The flora and fauna of high-elevation habitats are often particularly sensitive to disturbance. The Coast Mountains of BC receive very high levels of snow fall and, with the combination of high elevation and northern latitude, typically have very short growing seasons. Plant species that grow and animals that live at high elevations often are narrowly adapted to this specific habitat and thus potentially very sensitive to disturbance. Due to the magnitude of disturbance expected to result from the proposed pipeline work, these communities are likely to be locally heavily impacted by blasting and construction. The slow-growing plants and lichen mats, a very short growing and reproductive season for vegetation and animals, and a generally harsh and resource-limited environment that characterize high-elevation communities create unique challenges for restoration. Compounding the challenges for restoration in the high elevation is the small number of studies that have examined high-elevation biodiversity and ecosystem function (i.e., Hooper et al. 2005; Lecerf and Richardson 2009; Dangles et al. 2011), the inherent difficulty in accessing the sites, and the likely changes in substrate material (i.e., to cobble from blasting residuals) along much of the high-elevation portions of the route.
Much of the high-elevation route of the pipeline is covered with lichens and slow-growing alpine plants and, therefore, restoring the vegetation cover on the RoW will be challenging; particular care will be needed not to introduce invasive species. Revegetating the RoW and associated work areas will not necessarily ensure that ecological restoration has been accomplished (e.g., Majer 1983, 1989; Jansen 1997; Bowler 2000; Longcore 2003). Arthropods have been recognized as efficient indicators of ecosystem function and have been recommended for use in restoration assessment (Rosenberg et al. 1986; Kremen et al. 1993; Finnamore 1996). Similarly, the restoration of soil crusts and lichens not only promotes soil conservation, but also supports many biological processes that promote restoration of ecosystem functions (Bowker 2007) including nitrogen fixation.
Arthropods comprise a large proportion of the biodiversity present in any environment and can be valuable indicators of ecosystem health (Hodkinson and Jackson 2005), particularly in alpine ecosystems where the harsh environmental conditions exclude many other groups of animals. Different invertebrate species, within groups such as hexapods (i.e., insects, collembolans) and arachnids (i.e., spiders, mites), each have specific biological, physiological and ecological requirements, making them ideal taxa with which to assess environmental changes resulting from factors such as climatic events or anthropogenic disturbances (Gerlach et al. 2013). Due to the essential ecological services they provide, such as wildlife nutrition and pollination (Losey and Vaughan 2006), and their intermediary position in food web dynamics, they are intricately involved in the overall functioning of ecosystems.
Biological soil crusts are complex communities containing bacteria, cyanobacteria, algae, mosses, liverworts, fungi and lichens, which are important contributors to N2-fixation in alpine and polar environments (Nakatsu and Ohtani 1991, Wojciechowski and Heimbrook 1984; Stewart et al. 2011). Diazotrophic (i.e., nitrogen fixing) bacteria are ubiquitous soil surface micro-organisms in high-elevation environments and they are typically the primary source of newly fixed nitrogen in what are otherwise often nutrient-limited environments (Alexander et al. 1978, Holzman and Haselwandter 1988, Turk and Gartner 2003). Although high-elevation soils contain diverse diazotrophic communities, cyanobacterial species are the major component (Duc et al. 2009), often growing profusely within biological soil crust communities. Cyanobacterial symbioses with lichens are also important in alpine habitats, especially in xeric microsites, providing a major source of newly fixed nitrogen (Alexander et al. 1978, Crittenden and Kershaw 1979, Gunther 1989). As a functional group, soil surface diazotrophs typically colonize early successional and newly disturbed alpine habitats, where they play an important role in facilitating the development of soil properties (Belnap et al. 2001, Schmidt et al. 2008). Not only do soil crusts contribute newly fixed nitrogen to disturbed soils, but complex carbohydrates exuded by biological soil crusts increase soil organic matter content, binding soil particles together, and promote moisture retention in surface horizons (Belnap 2001). Soil crusts may act as keystone communities in establishing primary successional processes and returning disturbed ecosystems to a desirable trajectory (Bowker 2007).
Unlike commercial stabilization products, initial restoration efforts that
incorporate the use of soil crusts may offer soil protection, as well as
initiate a number of biological processes promoting restoration of ecosystem
functions (Bowker 2007; Doudle and Williams 2010). Nitrogen fixing cyanobacteria
are common pioneering species during the amelioration and revegetation of
degraded ecosystems and have been frequently regarded as biofertilizers and soil
conditioners (Rao and Burns 1990; Zimmerman 1993; Acea et al. 2001). Inoculation
of soils with cyanobacterial species leads to the formation of organo-mineral
aggregates composed of cyanobacterial filaments and extracellular
polysaccharides (EPS), where coating, enmeshment, binding and gluing of
aggregates and isolated mineral particles significantly improves soil stability
(Zimmerman 1993; Neuman et al. 1996; Zulpa de Caire et al. 1997; Acea et al.
2001; Malam Issa et al. 2001; Malam Issa et al. 2007). In addition, EPS increase
soil organic matter content and can be an important source of carbon, helping to
ensure microbial growth and survival in soils by their capacity to buffer
nutrient supply to microorganisms closely associated with their surfaces (Zulpa
de Caire et al. 1997). Biological soil crusts can also change the spatiotemporal
pattern of soil moisture and influence re-allocation of moisture by decreasing
rainfall infiltration, increasing topsoil water-holding capacity and altering
evaporation (Li et al. 2010; Spröte et al. 2010). These changes in hydrologic
conditions within the soil are important in controlling floristic and structural
changes in vegetation.