INTRODUCTION
Background & Rationale
The boreal forest of Alberta is a resilient ecosystem, with its core species composition remaining largely unchanged for 8000 years, despite dramatic changes in climate and historic disturbance regimes (Gauthier et al. 2015). Non-native plant species are defined as species introduced beyond their native range, either directly or indirectly through human action, exacting changes on the ecosystem to which they are introduced (Jeschke, 2014). Also referred to as 'invasive species', they are also often categorized as opportunistic, meaning that a physical disturbance may be required to provide an entry point for their establishment. Once non-native species are introduced there is the potential that they will propagate and spread, displace native species, and alter ecological functions.
Through anthropogenic forest fragmentation resulting from forestry and industrial activities, we provide new opportunities for non-native species to invade (Sakai, 2001). The fragmentation of these forests through linear disturbances, such as roads and seismic lines; or large, punctuated events like forest fires could provide an opportunity for non-native species to infiltrate (Morgan and Neuenschwander, 1988). There is already evidence to suggest that the combination of climate change and human disturbances pose a threat to the current state of our boreal forests (Steffen, et al. 2015). Invasion can be complimented through the dispersal ability of individual species, and disturbance regimes of the ecosystem (Brothers, et al. 1992).
The heavy disturbance regimes were are enacting on Alberta's boreal could unintentionally compliment the opportunistic nature of these invasive species. By studying common disturbances in Northern Alberta and the propagation of non-natives species that pose a threat of invasion, we hope to better understand the migration of these threatening species, and how the future composition of our boreal forest may be affected.
The boreal forest of Alberta is a resilient ecosystem, with its core species composition remaining largely unchanged for 8000 years, despite dramatic changes in climate and historic disturbance regimes (Gauthier et al. 2015). Non-native plant species are defined as species introduced beyond their native range, either directly or indirectly through human action, exacting changes on the ecosystem to which they are introduced (Jeschke, 2014). Also referred to as 'invasive species', they are also often categorized as opportunistic, meaning that a physical disturbance may be required to provide an entry point for their establishment. Once non-native species are introduced there is the potential that they will propagate and spread, displace native species, and alter ecological functions.
Through anthropogenic forest fragmentation resulting from forestry and industrial activities, we provide new opportunities for non-native species to invade (Sakai, 2001). The fragmentation of these forests through linear disturbances, such as roads and seismic lines; or large, punctuated events like forest fires could provide an opportunity for non-native species to infiltrate (Morgan and Neuenschwander, 1988). There is already evidence to suggest that the combination of climate change and human disturbances pose a threat to the current state of our boreal forests (Steffen, et al. 2015). Invasion can be complimented through the dispersal ability of individual species, and disturbance regimes of the ecosystem (Brothers, et al. 1992).
The heavy disturbance regimes were are enacting on Alberta's boreal could unintentionally compliment the opportunistic nature of these invasive species. By studying common disturbances in Northern Alberta and the propagation of non-natives species that pose a threat of invasion, we hope to better understand the migration of these threatening species, and how the future composition of our boreal forest may be affected.
RESEARCH OBJECTIVESBoreal resistanceExplore the relationship between initial non-native plant arrival, with varying disturbance regimes
Non-native migrationTest the assumption that our boreal forests are largely resistant to invasion, by measuring migration of invasives along linear disturbances
Boreal resilienceUnderstand how both natural and anthropogenic disturbances may contribute to the future composition of those forests
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Seismic line in Alberta's Boreal (Photo by Adam Sprott)
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EXPECTED RESULTS
Diagram of expected non-native concentrations, and distributions under varying disturbance regimes (Seed distribution is part of a larger study). Undisturbed forests have low invasion, and low penetration of invasives. A Burned forest is likely to be more invaded that an untouched forest. Linear disturbances are then likely to increase the distances that invasive species are able to penetrate within the forest.
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It is largely accepted that Alberta's boreal forest is both resistant and resilient, meaning that it is unlikely to be easily invaded, and that the forest composition will return to it's original state after a disturbance. If these assumptions hold true, then we would expect to find very little non-native species present within the forest itself; and we would also expect that sections of the boreal that have been disturbed, will regrow with a healthy composition of native species.
Opposing evidence on the opportunistic nature of non-native species, and suggest that we may find early evidence on non-native species after disturbances have occurred. (Honnay, 2002) has shown that when these undesirable species do infiltrate an ecosystem, they are often confined to the edges of ecosystems and disturbances. Suggesting that undisturbed forests will experience low invasion, and low migration of invasives. Increased levels on invasion will experience higher levels of invasion, with the greatest density of invasion occurring along edge of these disturbed sites. |