1.   Arthritis is particularly common among big animals such as elephants and rhinos who compact the soil in their exhibits until it is like concrete.

2.   A steady march of hikers compacts the soil and damages the roots of plants, especially vulnerable due to the soft wet soil, say park rangers.

3.   Build barriers around trees near a construction site to prevent parking or dumping of materials beneath those trees, practices that compact the soil.

4.   Disturbance from logging compacts soil and scrapes away natural sources of recovery, he said, among them the seeds of pine grass, huckleberry and beargrass.

5.   First a snow fence was erected to prevent the thousands of people using the park on any given day from further compacting the soil.

6.   Girdling can also occur when a root reaches clay or compacted soil at the edge of its hole and turns.

7.   If they are cut during the sidewalk work, or if heavy machinery compacts the soil above them, they can be easily damaged and may even die.

8.   Is the soil compacted?

9.   Just by walking around, park visitors compact soil, making it less absorbent.

10.   Street trees in urban and suburban areas where traffic compacts the soil and concrete raises the temperature often die young.