Karen Gill

• MSc
• Research Assistant at University of Lethbridge

Ecosystem invasion by non-native plants depends on plant life history characteristics that influence the species’ invasiveness, as well as environmental factors that determine site invasibility. Small, insular ecosystems are thought be especially vulnerable to invasion but evidence for this pattern has been mixed. Freshwater springs form island-lik...

The South Saskatchewan River Basin of southern Alberta drains the transboundary central Rocky Mountains region and provides the focus for irrigation agriculture in Canada. Following extensive development, two tributaries, the Oldman and Bow Rivers, were closed for further water allocations, while the Red Deer River (RDR) remains open. The RDR basin...

River regulation impacts riparian ecosystems by altering the hydrogeomorphic conditions that support streamside vegetation. Obligate riparian plants are often negatively impacted since they are ecological specialists with particular instream flow requirements. Conversely, facultative riparian plants are generalists and may be less vulnerable to riv...

The transboundary St Mary River drains Glacier National Park, USA, and was progressively dammed and diverted over the 20th century to support agricultural irrigation in northern Montana and southern Alberta, Canada. Following reduced instream flows, the riparian cottonwoods collapsed, and by 2000, few parental trees remained to provide seeds for co...

Reports of abruptly declining flows of Canada's Athabasca River have prompted concern because this large, free-flowing river could be representative for northern North America, provides water for the massive Athabasca oil-sands projects, and flows to the extensive and biodiverse Peace-Athabasca, Slave and Mackenzie River deltas. To investigate hist...

To investigate climatic influence on floodplain trees, we analyzed interannual correspondences between the Pacific Decadal Oscillation (PDO), river and groundwater hydrology, and growth and wood (13) C discrimination (Δ(13) C) of narrowleaf cottonwoods (Populus angustifolia) in a semi-arid prairie region. From the Rocky Mountain headwaters, river d...

Pollen of larch (Larix × marschlinsii) and Douglas-fir (Pseudotsuga menziesii) was used in homospecific and heterospecific crosses. Germination of heterospecific pollen in ovulo was reduced in post-pollination prefertilization drops. This provides evidence of selection against foreign pollen by open-pollinated exposed ovules in these two sister tax...

Riparian or streamside zones support dynamic ecosystems with three interacting components: flowing water, alluvia (river-transported sediments), and vegetation. River damming influences all three, and subsequent responses can provide insight into underlying processes. We investigated these components along the 315-km Hells Canyon corridor of the Sn...

To predict future river flows, empirical trend projection (ETP) analyses and extends historic trends, while hydroclimatic modelling (HCM) incorporates regional downscaling from global circulation model (GCM) outputs. We applied both approaches to the extensively allocated Oldman River Basin that drains the North American Rocky Mountains and provide...

We used two independent and complementary approaches to forecast future flows; the first approach was empirical trend projection - analyses of the actual, historic flows of the river and its tributaries to investigate possible changes over the last century. These patterns were extended into the future with an assumption that the near future will ex...

The narrowleaf cottonwood, Populus angustifolia, occurs in occasionally flooded, low elevation zones along river valleys near the North American Rocky Mountains. This small poplar has narrow leaves and fine branching and thus resembles willows, which are commonly flood-tolerant. We investigated the flood response of narrowleaf cottonwoods and a rel...

We used two different and complementary approaches to forecast future flows of the Red Deer River. The first approach was empirical trend projection - an analysis of the actual, historic flows of the river and its tributaries to investigate possible changes over the last century. These patterns were extended into the future with the assumption that...

In analyzing hydrologic consequences of climate change, we previously found declining annual discharges of rivers that drain the hydrographic apex of North America, the Rocky Mountain headwaters region for adjacent streams flowing to the Arctic, Atlantic and Pacific oceans. In this study we investigated historic changes in seasonal patterns of stre...

Under pre-settlement conditions the Yakima River in Washington state, USA was characterized by multiple channels, complex aquifers and extensive riparian cottonwood forests. Subsequent implementation of headwater dams to supply irrigation water has altered river and floodplain processes critical to the cottonwoods and associated riparian vegetation...

There has been a growing concern for the decline of the globally unique native cottonwood hybrids of Southern Alberta downstream from some of the regional dams. Recognition of this problem was followed by field and laboratory research examining the dependency of the life history of these riparian cottonwoods on the natural streamflow pattern, and a...