Rare Plants
Finding Uncommon Plant Species in Alberta’s Northeast
By ABMI

The Lower Athabasca Region (LAR) of Alberta is home to rich and diverse plant communities, including many rare or hard-to-find species. The Athabasca sand plain south of Lake Athabasca, for example, provides a habitat for incredible specimens, such as pink lady’s-slipper (Cypripedium acaule) and pitcher plant (Sarracenia purpurea).

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Pink Lady’s Slipper orchid. Photo: Charlie Sikkema

Researchers often lack basic information about rare or hard-to-find species, like what kind of habitat the species prefers, or which other species are often found with it. In the LAR, where human activity is expected to continue to transform the landscape, not knowing where rare plants are located puts them at greater risk of local extinction due to development pressures.

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Pitcher Plant. Photo: Julia Shonfield

As a result, in 2010, the ABMI’s Rare Plants project1 was launched to (among other goals):

  1. Identify the current state of rare plants in the LAR and develop a single, user-friendly database for rare plant observations; and
  2. Predict rare plant distributions to help prioritize future sampling efforts that, in turn, will improve our understanding of rare plant habitat preferences.

To start the work of predicting rare plant distributions, Dr. Scott Nielsen—associate professor of conservation biology at the University of Alberta and the ABMI Rare Plants project lead—and colleagues identified 25 rare vascular plant species for which there was sufficient data to develop species distribution models. Species distribution models are essentially mathematical predictions of how the abundance of a given species changes in relation to various habitat characteristics. These models were then used to predict where each species is likely to be found in the LAR. Finally, the predictions of all 25 target species were rolled up into a map of the region—a predictive map of rare plants for the LAR.

Map indicating probability of encountering a rare plant species (S1 or S2) in the Lower Athabasca region of Alberta.

In 2012 and 2013, crews went out into the field to test the map—determine whether species were present where they were predicted to be—which resulted in 51 new detections for 16 of the 25 target rare plant species!

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Pinweed. Photo: Sadie Miller.

An example of the value of this approach is, in 2013, a single record of Western panicgrass (Panicum acuminatum) was collected and led to the finding that panicgrass is closely associated with another rare plant, Lechea intermedia (pinweed). At the time, the pinweed observation was the second-ever record of the species in Alberta—with more detections in 2014—and was associated with one of only a handful of populations of this species that is native to the Athabasca Sand Dunes.

Each time additional observations are made of one of the target rare plants species, Nielsen and team go back to the respective species distribution models and refine them. Then, they use the updated models to return to the field to test the modeled predictions again. This “adaptive sampling” approach results in a continuous refinement of a model where new data from previous years of fieldwork feeds into the model and improves predictions of “rarity hotspots.” By improving the model for panicgrass, for example, the team may well encounter even more populations of the elusive pinweed.

The maps produced by the ABMI Rare Plants project allow for broad, regional assessments of rarity that can inform land-use planning and pre-disturbance assessments. The work helps fill a critical information gap for regional planning in the LAR: the difficulty to identify sites with potential rare plant habitats.

For more information, please contact Monica Kohler (project coordinator) at mkohler@ualberta.ca or Dr. Scott Nielsen at scottn@ualberta.ca.

 
Additional information on the sampling methods can be found in: Zhang J, Nielsen SE, Grainger TN, Kohler M, Chipchar T, et al. (2014) Sampling Plant Diversity and Rarity at Landscape Scales:
Importance of Sampling Time in Species Detectability. PLoS ONE 9(4): e95334. doi:10.1371/journal.pone.0095334
http://www.plosone.org


1 The ABMI’s Rare Plants project was originally conceived and initiated through the Ecological Monitoring Committee for the Lower Athabasca (EMCLA). The ECMLA, a consortium of oil sands companies, government ministries, and agencies coordinated by the ABMI, was established in 2010 with the goal of designing protocols to monitor rare and elusive species.


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