Offsite effects of mining on the frequency and abundance of five understorey plant species in western Québec (Canada)

Although the mining industry provides minerals and metals for the global market and represents important economic opportunities, it also constitutes a major anthropogenic disturbance in the ecosystems where it takes place. However, little is known about its offsite impacts on plant communities. We assessed the frequency and the abundance of five common boreal understorey plant species (Coptis trifolia, Cornus canadensis, Linnaea borealis, Lysimachia borealis and Maianthemum canadense) at different distances around six mines of Abitibi-Témiscamingue and Nord-du-Québec (Québec). Our results showed that Coptis trifolia and Maianthemum canadense were negatively affected by the presence of mines, suggesting that they might be sensitive to the loss of forest cover, particle deposition and soil contamination induced by mining. Conversely, Cornus canadensis was favoured by mining activity, which indicates its resilience to the stress caused by mines and its ability to exploit the niche space left by more sensitive species. No effects on Linnaea borealis and Lysimachia borealis were observed. Our study confirms the presence of offsite impacts of mines on plant communities and further studies considering enigmatic impacts should be made to develop our understanding of the broader environmental footprint of mining activity.

Habitat use by Veery (Catharus fuscescens) in southern Ontario

Veery (Catharus fuscescens) is a breeding migrant thrush that nests throughout much of the temperate forests within Canada. Habitat loss and degradation is thought to be responsible for a steady decline in Veery populations since 1970. We studied habitat characteristics of occupied Veery territories versus unoccupied adjacent areas in southern Ontario during the 2016 breeding season. Occupied territories were characterized as riparian deciduous forests dominated by ash (Fraxinus spp.), Black Cherry (Prunus serotina), and Red Maple (Acer rubrum) trees with an understorey of Balsam Fir (Abies balsamea) and ferns (order Polypodiales); the presence of fruit-producing plants such as Riverbank Grape (Vitis riparia) and Bunchberry (Cornus canadensis) also was important.

The Role of Water in Fast Plant Movements

Plants moved onto land ∼450 million years ago and faced their biggest challenge: living in a dry environment. Over the millennia plants have become masters of regulating water flow and the toolkit they have developed has been co-opted to effect rapid movements. Since plants are rooted, these fast movements are used to disperse reproductive propagules including spores, pollen, and seeds. We compare five plants to demonstrate three ways, used alone or in combination, that water powers rapid movements: the direct capture of the kinetic energy of a falling raindrop propels gemmae from the splash cups of the liverwort, Marchantia; the loss of water powers the explosive dispersal of the spores of Sphagnum moss; the alternate loss and gain of water in the bilayer of the elaters of Equisetum drive the walk, jump, and glide of spores; the gain of water in the inner layer of the arils of Oxalis drive the eversion of the aril that jettisons seeds from the capsule; and the buildup of turgor pressure in the petals and stamens of bunchberry dogwood (Cornus canadensis) explosively propels pollen. Each method is accompanied by morphological features, which facilitate water movement as a power source. The urn shaped splash cups of Marchantia allow dispersal of gemmae by multiple splashes. The air gun design of Sphagnum capsules results in a symmetrical impulse creating a vortex ring of spores. The elaters of Equisetum can unfurl while they are dropping from the plant, so that they capture updrafts and glide to new sites. The arils of Oxalis are designed like miniature toy “poppers.” Finally, in bunchberry, the softening of stamen filament tissue where it attaches to the anther allows them to function as miniature hinged catapults or trebuchets.

Antibacterial activity of northern Ontario medicinal plant extracts

Hassan, H. M., Jiang, Z.-H., Asmussen, C., McDonald, E. and Qin, W. 2014. Antibacterial activity of northern Ontario medicinal plant extracts. Can. J. Plant Sci. 94: 417–424. In the present study, the antibacterial activity (in vitro) of the leaf and/or flower crude extracts of Anaphalis margaritacea (L.) Benth & Hook.f., Grindelia squarrosa (Pursh) Dunal, Apocynum androsaemifolium L., Arctostaphylos uva-ursi (L.) Spreng, Cornus canadensis L. and Xanthium strumarium L. medicinal plants was analyzed through the hole-plate diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays against Escherichia coli, Aeromonas caviae, Paenibacillus alvei, Micrococcus luteus, Mycobacterium avium subsp. avium and Bacillus cereus bacteria. In addition, the time-kill dynamic processes of these extracts against A. caviae, B. cereus, P. alvei, and M. luteus bacteria were also tested. The leaf and flower extracts of Anap. margaritacea and G. squarrosa possess significant antibacterial activity against all the bacteria tested, with inhibition of A. caviae, P. alvei and M. luteus within 1–12 h of incubation at MBC. Particularly, at higher concentrations of the Anap. margaritacea flower crude extract (2–3×MBC), inhibition of A. caviae, B. cereus, P. alvei, and M. luteus bacteria is achieved between 0.5 and 4 h of incubation. In addition, these extracts exhibit high inhibition diameters (majority > 18 mm) and low MIC and/or MBCs (majority=1.25 mg mL−1). In contrast, the leaf extracts of Arct. uva-ursi, X. strumarium, Apoc. androsaemifolium and C. canadensis plants demonstrate moderate to low activity. These results indicate that extracts from Anap. margaritacea and G. squarrosa could be a source of novel antimicrobial scaffolds, compounds or pharmacophores with implications in the pharmaceutical industry and medicine.

Understory species interactions in mature boreal mixedwood forests

We explored interactions among plant growth forms in the understory of mature boreal mixedwood forests in western Canada by investigating the competitive influence of erect shrubs on herbs (forbs and grasses). We established 10 pairs of plots; all erect shrubs were removed in one plot of each pair (removals) and left intact in the other plot (controls). Two years later, we harvested all aboveground biomass of the herbaceous layer (herb biomass: this included graminoids, forbs, trailing shrubs, and species with a woody base but not woody stems) from the 20 plots. We tested for significant differences in understory species biomass and composition between control and removal plots and examined the influence of 25 environmental factors on species composition of the herbaceous layer. Competition intensity was measured by the natural logarithm of response ratio (ln RR) index based on herb biomass. After erect shrub removal, there was a significant increase in herb biomass, mostly due to an increase of the most common species (e.g., Cornus canadensis Linnaeus, Linnaea borealis Linnaeus). The values of competition intensity (ln RR) varied among herb species but were, overall, positive, indicating a release from competition following shrub removal. Composition of the herbaceous layer was significantly different between removal and control plots and was also significantly related to seven environmental factors, which explained 40% of the variation in composition. Our study suggests that there is asymmetric competition for light between erect shrub and herb species in boreal ecosystems.