural populations of mankind are left on earth.


This is where mankind's activities maintain an Ecosystem that remains viable despite a modification of it. Such Ecosystems are able to withstand shocks such as drought. Settled hunting and farming societies where productivity is maintained are precarious examples, threatened by modern societies around them.


Where Ecosystems are either degrading towards non-viability or are already non-viable as a result of mankind's presence. Most modern human societies are in this category. In fact so pervasive is modern society on the earth today that there are signs that the Biosphere is becoming a non-viable environment not only for humans themselves but for most other species as well.

Thus the key to human society's future on the planet is to manage ecosystems both locally and globally (the Biosphere) so as to ensure ecological viability. That is, to ensure that ecosystems continue to supply the natural renewable resources which we and our successors need. For the more developed societies this means both reducing consumption and taking responsibility for the international implications of present and future consumption patterns: for the less developed societies it means learning from the mistakes of more developed countries. For all societies, as the Rio Earth Summit stressed, international cooperation is required as never before in mankind's history.