4.3 Succession
How do communities change over time?- Do ecosystems return to “normal” following a disturbance?
ecological succession
primary succession
pioneer species
secondary succession
Compare/Contrast Table As you read, create a table comparing primary and secondary succession.
THINK ABOUT IT In 1883, the volcanic island of Krakatau in the Indian Ocean was blown to pieces by an eruption. The tiny island that remained was completely barren. Within two years, grasses were growing. Fourteen years later, there were 49 plant species, along with lizards, birds, bats, and insects. By 1929, a forest containing 300 plant species had grown. Today, the island is blanketed by mature rain forest. How did the island ecosystem recover so quickly?
Primary and Secondary Succession
How do communities change over time?
The story of Krakatau after the eruption is an example of ecological succession—a series of more-or-less predictable changes that occur in a community over time. Ecosystems change over time, especially after disturbances, as some species die out and new species move in. Over the course of succession, the number of different species present typically increases.
FIGURE 4–12 Primary Succession Primary succession occurs on newly exposed surfaces. In Glacier Bay, Alaska, a retreating glacier exposed barren rock. Over the course of more than 100 years, a series of changes has led to the hemlock and spruce forest currently found in the area. Changes in this community will continue for centuries.
ddPrimary Succession Volcanic explosions like the ones that destroyed Krakatau in 1883 and blew the top off Mount Saint Helens in Washington State in 1980 can create new land or sterilize existing areas. Retreating glaciers can have the same effect, leaving only exposed bare rock behind them. Succession that begins in an area with no remnants of an older community is called primary succession. An example of primary succession is shown in Figure 4–12.
Table of Contents
- Formulas and Equations
- Applying Formulas and Equations
- Mean, Median, and Mode
- Estimation
- Using Measurements in Calculations
- Effects of Measurement Errors
- Accuracy
- Precision
- Comparing Accuracy and Precision
- Significant Figures
- Calculating With Significant Figures
- Scientific Notation
- Calculating With Scientific Notation
- Dimensional Analysis
- Applying Dimensional Analysis