LWB: Lesson - Natural Disruptions to Ecosystems (Topic 2.5) 📖
⏳ Estimated Reading Time: 8 - 10 minutes
Explain how natural disruptions, both short- and long-term, impact an ecosystem.
Disruptions to Ecosystems
Natural disruptions are events that alter the structure, function, or composition of an ecosystem. Disruptions can be caused by natural factors, such as climate change, natural disasters, and invasive species, or by human factors, such as land use change, overexploitation, pollution, and urbanization. In this lesson, we will focus primarily on natural disruptions to ecosystems.
Natural disruptions can have both short- and long-term impacts on an ecosystem, depending on the type, frequency, intensity, duration, and scale of the disruption.
Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions.
Short-Term Disruptions
Short-term disruptions, such as storms, wildfires, or seasonal variations, can lead to immediate changes in ecosystem dynamics.
The short-term negative effects of a forest fire could be the destruction of habitats and a reduction in biodiversity, but the long-term positive effects, such as increasing the availability of nutrients and opportunity for regeneration often outweigh the negative effects in ecosystems adapted to periodic disruption by fire.
Short-term disruptions may also affect populations of organisms, leading to shifts in abundance and distribution. Some of the short-term impacts of natural disruptions on an ecosystem are:
- Loss of biomass, productivity, and diversity of organisms
- Change in the distribution, abundance, and behavior of organisms
- Alteration of the physical and chemical properties of the environment
- Disruption of the ecological processes and services, such as nutrient cycling, water purification, and pollination
Everglades Case Study
The Everglades of Florida cover about 18,000 square miles and are adapted to periodic flooding, which helps to recharge the aquifer, enhance water quality, sequester carbon, and provide habitats for wildlife. Many threatened or endangered species call the Everglades homes, such as the Florida panther, American crocodile, and the wood stork. The Everglades also provide many ecosystem services to humans, such as fresh water (provisioning), flood control (regulating), recreation (cultural), and tourism (cultural).
The Everglades is threatened by human activities and infrastructure, resulting in the loss of wetland area, the degradation of habitat, and the decline of wildlife populations. Natural floods, however, can cost hundreds of thousands of dollars in lost infrastructure and human life. Over time, we have altered the natural flow of water to the Everglades to reduce damage to human infrastructure by flooding.
However, we have learned that the disruption in ecosystem services provided by the Everglades has been costly in terms of water supply and flood protection. In 2000 Congress authorized the largest and most comprehensive environmental restoration plan in United States history, known as the Comprehensive Everglades Restoration Project (CERP).
The CERP seeks to balance the water-related needs of the region, such as water supply and flood protection, with the ecological needs of the natural system. By restoring the natural flow and function of the Everglades, the CERP can enhance the ecosystem services, such as water purification, carbon storage, and habitat provision, that support the human well-being and the environmental health of South Florida.
Long-Term Disruptions
Long-term disruptions can result from processes like climate change, geological events, or changes in sea level. For example, geological events like volcanic eruptions or tectonic activity can reshape landscapes, creating new features and altering soil composition.
Some of the long-term impacts of natural disruptions on an ecosystem are:
- Recovery, adaptation, or extinction of organisms
- Succession, evolution, or speciation of organisms
- Transformation, resilience, or collapse of the ecosystem
- Restoration, conservation, or enhancement of the ecosystem services
Earth system processes have different impacts on the Earth’s environment and life, depending on their scale and type. They are the natural phenomena that shape and regulate Earth’s environment, such as plate tectonics, climate, weather, and biogeochemical cycles. These processes operate on a range of scales in terms of time, meaning that they can occur at different frequencies and durations.
Some processes can cause gradual and continuous changes, such as the evolution of species and the formation of continents. Some processes can cause sudden and dramatic changes, such as the extinction of species and the alteration of climate. Some processes can cause both types of changes, depending on the context and perspective. In general, periodic processes can be forecasted with high accuracy, episodic processes are modeled with some uncertainty, and random processes are just that, random, with little to no predictability.
Explore the tabs below to learn about two long-term disruptions: climate change and sea level change. Which do you think would have the most wide-ranging consequences?
Climate Change
Earth’s climate has changed over geological time, which is the span of millions or billions of years, for many reasons. Explore the cards below to learn more about how natural events can change the Earth's climate:
Rising global temperatures can be a positive feedback loop that accelerates climate change.
Earth’s climate is not static, but dynamic and variable. It has experienced many cycles of warming and cooling, as well as periods of stability and instability, over geological time. These changes have affected the environment and life on Earth, and have left traces in the geological record, such as fossils, ice cores, and tree rings, that can be used to reconstruct past climate.
If you just look at JUST the last 65 million years, it looks like Earth's temperature has continually DECREASED:
A graph of how global temperatures have changed over the last 65 million years.
However, if you look at a longer time scale, 500 million years, you can see the cyclical nature of Earth's temperatures:
Earth system processes operate on a range of scales in terms of time. Processes can be periodic, episodic, or random.
Earth's climate has changed over geological time for many reasons.
Sea levels have varied significantly as a result of changes in the amount of glacial ice on Earth over geological time.
Results of Disruptions
Ecosystems exhibit varying levels of resilience, or the ability to recover and adapt to disturbances. Some species may be more resilient to certain disruptions, while others may struggle to cope. If you remember our lesson on biodiversity, the higher the species richness and evenness of an area, the more resilient an ecosystem is to disruptions.
Disruptions can redefine interactions among species, and the overall biodiversity of an ecosystem can be affected. Human activities can exacerbate or mitigate the impacts of natural disruptions.
Migration is the movement of animals from one location to another, usually in response to changes in the environment or the availability of resources. Migration can be short-term or long-term, depending on the duration and distance of the movement.
Short-term migration is usually seasonal, such as salmon swimming upstream to spawn.
Long-term migration is usually permanent, such as whales moving to different oceans or humans colonizing new lands.
Migration can be influenced by a variety of factors, including natural disruptions. These events can affect the habitat, food, water, or predators of wildlife, and cause them to migrate to find more suitable conditions. For example, some animals may migrate to escape a wildfire or a drought, while others may migrate to take advantage of the new resources or opportunities created by the disturbance. Wildlife migration is an important ecological process that affects biodiversity, population dynamics, and ecosystem functioning.
Major environmental change or upheaval commonly results in large swathes of habitat changes.
Wildlife engages in both short- and long-term migration for a variety of reasons, including natural disruptions.
[CC BY-NC-SA 4.0 Links to an external site.] UNLESS OTHERWISE NOTED | IMAGES: LICENSED AND USED ACCORDING TO TERMS OF SUBSCRIPTION - INTENDED ONLY FOR USE WITHIN LESSON.