Brazil will undertake the massive task of cataloging the trees of the Amazon, in an effort to better monitor and protect the world's largest tropical forest, the environment ministry announced Friday.

The planned tree census, set to take four years, "will allow us to have a broad panorama of the quality and the conditions in the forest cover," the ministry said in a statement.

The head of the national forest service said that the survey will provide a detailed knowledge of the rainforest, which has been under environmental threat from logging and climate change.

"We are going to come to know the rainforest from within," said Forestry Minister Antonio Carlos Hummel.

The last such exhaustive survey of the rainforest was undertaken in 1970.

Scientists say that the Amazon rainforest -- sometimes referred to as the lungs of the planet because of all the oxygen created by the plant life there -- has been shrinking at an alarming rate.

The government made a commitment in 2009 to reduce deforestation in the Amazon by 80 percent by 2020.