APES Notes 2.5 - Natural Disruptions to Ecosystems

Summary

In this lesson, Mr. Smeeds explains how natural disturbances, like hurricanes and asteroid impacts, affect ecosystems both in the short and long term. The video covers periodic, episodic, and random events, as well as natural climate changes such as variations in Earth's orbit, sea level rise, and their effects on habitats. The lesson emphasizes how environmental changes, both natural and human-driven, influence species migration, plant growth, and ecological patterns. The video concludes with an exercise on interpreting data trends related to climate effects on plant life cycles.

Takeaways

• 🌪️ Natural disturbances are events that disrupt ecosystem structures and functions, impacting energy and matter cycles.
• 🌋 Examples of natural disturbances include tornadoes, hurricanes, fires, and asteroid impacts, such as the one that caused the extinction of the dinosaurs.
• 📆 Natural disturbances can occur in three time scales: periodic (predictable), episodic (semi-predictable), and random (unpredictable).
• 🌦️ Periodic disturbances, like seasonal changes, follow a regular pattern, while episodic ones, like hurricanes, are less regular but somewhat expected.
• 🌍 Earth’s climate has varied naturally over time due to factors like shifts in Earth's orbit and tilt, which can lead to ice ages and warming periods.
• 📈 Carbon dioxide levels have naturally fluctuated, impacting climate over thousands of years, but current human-driven increases are unprecedented.
• 🌊 Sea level rise occurs naturally due to warming periods and ice melt, impacting coastal ecosystems by altering water salinity and flooding habitats.
• 🐦 Environmental changes, like climate change, can alter species' migration patterns, such as birds changing breeding times to match food availability.
• 🦢 Organisms may migrate due to changes in temperature, rainfall, or habitat conditions, with examples including wildebeest and ocean species.
• 📊 Data trends, like changes in the 'first leaf date' of plants, can reveal relationships between latitude and climate effects on ecosystems.

Q & A

What is a natural disturbance in an ecosystem?

A natural disturbance is an event that disrupts the structure or function of an ecosystem. It interrupts the cycling of energy and matter, displaces organisms, and can reshape or destroy ecosystems. Examples include tornadoes, hurricanes, fires, and asteroid impacts.

How do natural disturbances compare to human disturbances in ecosystems?

Natural disturbances can be even greater and more destructive than human-caused disturbances. For example, the asteroid that wiped out the dinosaurs was a natural disturbance far more impactful than most human activities such as farming or clear-cutting.

What are the three time scales for natural disturbances?

Natural disturbances can occur on three different time scales: periodic (occurring with regular frequency, like rainy and dry seasons), episodic (occurring somewhat frequently but not predictably, like hurricanes and fires), and random (events with no predictable timing, like earthquakes or asteroid strikes).

How does Earth's orbit and tilt influence natural climate change?

Slight changes in Earth's orbit and tilt cause natural variations in the climate, including periods of ice ages and warmer periods. These changes, occurring over thousands to hundreds of thousands of years, affect temperature and carbon dioxide levels in the atmosphere.

How do carbon dioxide levels and temperature interact over geologic time?

Carbon dioxide levels and temperature have fluctuated over geologic time. Warmer periods often coincide with increased CO2 levels, which can cause polar ice caps to melt, contributing to sea level rise. This also leads to a positive feedback loop where warmer oceans release more CO2, further increasing temperatures.

What impact does sea level rise have on coastal ecosystems?

Sea level rise floods coastal estuaries, altering their structure and function. It changes the salinity, depth, and availability of land for species that rely on the habitat, leading to the loss of estuaries and forcing species to either migrate or face extinction.

How do aquatic plants adapt to sea level rise?

As sea levels rise, aquatic plants that once thrived in shallow waters receive less sunlight due to increased water depth. This can lead to a decline in species that are unable to survive with reduced sunlight or adapt to deeper waters.

What role does migration play in response to environmental change?

Species may migrate in response to natural disturbances or climate change. For instance, wildebeest follow rainfall patterns, ocean species shift northward as waters warm, and birds adjust their migration and breeding patterns to align with earlier insect hatching due to climate change.

How has climate change affected bird migration and breeding patterns?

Climate change has caused insects, such as caterpillars, to hatch earlier in the spring. Birds have had to adjust their migratory and breeding patterns to ensure their peak food demand for hatchlings coincides with the availability of these insects.

What is the relationship between latitude and the change in first leaf date for the honeysuckle plant?

The map of the U.S. shows a relationship between latitude and the change in first leaf date for honeysuckle plants, with earlier dates occurring in southern regions and later dates in northern regions. This reflects climate change’s varying impacts on plant growth depending on the location's proximity to the equator.