Research Progress on the Degradation Mechanism of Wood-rot Fungi with Spectral Analysis Methods STUDY ON THE WOOD DEGRADING ABILITY OF 64 WOOD-ROTTING FUNGI IN THE NORTHEAST FORESTRY RESERVES OF CHINA Screening of Wood-rotting Fungi to Treat Stumps of Dead Pine Trees Caused by PWN(Bursaphelenchus xylophilus) Wood-decaying Fungi on Poplars in Northeastern China Determination of Lignolytic Activity in Wood-rot Fungi by Ultraviolet Spectra photometry