Chapter 2: Knowledge Module 1 – Ecological Principles and Ecosystem Resilience (version 1)


Apply knowledge of ecological principles in relation to conservation of biological diversity.

• Brief history of Ecology is explained within the context of Conservation.
• Importance of ecology in relation to conservation of biodiversity and restoration of the environment is explained.
• Indigenous principles of conservation ecology are identified and explained with a clear link to current principles.
• Evolution of ecology principles in relation to current environmental problems is explained.

Apply knowledge of conservation to restore ecological and resilience in ecosystems.

• Ecology related terms in relation to restoration of resilience in ecosystems are explained.
• Actions necessary for restoration of resilience in ecosystems are listed and explained.

2.1 Introduction

The purpose of this module is to provide a learner with an opportunity to apply knowledge of ecological principles in relation to conservation of biological diversity.

On completion, the learners will understand the following topic elements:
• Ecology, conservation biology, its evolution and principles: 30%
• Ecosystems: 30%
• Ecosystems resilience: 30%
• Climate change, ecology and ecosystems: 10%

2.2 Ecology, Conservation Ecology, its Evolution and Principles

This section covers the following Topic Elements:
• Ecology
• Evolution of ecology
• Indigenous principles of ecology

2.2.1 The History (or Evolution) of Ecology

Ecology, also called bioecology, bionomics, or environmental biology, study of the relationships between organisms and their environment. Some of the most pressing problems in human affairs—expanding populations, food scarcities, environmental pollution including global warming, extinctions of plant and animal species, and all the attendant sociological and political problems—are to a great degree ecological.

The word ecology was coined by the German zoologist Ernst Haeckel, who applied the term oekologie to the “relation of the animal both to its organic as well as its inorganic environment.” The word comes from the Greek oikos, meaning “household,” “home,” or “place to live.” Thus, ecology deals with the organism and its environment. The concept of environment includes both other organisms and physical surroundings. It involves relationships between individuals within a population and between individuals of different populations. These interactions between individuals, between populations, and between organisms and their environment form ecological systems, or ecosystems. Ecology has been defined variously as “the study of the interrelationships of organisms with their environment and each other,” as “the economy of nature,” and as “the biology of ecosystems.”

Ecology had no firm beginnings. It evolved from the natural history of the ancient Greeks, particularly Theophrastus, a friend and associate of Aristotle. Theophrastus first described the interrelationships between organisms and between organisms and their nonliving environment. Later foundations for modern ecology were laid in the early work of plant and animal physiologists.

In the early and mid-1900s two groups of botanists, one in Europe and the other in the United States, studied plant communities from two different points of view. The European botanists concerned themselves with the study of the composition, structure, and distribution of plant communities. The American botanists studied the development of plant communities, or succession. Both plant and animal ecology developed separately until American biologists emphasized the interrelation of both plant and animal communities as a biotic whole.

During the same period, interest in population dynamics developed. The study of population dynamics received special impetus in the early 19th century, after the English economist Thomas Malthus called attention to the conflict between expanding populations and the capability of Earth to supply food. In the 1920s the American zoologist Raymond Pearl, the American chemist and statistician Alfred J.Lotka, and the Italian mathematician Vito Volterra developed mathematical foundations for the study of populations, and these studies led to experiments on the interaction of predators and prey, competitive relationships between species, and the regulation of populations. Investigations of the influence of behaviour on populations were stimulated by the recognition in 1920 of territoriality in nesting birds. Concepts of instinctive and aggressive behaviour were developed by the Austrian zoologist Konrad Lorenz and the Dutch-born British zoologist Nikolaas Tinbergen, and the role of social behaviour in the regulation of populations was explored by the British zoologist Vero Wynne-Edwards.

Figure 2.1 – An understanding of Ecology helps conservation resource managers to manage natural ecosystems sustainably. (Infographic Source: Accessed on 30/08/2022)

While some ecologists were studying the dynamics of communities and populations, others were concerned with energy budgets. In 1920 August Thienemann, a German freshwater biologist, introduced the concept of trophic, or feeding, levels (see Figure 2.1 below), by which the energy of food is transferred through a series of organisms, from green plants (the producers) up to several levels of animals (the consumers). An English animal ecologist, Charles Elton (1927), further developed this approach with the concept of ecological niches and pyramids of numbers. In the 1930s, American freshwater biologists Edward Birge and Chancey Juday, in measuring the energy budgets of lakes, developed the idea of primary productivity, the rate at which food energy is generated, or fixed,
by photosynthesis. In 1942 Raymond L. Lindeman of the United States developed the trophic-dynamic concept of ecology, which details the flow of energy through the ecosystem. Quantified field studies of energy flow through ecosystems were further developed by the brothers Eugene Odum and Howard Odum of the United States; similar early work on the cycling of nutrients was done by J.D. Ovington of England and Australia.

The study of both energy flow and nutrient cycling was stimulated by the development of new materials and techniques—radioisotope tracers, microcalorimetry, computer science, and applied mathematics—that enabled ecologists to label, track, and measure the movement of particular nutrients and energy through ecosystems. These modern methods encouraged a new stage in the development of ecology—systems ecology, which is concerned with the structure and function of ecosystems.

Ecology is necessarily the union of many areas of study because its definition is so all-encompassing. There are many kinds of relationships between organisms and their environment. By organisms one might mean single individuals, groups of individuals, all the members of one species, the sum of many species, or the total mass of species (biomass) in an ecosystem. And the term environment includes not only physical and chemical features but also the biological environment, which involves yet more organisms.

In practice, ecology is composed of broadly overlapping approaches and further divided by the groups of species to be studied. There are many, for example, who specialize in the field of “bird behavioral ecology.” The main approaches fall into the following classes.

Evolutionary ecology examines the environmental factors that drive species adaptation. Studies of the evolution of species might seek to answer the question of how populations have changed genetically over several generations but might not necessarily attempt to learn what the underlying mechanisms might be. Evolutionary ecology seeks those mechanisms. Thus, in the well-known example of
the peppered moth, the populations in the industrialized English Midlands changed over generations from having wings coloured largely grayish white, peppered with black spots, to wings that were mostly blackish. The ecological mechanism involved predation—birds readily detected the light-coloured moths against the background of the tree trunks that industrial pollution had darkened, whereas the darkcoloured moths remained generally undetected.

Evolutionary ecology also examines broader issues, such as the observations that plants in arid environments often have no leaves or else very small ones or that some species of birds have helpers at the nest—individuals that raise young other than their own. A critical question for the subject is whether a set of adaptations arose once and has simply been retained by all species descended from a common ancestor having those adaptations or whether the adaptations evolved repeatedly because of the same environmental factors. In the case of plants that live in arid environments, cacti from the New World and euphorbia from the Old World can look strikingly similar even though they are in unrelated plant families.

Physiological ecology asks how organisms survive in their environments. There is often an emphasis on extreme conditions, such as very cold or very hot environments or aquatic environments with unusually high salt concentrations. Examples of the questions it may explore are: How do some animals flourish in the driest deserts, where temperatures are often high and freestanding water is never available? How do bacteria survive in hot springs, such as those in Yellowstone National Park in the western United States, which would cook most species? How do nematodes live in the soils of dry valleys in Antarctica? Physiological ecology looks at the special mechanisms that the individuals of a species use to function and at the limits on species imposed by the environment.

Behavioral ecology examines the ecological factors that drive behavioral adaptations. The subject considers how individuals find their food and avoid their enemies. For example, why do some birds migrate while others are resident? Why do some animals, such as lions, live in groups while others, such as tigers, are largely solitary?

Population ecology, or autecology, examines single species. One immediate question that the subject addresses is why some species are rare while others are abundant. Interactions with other species may supply some of the answers. For example, enemies of a species can restrict its numbers, and those enemies include predators, disease organisms, and competitors—i.e., other species. Consequently,
population ecology shares an indefinite boundary with community ecology, a subject that examines the interactions between several to many species. Species abundances vary both from year to year and across the species’ geographic range. Population ecology asks what causes abundances to fluctuate. Why, for example, do numbers of some species, typically birds and mammals, change perhaps threefold or fourfold over a decade or so, while numbers of other species, typically insects, vary tenfold to a hundredfold from one year to the next? Another key question is what limits abundance, for, without limits, species numbers would grow exponentially.

Biogeography is the study of the geographical distribution of organisms, and it asks questions that parallel those of population ecology. Some species have tiny geographical ranges, being restricted to perhaps only a few square kilometres, while other species have ranges that cover a continent. Some species have more-or-less fixed geographical ranges, while others fluctuate, and still others are on the increase. If a species that is spreading is an agricultural pest, a disease organism, or a species that carries a disease, understanding the reasons for the increasing range may be a matter of considerable economic importance. Biogeography also considers the ranges of many species, asking why, for example, species with small geographic ranges are often found in special places that house many such species rather than scattered randomly about the planet.

Community ecology, or synecology, considers the ecology of communities, the set of species found in a particular place. Because the complete set of species for a particular place is usually not known, community ecology often focuses on subsets of organisms, asking questions, for example, about plant communities or insect communities. A fundamental question deals with the size of the “set of species”— that is, what ecological factors determine how many species are present in an area. There are many large-scale patterns; for example, more species are present in larger areas than smaller ones, more on continents than on islands (especially remote ones), and more in the tropics than in the Arctic. There are many hypotheses for each pattern. Ecological factors also cause the diversity of species to vary over smaller scales. For example, though predators may be harmful to individual species, the presence of a predator may actually increase the number of species present in a community by limiting the numbers of a particularly successful competitor that otherwise might monopolize all the available space or resources.

Conservation biology seeks to understand what factors predispose species to extinction and what humans can do about preventing extinction. Species in danger of extinction are often those with the smallest geographic ranges or the smallest population sizes, but other ecological factors are also involved.

Ecosystem ecology examines large-scale ecological issues, ones that often are framed in terms not of species but rather of measures such as biomass, energy flow, and nutrient cycling.

Questions include how much carbon is absorbed from the atmosphere by terrestrial plants and marine phytoplankton during photosynthesis and how much of that is consumed by herbivores, the herbivores’ predators, and so on up the food chain. Carbon is the basis of life so these questions may be framed in terms of energy. How much food one has to eat each day, for instance, can be measured in terms of its dry weight or its calorie content. The same applies to measures of production for all the plants in an ecosystem or for different trophic levels of an ecosystem. A basic question in ecosystem ecology is how much production there is and what the factors are that affect it. Not surprisingly, warm, wet places such as rainforests produce more than extremely cold or dry places, but other factors are important. Nutrients are essential and may be in limited supply. The availability of phosphorus and nitrogen often determines productivity—it is the reason these substances are added to lawns and crops—and their availability is particularly important in aquatic systems. On the other hand, nutrients can represent too much of a good thing. Human activity has modified global ecosystems in ways that are increasing atmospheric carbon dioxide, a carbon source but also a greenhouse gas and causing excessive runoff of fertilizers into rivers and then into the ocean, where it kills the species that live there.

(This section sourced from: Accessed on 30/08/2022)

2.2.2 Definitions of Principles of Ecology

Ecology is the study of the diversity of life and of the interactions between organisms and their abiotic (non-living) and biotic (living) environments.

All living things on the Earth depend on 4 basic resources that allow life to exist. Without these things, there would be no life on Earth. They are:

•    Sunlight – this provides light, heat and energy for living things.
•    Water – all life requires clean and unpolluted water to survive.
•    Soil – plants on land get their nutrients, minerals and water from the soil that they grow in.
•    Air – plants absorb carbon dioxide from the air and release oxygen while animals breathe in and use oxygen and release carbon                         dioxide so there is always a balance. Some bacteria in the soil convert nitrogen from the air into forms that plants can use.

These four things and the way they interact with each other make up the physical environment and are also known as abiotic factors because they are non-living.

Animals are unable to get energy directly from the sun. Only plants can do that and they do it through a process called photosynthesis – this is a chemical process that takes place in the leaves of plants that uses the energy from the sun, water and carbon dioxide as well as nutrients from the soil to grow their roots, stems, leaves and fruit or seeds. These contain energy that animals can eat and then use to grow their bodies and have energy for moving around.

For this reason, plants are called PRODUCERS (they produce all the food and energy that animals depend on). Animals are known as CONSUMERS (they cannot produce their own food from the sun but consume it from plants). Some animals eat only plants and they are known as HERBIVORES. Other animals eat only other animals and they are known as CARNIVORES. Animals that eat both plants and other animals are known as OMNIVORES.

Figure 2.2 – Energy moves from the sun to plants then to primary consumers (herbivores) and secondary and tertiary consumers (carnivores). This is also known as the food chain. (Image Source: levels Accessed on 29/08/2022)


Biodiversity is “the variety of species and ecosystems on Earth and the ecological processes of which they are a part – including ecosystem, species, and genetic diversity components.” (Source: Accessed on 29/08/2022)

Figure 2.3 – An ecosystem consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. (Image Source: Accessed on 29/08/2022)

Species are a complete, self-generating, unique collective of genetic variation, capable of interbreeding and producing fertile offspring.

Genes are the working units of heredity; each gene is a segment of the DNA molecule that encodes a single enzyme or structural protein unit. Genetic diversity is the foundation of all biodiversity. Genetic variation permits populations to adapt to changing environments and continue to participate in life’s processes. (Source: Accessed on 29/08/2022)

Three main attributes of biodiversity are composition, structure and function:

•    Composition is the identity and variety of an ecological system. Descriptors of composition are typically lists of the species resident in an area or an ecosystem and measures of composition include species richness and diversity of species.
•    Structure is the physical organization or pattern of a system, from habitat complexity as measured within communities to the pattern of habitats (or patches) and other elements at a landscape scale.
•    Functions are the result of one or more ecological and evolutionary processes, including predation, gene flow, natural disturbances and mycorrhizal associations as well as abiotic processes such as soil development and hydrological cycles. Examples of functions include predator-prey systems, water purifications and nutrient cycling.
(Source: Accessed on 29/08/2022)

Biodiversity is the foundation of a vast number of ecosystem services essential for human well-being (see Figure 2.3 below). Ecosystems support all forms of life, moderate climates, filter water and air, conserve soil and nutrients and control pests. Species (animal and plant) provide us with food, building materials, energy and medicines. They also provide vital services such as pollination, waste assimilation, water filtration and distribution of seeds and nutrients.

Genetic diversity enables us to breed higher-yield and disease-resistant plants and animals and allows the development or natural evolution of breeds and races that thrive under a variety of environmental conditions. For instance, genetic variability in a species allows adaptation over time to changing climatic conditions.

The cultural services that ecosystems provide include recreational, aesthetic and spiritual values that are vital to individual and societal well-being. (Source: Accessed on 29/08/2022)

Key public concerns about human impacts on biodiversity include effects on rates of extinction, future options, productivity of ecosystems, and loss of economic opportunities. Retaining a variety and abundance of individuals and species permits the adaptability that sustains ecosystem productivity in changing environments and promotes further diversity (future adaptability and options), thereby potentially sustaining desirable economic and environmental opportunities and maintaining future options for the benefit of human communities. (Source: Accessed on 29/08/2022)

In addition, many people believe that all life forms have an intrinsic value (i.e. valued for their own sake) and that humans have a moral obligation to protect them and ensure that they survive for their own sake apart fromtheir potential value to future human generations.

Figure 2.4 – Healthy ecosystems provide a number of beneficial services.


Ecology is an entire field of study in its own right and you can go to university and study a 3 year degree in it and even further up to Masters and PhD level. So the following is just a brief overview of some of the most important concepts that you would need to know as an Eco Ranger.

Adaptation – is the adjustment of organisms to their environment in order to improve their chances at survival in that environment.

Example: Succulent plants have adapted to hot and dry conditions by storing water in their leaves. Giraffes have adapted to competition for browsing plants by developing a long neck that allows them to reach leaves that other browsers cannot.

Amensalism – an interaction between two organisms, where one suffers a reduction in resources, or an increase in costs imposed by conditions, due to the presence of another organism.

Example: When gum tree (Eucalyptus sp.) leaves fall to the ground, they release allelopathic compounds (that are also released by their roots) which are toxic to plants and soil organisms. These chemicals prevent other plants from growing and therefore reduce competition for the gum tree for nutrients, water and light as well as growing space.

Figure 2.5 – You may have noticed that the ground below gum trees is usually bare of other plants.

Climate Change – long-term changes in the climatic variables experienced in a defined spatial area (which could vary from local weather to global climate). Climate change is anthropogenic which means it is caused by humans through the release of greenhouse gasses such as carbon dioxide or methane into the atmosphere. It is expected to impose stresses on human standards of living and is considered to be the greatest environmental challenge facing the world.

Example: Burning of fossil fuels such as petrol in cars releases carbon dioxide. Climate change can lead to increases in severe weather such as storms, floods and droughts.

Commensalism – this refers to the interaction between two species where one organism gains resources or shelter from conditions, due to the presence of the other species. The latter species gains no benefit or cost from its interaction with the commensal.

Example: An epiphyte is any type of plant such as many orchid species, ferns and mosses that grow on the trunks or branches of other trees in the forest in order to access more light. Their roots do not penetrate the host tree or damage it in any way.

Figure 2.6 – An orchid and moss growing on a tree are both epiphytes, an example of commensalism.

Community – this refers to all species in a defined spatial area or ecosystem, which interact via trophic, competitive, commensal, amensal or mutualistic interactions.

Example: All the plants, animals and microbes in a forest make up the forest community.

Competition – is the process where organisms gain a greater or lesser share of a limited resource. During exploitation competition, strategies concentrate on the gathering of the resource. During interference competition, organisms engage in strategies that protect their share of the resource for future use, or prevent competitors from exploiting that resource.

Example: Many different species of antelope compete for grazing. Due to competition, some have adapted by eating short grasses e.g. blue wildebeest or zebras and are known as bulk feeders while others are selective feeders that eat grass with high-quality carbon (normally medium to tall grasses) e.g. sable and eland.

Ecological niche – the sum total of all the resources used by, and the biotic and abiotic conditions suffered by, a species. Each resource (e.g. food) and condition (e.g. temperature) forms an axis of a multi-dimensional ‘hypervolume’ that describes the ecological requirements and constraints that allow a species to maintain long-term average population growth.

Example: An example of an ecological niche is that of the dung beetle. The dung beetle, as its name suggests, consumes dung both in larval and adult form. Dung beetles store dung balls in burrows, and females lay eggs within them. This allows hatched larvae immediate access to food.

Figure 2.7 – A dung beetle (Scarabaeus sp.) is a good example of an ecological niche.

Ecosystem – all organisms and the abiotic environment found in a defined spatial area, generally assumed to be the collective description of a community and its physical environment.

Example: A wetland is an example of an ecosystem and has its own unique plants and animals and abiotic conditions.

Ecosystem Services – ecosystems have measurable emergent properties, such as productivity, diversity, stability. A subset of these properties can be considered ‘useful’ in some way to human standard of living called ‘ecosystem services’. The phrase is commonly used to help quantify the economic benefits of conserving biodiversity.

Example: A wetland purifies and cleans water and controls flooding. Many wetland plants are also used for the making of crafts and utensils e.g. Ncema (Zulu name), matting rush (English) (Juncus kraussi) is used by Zulu people to make sleeping mats and baskets.

Figure 2.8 – Ncema is a useful wetland plant used for weaving traditional Zulu baskets, a good example of an ecosystem service.

Invasive Species – as a broad definition, any species that has recently expanded its normal niche to colonise a new biogeographical area. It is often used synonymously with ‘non-native’ or ‘alien’. The negative connotations of the word ‘invasive’ makes ‘invasive species’ commonly synonymous with ‘exotic pest’ or ‘exotic weed’, i.e. a species from ‘elsewhere’ that causes harm to human economy or standard of living. Note that only a fraction of non- native species that colonise a new area become established, and that only a fraction of these cause harm to humans or to biodiversity.

Example: The black wattle tree (Acacia mearnsii) from Australia has invaded large parts of South Africa where it causes loss of biodiversity and has negative effects on the water cycle.

Mutualism – a biotic interaction between two organisms, where they gain an increase in resources, or a reduction in stressful conditions, from the presence of the other organism. Some mutualisms are obligate, where neither species can exist without the other, while many are facultative, such that the mutualists can persist but with less numerical success in the other’s absence.

Example: Lichen is a good example of mutualism as it is actually two different species living together: a fungus and an algae. The fungus protects the algae from dehydration and provides it with nutrients while the algae produces food through photosynthesis that benefits the fungus.

Figure 2.9 – Lichens are good examples of mutualism.

Natural selection – the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as the main process that brings about evolution.

Example: Peacock females pick their mate according to the male’s tail. The ones with the largest and brightest tails mate more often. Today, because most breeding males have large, bright tales, it is rare to find males that do not have bright feathers. This is because tail characteristics are passed from adult breeding peacocks to their offspring.

Parasitism – a trophic interaction in which individuals of one species, called the parasite, feeds upon the tissues of living individuals of another species called the host that can harm the host.

Example: Malaria, which is caused by a protozoan of the genus Plasmodium transmitted to humans by the bite of an Anopheles mosquito, is an example of this interaction.

Figure 2.10 – A map of malaria risk areas in South Africa. Mosquitos are an example of parasitism. Travelling for tourists in these areas would pose a health and safety risk.

Predation – a trophic interaction in which individuals of one species (the predator) kills and eats individuals of the other species (the prey).

Example: A fish eagle (predator) hunts, kills and eats fish (prey).

(Source: Accessed on 29/08/2022)

2.2.3 Importance of Ecology

Ecology enriches our world and is crucial for human wellbeing and prosperity. It provides new knowledge of the interdependence between people and nature that is vital for food production, maintaining clean air and water, and sustaining biodiversity in a changing climate.

(Source: Accessed on 30/08/2022)

• Conservation of Environment
Ecology helps us to understand how human actions affect the environment, in both negative and positive ways. It helps conservation managers to understand the extent of damage that has been caused to the environment and develop management plans and activities to restore and manage the environment in a sustainable way.

A lack of understanding of ecology has led to the degradation of land and the environment. Human development and activities, such as hunting for example, have led to some species becoming endangered or even extinct. A proper understanding of ecology allows land managers from farmers and conservationists, as well as law-makers in government, to make decisions that lead to a healthy and thriving ecosystem and natural environment in the areas they are responsible for.

• Resource Allocation
With the knowledge of ecology, we are able to know what resources are necessary for the survival of different organisms and ecosystems. The proper management of natural areas, whether on private land or public nature reserves and open spaces, requires resources that cost money including employment of staff, development and management of infrastructure, management of the ecosystem such as burning and invasive alien plant eradication to name just a few examples.

• Eco-Friendliness
An understanding of ecology enables and encourages people to live in harmony and balance with nature by helping them to adopt a lifestyle that protects natural ecosystems and life. For example, by recycling in our homes, we can reduce the amount of materials that need to be mined for producing the goods we use and therefore more areas can be conserved.

Figure 2.11 – An understanding of ecology can help us manage natural resources in a sustainable manner.


• Biodiversity supports food security and sustained livelihoods through overall genetic diversity.
• Genes regulate all biological processes on the planet and increase the ability of organisms to cope with environmental stressors.
• Preserving genetic diversity ensures the continuing existence of a wide-range of crops that may be able to withstand disease, and potentially useful biochemicals such as those used in healthcare. It also means availability of species for pollination and pest control.
• Losses in genetic diversity will decrease an organisms’ coping ability and risk losing potentially beneficial biological information.
• Biodiversity has greatly contributed to modern medicine and advancements in human health research and treatment.
• Many modern pharmaceuticals are derived from plant species, including the anti-tumour agent Taxol from the Pacific yew tree, the anti-malarial artemisinin from sweet wormwood (Artemesia sp.), and the cardiac drug digoxin from the digitalis plant.
• Pharmaceuticals can also be derived from non-plant species, such as the drug ziconotide, which has been highly effective in relieving nerve pain and severe pain in cancer patients and is derived from the venom of predatory cone snails.
• Without the species that provide these drugs, it is possible that treatments for ailments like malaria, tuberculosis, cancerous tumours, congestive heart failure and multiple other illnesses may never have been discovered.
• As conversion of habitats and subsequent losses in diversity take place, the potential for losing cures for some of the world’s most troubling ailments increases.
• In addition to the many medicinal benefits from biodiversity, human health can be positively affected simply by spending time in outdoor environments, which has been linked to increases in life satisfaction and happiness, and decreases in blood pressure, anxiety, and cardiovascular disease symptoms.
• Conserving biodiversity and protecting a wide range of habitats maintains the many benefits that this diversity provides for all species. Highly diverse environments, such as National Parks, are prime ecosystems that support many species in addition to being aesthetically beautiful, educational, and interesting recreation sites.
• Biodiversity conservation efforts are essential in maintaining functioning ecosystems, a steady food supply, and the multiple other benefits including aesthetics, recreation, and spiritual purposes to Indigenous People.

(Source: Accessed on 30/08/2022)

Figure 2.12 – Plants have been used in pharmaceuticals for hundreds, if not thousands, of years and are part of the benefits that genetic diversity, a component of biodiversity, bring to humans.

2.2.4 Resilience in Ecosystems

Ecological resilience, also called ecological robustness, is the ability of an ecosystem to maintain its normal patterns of nutrient cycling and biomass production after being subjected to damage caused by an ecological disturbance. The term resilience is a term that is sometimes used interchangeably with robustness to describe the ability of a system to continue functioning amid and recover from a disturbance.

The resilience or robustness of ecological systems has been an important concept in ecology and natural history since the time of British naturalist Charles Darwin, who described the interdependencies between species as an “entangled bank” in his influential work On the Origin of Species (1859). Since then, the concept has come to hold special importance in the areas of environmental conservation and management. Its significance to the wellbeing of humans and human societies has also been recognized. The loss of an ecosystem’s ability to recover from a disturbance—whether due to natural events such as hurricanes or volcanic eruptions or due to human influences such as overfishing and pollution— endangers the benefits (e.g., food, clean water, and aesthetics) that humans derive from that ecosystem.

However, resilience is not always a positive feature of a system. For example, an ecosystem may be locked in an undesirable state, such as in the case of a eutrophic lake, where an overabundance of nutrients results in hypoxia (depleted oxygen levels), which can lead to the demise of desirable fish species and the proliferation of undesirable pests.

In 1955 Canadian-born American ecologist Robert MacArthur proposed a measure of community stability that was related to the complexity of an ecosystem’s food web. He stated that ecosystem stability increased as the number of interactions (complexity) between the different species within the ecosystem also increased. His collaborator, Australian theoretical physicist Robert May, later showed that communities of species that were more diverse and more complex were actually less able to maintain an exact stable numerical balance among species.

This seemingly counterintuitive idea occurs because resilience or robustness at the level of the ecosystem is actually enhanced by a lack of rigidity at the level of its individual components (i.e., the populations or species within the ecosystem). This elasticity means that ecosystem properties, such as changes in nutrient flow or the number of species, are more resilient due to changes in species composition. For example, the disappearance of the American chestnut (Castanea dentata) in many forests in eastern North America due to chestnut blight has been largely compensated for by the expansion of oak (Quercus) and hickory (Carya) species, although there are certainly commercial consequences of this replacement.

In 1973 Canadian ecologist C.S. Holling wrote a paper that focused on the dichotomy between a type of resilience inherent in an engineered device (that is, the stability that comes from a machine designed to operate within a narrow range of expected circumstances) and the resilience that emphasizes an ecosystem’s persistence as a particular ecosystem type (e.g., a forest as opposed to grassland), the latter being affected by substantially more factors than the former. Holling recognized the importance of the qualities that allowed a forest to persist as a functioning forest rather than its ability to harbour particular species at fixed levels or to maintain an arbitrary level of primary production. Holling’s seminal paper brought heightened attention to the resilience of ecological systems and influenced other disciplines, such as economics and sociology. It has resonated in particular with the perspectives of individuals such as American biophysicist and geographer Jared Diamond, who is known for his examination of the conditions under which human societies developed, thrived, and collapsed.

Resilience and the development of management tools

Ecological resilience or robustness has also become central to conservation practices and ecosystem management, particularly as the latter has shifted its attention to the importance of ecosystem services. Such services include the provision of food, fuel, and natural products (e.g., substances for pharmaceutical development); the mediation of climate; the removal of toxic materials from environmental reservoirs; and the aesthetic enjoyment that humans derive from the natural world. Although many species retain importance within the framework of ecosystem services, much of the focus of conservation has moved from individual species to the maintenance of the ecosystem as a whole, especially its ability to retain its structure and rate of productivity.

Many lakes, for example, are managed to remain oligotrophic (relatively nutrient poor), with ample oxygen to support species such as lake trout, rather than managed to retain excess nutrients and algae. In addition, many terrestrial dryland ecosystems are managed to keep a richly vegetated area from undergoing desertification. Ecologists continue to look for ways to manage forests, such as those in Africa, to resist the transformation into a savanna through periods of extended drought or frequent wildfire episodes. Furthermore, in the ocean, where individual fish species have long been the subject of regulation, there is growing recognition of the need to expand efforts to manage large areas as integrated ecosystems.

Predicting the onset of disturbances such as eutrophication, desertification, and the collapse of fisheries has become an important component of ecosystem management. A greater emphasis on the identification of early-warning indicators, such as statistical fluctuations or correlations, has emerged. In particular, the ideas and techniques are being applied to medicine (such as in the onset of migraines or cardiac problems), research into climate change, and the operation of financial systems and markets. These indicators might serve as aids to management, much the same way that the detection of swarms of small earthquakes near a fault or an active volcano may portend the arrival of a larger seismic or eruptive event in the near future.

Equally important is the identification of the system’s structural features that might impede the risk of systemic collapse or endow a system with the ability to recover from a disturbance. In ecological systems, ecologists might consider the diversity and heterogeneity among individual components (such as whole species, populations, or individual organisms) and landscape features within an ecosystem. Forest managers, for example, try to prevent the spread of wildfires throughout a forest by building firebreaks that follow changes in the landscape, such as those that separate one patch of trees from another. In addition, redundancy (niche overlap between species) and modularity (the interconnectedness of a system’s components) are considered to be important factors that determine an ecosystem’s resilience.

(Source: Accessed on 30/08/2022)

2.2.5 Indigenous Principles of Conservation

Humans and human culture and society have evolved over millions of years to become what we know as the modern world today. Due to globalisation (the easy flow of information, finance and movement of people all over the planet), a global culture and way of life has emerged over the past 100 years or more. If we go back a few hundred years, humans were more isolated and lived in separate tribes or civilisations that had much less interaction with each other than is possible today. Each tribe or civilisation developed unique cultures that were deeply embedded in and influenced by the natural environment that they evolved in.

Only in recent times has the human population and the development of technology, science and commerce led to the huge environmental impacts that humans are having on the planet. Although certain civilisations did impact negatively on the natural environment even thousands of years ago, which often led to the collapse of those civilisations, the large and global scale of environmental degradation today is unique. The field of nature conservation emerged as a response to these negative impacts that human society and the economy were having on the natural world. This started when people began to realise that the destruction of the natural environment was mostly caused by human activities through the extraction of natural resources for production and manufacturing and the production of waste and pollution that led to destruction or harm to natural ecosystems. The scale of human impact on the environment increased greatly with the start of the industrial revolution in Europe about 300 years ago that gradually spread all over the globe.

Natural scientists, conservationists and environmentalists have drawn on the sciences to better understand how natural ecosystems work (for example the science of ecology) and come up with better ways to manage natural resources and ecosystems so that a better balance between human society/economy and the natural environment can be found. At the same time, many have also looked at human behaviour and culture (the social sciences) to better understand how human society needs to change or adapt to become more environmentally sustainable or in balance with the natural world that human civilisation depends on.

The role of Indigenous Knowledge Systems (IKS) in nature conservation and sustainable development has become more widely recognised in recent decades as natural scientists have come to understand that native people throughout the world have developed knowledge and practices (cultural heritage) that is closely linked to the natural environment in which they evolved and are situated in. Much of this knowledge and cultural practice has developed as a way of keeping a balance between these societies and the natural world that they depend on. One can understand this as an evolutionary pressure that applies at the level of a society in the sense that knowledge and practices that are sustainable and do not harm the natural environment are more likely to survive and be passed on to future generations than knowledge and practices that harm or destroy the natural ecosystems in which these societies live.

Effective conservation management must be informed by robust information on the status of species and their habitats of concern. In relation to human interactions, this is generally derived from research-led scientific studies. Increasingly, however, it is recognised that indigenous communities around the world possess an extremely rich body of knowledge about local environmental resources and biodiversity, developed through interactions with the non-human environment around them. Indigenous knowledge has the potential to be an invaluable tool to aid conservation around the world – helping to monitor key components of biodiversity, support sustainable use of environmental resources and enforce conservation management through indigenous value systems. Although there is huge scope to integrate indigenous knowledge into conservation management, nonscientific knowledge systems are becoming progressively eroded worldwide and the information cannot always be easily interpreted, creating barriers for use in many social-ecological conservation systems.

(Source: Accessed on 31/08/2022)

Figure 2.13 – Indigenous communities with their knowledge and cultures have a lot to offer to nature conservation in developing sustainble land management practices.



2.2.6 Climate Change

Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, such as through variations in the solar cycle. But since the 1800s, human activities have been the main driver of climate change, primarily due to burning fossil fuels like coal, oil and gas.

Burning fossil fuels generates greenhouse gas emissions that act like a blanket wrapped around the Earth, trapping the sun’s heat and raising temperatures.

Examples of greenhouse gas emissions that are causing climate change include carbon dioxide and methane. These come from using petrol for driving a car or coal for heating a building, for example. Clearing land and forests can also release carbon dioxide. Landfills for garbage are a major source of methane emissions. Energy, industry, transport, buildings, agriculture and land use are among the main emitters.

Greenhouse gas concentrations are at their highest levels in 2 million years and emissions continue to rise. As a result, the Earth is now about 1.1°C warmer than it was in the late 1800s. The last decade (2011-2020) was the warmest on record.

Many people think climate change mainly means warmer temperatures. But temperature rise is only the beginning of the story. Because the Earth is a system, where everything is connected, changes in one area can influence changes in all others.

The consequences of climate change now include, among others, intense droughts, water scarcity, severe fires, rising sea levels, flooding, melting polar ice, catastrophic storms and declining biodiversity.

People are experiencing climate change in diverse ways. Climate change can affect our health, ability to grow food, housing, safety and work. Some of us are already more vulnerable to climate impacts, such as people living in small island nations and other developing countries. Conditions like sea-level rise and saltwater intrusion have advanced to the point where whole communities have had to relocate, and protracted droughts are putting people at risk of famine. In the future, the number of “climate refugees” is expected to rise.

Every increase in global warming matters. In a series of UN reports, thousands of scientists and government reviewers agreed that limiting global temperature rise to no more than 1.5°C would help us avoid the worst climate impacts and maintain a livable climate. Yet based on current national climate plans, global warming is projected to reach around 3.2°C by the end of the century.

The emissions that cause climate change come from every part of the world and affect everyone, but some countries produce much more than others. The 100 least-emitting countries generate 3 per cent of total emissions. The 10 countries with the largest emissions contribute 68 per cent. Everyone must take climate action, but people and countries creating more of the problem have a greater responsibility to act first.

Figure 2.14 – Climate change is one of the biggest threats facing humanity today.

We face a huge challenge but already know many solutions. Many climate change solutions can deliver economic benefits while improving our lives and protecting the environment. We also have global frameworks and agreements to guide progress, such as the Sustainable Development Goals, the UN Framework Convention on Climate Change and the Paris Agreement. Three broad categories of action are: cutting emissions, adapting to climate impacts and financing required adjustments.

Switching energy systems from fossil fuels to renewables like solar or wind will reduce the emissions driving climate change. But we have to start right now. While a growing coalition of countries is committing to net zero emissions by 2050, about half of emissions cuts must be in place by 2030 to keep warming below 1.5°C. Fossil fuel production must decline by roughly 6 per cent per year between
2020 and 2030.

Adapting to climate consequences protects people, homes, businesses, livelihoods, infrastructure and natural ecosystems. It covers current impacts and those likely in the future. Adaptation will be required everywhere, but must be prioritized now for the most vulnerable people with the fewest resources to cope with climate hazards. The rate of return can be high. Early warning systems for disasters, for instance, save lives and property, and can deliver benefits up to 10 times the initial cost.

We can pay the bill now, or pay dearly in the future. Climate action requires significant financial investments by governments and businesses. But climate inaction is vastly more expensive. One critical step is for industrialized countries to fulfil their commitment to provide $100 billion a year to developing countries so they can adapt and move towards greener economies.

(Source: Accessed on 31/08/2022)

The infographic on the next page is sourced from: Accessed on 31/08/2022)


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