Inland Rainforest Research Articles

Climate, wildfire, and volcanic ash drivers of ecosystem change in high mountain forests, British Columbia, Canada

Northwest North America has unique high elevation Picea–Abies forests and parkland classified in British Columbia as the Engelmann Spruce–Subalpine–fir (ESSF) Biogeoclimatic zone. These ecosystems occur on a topographically and climatically complex landscape, juxtaposed with diverse vegetation types including alpine tundra, inland rain forest, dry conifer forest, and grasslands. Spatio-temporal ecosystem disturbance is varied, driven by factors such as climate variation, wildfire, volcanic eruptions, and insect herbivory. A pollen and charcoal record derived from a lake sediment core from the ESSF reveals a unique late-glacial to modern vegetation history progressing from alpine steppe through dry open conifer forest to moist spruce–fir ecosystems, the latter arising only 4600 years ago, late by comparison to other ESSF sites in the region. Repeated disturbance in the mid Holocene by wildfire coupled with volcanic ash deposition and increased climatic variation resulted in recurring Pinus contorta-dominated seral forest stands before cooling and moistening in the late Holocene led to stable Picea–Abies forest. With rapid climate change, changing disturbance regimes, and timber harvest, the management of dry ESSF forests needs to consider that this forest-type could transform into parkland or open seral pine stands, with a high frequency disturbance regime.

Genomic evidence of an ancient inland temperate rainforest in the Pacific Northwest of North America.

The disjunct temperate rainforests of the Pacific Northwest of North America (PNW) are characterized by late‐successional dominant tree species Thuja plicata (western redcedar) and Tsuga heterophylla (western hemlock). The demographic histories of these species, along with the PNW rainforest ecosystem in its entirety, have been heavily impacted by geological and climatic changes the PNW has experienced over the last 5 million years, including mountain orogeny and repeated Pleistocene glaciations. These environmental events have ultimately shaped the history of these species, with inland populations potentially being extirpated during the Pleistocene glaciations. Here, we collect genomic data for both species across their ranges to test multiple demographic models, each reflecting a different phylogeographical hypothesis on how the ecosystem‐dominating species may have responded to dramatic climatic change. Our results indicate that inland and coastal populations in both species diverged ~2.5 million years ago in the early Pleistocene and experienced decreases in population size during glacial cycles, with subsequent population expansion. Importantly, we found evidence for gene flow between coastal and inland populations during the mid‐Holocene. It is likely that intermittent migration in these species during this time has prevented allopatric speciation via genetic drift alone. In conclusion, our results from combining genomic data and demographic inference procedures establish that populations of the ecosystem dominants Thuja plicata and Tsuga heterophylla persisted in refugia located in both the coastal and inland regions of the PNW throughout the Pleistocene, with populations expanding and contracting in response to glacial cycles with occasional gene flow.

Estimating carbon stocks and stock changes in Interior Wetbelt forests of British Columbia, Canada

AbstractThe Interior Wetbelt (IWB) of British Columbia includes the globally rare Inland Temperate Rainforest (ITR) that if managed for its substantial carbon (C) stocks can contribute to Canada's Nationally Determined Commitment under the Paris Climate Agreement. We provide spatially explicit estimates of above‐ and belowground live and dead biomass and soil C stocks derived from three sources: (1) government online Vegetation Resources Inventory (VRI); (2) the GlobBiomass spatial dataset; and (3) field plots (n = 27) within old‐growth forests of the ITR. For live aboveground C, we summarize C stocks by elevation classes and decadal forest age. The upper bound on total C densities (above‐ and belowground live and dead biomass and soil C) based on VRI was a maximum of 806 megagrams (Mg) C ha−1. The mean total biomass C density measured in field plots was 583 Mg C ha−1 with a maximum of 1275 Mg C ha−1, which is on par with some of the world's most C‐dense temperate forests. About half the C is in live biomass pools with the rest in dead biomass and soil organic C pools. The mean C density from the VRI over all elevations was 182 Mg C ha−1, with soil organic C ~40% and live tree stems ~27%. Vegetation Resources Inventory estimates were 75% lower than field‐based measurements with the greatest mismatch in areas with the highest C density. Approximately 22% of the IWB has been logged, the majority since 1970s, resulting in live above ground C declining by at least 18%, although this is likely an underestimate. Logging was heavily concentrated in low (<1000 m; 28.3% of elevation zone) to mid‐elevations (1000–2000 m; 20.9%) compared with upper elevations (>2000 m; 1.2%). The region contains underappreciated C stocks that can help Canada meet its climate and conservation targets, but only if there are major forestry reforms that protect C‐dense old‐growth forests, allow degraded forests time to recover the logging‐related C debt, and improve monitoring of C stocks and stock changes.

Silvicultural strategies for lichen conservation: Smaller gaps and shorter distances to edges promote recolonization

AbstractConservation of epiphytic lichens in managed forest landscapes relies on understanding limitations to their dispersal and establishment after harvesting. A hot spot for cephalo‐ and cyanolichens, the Kispiox inland temperate rainforest of British Columbia, Canada, is an example of where forest managers seek silviculture options that allow for forest harvesting to continue, while also conserving threatened species. To characterize colonization of these lichens (including the nationally threatened Nephroma occultum and Lobaria retigera), we quantified thalli on 25‐year‐old regenerating spruce trees at varying distances from forest edges in logged openings of different sizes surrounded by mature (160 years) or old‐growth (≥350 years) forest. Lichen colonization 25 years after logging was influenced by distance from the forest edge, surrounding forest age, and opening size. Total mean colonization and number of species per three branches were 81 thalli and 8 species at the forest edge, declining to 18 and 4, respectively, approximately 50 m into the openings. Colonization of most species reached minimum levels within 80 m. Nationally threatened species and old‐forest associates had higher abundances and longer colonization distances in openings surrounded by old‐growth forests; whereas widespread species had greater colonization when surrounded by mature forests. Logged gaps <0.6 ha promoted higher and more diverse lichen colonization than clearcuts (>3.8 ha). This study demonstrates that forest managers should consider the spatial patterning of harvesting, with smaller openings and shorter distances between edges (likely in tandem with higher levels of retention) in forests rich in epiphytic lichens to facilitate their recolonization and conservation.

Red-Listed Ecosystem Status of Interior Wetbelt and Inland Temperate Rainforest of British Columbia, Canada

The Interior Wetbelt (IWB) of British Columbia, which includes the globally rare Inland Temperate Rainforest (ITR), contains primary forests poorly attributed and neglected in conservation planning. We evaluated the IWB and ITR using four IUCN Red List of Ecosystems Criteria: geographic distribution, environmental degradation (abiotic and biotic factors), and likelihood of ecosystem collapse. Clearcut logging (3.2M ha) represented 57% of all anthropogenic disturbances, reducing potential primary forest by 2.7 million ha (28%) for the IWB and 524,003 ha (39%) for the ITR. Decadal logging rates nearly doubled from 5.3% to 10.2% from 1970s–2000s. Core areas (buffered by 100-m from roads and developments) declined by 70% to 95% for the IWB and ITR, respectively. Vulnerable was assigned to karst, the only abiotic factor assessed, because it was associated with rare plants. For biotic factors, Old-Growth Birds were Vulnerable, Southern Woodland Caribou (Rangifer tarandus caribou) habitat and Sensitive Fish were Endangered, and Old-Growth Lichens habitat was Critical. Overall, the IWB was ranked as Endangered and the ITR as Critical with core area collapse possible within 9 to 18 years for the ITR, considered one of the world’s most imperiled temperate rainforests.

Review: British Columbia's Inland Rainforest: Ecology, Conservation, and Management

Stevenson, Susan K., Armleder, Harold M., Arsenauly, Andre, Coxson, Darwyn, Delong, S. Craig and Jull, Michael. British Columbia's Inland Rainforest: Ecology, Conservation, and Management. Vancouver, Canada: University of British Columbia Press, 2011. 456 pp. ISBN: 9780774818506, paperback. US$ 41.95, illustrated. Also available in hardcover format ISBN 9780774818490.A fact-filled and extremely useful offering from silvicultural and ecosystem professionals, biologists, ecologists, systems scientists and others, British Columbia's Inland Rainforest provides a snapshot, a look at the present conditions of this unique ecosystem in light of past and future management choices. Included are 128 figures, color plates and illustrations, 20 tables, three appendices, a species index, glossary and various exposes that highlight features of the text, which itself includes more than 50 sections detailing everything from carbon stocks to soil horizons to forest edge effects on plant and animal life to native medicine and many others. The book grew from a project with scientific goals-to supplement a government forestry report with data so that managers and other stakeholders could make well-informed choices. The authors made a wonderful choice to expand their scope and offer the work to the public.British Columbia's inland rainforest is unique. There is no other place on the planet where a temperate rainforest exists so far from the coast, with much of its biome determined by continental rather than coastal geography. For example, many of the species in the inland rainforest migrated from elsewhere in continental North America during the end of the last glaciation, or from the coast via specific vectors. They continue to survive in a setting that includes thousand-year-old red cedar trees and lichen species (e.g. cyanolichen) that are not found elsewhere or nowhere else in such great diversity and abundance. Snowmelt during the summer promotes groundwater abundance and a humidity level unrivaled in a continental forest setting.Here, ancient red cedar and western hemlock make unique rotted-out settings for fungus, bryophyte, lichen, vascular plants, invertebrates and vertebrate animals, dens in hollowed out trees for martens and black bears. Yet in human terms, the same trees providing the substrate for such a rich ecology have also driven management choices that have led to their destruction.Historically, such immense trees with internal voids are called decadent and forest management has opted to harvest these old landscapes to allow planting of young plantation stands that replace them, often with changes to species for a standardized harvest regime. Ironically, the work is done in winter when the marshy rainforest soil has frozen and ice roads or other means of transport can be constructed. …

Links between paleoclimate and prehistorical human dispersal in Sri Lanka: a critical view

Sri Lanka represents rich sources of prehistorical archaeological data such as the earliest: 1) Homo sapiens fossils; 2) geometric microliths in South Asia. Climatic and geological events were considered with known archaeological evidences that provide opportunities for comparative research. The author proposed that climatic transition from Marine Isotope Stage (MIS) 4 to MIS 3 and MIS 3 to MIS 2 could probably identify as main traverse periods of prehistoric modern Homo sapiens into Sri Lanka. Glacial eustatic sea-level drops create possible prehistoric migration routes between India and Sri Lanka across the Palk Strait during a number of phases under semi-arid climate. The interglacial sea-level rise had opened supplementary routes towards tropical inland rainforests along river valleys. The early-middle to late Holocene sea-level highstands can be recognised as the latest geographic isolation of island Sri Lanka.

Links between paleoclimate and prehistorical human dispersal in Sri Lanka: a critical view

Sri Lanka represents rich sources of prehistorical archaeological data such as the earliest: 1) Homo sapiens fossils; 2) geometric microliths in South Asia. Climatic and geological events were considered with known archaeological evidences that provide opportunities for comparative research. The author proposed that climatic transition from Marine Isotope Stage (MIS) 4 to MIS 3 and MIS 3 to MIS 2 could probably identify as main traverse periods of prehistoric modern Homo sapiens into Sri Lanka. Glacial eustatic sea-level drops create possible prehistoric migration routes between India and Sri Lanka across the Palk Strait during a number of phases under semi-arid climate. The interglacial sea-level rise had opened supplementary routes towards tropical inland rainforests along river valleys. The early-middle to late Holocene sea-level highstands can be recognised as the latest geographic isolation of island Sri Lanka.

Old-Growth Forest Values: A Case Study of the Ancient Cedars of British Columbia

The Inland Temperate Rainforest of British Columbia is a globally unique ecosystem containing areas of high biodiversity and stands of ancient cedars. The ancient cedars, which are estimated to be 1000–2000 years old, are located in a region historically focused on the economic values of timber. Yet recent scientific discoveries and new recreational uses of the forest have changed people's interest in and perceptions of this old-growth forest. The purpose of this research is to document the range of values associated with the ancient cedar forest identified as important to residents of two communities and discuss how these nascent values fit within, shape, and inform recent policy developments. Using a case-study approach, data were collected through household surveys and content analysis. Results reveal a set of old-growth forest values focused on life-support and ethical values that have successfully challenged resource management policy.

Net Snowpack Accumulation and Ablation Characteristics in the Inland Temperate Rainforest of the Upper Fraser River Basin, Canada

This study examines the net snow accumulation and ablation characteristics and trends in the Inland Temperate Rainforest (ITR) of the Upper Fraser River Basin, British Columbia (BC), Canada. It intends to establish whether elevation and/or air temperature play(s) a dominant role in hydrological year peak snow water equivalent (SWE) and whether regional patterns emerge in the interannual variability in peak accumulation. To that end, SWE and air temperature data from seven snow pillow sites in the Upper Fraser River Basin at elevations ranging from 1118 to 1847 m above sea level are analyzed to infer snowpack characteristics and trends for hydrological years 1969–2012, with 2005–2012 being the actual period of data overlap. Average peak SWE ranges from 391.3 mm at Barkerville, BC on 16 April to 924.4 mm at Hedrick Lake, BC on 27 April. Snow cover duration lasts 206–258 days, with snow onset dates from mid-October to early November and snow off dates from late May to early July. Statistically-significant (p ≤ 0.05) cross correlations exist between peak SWE at nearly all sites, indicating regional coherence in seasonal synoptic activity across the study area. However, the lack of relationships between peak SWE and elevation as well as air temperature parameters indicate that mesoscale to local processes lead to distinct snow accumulation and ablation patterns at each site. Four sites with the longest records exhibit no trend in peak SWE values between 1990 and 2012. Changes to snowpack regimes may pose a threat to the productivity and immense biodiversity supported by the ancient western red cedar and hemlock stands growing in the wet toe slopes of the ITR. Thus, it is imperative that continued monitoring of snowpack conditions remains a top priority in the Upper Fraser River Basin, allowing for a better understanding of ecosystem changes in a warming climate.

A comparison ofLobaria pulmonariapopulation structure between subalpine fir (Abies lasiocarpa) and mountain alder (Alnus incana) host-tree species in British Columbia’s inland temperate rainforest

In a study using dated branch segments, we determined the size class distribution and reproductive status of Lobaria pulmonaria (L.) Hoffm. growing on subalpine fir (Abies lasiocarpa Nutt.) and mountain alder (Alnus incana (L.) Moench) alongside small streams in British Columbia’s inland temperate rainforest (ITR). The number of thalli per branch segment did not significantly differ between Abies and Alnus, although mean L. pulmonaria biomass on entire branches was 71.03 g on fir and 12.31 g on alder. Branch diameter was a significant predictor for reproductive status of thalli on fir, whereas branch age was a better predictor for thalli on mountain alder. The presence of sorediate and (or) isidiate individuals on branch segments <10 years old suggests a rapid generation time for L. pulmonaria in the ITR. Annual growth rates of L. pulmonaria thalli reached up to 1.16 cm2·cm−2·yr−1on branch segments less than 15 years in age. Specific thallus mass (STM) was significantly higher for thalli on alder. STM was strongly dependent on thallus size on both host-tree species, with values from above 10 mg.cm−2in large thalli (>100 cm2), to <3 mg.cm−2in small thalli (<0.1 cm2). These differences between host-tree species can be interpreted in context of both adjacent canopy structure and the differences in tree growth form between these two host-tree species, both of which factors lead to greater light availability at the surface of mountain alder branches. The fast growth rates and short generation time observed in L. pulmonaria thalli growing on both alder and fir highlights the favorable conditions riparian habitats create for lichen growth in British Columbia’s ITR.

Climate Biomonitoring with Lichens in British Columbia’s Inland Temperate Rainforest

Rapid climate change is predicted for British Columbia’s Inland Temperate Rainforest (ITR), a globally unique ecosystem. Lichens, which may serve as effective biomonitors of ecosystem health, have been proposed for use as climate change indicators for a variety of ecosystems globally. This research presents a climate biomonitoring protocol using arboreal macrolichen communities in the inland rainforest in British Columbia. We report our initial findings of 39 lichen taxa, including a number of rare species and cyanolichens, which may be especially sensitive to climate. Comparisons of these data with future measurements will provide an indication of how the inland rainforest may be responding to climate change.

Analysis of Ancient Western Redcedar Stands in the Upper Fraser River Watershed and Scenarios for Protection

Emerging research has highlighted the significance of ancient western redcedar (Thuja plicata) stands within the upper Fraser River watershed as examples of rare forest types within British Columbia’s inland temperate rainforest (ITR). These stands represent a globally significant repository of canopy lichen biodiversity. Ancient redcedar stands were historically found in greatest abundance in wet “toe-slope” topographic positions, where mountain slopes flatten out as they reach the valley bottom. Abundant groundwater runoff and wet soils in these topographic positions provided protection from fires and sustained trees during dry summer periods. However, the placement of road and rail corridors in these same topographic positions has facilitated the logging of many ancient redcedar stands. The result has been the widespread loss of ancient cedars, which today account for only 3.7% of the 130 571 ha ICHvk2 biogeoclimatic zone east of Prince George. Of the remaining ancient cedar stands found in the ICHvk2 less than 2% (approx. 100 ha) are currently protected within BC provincial parks. Here we outline three scenarios that would increase the proportion of this ecosystem within BC parks and would support landscape-level planning objectives for the upper Fraser River watershed. We suggest that the cultural and biological values represented by these proposed areas would meet criteria for nomination as a UNESCO World Heritage or Biosphere Reserve site, ultimately resulting in widespread positive benefits for diversification of the regional economy, by building on a regional tourist attraction that has already developed at the site of the Ancient Forest Trail.

Giant Robber Crabs Monitored from Space: GPS-Based Telemetric Studies on Christmas Island (Indian Ocean)

We investigated the navigational capabilities of the world's largest land-living arthropod, the giant robber crab Birgus latro (Anomura, Coenobitidae); this crab reaches 4 kg in weight and can reach an age of up to 60 years. Populations are distributed over small Indo-Pacific islands of the tropics, including Christmas Island (Indian Ocean). Although this species has served as a crustacean model to explore anatomical, physiological, and ecological aspects of terrestrial adaptations, few behavioral analyses of it exist. We used a GPS-based telemetric system to analyze movements of freely roaming robber crabs, the first large-scale study of any arthropod using GPS technology to monitor behavior. Although female robber crabs are known to migrate to the coast for breeding, no such observations have been recorded for male animals. In total, we equipped 55 male robber crabs with GPS tags, successfully recording more than 1,500 crab days of activity, and followed some individual animals for as long as three months. Besides site fidelity with short-distance excursions, our data reveal long-distance movements (several kilometers) between the coast and the inland rainforest. These movements are likely related to mating, saltwater drinking and foraging. The tracking patterns indicate that crabs form route memories. Furthermore, translocation experiments show that robber crabs are capable of homing over large distances. We discuss if the search behavior induced in these experiments suggests path integration as another important navigation strategy.

Dispersal limitation, speciation, environmental filtering and niche differentiation influence forest tree communities in West Polynesia

AbstractAimRegional patterns of forest composition in West Polynesia were analysed to determine the relative importance of dispersal limitation, speciation, environmental filtering and biotic interactions.LocationWest Polynesia (Fiji, Tonga, Samoa).MethodsWe applied clustering and indicator species analysis to presence/absence data for 397 tree taxa in 338 forest plots to detect groups of plots sharing similar species composition. Patterns of plot composition and co‐occurrence of congeneric species were compared between archipelagos for evidence of dispersal limitation, speciation, and environmental filtering versus competitive displacement or niche differentiation across the three archipelagos at the local (plot) and regional scales.ResultsDispersal limitation was evident in the compositional segregation of inland rain forests across the three archipelagos, whereas compositional overlap was widespread for coastal forests, which are composed of species dispersed by water. Within genera, species numbers attenuated from Fiji to Tonga to Samoa, but speciation also contributed to compositional differences in all three island groups. Environmental filtering was suggested by the distinct composition of both secondary and mature inland rain forest versus coastal forest. At the local scale, however, clumping of congeners, which might suggest fine‐scale environmental filtering, was observed for only a minority of inland forest genera. Most genera showed either overdispersion, suggesting competitive displacement or niche differentiation, or patterns not significantly different from random.Main conclusionsWell‐established biogeographical patterns of dispersal limitation and speciation contribute to West Polynesian tree diversity at the community scale. Environmental filtering and competitive displacement further structure forest communities; the evidence from this study suggests that environmental filtering is more important at a landscape scale, while competitive displacement may be more important at a local scale, although their relative importance varies considerably among taxa.

British Columbia's inland rainforest: ecology, conservation, and management

British Columbia's inland rainforest: ecology, conservation, and management

Trace-element evidence for foreigners at a Maya port in Northern Yucatan

The present paper explores the potentials of trace elements in human dental enamel to indicate mobility and to detect the presence of individuals who had migrated into a community after childhood. Three Pre-Hispanic samples of infants from the Yucatán peninsula were chosen, one from the northern coast (Xcambó), one from the coast of the Gulf of Mexico (Campeche) and the last one from the tropical inland rain forest (Calakmul). Infants’ first permanent molars are the term of reference because infants were very likely born in the same place where they died and therefore are supposed to represent the local geo-chemical environment. Their chemical signature was then compared to the one of the adults from the site of Xcambó. The elemental composition was recorded by means of laser ablation-time of flight-ICP-MS. Sr and Ba (and secondly Mg and I) discriminate well the three infant samples. All the Early Classic adults from Xcambó fall within the range of variation of the site’s infants, while 25% of the Late Classic adults fall outside the range in agreement with archaeological, bioarcheological, and isotopic evidence. LA-ICP-Ms analyses of trace elements in archaeological samples can be an important analytical tool to detect foreigners in local populations. The selection of infants as reference values helps reduce the limits faced by trace element analyses in past human populations studies.

Paleosol record of Neogene climate change in the Australian outback

Effects in Australia of a global spike of warm-wet climate during the middle Miocene (ca16 Ma) have been controversial, with one faction arguing for inland rain forest and the other faction for dry woodland. This question is here addressed using the Oligocene–Miocene sequence of fossil mammal localities at Lake Palankarinna, South Australia, which includes numerous paleosols that have been dated by paleomagnetism, palynology, biostratigraphy, and radiometric methods to straddle this paleoclimatic event. Paleosols of the Oligocene–Miocene Etadunna and Pliocene Tirari Formations formed in arid paleoclimates and include pedogenic gypsum. The Maralji paleosol, developed on early Miocene Etadunna Formation and overlain by late Miocene–Pliocene Mampuwordu Sands, is middle Miocene in age based on mammal fauna at correlative horizons in nearby Lake Ngapakaldi. The Maralji paleosol has shallow calcareous nodules and stout root traces suggesting vegetation like dry woodland (mallee). Mallee vegetation now grows no closer than 1200 km to the southwest, so middle Miocene warm-wet climate enabled range extension of mallee and woody thickening of plants in the Australia outback. There is no evidence in the outback of middle Miocene rain forest, which may have expanded its range to form kaolinitic Ultisols near Sydney, Mudgee and Gulgong, all in New South Wales. Nor is there evidence so far inland of swamp woodlands and heaths like those producing brown coals in the Latrobe Valley, Victoria.

Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

Abstract. Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, Elaeis guineensis, and the shrub, Alchornea cordifolia (Euphorbiaceae). A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed were driven by human impact.

Predicting canopy macrolichen diversity and abundance within old-growth inland temperate rainforests

Windward slopes of the inland mountain ranges in British Columbia support a unique inland temperate rainforest (ITR) ecosystem. Increasing fragmentation and the loss of old ITR stands have highlighted the need for determining conservation biology priorities among remaining old forest stands. We have addressed this issue by surveying foliose macrolichens within 53 old ITR stands in British Columbia's 135,000 ha very wet-cool interior-cedar hemlock (ICHvk2) biogeoclimatic subzone in the upper Fraser River watershed. Study plots were stratified by leading tree species and by “wet” versus “dry” relative soil moisture conditions. Other plot variables included: temperature, precipitation, incident solar loading, and canopy openness. Ordination plots showed a distinct assemblage of foliose cyanolichens, including Lobaria pulmonaria, Lobaria retigera, Sticta fuliginosa, Nephroma isidiosum, Nephroma occultum, and Pseudocyphellaria anomala, whose abundance was correlated with increasing relative soil moisture, temperature, canopy openness, precipitation, and basal area of spruce. Logistic regression models similarly identified relative soil moisture and temperature in all parsimonious models. Leading tree species, in combination with “wet” relative soil moisture and/or temperature, were important factors explaining the presence or absence of five ( Cavernularia hultenii, L. retigera, N. occultum, Platismatia norvegica, and Sticta oroborealis) of the eight modeled old-growth associate lichen species. This combination of conditions favouring the development of canopy lichen communities in old forests was best expressed in low elevation water receiving sites. We hypothesize that groundwater availability in these sites promotes species richness and abundance of canopy lichens by creating more favourable conditions for growth, and by reducing fire return intervals which allows for the accumulation of rare species over time. Historically, forests in these wet “toe-slope” positions were disproportionately targeted for logging. Their conservation should now be a high priority, given their disproportionate significance to maintaining canopy lichen diversity in the present-day landscapes.