Natural Disruptions to Ecosystems Lecture Notes

Flashcards covering key vocabulary related to natural disruptions, climate and sea level changes, and ecosystem responses from the lecture notes.

Ice Cores

Long tubes of ice extracted from very cold regions of the world that contain tiny, trapped air bubbles of ancient air.

Purpose of Ice Cores

Provide indirect estimates of past greenhouse gas concentrations and global temperatures over long periods of time (up to 500,000 years).

Oxygen-16 (16O)

A light oxygen isotope (8 protons plus 8 neutrons) found in air bubbles of ancient ice, used to determine past temperatures.

Oxygen-18 (18O)

A heavy oxygen isotope (8 protons plus 10 neutrons) found in air bubbles of ancient ice; ice formed during warmer temperatures contains a higher percentage of this isotope.

Historic Temperature Changes

Ice core data indicates temperatures have seen 10
C decreases and 4
C increases over the past 400,000 years, often linked to ice ages.

Causes of Historic Temperature Shifts

Small, regular shifts in Earth's orbit, axial tilt, and position relative to the Sun, which alter the amount of sunlight hitting high northern latitudes.

Relationship between Historic CO2 and Temperature

A complex relationship where both factors play a role; increased CO2 causes warming, and warmer oceans release CO2.

Sea Level Estimation

Indirectly determined by examining dated fossils on land that contain aquatic species, indicating past water presence and age.

Historic Sea Level Changes

Varied greatly over Earth's history; for example, dropped more than 120 m during the last Ice Age and subsequently rose approximately 130 m.

Intermediate Disturbance Hypothesis

The hypothesis that ecosystems experiencing intermediate levels of disturbance will favor a higher level of diversity of species than those with high or low disturbance levels.

Effect of Intermediate Disturbance

Such disturbances prevent dominant competitors from excluding other species, and also prevent the elimination of most species, leading to increased species diversity.

Seasonal Disruptions

Regular changes in the climate that alter habitats, often leading to responses like animal migrations.

Animal Migrations

A common response to seasonal disruptions, where animals move to new habitats in search of more abundant food supplies (e.g., wildebeests in Serengeti).