Feedback loops: How nature gets its rhythms - Anje-Margriet Neutel

Summary

This script explores the concept of feedback in nature, comparing it to a grand orchestra. It explains how mutual causal interactions create feedback loops that govern ecosystems, with examples of both positive and negative feedback. The script highlights the complexity of these loops, emphasizing how they contribute to the balance and resilience of natural systems, and how they can be disrupted by human actions like deforestation.

Takeaways

• 🔁 Feedback loops are crucial for the natural world's functioning, involving mutual causal interactions where changes in one element affect another, creating a cycle.
• 🌿 Positive feedback loops are not always beneficial; they amplify changes, exemplified by the accumulation of humus enriching soil for plant growth.
• 📉 Negative feedback loops help maintain stability by counteracting changes, like predator-prey relationships regulating population sizes.
• 🌱 The death of plants and the creation of humus is a positive feedback loop that contributes to ecosystem buildup.
• 🪵 Removing forests can lead to a harmful positive feedback loop, causing erosion and the loss of soil nutrients.
• 🐺 The interaction between lynx and snowshoe hares is an example of a negative feedback loop, maintaining a balance in their populations.
• 🌳 Feedback processes can seem counterintuitive, as they involve complex, non-linear interactions rather than simple cause and effect.
• 🐞 The use of pesticides can trigger unexpected reactions, demonstrating how feedback loops can have indirect and interconnected effects.
• 🔗 Each link in a feedback loop is essential; adding or weakening a link can significantly alter the feedback's effect.
• 🎶 Ecosystems are not a series of isolated chains but a network of interactions, with feedback loops often indirect and occurring through longer chains.
• 🎵 The analogy of ecosystems to music illustrates how feedback loops create harmonious patterns, with negative feedback loops providing stability like a rhythm section in an orchestra.

Q & A

What is feedback in the context of the natural world?

Feedback in the natural world refers to a phenomenon called mutual causal interaction, where one element affects another, which in turn affects the first, creating an ongoing process known as a feedback loop.

How does positive feedback contribute to the buildup of ecosystems?

Positive feedback contributes to the buildup of ecosystems by amplifying a particular effect or change from previous conditions. An example is the production of humus from dead plant material, which enriches the soil and allows more plants to grow.

What is an example of a harmful positive feedback loop?

A harmful positive feedback loop is exemplified by deforestation, which makes land vulnerable to erosion, removing organic matter and nutrients from the soil, leading to less plant growth and more erosion.

How does negative feedback help maintain stability in ecosystems?

Negative feedback helps maintain stability by diminishing or counteracting changes in an ecosystem. A classic example is the predator-prey relationship, where an increase in predators leads to a decrease in prey, which then leads to a decrease in predators, allowing the prey population to recover.

Why is feedback considered counterintuitive by many people?

Feedback is considered counterintuitive because many people are accustomed to more predictable linear scenarios of cause and effect. Feedback loops involve complex, interrelated processes that can lead to unexpected outcomes.

What is a simple example of how feedback loops can have unexpected reactions?

A simple example is the use of pesticides, which may initially help plants by killing pests, but can also lead to a decrease in the pest's predators, allowing the pest population to rebound and counteract the pesticide's effects.

How do the links in a feedback loop affect the overall feedback force?

Each link in a feedback loop is crucial; adding a negative link can reverse the feedback force, a weak link can reduce the effect, and losing a link can break the loop entirely.

How do feedback loops interact within a food web?

Feedback loops in a food web often interact indirectly through longer chains. A complex food web with many populations can generate thousands of loops, each potentially having a significant impact on the ecosystem.

What is the role of negative feedback in ecological systems?

Negative feedback in ecological systems acts to keep positive feedbacks in check, maintaining a balance and preventing runaway effects that could destabilize the ecosystem.

How are ecosystems and their feedback loops compared to music?

Ecosystems and their feedback loops are compared to music through the analogy of different habitats having unique 'sounds' or patterns. Ocean environments with strong feedbacks are likened to powerful and loud music, while desert ecosystems with slow biomass turnover are compared to a constant drone.

How can ecosystems change over time, as mentioned in the script?

Ecosystems can change over time due to various factors such as deforestation, which can turn a lush tropical rainforest into a barren area, or the natural process of succession, where an abandoned farmland may revert to a forest over time.

Outlines

00:00

🔁 Understanding Feedback Loops in Nature

This paragraph introduces the concept of feedback in nature, contrasting it with the negative connotation of feedback in sound systems. Feedback is defined as mutual causal interaction, creating a feedback loop where changes are amplified or diminished. The paragraph explains positive feedback through the example of humus enriching soil, leading to more plant growth, and negative feedback through predator-prey relationships, maintaining balance in ecosystems. It also discusses how feedback processes can be counterintuitive, as they involve complex interactions rather than simple linear cause and effect.

Keywords

💡Feedback

Feedback refers to the mutual causal interaction where x affects y, and y affects x, creating a continuous loop. In the context of the video, feedback mechanisms are crucial in natural systems, helping to regulate processes such as population control, nutrient cycling, and ecosystem resilience. Examples include positive feedback like the accumulation of humus in soil or negative feedback like the predator-prey population cycles.

💡Feedback Loop

A feedback loop is an ongoing process where outputs of a system are fed back into it, influencing future outputs. In nature, feedback loops connect living and nonliving elements, allowing ecosystems to respond to changes. The video describes how dead plant material enriches the soil, which then supports more plant growth, illustrating a positive feedback loop.

💡Positive Feedback

Positive feedback amplifies changes in a system. In ecosystems, this can drive growth or degradation. The script provides an example where the death of plants creates more humus, which fosters further plant growth. However, positive feedback can also be harmful, as seen when deforestation leads to erosion, accelerating further environmental damage.

💡Negative Feedback

Negative feedback counteracts changes in a system, helping maintain balance. In predator-prey relationships, for instance, a decrease in prey causes a subsequent decrease in predators, which allows the prey population to recover. This cyclical process stabilizes population sizes over time, forming a self-regulating system.

💡Ecosystem

An ecosystem is a community of living organisms interacting with their physical environment. The video emphasizes how feedback mechanisms within ecosystems contribute to their stability and evolution. For example, ecosystems like tropical rainforests and deserts have distinct feedback processes that shape their characteristics.

💡Humus

Humus is a stable, organic component of soil formed from decomposed plant material. In the video, humus is central to the process of positive feedback, as it provides essential nutrients and moisture for plant growth. The more plants grow and die, the more humus accumulates, promoting further growth.

💡Predator-Prey Cycle

The predator-prey cycle is a natural feedback process where the population of predators and their prey rise and fall in response to each other. The script highlights the interaction between lynx and snowshoe hares as an example of negative feedback, where changes in prey populations directly affect predator numbers and vice versa.

💡Erosion

Erosion is the process by which soil and rock are removed from the Earth's surface, often accelerated by environmental disturbances like deforestation. In the video, erosion is given as an example of harmful positive feedback, where the removal of plants leads to soil degradation, further reducing the land's ability to support vegetation.

💡Food Web

A food web is a complex network of interconnected food chains within an ecosystem. The video explains how food webs are governed by numerous feedback loops, with each population interacting with others in ways that create stability or drive changes in the ecosystem. A food web with twenty populations could generate thousands of feedback loops.

💡Resilience

Resilience refers to an ecosystem's ability to absorb disturbances and still maintain its functions and structure. The video discusses how feedback mechanisms, both positive and negative, contribute to the resilience of ecosystems by allowing them to adapt to changes, such as nutrient cycling or predator-prey dynamics.

Highlights

Feedback is a mutual causal interaction that creates a feedback loop.

Feedback loops are essential in governing ecosystems and populations.

Positive feedback is a force that amplifies effects or changes.

An example of positive feedback is the enrichment of soil with humus from dead plants.

Negative feedback maintains a stable balance in ecosystems.

Predator-prey relationships exemplify negative feedback loops.

Feedback processes can seem counterintuitive due to their non-linear nature.

Feedback loops can have indirect effects through longer chains in a food web.

Ecosystems are not just food chains but networks of interactions.

Feedback loops in ecological systems create harmonious patterns.

Negative feedbacks keep positive feedbacks in check, maintaining rhythm.

Ecosystems can be likened to different types of music based on their feedback loops.

Desert ecosystems have slow biomass turnover and weak feedback loops.

Tropical rainforests have high diversity and strong feedbacks among living and dead matter.

Ecosystems and their habitats change over time, affecting their harmonies.

Deforestation can drastically alter an ecosystem's dynamics.

Abandoned farmland can evolve into a forest, reflecting ecosystem development.

Transcripts

Testing, testing, one, two, three.

When your band is trying to perform, feedback is an annoying obstacle,

but in the grand orchestra of nature, feedback is not only beneficial,

it's what makes everything work.

What exactly is feedback?

The key element, whether in sound, the environment or social science,

is a phenomenon called mutual causal interaction,

where x affects y, y affects x, and so on,

creating an ongoing process called a feedback loop.

And the natural world is full of these mechanisms

formed by the links between living and nonliving things

that build resilience by governing the way populations

and food webs respond to events.

When plants die, the dead material enriches the soil with humus,

a stable mass of organic matter, providing moisture and nutrients

for other plants to grow.

The more plants grow and die, the more humus is produced,

allowing even more plants to grow, and so on.

This is an example of positive feedback,

an essential force in the buildup of ecosystems.

But it's not called positive feedback because it's beneficial.

Rather, it is positive because it amplifies a particular effect or change

from previous conditions.

These positive, or amplifying, loops can also be harmful,

like when removing a forest makes it vulnerable to erosion,

which removes organic matter and nutrients from the earth,

leaving less plants to anchor the soil, and leading to more erosion.

In contrast, negative feedback diminishes or counteracts changes in an ecosystem

to maintain a more stable balance.

Consider predators and their prey.

When lynx eat snowshoe hares, they reduce their population,

but this drop in the lynx's food source will soon cause their own population to decline,

reducing the predation rate and allowing the hare population to increase again.

The ongoing cycle creates an up and down wavelike pattern,

maintaining a long-term equilibrium and allowing a food chain to persist over time.

Feedback processes might seem counterintuitive because many of us

are used to more predictable linear scenarios of cause and effect.

For instance, it seems simple enough that

spraying pesticides would help plants grow by killing pest insects,

but it may trigger a host of other unexpected reactions.

For example, if spraying pushes down the insect population,

its predators will have less food.

As their population dips,

the reduced predation would allow the insect population to rise,

counteracting the effects of our pesticides.

Note that each feedback is the product of the links in the loop.

Add one negative link and it will reverse the feedback force entirely,

and one weak link will reduce the effect of the entire feedback considerably.

Lose a link, and the whole loop is broken.

But this is only a simple example,

since natural communities consist not of separate food chains,

but networks of interactions.

Feedback loops will often be indirect, occurring through longer chains.

A food web containing twenty populations can generate thousands of loops

of up to twenty links in length.

But instead of forming a disordered cacophany,

feedback loops in ecological systems play together,

creating regular patterns just like multiple instruments,

coming together to create a complex but harmonious piece of music.

Wide-ranging negative feedbacks keep the positive feedbacks in check,

like drums maintaining a rhythm.

You can look at the way a particular ecosystem functions within its unique habitat

as representing its trademark sound.

Ocean environments dominated by predator-prey interactions,

and strong negative and positive loops stabilized by self-damping feedback,

are powerful and loud, with many oscillations.

Desert ecosystems, where the turn over of biomass is slow,

and the weak feedbacks loops through dead matter are more like a constant drone.

And the tropical rainforest, with its great diversity of species,

high nutrient turnover, and strong feedbacks among both living and dead matter,

is like a lush panoply of sounds.

Despite their stabilizing effects,

many of these habitats and their ecosystems develop and change over time,

as do the harmonies they create.

Deforestation may turn lush tropics into a barren patch,

like a successful ensemble breaking up after losing its star performers.

But an abandoned patch of farmland may also become a forest over time,

like a garage band growing into a magnificent orchestra.