Arboreal forage lichens in partial cuts – a synthesis of research results from British Columbia, Canada

The mountain ecotype of the woodland caribou (Rangifer tarandus caribou) is highly dependent on the arboreal hair lichens Bryoria spp. and Alectoria sarmentosa during winter. In parts of British Columbia, partial-cutting silvicultural systems have been used in an effort to provide continuously usable winter habitat for mountain caribou, while allowing some timber removal. We reviewed available information about the changes in hair lichens after partial cutting in Engelmann spruce (Picea engelmannii) – subalpine fir (Abies lasiocarpa) forests of British Columbian and Idaho. Generally, abundance of Bryoria spp. in the lower canopy of individual residual trees increases with increased exposure after partial cutting, until the new regeneration begins to shelter the lower canopy of the residuals. Heavy basal area removal, however, results in low lichen availability at the stand level for many years. Abundance of Bryoria on the regeneration is low, and appears to be limited largely by the structure of the young trees, not by lichen dispersal, although dispersal capability may be limiting in Alectoria. Both distributional and physiological data suggest that Bryoria is intolerant of prolonged wetting, and that increased ventilation, rather than increased light, accounts for enhanced Bryoria abundance in the partial cuts. Alectoria sarmentosa reaches its physiological optimum in the lower canopy of unharvested stands; its growth rates are somewhat reduced in the more exposed environment of partial cuts. Both genera are capable of rapid growth: over a 7-year period, individual thalli of A. sarmentosa and Bryoria spp. (excluding those with a net biomass loss due to fragmentation) in an unlogged stand more than tripled their biomass. Calculated growth rates, as well as dispersal potential, are influenced by fragmentation. Bryoria produces more abundant, but smaller, fragments than Alectoria, and fragmentation in both genera increases in partial cuts. In subalpine mountain caribou habitat, partial-cutting prescriptions that enhance exposure of residual trees while keeping basal area removal low will maintain forage best. Regeneration management should focus on maintaining ventilation in the lower canopy of the residual stand

Can partial‐cut harvesting be used to manage terrestrial lichen habitat? A review of recent evidence

Recent research suggests that partial-cut harvesting techniques can be used to alter successional trajectories in pine- and spruce-lichen woodlands, allowing forest managers to extend the period of reindeer lichen growth in mid- to late seral boreal forest stands. In Quebec, a fully replicated partial-cutting trial found that terrestrial lichen abundance remained at least as high in the partial cut as in the clearcuts or unlogged stands, and that the partial cut appeared to be on a trajectory to have even more terrestrial lichen due to sustained higher growth rates. In Alberta, a retrospective study found higher terrestrial lichen abundance in an early horse-logged partial cut than in undisturbed adjacent old forests or in clearcuts. Follow-up studies of partial-cut harvesting trials in British Columbia found that group selection plots 10 years after harvesting had lichen cover equivalent to that of undisturbed forest. In contrast, studies on lichen woodlands that have been defoliated by mountain pine beetle showed a major decline in reindeer lichen cover and a corresponding increase in vascular plant cover, similar to the results of previous studies on clear-cut logging impacts. Taken together these studies provide qualified support for the hypothesis that partial-cut harvesting can be used to enhance, or at least maintain, terrestrial lichen mats used as forage by caribou

Riparian alder ecosystems as epiphytic lichen refugia in sub-boreal spruce forests of British Columbia. Botany 88

Abstract: Alder-dominated riparian forests represent only a small proportion of the landscape in central-interior British Columbia. However, they possess a suite of attributes that may allow them to function as refugia for canopy macrolichens. These include their deciduous habitat, their location in moist nutrient receiving sites, and their distribution as narrow corridors that cross broad regional landscapes. We have examined their potential role as lichen refugia by assessing canopy macrolichen communities in 75 riparian alder forests across a 200 km longitudinal gradient in central-interior British Columbia. Study sites were stratified equally between three climate subzones of the Sub-Boreal Spruce biogeoclimatic zone. Forty-nine macrolichen taxa were observed, including the old-growth indicator cyanolichen species Lobaria scrobiculata (Scop.) DC., L. retigera (Bory) Trevisan, Nephroma isidiosum (Nyl.) Gyelnik, and Sticta limbata (Sm.) Ach. Canonical correspondence analysis identified mean annual temperature, mean annual precipitation, age of adjacent conifer forest, and abundance of large stems (dbh >10 cm) as significant explanatory variables. Regional precipitation gradients explained the exclusion of many lichen species from both the most westerly and most easterly riparian forests, with drier summer conditions and heavy winter snowpack, respectively, being major limiting factors. Lichens preferentially occupied large leaning stems, which may provide greater precipitation interception and continuity of substrate, when compared with smaller upright alder stems. We conclude that alder-dominated riparian forests represent a major refugium for old-growth dependent lichens in British Columbia's sub-boreal spruce landscapes and as such may provide valuable dispersal corridors between remnant old-growth coniferous forest patches. Key words: Alnus, riparian gallery, canopy macrolichens, sub-boreal spruce, old growth, lichen indicator species. Résumé : Les forêts riveraines dominées par les aulnes ne représentent qu'une faible proportion du paysage dans la région du centre-intérieur de la Colombie Canadienne. Cependant, elles possèdent un ensemble d'attributs qui pourraient leur permettre d'agir comme refuge pour les macrolichens de la canopée. Ceux-ci incluent leur habitat décidu, leur localisation sur des sites recevant des embruns nutritifs, et leur distribution le long d'étroits corridors traversant un ensemble de paysages régionaux. Les auteurs ont examiné leur potentiel comme refuge pour les lichens, en évaluant les communautés de macrolichens de la canopée dans 75 forêts riveraines le long d'un gradient longitudinal de 200 km, dans le centre-intérieur de la Colombie Canadienne. Les sites d'études furent également stratifiés entre trois sous-zones de la zone biogéoclimatique de la pessière sub-boréale. Les auteurs ont observé 49 taxons de macrolichens, incluant les Lobaria scrobiculata (Scop.) DC., L. retigera (Bory) Trevisan, Nephroma isidiosum (Nyl.) Gyelnik et Sticta limbata (Sm.) Ach., des espèces de cyanolichens indicatrices des forêts surannées. L'analyse des correspondances canoniques identifie comme variables explicatives significatives, la température annuelle moyenne, la précipitation annuelle moyenne, l'âge des forêts conifériennes adjacentes, et l'abondance de tiges à fort diamètre (dhp >10 cm). Les gradients de précipitation régionale expliquent l'exclusion de plusieurs espèces de lichens le long des forêts riveraines à la fois les plus à l'ouest et les plus à l'est, subissant respectivement des conditions estivales plus sèches et d'enneigement hivernal plus importantes qui agissent comme facteurs limites. Les lichens occupent de préférence les longues branches traînantes qui peuvent permettre une interception plus importante des précipitations et une continuité de substrat, lorsqu'on les compare aux plus petites tiges dressées des aulnes. Les auteurs concluent que les forêts riveraines dominées par des aulnes constituent un refuge de premier ordre pour les lichens dépen-dant de forêts surannées dans les paysages de la pessière sub-boréale de la Colombie Canadienne, en fournissant des corridors utiles entre les aires de forêts conifériennes surannées. Mots-clés : Alnus, galerie riveraine, macrolichens de la canopée, pessière sub-boréale, espèces de lichens indicatrices d'âge avancé. [Traduit par la Rédaction

rotundifolia

Campanula rotundifolia Linnaeuscampanule à feuilles rondes;campanule à feuille rondeCampanula rotundifoliaOldman river valley W of Summerview RoadDry coulee flat, river valle

viscosissimum

Geranium viscosissimum Fischer & C.A. Meyer ex C.A. Meyersticky purple geranium;sticky purple cranesbill;sticky geranium;purple geraniumgéranium visqueuxviscosissimumOldman River Valley north of Pincher CreekNorth facing wooded slope

hookeri

Prosartes hookeri TorreyHooker's fairybellsprosartès de HookerDisporum hookeriNorth facing cliff over oldman river N. of PearceNorth facing clif

deflexa

Hackelia deflexa (Wahlenberg) Opiznodding stickseed;northern stickseedHackelia deflexaalong creek in coulee bottom, Oldman River valley west of Summerview roadmoist are

rubra

Actaea rubra (Aiton) Willdenowred baneberry;western baneberryrubraOldman river and Pincher Creek junctionNorth facing protected slop

cernuum

Allium cernuum RothNodding Onionail penchéOldman River Valley West of MaycroftSouth facing dry prairi

vulgaris

Prunella vulgaris Linnaeuscommon self-heal;self-heal;common heal-all;heal-all;carpenter weedvulgarisOldman River Valley by Summerview RoadMoist clearing in P. tremuloides groveP. tremuloide