Journal Article Research Support, Non-U.S. Gov't 27YLU75U4W Congress N762921K75 Nitrogen Phosphorus arbuscular mycorrhizal fungal succession arbuscular mycorrhizal fungi climate change ecosystem progression ecosystem retrogression long-term chronosequence nitrogen nutrient leaching phosphorus pyrosequencing rainfall regimes soil nutrient gradients terminal restriction fragment length polymorphism (T-RFLP)