The effects of ambient moisture on foliose lichen growth and distribution on Pinus strobus.

Abstract

Previous field observations suggest that lichen growth is positively affected by humid conditions. From these observations, it can be hypothesized that areas closer to the lake will have greater lichen growth than areas inland (lake effect). In addition, microclimate changes in humidity would suggest that lichens would grow more on aspects facing towards the lake than away from the lake. To test these hypotheses, total growth of four species of foliose lichen (Parmelia sulcata, Pseudoparmelia caperata, Parmelia subaurifera, and Xanthoria fallax) were measured on Pinus strobus using a quadrat division system between the heights of 0.5 and 1.5 meters. Measurements were taken on three sites near Douglas Lake (Pellston, Michigan), one site on the north side of the lake, one on an east lake site, and one non-lake site. It was found that lichen growth is randomly distributed on the non-lake site, but is distributed non-randomly on each lake site. It was also found that on the lake sites, distribution favors the aspects of the trees that face the lake. Overall, these distributions suggest that lichen growth is significantly affected by the lake effect, with secondary relationships to wind factors.