About: http://webisa.webdatacommons.org/149376196

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	In fact, the crucial factor is a decline in the biological productivity of the land???the amount of vegetation that grows (either naturally or that people have planted)???as well as the animal life supported by the plants.
http://www.w3.org/ns/prov#wasQuotedFrom	usgs.gov