Why are evergreen soils ph levels acidic? And how does it happen?

I am a student at Olds College and I am wondering why evergreen soils are acidic in regards to ph levels.

 

Preface: I'm not a soil scientist.

Soils associated with evergreens maintain their acidity via:

• the decay of fallen needles releasing organic acids
• the prevention or hindering of neutralizing microbial activities
• the leaching of minerals due to a combination of heavy rainfall and shallow soil profiles

Reference web site: Spodosols via the University of Florida

How does it happen in the first place?

I'll have to refer you to:

Soil Acidification - The Cause via Australia's The Regional Network, "an independent, non-profit publisher of educational and research information. It works to raise community awareness of science."

 

As a different thought, are the soils of predominantly evergreen (I assume conifers) acid before the plant arrived and if they weren't, have the plants changed the soil condition or have the cultural practices? Bit of a chicken and the egg situation.