Although the restriction of Cladonia / Cladina lichen species to gaps in the forest canopy has been widely taken to represent their "photophilous" character, earlier research at UMBS (1977-1984) found that (a) abundance and growth rates were greater at the edges (and particularly the more shaded southern edges) of openings, (b) dessication is a limiting factor for species with higher SA/V ratios, with throughfall and nightime longwave emmitance attending dew condensation being important mitigating factors, and (c) for all species, longterm transplant experiments demonstrated that leaffall and not light is actually the determinative factor restricting distribution to gaps and edges. Two permanent transects were established across from the station on the south side of Riggsville Road. For the last three decades, canopy closure, longwave & PAR; dew, throughfall, ground & air temperatures; and distribution, abundance, and growth rates of Cladonia / Cladina in 2m**2 quadrats have been assessed every five years. 2019 will culminate this project with 40 years of data.