EFFECT OF PRESCRIBED BURNING ON THE ECTOMYCORRHIZAL INFECTIVITY OF A FOREST SOIL

Ectomycorrhizae formation, seedling health index, and seedling surviva l were assessed for two-year-old nursery-grown seedlings of Pinus resi nosa and Pinus strobus two months after planting in clear-cuts that ha d received prescribed burning under different fire intensities. Contro ls consisted of seedlings planted in unburned clear-cuts. Fire intensi ty positively correlated with percent ectomycorrhizal roots for P. str obus but not for P. resinosa. Seedling health index and survival were highest in burned-over sites as compared to control sites for both pin e species. Fire intensity correlated with seedling health index for P. strobus but not for P. resinosa. Fire intensity correlated with seedl ing survival for both species. Colonization of seedlings by ectomycorr hizal fungi did not correlate with seedling health index or seedling s urvival. P. resinosa seedlings planted in burned-over sites had a smal ler number of lateral roots per unit length primary/secondary roots co mpared to seedlings planted in control plots.