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

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.

The concept of lichen refugia classification. A proposal based on the case study of Krajeńskie Lakeland, Poland

“…The results of research carried out in the Krajeńskie Lakeland confirm that this is currently a matter of particular importance. For in the process of broadly understood anthropogenic changes and lichen protection proposals submitted for a long time (including Motyka, 1934;Szwejkowski & Tobolewski, 1959;Lipnicki, 1988Lipnicki, , 1991Fałtynowicz, 1992), refuges have played and will play an increasingly important role in preserving biodiversity Cieśliński, 2009), or as a source of propagules, from which lichens will be able to spread (Doering & Coxson, 2010). Białowieża Forest Kościelniak, 2008;Golubkov et al, 2012), Bieszczady (Kościelniak, 2009, 6 -"Torfowisko Messy" Landscape-Nature Protected Complex; 7 -"Struga Białośliwka" Nature 2000 area; 8 -"Zielona Góra" nature reserve ; 9 -"Borek" nature reserve and literature cited therein) and Tuchola Forest (Lipnicki, 2012) are among the most important national centers of lichen species diversity.…”

Dismantling the treasured flagship lichen Sticta fuliginosa (Peltigerales) into four species in Western Europe

“…They indeed qualify for being very sensitive to human activities and are considered pertinent bioindicators and priority targets of conservation programs. Species of Sticta play a crucial role in the calculation of Indices of Ecological Continuity for woodland habitats in the British Isles (Coppins and Coppins 2002), as well as in the Pacific Northwest in North America (Tønsberg and Goward 2001;Doering and Coxson 2010;Radies and Coxson 2004;Radies et al 2009). They also indicate very low levels of nitrogen deposit in forests throughout Europe (Giordani et al 2014) and were recently included in newly designed indices for air quality in the Pacific Northwest (Root et al 2015).…”

Lichens in the inland rainforest: Climate biomonitoring and population structure of Lobaria pulmonaria (L.) Hoffm.

“…Based on field observations, alder stems smaller than the ones included in our study also hosted less lichenspecies richness. Doering and Coxson (2010),studying similar riparian alder ecosystems in the adjacent SBS zone, also found stems below 10 cm DBH to have much lower lichen species richness. It is therefore likely that the medium diameter trunks (i.e., the smaller trunks that were sampled) represent the peak lichen floras for these alders.…”

“…Riparian zones are examples o f humid habitats that serve as important lichen biodiversity hotspots and corridors in western North America, particularly for cyanolichens Peterson and McCune, 2003;Doering and Coxson, 2010), supporting species that are rare or absent from the surrounding upland (non-riparian) forest. Doering and Coxson (2010) found riparian corridors near British Columbia's wet ITR forests to be refugia for old growth associated macrolichens, including many rare cyanolichens. Peterson and McCune (2003) similarly studied lichen hotspots in riparian zones in Oregon, and found higher lichen diversity in riparian zones.…”

“…Peterson and McCune (2003) similarly studied lichen hotspots in riparian zones in Oregon, and found higher lichen diversity in riparian zones. Riparian zones in the ITR are also nutrient-receiving sites (Stevenson et al 2011), and this may further augment the diversity o f epiphytic cyanolichens (Doering and Coxson, 2010), which are more abundant where soil nutrient levels are high (Goward and Arsenault, 2000b).…”