Ecology and conservation of a rare, old-growth-associated canopy lichen ina silvicultural landscape

Nephroma occultum Wetm. is a rare, epiphytic lichen associated with old-gro wth forests of northwestern North America. We describe its distribution, ab undance, and habitat within the managed landscape of a southwestern Oregon watershed Because this species is found mainly in the canopy, we used direc t canopy access (tree climbing) in combination with ground (litter) searche s for our surveys. We recommend this dual approach when confident determina tion of presence or absence of a canopy species is needed. Our surveys conf irm that N. occultum is a rare old-growth associate within the area of this study, the southernmost extension of its known range. It was both rare acr oss the landscape and uncommon in our primary study site, a 500 yr old stan d It was most often found growing close to the trunk on branches of large P seudotsuga menziesii, but its distribution was sporadic even within an old- growth stand. The scarcity of very old stands, in combination with the limi ted ability of this species to disperse within and between stands, has like ly contributed to its rarity within the watershed. Management for N. occult um should focus on populations and habitat needs rather than on individuals . Our calculations show that cutting with retention of individual trees sur rounded by small buffers could result in the eventual loss of N. occultum f rom the study area.