Mangrove swamps,mud flats,and saltwater marshes are all types of

Untreated watse water,PCBs,and fertilizers form___________ that damages ecosystems.

The ______ of the Hudson River ecosystem has brought life back to the river,but is not yet complete.

Plants that grow during the first stage of succession are called__________

When pollutants such as nitrogen oxides and sulfur dioxide combine with water vapor and condense,________results.

Primary _____ occurs on new,barren land,such as the land exposed by a receding glacier.

If you cut down the resources you use, you ______.If you _______ items,you use them for new purposes.

Reducing,reusing,and recycling are three ways of ______ resources.

A spruce and hemlock forest is a final stage of succession ,or a _____.

When you _______, you recover a resource from an item and use the resource to make a new item.

The last stage of succession is called______

An example of a pioneer plant is the _________

The causes of acid rain do NOT include _____

The three Rs are _____

The reclamation of ecosystems does NOT include ________

What human activities damage ecosystems?

Acid rain is NOT caused by

What is a landfill?

Name three types of wetlands

What can people do to help restore ecosystems?