Canadian Journal of Forest Research Lifeboat or sinking ship: Will the size and shape of Old- Growth Management Areas provide viable future habitat for temperate rainforest lichens? Journal: Canadian Journal of Forest Research Manuscript ID cjfr-2019-0381.R2 Manuscript Type: Article Date Submitted by the 24-Mar-2020 Author: Complete List of Authors: Bezzola, Aita; University of Northern British Columbia, Ecosystem Science and Management Coxson, Darwyn; Univ No British Columbia, Ecosystem Science and ManagementDraft managed forests, protected areas, lichens, temperate rainforest, edge Keyword: effects Is the invited manuscript for consideration in a Special Not applicable (regular submission) Issue? : https://mc06.manuscriptcentral.com/cjfr-pubs Page 1 of 58 Canadian Journal of Forest Research 1 Lifeboat or sinking ship: Will the size and shape of Old-Growth Management Areas provide 2 viable future habitat for temperate rainforest lichens? 3 4 5 Aita Bezzola and Darwyn Coxson1. 6 7 Ecosystem Science and Management Program 8 University of Northern British Columbia 9 3333 University Way, Prince George, B.C., V2N 4Z9 10 11 1. Corresponding author (email: [email protected] , phone: 250-960-6646) Page 1 https://mc06.manuscriptcentral.com/cjfr-pubs Canadian Journal of Forest Research Page 2 of 58 12 Abstract: 13 The Kispiox Timber Supply Area, a 1.3 million ha region in northwestern British Columbia, 14 supports a significant assemblage of old-forest dependant temperate rainforest (oceanic) lichens. 15 Given their known sensitivity to edge effects, we ask whether or not the current configuration of 16 Kispiox Old-Growth Management Area reserves (OGMAs) will provide viable future habitat for 17 oceanic lichens as surrounding landscapes are progressively logged in coming decades. 18 Landscape indicators were calculated from provincial map datasets. Old cedar-hemlock forests, 19 the primary habitat for Kispiox oceanic lichens, had a landscape shape index of 6.4 in OGMAs, 20 indicative of elongate shapes susceptible to edge effects. Mean patch size in OGMAs was 43 ha, 21 with the largest patch size 1,378 ha. In contrast, the landscape shape index for pre-industrial old 22 cedar-hemlock forests was 1.3, with a meanDraft patch size of 1293 ha, and largest patch size 23,357 23 ha. When modelled edge effects were extended to 120 m, only 25% of cedar-hemlock forests in 24 Kispiox OGMAs remained interior habitat (7,754 ha total). Adoption of silvicultural practices 25 that maintain buffer zones around existing OGMAs, and the designation of additional OGMAs, 26 especially in watersheds with intact old cedar-hemlock forests, is recommended to conserve 27 oceanic lichen communities in the Kispiox. 28 29 30 Keywords: managed forests, protected areas, edge effects, lichens, temperate rainforest, variable- 31 retention harvesting 32 Page 2 https://mc06.manuscriptcentral.com/cjfr-pubs Page 3 of 58 Canadian Journal of Forest Research 33 Introduction 34 Wet-temperate rainforests in the headwaters of the Skeena and Nass River watersheds in 35 northwestern British Columbia (B.C.) represent a biodiversity hotspot for old-forest dependant 36 temperate rainforest (oceanic) lichen species in western North America (Goward 1994; Goward 37 and Spribille 2005). This area falls within a zone of ecological transition, between the very-wet 38 coastal mountain ranges, where canopy lichens are outcompeted by mosses and liverworts, and 39 drier central-interior plateau habitats, where summer precipitation is insufficient to support 40 temperate rainforest lichen communities (Goward and Spribille 2005). This ecosystem was 41 recently described as the Kispiox Inland Temperate Rainforest (Coxson et al. 2019). 42 As a group, canopy lichens haveDraft commonly been used as indicators, both for their 43 sensitivity to air pollution, and as markers of forest successional stages (Esseen and Coxson 44 2015). Conditions suitable for the establishment and growth of old-forest dependant oceanic 45 lichen communities typically do not occur for upwards of two centuries or more after stand- 46 replacing disturbance events (Campbell and Fredeen 2004; Price et al. 2017). This is a reflection 47 of the time needed for development of the stand structural complexity required by habitat 48 specialists (Goward 1994). 49 Over the next five to six decades, most timber supply areas in B.C. will see a transition 50 from relying mainly upon old-forests as their primary timber supply to using second-growth 51 stands to meet timber supply needs, a transition described as the “fall-down” effect (Marchak et 52 al. 1999). Within the Kispiox region, the timber supply from natural (predominantly old) cedar- 53 hemlock forests is expected to fall by 75% or more within the next 50 years (Timberline 2007; 54 Snetsinger 2008). Habitat for old-forest dependant oceanic lichens in these future landscapes will Page 3 https://mc06.manuscriptcentral.com/cjfr-pubs Canadian Journal of Forest Research Page 4 of 58 55 consequently be highly constrained, with current forest management decisions having a major 56 influence on the long-term viability of oceanic lichen communities in the Kispiox. 57 Although lichen communities can be conserved on retained individual (green) trees 58 within regenerating cutblocks in managed forests (Hofmeister et al. 2016), this mainly benefits 59 species that already grow in open light environments (Lundstrom et al. 2013). For old-forest 60 dependant lichens, the post-harvest transition to high light and desiccating environments 61 typically leads to widespread dieback of canopy lichen communities (Gauslaa and Solhaug 62 1996). Old-forest dependant lichens with a cyanobacterial photosynthetic partner (symbiont), in 63 particular, are highly sensitive to prolonged high light exposure when dry (Gauslaa et al. 2006). 64 Creating suitable spatially-defined reserves where old-forest conditions are maintained is 65 therefore generally regarded as a preferredDraft conservation strategy for oceanic lichen species 66 (Ylisirniöa and Hallikainen 2018). 67 The concept of designating forestry retention patches or reserves within the timber 68 harvesting landbase to act as refugia or “lifeboats” for old-forest dependant biota such as lichens 69 is well established in forest management practices across North America and Europe 70 (Matveinen-Huju et al. 2006; Gustafsson et al. 2010; Gustafsson et al. 2012; Mori and Kitagawa 71 2014). Perhans et al. (2009), for instance, describes how forest reserves function as “lifeboats” 72 for old-forest dependant lichens during the forest regeneration phase, though cautioning that 73 small retained forest fragments or reserves may be unable to perform this function. Three major 74 factors have repeatedly been raised when the design of forest reserves in managed landscapes is 75 discussed. 76 Reserve placement must first consider the adjacency of other reserves. Old-forest 77 dependant lichens commonly have limited dispersal abilities (Sillett et al 2000; Öckinger et al. Page 4 https://mc06.manuscriptcentral.com/cjfr-pubs Page 5 of 58 Canadian Journal of Forest Research 78 2005). Aune et al. (2005) raised concerns about the increasing isolation of forest reserves in 79 Sweden, recommending both the designation of larger reserves and the increased utilization of 80 buffer zones around reserves so that matrix landscapes can better support dispersal of old-forest 81 dependant taxa between reserves. 82 Second, reserve design must consider the sensitivity of old-forest dependant lichens to 83 edge effects, especially when considering the size and shape of forest reserves. This concern 84 arises from the requirement of many old-forest dependant lichens for ‘interior” forest conditions, 85 due to their intolerance of extremes of desiccation, high light exposure, and thermal conditions 86 (Esseen and Renhorn 1998; Gehlhausen et al. 2000; Hilmo and Holien 2002; Gauslaa et al. 87 2006). Cantú-Salazar and Gaston (2010), in discussing the relative contributions of many small 88 versus few large protected areas, note thatDraft the high perimeter-to-area ratios of small reserves 89 frequently limits their effectiveness, allowing external conditions to penetrate reserve 90 boundaries. 91 Third, habitat quality within designated reserves is critical to sustaining lichen 92 communities. Radies et al (2009) found that the distribution and abundance of old-forest 93 dependant temperate rainforest lichens was greatest in wet nutrient-receiving sites (wet “toe- 94 slope” positions), sites that historically had long time intervals between stand destroying events 95 such as fire. Fritz et al. (2008) found that long-term site continuity (>350 years) was a critical 96 factor in predicting the presence of red-listed lichens in retained forest patches in managed 97 landscapes of southern Sweden, noting that the generally higher quality habitat in patches with 98 long-term site continuity was an important contributing factor. Franklin et al. (2007) emphasized 99 the importance of providing continuity of forest cover in reserves, including both compositional 100 (tree species diversity) and structural (such as snags and coarse woody debris) elements. These Page 5 https://mc06.manuscriptcentral.com/cjfr-pubs Canadian Journal of Forest Research Page 6 of 58 101 considerations are particularly important in temperate rainforest ecosystems of western North 102 America, where prevailing natural disturbance dynamics historically allowed the development of 103 landscapes dominated by