COLUMNA de AZTLAN

PIEDRAS NEGRAS, Mexico Associated Press -- The first of 400,000 trees are being planted to form a "green wall" in protest of the fence the U. S. is building along the border with Mexico.

The treeline will eventually stretch for 512 kilometres along the border between the Mexican state of Coahuila and Texas.

Coahuila Gov. Humberto Moreira Valdes says "our wall is of life, and it competes with shame and hate."

The U. S. government says the fence is critical to security. Critics say it fuels animosity between the two countries and raises environmental and private property concerns.