1.
low population density areas outside the city
2.
cities fall apart as people migrate to the suburbs
3.
large expanses of undeveloped land, suitable for grazing but not farming
4.
threats include soil erosion, soil compaction, etc.
5.
land degraded so much it is unable to support vegetation
6.
one strategy to deforestation
7.
leaving some full-grown trees to create a shelter for new trees
8.
used by timber companies to grow a lot of trees very fast
9.
fire that only burn underbrush, little damage to mature trees, is beneficial
10.
used to extract substances
11.
ground sinking down into open spaces below
12.
used to remove natural gas and petroleum
13.
increase demand for water
14.
amount of water taken that can be returned quickly through water treatment
