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Saltcedar (Tamarixspp.) is an invasive plant that has only recently been detected in Canada. The goals of our research were to predict the potential geographical distribution of saltcedar in Prairie Canada (Alberta, Saskatchewan and Manitoba) and to enhance our invasive species models by incorporating expert knowledge. We used ecological niche modelling (ENM) to build our predictive models and a jackknife procedure to select the predictive variables. To test model predictivity, occurrence points were spatially partitioned into quadrants. We developed a questionnaire that was then used by four local weed experts to evaluate the performance of each model and then used the expert knowledge to refine the ENM. The resulting model indicated that the potential distribution of saltcedar extended well beyond the known distribution into areas of Alberta, Saskatchewan and Manitoba. Areas identified by our model as having potential distribution should be targeted by resource managers and decision makers for early detection surveys and efforts to prevent further spread of saltcedar. [ABSTRACT FROM AUTHOR]

The article describes Pueraria montana var. lobata, a perennial climbing vine known for its rapid and competitive growth. Pueraria Montana var. lobata also known as kudzu is a perennial climbing vine with stems re-growing from the root system each spring; it produces an extensive root system with massive tuber-like swellings. Although known for its ornamental value, once established, kudzu is difficult to eliminate or control; herbicides, burning, mowing can be effective control measures.

Purple Loosestrife (Lythrum salicaria) is an invasive plant introduced into North America in the early 1800s. It has since spread into the prairie provinces of Canada (Manitoba, Saskatchewan, and Alberta). It invades wetland habitats, marshes, riparian areas, and natural areas, and it outcompetes native wetland vegetation. In this study we modelled the potential distribution of Purple Loosestrife in the Prairies, explored which suites of predictive variables produced the best ecological niche models, and explored two different approaches to the partitioning of data in evaluating models. We used a number of performance measures and expert evaluation to select our best models. The best model was developed using a suite of climate variables and growing degree-days as the predictive variables and by partitioning testing and training data using stratified random sampling. The model indicated that Purple Loosestrife has not yet reached its full potential distribution in the Prairies. The modelling techniques presented in this paper may be used to predict the potential distribution of other emerging invasive plants, and the results can be used to optimize early detection and surveillance strategies for Purple Loosestrife in areas of the Prairies. [ABSTRACT FROM AUTHOR]

Purple Loosestrife (Lythrum salicaria L.) has become recognized as an invasive alien plant having deleterious impacts on Manitoba's natural areas. The first herbarium specimen of Purple Loosestrife was collected in 1896 near Neepawa followed by infestations in 1944 at Lockport and in 1951 in Winnipeg. As of 1991 there were 38 known populations of Purple Loosestrife in Manitoba. By the fall of 2001, there were a known 492 populations covering an estimated 5575 ha of habitat. These data indicate a 13-fold increase in the number of Purple Loosestrife infestations between 1991 and 2001 in Manitoba. The majority of Purple Loosestrife (77.6%) was found in central Manitoba infesting 4324 ha. The Netley-Libau Marsh, located in central Manitoba accounted for 26% of all Purple Loosestrife in Manitoba. Central Manitoba (42.6%) had the majority of all Purple Loosestrife infestations followed by the city of Winnipeg (41.4%), eastern Manitoba (9.9%) and western Manitoba (6.1%), Purple Loosestrife was commonly found in roadside ditches (46%), river banks (25%) and wetland habitats (10%,). Typha spp., Phalaris arundinacea and Carex spp. were commonly associated with Purple Loosestrife infestations. Infestations ranged from one plant to thousands of plants. Of the infestations surveyed, 9% had over 1000 plants while 52% had under 100 plants. [ABSTRACT FROM AUTHOR]