5. Simple complex questions

‘Simple complex questions’ contrasts top-down and bottom-up approaches to ecological puzzles. For example, plants evade herbivores with physical defences that render them toxic or unpalatable, and the predators then evolve their own defences. How can a tropical forest support over 1,000 different tree species in a 50-hectare plot? When trees in the same forest differ in their response to environmental changes, can we still describe their environment as a niche? In species-rich systems, is there stability in complexity? Do we need so many species? Even when answering this question, we might benefit from a less human-centred approach. Earth’s biological richness has resonance beyond the dominant species.

4. Communities

‘Communities’ begins by looking at mutualisms, collaborative interactions between species, and goes on to explore ecosystem structure and change. True mutualism is rare, and cooperative relationships easily become exploitative. Entire communities can depend on a ‘keystone’ species, the loss of which has impacts that cascade across the biological system. Succession is the sequential development of increasingly complex ecological communities. Raymond Lindeman’s great insight was to interpret complex ecosystems as flows of energy and matter between living and non-living system components. Successional processes, ecosystem structures, and energy transfers all arise from the myriad of antagonistic and mutualistic interactions among individual organisms.

3. Populations

‘Populations’ considers the factors behind animal, plant, and insect population outbreaks. Influenced by weather and food, population outbreaks fast exceed available resources and populations crash. It is difficult to determine whether predators control the prey population or vice versa. Competition is a more persuasive argument for population control, acting through density-dependent processes. Carrying capacity is the population size that can be maintained given available resources, which might well be affected by environmental factors. Ecologists define two types of species—r species which reproduce early and produce many offspring, and k species which inhabit more tranquil environments. The picture is complicated by life trade-offs between two variables, such as reproduction and growth or survival.

8. Future ecology

Ecological science is evolving. ‘Future ecology’ looks at how new technologies, from satellites to software, have increased the depth and breadth of ecological science, increased its spatial outlook, and provided new opportunities to track climate change and engage with society. The prevalence of mathematical modelling, DNA reference libraries and remotely sourced data has provided scientists with new tools but has paradoxically taken them away from the ecological fieldwork that allows them to observe the complex reactions of ecosystems. The coming decades will experience extreme disturbances, and their ability to respond is based on their resilience, itself affected by human activities that alter ecosystem composition.

6. Applied ecology

‘Applied ecology’ looks at the application of ecological theories in modelling renewable resources and population dynamics, particularly in relation to species we wish to control or preserve. The collapse of cod fisheries shows the consequences when the bottom of the food chain (changes in phytoplankton) impacts the top. Changes in climate and fire regimes in America’s forests suggests current models may no longer be sustainable in future. How do species mixes help alleviate pressure from pests or pathogens? Successes in the lab have failed in the field, or not taken into account alternative problems that arise from manipulating the ecosystem. Biological and pest control strategies require a holistic approach.

7. Ecology in culture

The science of ecology is often conflated with environmentalism. ‘Ecology in culture’ looks at the transfer of ecological insights to moral and political fields. Has ecological science enabled us to develop an ecological conscience that will help the planet withstand unprecedented environmental challenges? Transformative movements include Gaia Theory (the idea of the earth as a living, self-regulating organism); Deep Ecology (a movement that disregards a human-centred approach); Cultural Ecology (which advocates for our environment’s ability to sustain culture); and Sacred Ecology (a new perspective on how to interact with nature and the elements. To restore environmental health, should we rebuild a cultural ecology?

2. The dawn of ecology

‘The dawn of ecology’ introduces the Greek writer Theophrastus and his discovery that plants flourish in places suited to their intrinsic attributes. The word ‘ecosystem’ was coined by 20th-century botanist Andrew Tansley, who argued that organisms and their environment should be considered together. Charles Elton created the ‘pyramid of numbers’, with producers at the bottom and primary consumers at the top. Georgy Gause discovered competition among species—if two organisms in competition for the same resource were put together, one would wipe the other out. Mathematical and scientific predictive models would become useful in unstable climate conditions, allowing specialists to identify potential tipping points.

1. What is ecology?

Ecology is the process by which organisms interact with each other and their environment, with the environment as a stage and ecology as the performance. ‘What is ecology?’ explains what happens when organisms feed on and compete with others. These interactions create new patterns in nature. Ecology and evolution are interdependent. As a science, ecology is sometimes accused of ‘physics envy’. There are more precise rules in physics, whereas patterns in ecology are contingent on the past historical and geographical events that created them. In modern culture, ecology has become almost synonymous with environmentalism. However, its scientific aspects are significant to our everyday lives even without links to culture.