Association of the arboreal forage lichenBryoria fremontiiwithAbies magnificain the Sierra Nevada, California

A strong positive association exists between Bryoria fremontii (Tuck.) Brodo & D. Hawksw. and red fir ( Abies magnifica A. Murray) in mixed-conifer forest of the south-central Sierra Nevada in California. The hypotheses that red fir microclimate, foliar leachate pH, mineral nutrients, and needle morphology may be especially favorable for B. fremontii were investigated in this study. There were no statistically significant differences in fall–winter–spring period within-crown vapor pressure deficits among five conifer species. In spring leachate solutions, NH4+and K+were significant indicators of red fir, which had generally greater ion concentrations than other species. Sugar pine ( Pinus lambertiana Douglas) leachate had the lowest pH. Mineral nutrient concentrations and acidity increased across species in fall samples. Growth and establishment of B. fremontii transplants were compared among the five conifer species. Grand mean annual transplant relative growth across conifer species was 6.28% with no statistically significant differences among species. Thallus retention in an establishment experiment was significantly greater in red fir than in shaded white fir ( Abies concolor (Gordon & Glend.) Hildebr. var. lowiana (Gordon) Lemmon) or the other three investigated conifers. The most important factor explaining the association of B. fremontii with red fir was the latter’s erect needle morphology.