## 3 Ecological Impacts of Energy Development
### Introduction of Novel Ecosystems  
Forest land uses can have dramatic direct and indirect effects on community structure. Access corridors are common throughout North American forests and these features can serve as vectors for transporting invasive species throughout a landscape. Invasion of non-native species can result in changes to ecosystem composition, structure and function. Novel combinations of flora and fauna make the future state of a forested landscape challenging to predict and render comparisons to historical states unreliable. Non-native species can be introduced into forests directly by intentional planting, as in the case of Alberta where, up to _ca_. 1990, cut lines and well sites were re-planted with non-native plant species [29,46], or indirectly by unintentional transportation on vehicles and people [64]. Such dispersal mechanisms are exacerbated in forests undergoing significant energy development because density of access features can be as much as four times greater on these landscapes due to pipelines, cut lines, and roads connecting to well sites [65]. Moreover, forest edge habitats are particularly prone to be invaded by non-native plant species due to exposure to wind, light, and nutrient availability [46]. The ecological impacts of non-native species are numerous and [PERSON] and colleagues [66] review and compile hypotheses of the mechanisms related to each. In North America, the distribution and abundance of predators has been altered by forest land uses related to energy development [67]. In the Rocky Mountain Foothills of Alberta, grizzly bear (_Urtsus arctos_) populations have declined due to human-related mortality associated with the increasing density of access corridors in the region and the range of the species has been constrained by a greater presence of humans [67,68]. Wolves (_Canis lupus_) showed similar responses to human presence on heavily developed landscapes and, as a result, the predation success and behavior of the species was altered leading to other changes in the trophic web [41]. Since the 1960s, predators have been perceived to exert top-down controls on community structure [69]. Anthropogenic activity is believed to mediate trophic cascading by removing predators or increasing the rate of predation [41]. For example, in Yellowstone the expatriation of wolf was \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type of** & **Ecosystem** & **Example** & **References** \\
**Disturbance** & **Services Impacted** & & \\ \hline Pipelines & Erosion control & Dredging of the Mississippi River delta plain for navigation and pipelines & \\  & Storm surge & has resulted in significant loss of native marsh vegetation due to high influx & [61] \\  & and flood buffering & of salt water, which has also increased erosion of the delta. & \\ \hline  & & After 35 years, most seismic lines in Alberta had not recovered to a forested & \\  & Carbon storage & condition, thus reducing carbon storage of the forest. & \\ Seismic lines & Carbon storage & Caribou (_Ranger_) avoid linear features, presumably due to increased risk of & [20,32, 33, 34] \\  & Subsistence resources & predation by wolves, although the association between caribou mortality & \\  & and distance to linear features like seismic lines remains disputed. & & \\ \hline  & & Methane contamination of drinking water from hydraulic fracturing in the & \\  & Water purification & Marcellus and Utica shale formations of Pennsylvania. & \\ Well sites & Carbon storage & Poor productivity of abandoned well sites and the conversion of a carbon & \\  & Subsistence resources & sink (forest) to a source (producing well site). & [29,31,32,35] \\  & & Ungulates have been observed to avoid industrial features like well sites, & \\  & & thus resulting in functional loss of otherwise suitable habitat. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._related to reduced cottonwood (_Populus_ spp.) and aspen (_Populus tremuloides_) recruitment [70, 71].