Forest Investment Account (FIA) - Forest Science Program
FIA Project Y102186

    Identifying factors affecting the succession of terrestrial lichen communities in the Omineca Region of north-central British Columbia
 
Project lead: Scott McNay (Resources North Association)
Contributing Authors: Wildlife Infometrics Inc.; McNay, R. Scott
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
In the Omineca region of BC, Government has implemented ungulate winter range (UWR) legislation to manage low-elevation pine-lichen woodlands on more than 133,430 ha of forests used by woodland caribou (Rangifer tarandus caribou). Woodland caribou are: a species at risk under the Forest and Range Practices Act in BC, are commonly considered to be a leading indicator of biodiversity and ecosystem health (e.g., see ENGO programs such as Caribou Nation, Grey Ghosts, and Staring at Extinction), and depend on UWRs with abundant terrestrial lichens for their over-winter survival. Legally designated UWR in the Omineca was stratified into units of terrestrial lichen habitat within which management direction is focused on the maintenance of forage. It was assumed that forage could be maintained using a 2-pass, 140-year rotation of forests where disturbance from logging would “restart” the ecological succession of terrestrial forage lichens (Province of BC 2005). Development of management direction was, at the time, limited in ecological scope and taken from resource conditions prior to attack by the mountain pine beetle (Dendroctonus ponderosae; MPB). After 3 years, implementation of UWR policy in the region is now considered to have been impeded by 2 fundamental assumptions: 1) all sites with terrestrial lichen follow the same ecological succession trajectory and 2) pine-lichen woodlands have sufficient economic viability to attract industrial development. In a recent workshop (Whittaker and Wiensczyk 2007), domain experts from around BC acknowledged considerable variation in succession trajectories of lichen-plant associations both within and between 3 broad regions of the province; the Chilcotin, the Entiako, and the Omineca. Current management direction for UWRs in the Omineca does not take this ecological variation into consideration. Discussion at this workshop also focused on the fact that MPB attack is replete in these regions and the effect of MPB-killed timber on UWR value is still unclear (Cichowski 2007). For example, in the Omineca, uncertainties such as “shelf life” of MPB-attacked pine, current economic factors in the industry, and policy constraints will likely lead to avoidance of UWRs by licensees; hence, largely due to the MPB, the tools assumed to manage UWRs may not be as available as initially expected.

Active management of UWRs is crucial to the long-term supply of habitat for caribou. Lack of management was predicted to lead to mid-term shortages in the supply of UWR (McNay et al. 2006; Sulyma 2001). We seek to undertake research that synthesizes several aspects of UWR ecology building new understanding of relationships among site factors, terrestrial lichen abundance, MPB-killed timber, and snowpack development. With this new knowledge, a second phase of research is focused on the relationships between fire and lichens to test management for regenerating terrestrial forage lichens. Outcomes are expected to improve local UWR management and aid the persistence of caribou populations by: a) distinguishing UWRs that require active management from those that do not; b) specifying management options for sites requiring active disturbance; c) improving the understanding of regional differences in UWR ecology; and d) improving the understanding of the likely response of caribou to MPB-attacked range.

The ecology of pine-lichen woodlands can be summarized as a sere which develops to a zonal plant community with lichens being replaced by either Arctostaphylos uva-ursi or feather moss (Coxson and Marsh 2001; Pharo and Vitt 2000; Rowe 1984; Sulyma and Coxson 2001; Williston et al. 2006). However, this generalization is too simplistic (Ahti 1977) to guide management of UWRs for caribou in northern BC. In the Chilcotin, lichen ecology is driven by climate; in the Omineca lichen presence it is a function of site factors; and in the Entiako lichen ecology is driven by both climate and site factors (Whittaker and Wiensczyk 2007). Where lichen development is primarily influenced by site factors (i.e., the Omineca), soils are key. Very coarse textured soils and gravels create conditions suitable for terrestrial lichens (basically because few other vegetation types can grow there) on sites that would be considered non-successional. By comparison, on sites with relatively higher fine fraction components in the soil, complex patterns of vegetation succession processes are more evident (Sulyma 2001). For these reasons, we expect the generalized ecology of lichen succession (Coxson and Marsh 2001) to characterize some, but not all UWR sites in the Omineca. We propose that more effective management of pine-lichen woodlands could be achieved through refined understanding and geographic delineation of the site factors contributing to succession of terrestrial forage lichens.

Caribou in the Omineca region spend much of the winter in low-elevation UWRs (Unpubl. data, Wildlife Infometrics Inc.) but use among sites is transitional and related to snow depth and snowpack development (Johnson 2000). Site factors also contribute to the development of forest overstory, the primary factor responsible for snow interception (McNay et al. 1988). In this phase of research, we seek to understand the breadth of site and forest canopy conditions within UWRs, the relationships of these factors with snow interception, and use by caribou. Data for this component were collected as part of an earlier project (FIA Land-Based Investment Program) but have never been used in this way. We expect the assessment of these data to reveal relationships between snow pack and lichen abundance and believe correlation of these factors is tied to the transitional use by caribou pending tradeoffs between them. We propose that more effective management of UWRs could be achieved if this trade-off was better understood and delineated geographically.

MPB attack on UWRs has potential to influence snow interception and terrestrial lichen abundance. Based on site factor relationships identified above, we propose that on some but not all sites, the loss of the overstory canopy from MPB attack will influence snow conditions and lichen abundance (Pharo and Vitt 2000; Sulyma and Coxson 2001) in a manner that reduces opportunities for caribou to dig for terrestrial forage lichens. In the Omineca, some healthy pine stands still exist and are forecasted to remain free from attack by the MPB through to 2010 (Walton et al. 2006) providing the opportunity to undertake pre-beetle measurements on crown closure, snow interception, and lichen abundance. A reduction in availability of low-elevation UWR due to MPB attack may elevate the importance of high-elevation ranges during winter and either shift emphasis of current recovery efforts from one range type to another or demonstrate the urgency to actively manage for an increased supply of terrestrial lichens in the mid-term.

The role of fire in the succession trajectory of terrestrial lichens has been well documented (Johnson 1981; Maikawa and Kershaw 1976; Thomas and Alaie 1996; Webb 1998). Fire maybe a useful tool to perpetuate long-term supply of terrestrial forage lichens on those sites delineated as non-climax. Fire can reduce ground vegetation and organic accumulations creating favorable conditions for terrestrial lichens. Identifying and developing tools for lichen woodland management could be paramount in a post beetle era. If successional sites are left undisturbed after beetle attack, it is possible that they may be lost over the next 150 years from areas deemed to provide winter forage and cover attributes for caribou. In the absence of industrial activities, and in partnership with BC Parks, we propose adaptive management using prescribed fire to determine the feasibility of restoring lichen microsite conditions where necessary to do so.
Related projects:  FSP_Y091186FSP_Y113186

    Deliverables:

Executive summary - year 2 (86Kb)
Wildlife Infometrics news bulletin v5i1, April 2010 (0.6Mb)
Slide presentation: Omineca Northern Caribou Project (3.9Mb)

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Updated May 02, 2011 

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