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Regional and global biodiversity may be underestimated due to the presence of cryptic species: species that are morphologically similar, but genetically distinct. Here, we focus on two cryptic duckweed species, Lemna minor L. and Lemna turionifera Landolt, which have overlapping geographic ranges and are easily mistaken for one another. We developed species-specific primers based on DNA barcoding sequences to facilitate the rapid identification of these two monomorphic duckweeds, allowing us to investigate their presence and distribution in Alberta, Canada. While current reports indicate the presence of L. turionifera (and the morphologically distinct Lemna trisulca L.) in Alberta, our data indicate that L. minor is also present, predominantly in the southern part of the province. Thus, this paper (i) contributes to the accuracy and completeness of a regional flora, and (ii) provides useful and flexible tools for the rapid molecular identification of cryptic Lemna species, which are of wide interest in diverse fields such as biotechnology, toxicology, bioremediation, and ecology.

Understanding the ecology and life history of rare species is critical to assessing their conservation status and developing effective management strategies. We examined the habitat and demography of impoverished pinweed (Lechea intermedia var. depauperata), a rare, narrowly endemic post-fire coloniser native to the Athabasca Plain of Canada, using a combination of germination tests, plant community assessments, and microclimate monitoring. In addition, we monitored demographic trends over three years in five of six known extant populations to explore the temporal dynamics of impoverished pinweed populations. Areas supporting impoverished pinweed populations were found to be warmer than adjacent areas during the growing season; however, warmer temperatures did not correlate with higher seed germination. Plant community composition varied little between occupied and unoccupied areas. Demographic assessments suggest the taxon is likely a short-lived perennial, and populations appear to be self-sustaining in the short term. Based on work presented here and in a previous study, we suggest that impoverished pinweed has several characteristics of inherently vulnerable taxa, and we recommend that population trends be monitored over time. Further, we recommend directions for future work to address identified outstanding knowledge gaps.

Rare species are an ecologically important component of biological communities, but may be at risk of decline as a result of human disturbance and other sources of environmental change. Rare species are also ecologically idiosyncratic, making their occurrence difficult to predict a priori, and leading to efforts to find surrogate measures of rare species occurrence to inform conservation decisions. Using floristic data collected at 602 sites in the western Canadian boreal forest, we studied relationships between rare species occurrence, species richness and habitat type, with rarity defined according to the classification system developed by Rabinowitz (in: Synge (ed) The biological aspects of rare plant conservation, Wiley, Somerset, 1981). Relative to similar studies in other temperate regions, we found that a smaller proportion of species were classified as rare in our study region, and that common species dominate the flora. Regional-scale relationships were positive between richness and the occurrence of rare species; however, due to variation in these relationships among habitat types, richness is not a suitable surrogate for a site’s conservation value with respect to species rarity.

Impoverished pinweed (Lechea intermedia var. depauperata Hodgdon, Cistaceae) is a narrow endemic restricted to the dry, fire-prone Athabasca Plain in northeastern Alberta and northwestern Saskatchewan, Canada. Little is known about the ecology or life history of the taxon that could be used to inform conservation or management decisions. We investigated the reproductive biology of impoverished pinweed to determine whether it exhibits the suite of traits characterizing the temporal disperser syndrome, which is prevalent among Cistaceae species inhabiting fire-prone environments. Specifically, we examined the soil seedbank, characterized seed production, and conducted three sets of germination trials examining the interaction of heat and scarification, burial, and alternate wetting and drying. Our results show that impoverished pinweed is similar to other Cistaceae with respect to seed production, dispersal, and germination, supporting the classification of impoverished pinweed as a temporal disperser. Exposing seeds to temperatures between 125 and 175 °C significantly increased germination as compared with the untreated controls. We discovered an additional cause of seed loss incidentally; here we report the first western Canadian records of Anthonomus pusillus Le Conte, a seed-predating weevil. Our results suggest that the temporal and spatial dynamics of impoverished pinweed populations are strongly shaped by fire and the distribution of soil seedbanks.

Species sensitivity values can be used to trigger management interventions and prioritize areas for conservation, with sensitivity estimation methods ranging from expert opinion to empirical modelling. The opinion and modelling approaches each have strengths and weaknesses, raising questions of how much they (dis)agree or which one to follow in conservation assessments. We compared conservatism values assigned by botanists to modelling estimates of sensitivity (change in abundance between current and reference conditions) for 123 wetland macrophyte species across northern prairie and boreal forest regions of Alberta, Canada. Scores from each method were positively correlated and showed limited differences especially in the boreal region. Conservatism distributions for species were broadly similar between regions whereas model-based score distributions differed between regions, probably because the modelling incorporated site-specific responses of species to environmental conditions prevalent in each region. A few species had large mismatch between conservatism and model-based scores, but these cases resulted from extenuating factors and do not reflect systematic bias in expert opinions or the modelling process. Overall the results indicate potential for general agreement between quantitative and qualitative methods of sensitivity estimation, and a complementary approach of expert opinion and modelling may offer the most valuable currency for conservation assessments.

We created and evaluated indices of plant performance using plant morphological and physiological attributes and assessed their potential as wetland condition indicators by studying their consistency along a stress gradient. Based on Spearman coefficients, we selected promising morphological and physiological metrics that showed consistent responses along a physico-chemical stress gradient. Metrics consistently associated with wetland condition were ranked and combined into morphological (mPPI) or physiological Plant Performance Indices (phPPI). Six morphological metrics were able to discern between good and poor wetland conditions along the impact gradient and were thereafter combined into the mPPI. The resulting mPPI was found to be a strong indicator of stress and accurately identified degraded wetlands (r s = −0.52; P = 0.030). In contrast, most of the physiologic metrics showed lower correlations to the stress gradient. Consequently, the resulted phPPI had a lack of association with the stress gradient and failed to identify even heavily-impacted wetlands (r s = −0.30; P = 0.194). We conclude that the morphological characteristics of plants, the reliability of the mPPI, and its ability to simply and easily convey habitat information makes it worthy of further refinement and validation as a tool for evaluating mitigation and restoration efforts in wetlands.

Recreational activities in alpine areas have been increasing in recent decades, creating the need to improve our understanding of the impacts of these activities and how they are best managed. We explored impacts of recreational trail use on dry alpine meadows in the northern Canadian Rockies of Alberta. Data collected in 142 plots (0.5 m × 1 m) were used to compare plant community metrics among (1) a recreational trail, (2) intact tundra meadows (undisturbed), and (3) sparsely vegetated gravel steps formed by frost disturbance (naturally disturbed). As compared to undisturbed tundra, trails had substantially lower cover of vascular plants (4% vs. 35%), lichen (0% vs. 10%), and cryptogamic crust (0% vs. 4%); trails also had lower species richness (7 vs. 11 species per plot), but greater soil compaction (2.75 vs. 1.25 kg cm-2). Trails differed from natural gravel steps, which had three times more biotic cover and different composition. This highlights the difference in effects of human and natural...