Effects of different disturbance ways on the diversity of pine forest invaded by pine wood nematode (Bursaphelenchus xylophilus) Seasonal responses of soil respiration to simulated nitrogen deposition in a citrus plantation and masson pine forest in Mt. Jinyun, Chongqing, China Effect of limestone and magnesite applications on masson pine(Pinus massoniana) forest growing on acidified soil The litter-fall characteristics and their response to drought stress in the Masson pins forests damaged by acid rain at Chongqing, China