Note on Taxonomyfor Heterodermia Sitchensis: Lichen Are Composite Organisms Consisting

Note on Taxonomyfor Heterodermia sitchensis: Lichen are composite organisms consisting of a fungus and a photosynthetic partner, usually an algae which form a symbiotic relationship. Seaside centipede is a member of the family Physciaceae and is also referred to as Sitka shield lichen (E-Flora, USDA). Lichens are generally assigned to one of four groups: Foliose Macrolichens(of which Heterodermia sitchensis belongs to), Mesolichens, Fruticose Lichens and Crustose Lichens.These groups reflect the ecology and physical attributes of the species within each group (from “Ways of Enlichement” 2010).

Distribution: Elevation 0-200 mA unique lichen to North America, seaside centipede is known only from one remote area (Pacific RimNational Park) on the west coast of Vancouver Islandin BC and one site on the Oregon coast (Cape Lookout). Within its area of occurrence in BCnearly 70percent of these lichen are confined to the seaside forests of coves and inlets which range along the coastlines of the MissionGroupIslands in Kyoquot Sound toFolgerIsland in Barkley Sound (NRT, BCCDC 2007).

Description: This semi-erect arboreal lichen forms cushiony structures of irregularly branched lobes averaging 20mm across. The stiff lobes are short to slightly elongated, and quite thin (0.5-2 mm wide). The top surface is usually a faint greenish-white colour but can also have a deep blue appearance. The smooth upper surface is strongly convex like a cup, with occasional warts and whitish spots. The lower surface has a white colour and cottony texture. Reproductive formations shaped like small urns and minute wispy hair-like structures rim the upper edges or lip(NRT, BCCDC 2007)..

Look’s Like? The hair-like structures, urn-shaped outgrowths, pale greenish lobes and cottony lower surface all make this species structurally unique to other lichesn which may be found in association with it. It may be confused with another Heterodermia species, elegant centipede however this species has distinctly elongated lobes and lacks the urn-shaped outgrowths of seaside centipede.

Primary Habitat: This lichen has an extremely narrow range of habitat and nutrient requirements revolving around ventilation, humidity, substrate and temperature. Ideal conditions appear restricted to localized micro-climates found on the lower branches of maritime variant Sitka spruce trees in association with undisturbed old-growth western hemlock-dominated forests. All of which combine to restrict this species in its ability to colonize and reproduce effectively.

Secondary Habitat:There is some indication that this species can survive desiccation and dryer exposed conditions, however its prolonged ability to tolerate such changes to habitat and moisture regimes (i.e. changes due to climate change) is unknown (NRT, BCCDC 2007).

Critical Features: Within its narrow ecological niche, seaside centipede is only associated with small defoliated twigs in the lower canopy of Sitka spruce within several meters of the high tide zone. This proximity to the marine environment is a critical factor as this lichen depends on very high moisture such as that provided by sea-spray drift or fog. Protection from direct exposure may also be important (i.e. leeward sides of bays, coves and inlets). Nutrient sources appear to be a key requirement. This species appears to be associated with locations where surrounding geology provides high mineral inputs (calcium rich bedrock), marine and terrestrial inputs of fecal matter (below bird perches or high levels of seabird flyby, sea lion scat) as well as First Nations shellfish midden sites (NRT, BCCDC 2007).

Seasonal Life Cycle

Habitat Guild: Maritime variant mature and old growth coniferous forests

Threats:

This species has a life history that suggests a strong dependence on local micro-climate factors and a need for habitat unlikely to go through any sudden changes.A short lifespan, poor dispersal ability, highly specific habitatrequirements, ephemeral nature of its preferred habitat and limited suitable habitat

availability contribute to this species rarity and vulnerability to declines.

Development, clearing, forestry and silviculture management practices, collection of branches for community purposes (e.g. firewood) and other disturbance factors remain a significant issue.

Recovery and recolonization rates for disturbed, damaged or destroyed colonies could take decades in order for suitable host tree maturation to occur.

Clearing of forest understory and thinning and pruning of lower tree branches for recreational access or improvement of sightlines can involve loss of lichen colonies and associated habitat potential.

Forest harvesting within or in close proximity to seaside centipede colonies can reduce microclimate suitability and function and subsequent colony viability. It has been suggested that a minimum buffer at least 60 meters wide is required to reduce harvesting impacts to sensitive lichens such as Heterodermia sitchensis.

Changes to the critical nutrient regimes this species requires to persist can lead to significant declines.

Increased severity of weather events (precipitation, storm surges) and related impacts from climate change (potential loss of critical moisture regimes) are difficult to project and manage for.

Key Conservation & Management Objectives

A targeted inventory is needed to determine if undiscovered populations exist elsewhere within the Coast Region (i.e. Pacific Rim area) and to assess the status of all known populations.

Monitor existing populations on an ongoing basis to assess viability and reduce potential disturbance from land use activities.Where suitable habitat occurs, work with land managers and land owners to ensure development or recreational activities do not disturb or encroach on sensitive areas.

Conduct outreach to raise awareness of this species and how to identify it to improve distribution knowledge

Prevent activities that will lead to changes to critical seaside centipede habitat requirements (kindling collection, clearing and slash removal) that will reduce viability of existing populations.

Meet objectives for this species and the conservation of its habitat as set out in the “Recovery Strategy for Seaside Centipede Lichen (Heterodermia

sitchensis) in Canada”.

Sightings, specimens, or observations of activities threatening its habitat should be reported to the regional Species at Risk Biologist at the Ministry of Environment office.

Main References/Literature Cited

National Recovery Team for Heterodermia sitchensis (Seaside Centipede Lichen). 2007.Recovery Strategy for Seaside Centipede Lichen (Heterodermia

sitchensis) in Canada.Species at Risk Act Recovery Series. Parks Canada Agency. Ottawa. vi + 19 pp.

Goward, Trevor. 2004. SEASIDE CENTIPEDE (HETERODERMIA SITCHENSIS): PORTRAIT OF A LICHEN. In the Botanical Electronic News, No. 335

September 29. Accessed online July 2010.

BC Species & Ecosystems Explorer (BC ConservationDataCenter Summary Report)

Bjork, Curtis et al. 2010. Ways of Enlichenment: The Book (online). Accessed online July 2010.

International Forest Products Limited and BC Ministry of Environment. 2003.A Field Guide to Species at Risk in the CoastForest Region of British Columbia

Develop With Care: Environmental Guidelines for Urban and Rural Land Development in British Columbia.

BC Species & Ecosystems Explorer (BC ConservationDataCenter Summary Report)

NatureServe Explorer

Committee on the Status of Endangered Wildlife in Canada

E-Flora Electronic Atlas of the Plants of British Columbia

USDA, NRCS. 2010. The PLANTS Database

Image credits:

Seaside Centipede: Tim Wheeler

Habitat: Random Truth (Flickr)

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Draft 2010

Disclaimer: This species account and related conservation recommendations are draft only and presently under review and subject to change.