Habitat preferences of an arboreal forage lichen in a Sierra Nevada old-growth mixed-conifer forest

Abstract

The arboreal forage lichen Bryoria fremontii (Tuck.) Brodo & D.Hawksw. appears sensitive to conditions of prolonged hydration in wet forests of British Columbia. I estimated the abundance of this lichen in mixed-conifer forest canopy in the contrasting Mediterranean climate of the southern Sierra Nevada in relationship to the vertical gradient of vapor pressure deficit. Abundance was estimated by biomass in 5 m strata from the ground to the tops of 50 trees. Transplants of Bryoria thalli were installed in 18 fir trees for 1 year to assess their growth relative to distance from perennial streams. VPD generally increased with height, being significantly greater at 45 m than 5 m. Bryoria biomass averaged across tree heights was estimated as 15.9, 0.60, 0.15, 0.25, and 0.19 gÁm -1 in red fir (Abies magnifica A.Murray), white fir (Abies concolor (Gordon & Glend.) Hildebr. var. lowiana (Gordon) Lemmon), incense cedar (Calocedrus decurrens (Torr.) Florin), Jeffrey pine (Pinus jeffreyi Balf.), and sugar pine (Pinus lambertiana Douglas), respectively. Transplant growth was significantly greater in trees <25 m from water (11.4%) than in trees >25 m from water (9.7%). Bryoria had strong positive associations with red fir, proximity to streams, and decreasing VPD. The sensitivity of Bryoria to prolonged hydration does not appear to be important in this climate characterized by extended summer dryness.Résumé : Le lichen arboricole qui sert de nourriture, Bryoria fremontii (Tuck.) Brodo & D.Hawksw., semble sensible aux conditions d'hydratation prolongée dans les forêts humides de la Colombie-Britannique. J'ai estimé l'abondance de ce lichen dans le couvert de forêts mixtes de conifères sous le climat méditerranéen très différent de la partie sud de la Sierra Nevada en relation avec le gradient du déficit de saturation (DS). L'abondance a été estimée par la biomasse dans des strates de 5 m allant du sol jusqu'au sommet de 50 arbres. Des thalles de Bryoria ont été repiqués sur 18 tiges de sapin pendant un an pour évaluer leur croissance relative en fonction de la distance d'un cours d'eau permanent. Le DS augmentait généralement avec la hauteur; il était significativement plus élevé à 45 qu'à 5 m. En moyenne sur l'ensemble de la hauteur des arbres, la biomasse de Bryoria atteignait respectivement 15,9, 0,60, 0,15, 0,25 et 0,19 gÁm -1 chez le sapin rouge (Abies magnifica A.Murray), le sapin concolore (Abies concolor (Gordon & Glend.) Hildebr. var. lowiana (Gordon) Lemmon), le calocèdre à encens (Calocedrus decurrens (Torr.) Florin), le pin de Jeffrey (Pinus jeffreyi Balf.) et le pin à sucre (Pinus lambertiana Douglas). La croissance des thalles repiqués était significativement plus élevée chez les arbres situés à moins de 25 m de l'eau (11,4 %) que chez les arbres situés à plus de 25 m de l'eau (9,7 %). Bryoria était étroitement et positivement associé au sapin rouge, à la proximité des cours d'eau et à la diminution du DS. La sensibilité de Bryoria à une hydratation prolongée ne semble pas importante sous ce climat caractérisé p...

Influence of fuel-reduction forest thinning on growth of an arboreal forage lichen

“…It was the only prominent forage lichen found in a survey of Yosemite, Sequoia and Kings Canyon National Parks and Devils Postpile National Monument . It is found pendant on twigs and foliage sprays of mainly coniferous trees, and at our site it is strongly associated with red fir (Abies magnifica) (Rambo, 2010). Red fir here inhabit a climatic zone that receives greater 0378-1127/$ -see front matter Ó 2011 Elsevier B.V. All rights reserved.…”

“…It was nearly adjacent to Teakettle O-thin plots on two sides and more upland Jeffrey pine-dominated forest on a third side, which was much less favorable habitat for both Bryoria and flying squirrels. Flying squirrels (Myer et al, 2005) and Bryoria (Rambo, 2010) were most strongly associated with red fir in the mixedconifer composition of the Teakettle Forest. The lack of critical winter forage that Bryoria provided could have caused a decline in the resident flying squirrel population between the first and second post-thin years, which would account for the slight rebound in Bryoria growth that second year.…”

“…2) to make 72 sample strings. Four strings were installed in each fir by spanning their lines between live branches at midcrown height (mean = 32.4 m) where Bryoria abundance was at its peak (Rambo, 2010). This positioning approximated the openness and ventilation to which naturally occurring Bryoria thalli were exposed.…”

“…In the summer Mediterranean climate of the Sierra Nevada Bryoria thalli are nearly always air-dried and physiologically dormant. Most Bryoria growth likely occurs during the fall to spring period of hydration (Rambo, 2010). Repeated measures ANOVAs were used to compare VPDs between SW and NE aspects within crowns.…”

“…One such epiphyte in the Sierra Nevada is Bryoria fremontii, which is directly ecologically linked as forage for the northern flying squirrel (Glaucomys sabrinus) and indirectly with three Forest Service Designated Sensitive Species (USDA, 1993), the California spotted owl (Strix occidentalis occidentalis), pine marten (Martes americana), and American fisher (Martes pennanti) (Rambo, 2010). B. fremontii was described as being fairly common and locally abundant on the western slopes of the Sierra Nevada from Tulare County north to Modoc County (Hale and Cole, 1988) and common in Calaveras Big Trees State Park (Pinelli and Jordan, 1978).…”