Effects of one dark septate endophytic fungal and two Helotiales strains on the growth of Salix planifolia cuttings on iron ore waste rock

Plants maintain beneficial mutualistic relationships with the mycobiont communities found in their rhizosphere, leading to an increase in plant productivity and health. In nutrient-depleted substrates like mine tailings, mycobiont inoculation is often recommended to help restore a successful plant cover. Our 15-week greenhouse experiment aimed to assess the individual effects of a dark septate endophyte (Phialocephala fortinii #4; KX611529) and two Helotiales strains (Rhizoscyphus ericae #22; EU221877 and Meliniomyces sp #1; KT275679) on the growth of Salix planifolia cuttings on sterilized and unsterilized waste rock. Rhizoscyphus ericae increased cuttings shoot biomass on sterilized waste rock while Meliniomyces sp had a positive effect for cuttings grown on unsterilized waste rock. However, P. fortinii strain had no effect on the survival rate, shoot production, and biomass production of S. planifolia cuttings. This study demonstrates that controlled inoculation with ecologically well-adapted mycobionts could promote plant establishment and productivity on abandoned waste rock and be an efficient and integrated biotechnological approach for ecological restoration of canadian mining boreal ecosystems.

Effect of browse on post-ingestive energy loss in an Arctic ruminant: implications for muskoxen (Ovibos moschatus) in relation to vegetation change

Shrubs are predicted to dominate tundra with warmer temperatures at northern latitudes. We tested the null hypothesis that addition of browse to a graminoid diet would not alter post-ingestive energy loss in muskoxen ( Ovibos moschatus (Zimmermann, 1780)). Energy losses over 8 h following feeding were used to test our hypothesis. Willows ( Salix alaxensis (Anderss.) Coville, Salix planifolia ssp. pulchra (Cham.) Argus) and birch ( Betula nana L.) (twigs in winter, leaves in summer) were separately mixed at graded levels (0%, 20%, 40%, 60%, and 80%) with chopped hay ( Bromus inermis Leyss.) and fed as single meals to muskoxen. Meals containing ≥60% browse were often partially or completely rejected. Meals containing 20%–60% woody or leafy S. alaxensis or S. p. pulchra resulted in higher energy expenditure than meals of 100% hay. Meals containing 20%–60% woody B. nana tended to decrease energy expenditure relative to 100% hay, while 20%–60% leafy B. nana was similar to 100% hay. We conclude there is an energy cost associated with consuming browse. This cost varies by browse species and type. Since muskoxen tolerated up to 40% browse in the diet, this cost may be within their ecological tolerance. This tolerance has important implications under global warming scenarios.

Leaf thickness of Salix spp. (Salicaceae) from the Athabasca sand dunes of northern Saskatchewan, Canada

Leaf thicknesses of Salix taxa (Salix brachycarpa Nutt. var. psammophila Raup, Salix planifolia Pursh subsp. tyrrellii (Raup) Argus, Salix silicicola Raup, and Salix turnorii Raup) from the Athabasca sand dunes in northern Saskatchewan, Canada, were evaluated and compared with those of their respective widespread progenitors (S. brachycarpa Nutt. var. brachycarpa, S. planifolia Pursh subsp. planifolia, Salix alaxensis (Anders.), and Salix eriocephala Michx. var. famelica (C. R. Ball) Dorn). Leaf thickness was measured using standard light microscopy, and results were compared with the occurrence of amphistomaty in these Salix species. Leaf thickness values varied among the species and differed significantly within each derivative–progenitor Salix pair. The two amphistomatic taxa from Yakow Lake dunes, S. turnorii and S. planifolia subsp. tyrrellii, had significantly thicker leaves (337.65 ± 5.99 µm and 226.00 ± 5.22 µm, respectively) than their widespread progenitors, as well as the thickest leaves overall. The data comparison indicates a relationship between amphistomaty and leaf thickness among the Salix taxa, as thicker leaves tend to be amphistomatic.Key words: amphistomaty, Athabasca sand dunes, leaf thickness, Salix, willow.

Patterns of distribution of microfungi in decomposing bog and fen plants

The microfungal assemblages from the litter of the dominant vegetation of a forested bog and a riverine, sedge-dominated fen in southern boreal Alberta, Canada, were investigated over a 2-year period. Canonical correspondence analyses showed distinctly different fungal communities associated with litter of the dominant plant species of this bog (Sphagnum fuscum (Schimp.) Klinggr.) and fen (Carex aquatilis Wahlenb. leaves and rhizomes and Salix planifolia Pursh leaves and roots). Plant tissue quality variables, including total phosphorus and total nitrogen tissue concentrations, correlated most strongly with the fungal communities. In contrast, site-specific environmental (surface water chemical variables) and physical (peat and water temperatures, water level) variables were not correlated with the fungal communities of these five decomposing fen and bog plant litters. Of 93 identified fungal taxa, 25% occurred exclusively in the bog and 56% occurred exclusively in the fen. Eighteen species (19%) were common to the materials examined from both peatlands. Several species of (i) Aspergillus, Mortierella, and Oidiodendron were restricted to the Sphagnum litter in the bog, and species of (ii) Phialophora, Phialocephala, Fusarium, Dimorphospora foliicola, Monocillium constrictum, and several basidiomycetes were restricted to the Carex and Salix plant litters in the fen. These taxa constitute components of the bog and fen fungal communities, respectively.Key words: fungal communities, decomposition, bog, fen, canonical correspondence analysis (CCA).

A comparative epidermis study of the Athabasca sand dune willows (Salix; Salicaceae) and their putative progenitors

The Athabasca sand dunes are located on the south shore of Lake Athabasca in northern Alberta and Saskatchewan, Canada. Four willow shrubs (Salix; Salicaceae) occur on the open sands, two of which are endemic to the Athabasca sand dunes. Light and scanning electron microscopy were used to quantify stomatal frequency, stomatal index, trichome density, and cuticle thickness, for the Athabasca sand dune willows and their associated putative progenitors. The Athabasca sand dune taxa (Salix brachycarpa var. psammophila, Salix planifolia subsp. tyrrellii, Salix silicicola, and Salix turnorii) occur primarily on the inner dunes, and each has certain leaf epidermal features that appear to be adaptive to the exposed nature of the open sand habitat and the high light intensity. Salix brachycarpa var. psammophila and S. silicicola have tomentose leaves, with trichome densities that are significantly greater than those of their respective widespread progenitors. Salix planifolia subsp. tyrrellii and S. turnorii have amphistomatic leaves and substantially thicker cuticles than their associated progenitors. This investigation is the first to compare adaptive leaf epidermis features within the derivative–progenitor Salix pairs. Considerations for the significance of amphistomaty in the Athabasca sand dune Salix taxa are discussed.Key words: Athabasca sand dunes, cuticle, Salix, stomata, trichomes, willow.