| A | B |
| succession | gradual natural change in an ecosystem |
| pioneer plants | first plants to invade a bare area |
| climax community | last stage of primary succession |
| pollution | waste products that damage an ecosystem |
| acid rain | nitric and sulfuric acid condensing into clouds and falling to Earth |
| conserving | saving resources |
| reduce | to cut down on the use of resources |
| reuse | to keep items that can be used again |
| recycle | to recover a resource from an item and use it to make a new item |
| reclamation | process of restoring a damaged ecosystem |
| wetlands | water ecosystems, such as saltwater marshes, mangrove swamps, and mud flats |