In boreal peatlands, the aboveground (plant) and belowground (microbial) communities are acutely linked because the whole soil profile is partially decomposed plant matter (peat), and dictates the nutrients available to the belowground system. We characterized the aboveground and belowground communities in two boreal peatlands: a Sphagnum-dominated fen and a Carex-dominated fen. We link the plant and microbial communities by observing plant, litter and peat carbon and nitrogen values. The Sphagnum-dominated fen had greater plant diversity but provided low quality litter inputs (high carbon:nitrogen) that formed peat and that corresponded with greater fungi:bacteria and Gram-positive:Gram-negative bacteria microbial community compared to the Carex-dominated fen. The higher quality plant inputs in the Carex-dominated fen supported a 5 × greater microbial biomass that was also 2 × more active (as measure by CO2 production). In this approach we highlight that peatlands and their component plant and microbial communities play-out along a common resource-spectrum that dictates ‘fast’ vs ‘slow’ carbon and nutrient cycling (i.e., a plant–soil interaction spectrum) that can, in turn, affect carbon storage potential. As peatland plant community composition is predicted to shift and decomposition rates are expected to increase under climate change, our work highlights the importance of understanding plant–soil microbial interactions.

Questions Climate warming has been demonstrated to shift peatland plant community composition fromSphagnummosses to vascular plants inSphagnum-dominated peatlands. However, fewer studies have determined how increasing temperature affects vegetation patterns inCarex-dominated peatlands. As plants are important determinants of carbon storage potential in peatlands, we aim to determine how climate warming alters plant community composition in peatlands of two different vegetation types. Location Boreal peatlands in north-central Ontario, Canada. Methods In aSphagnum- and aCarex-dominated peatland over two growing seasons, we instigated passive warming using clear open-topped chambers, providing a modest increase (1-2 degrees C) in temperature. In replicated plots we examined shifts in plant community composition using the point intercept method, and total above-ground biomass using Leaf Area Index (LAI) against non-warmed control plots. Results While there was no difference in species diversity between control and warmed plots in either fen site, warming significantly increased above-ground biomass in theCarex-dominated fen and decreased moss abundance in theSphagnum-dominated fen. Both fens also displayed significantly different plant community composition between warming and control plots, and increased heterogeneity under warming. Conclusion Peatlands are important global carbon stores and the plant community contributes to their carbon storage;Sphagnummosses, in particular, are linked to high peatland carbon storage potential. Previous studies inSphagnum-dominated peatlands have shown concomitant declines inSphagnumbiomass and increases in vascular plant biomass, and in the short term, we show only a decline inSphagnum. At both sites the increase in plant community heterogeneity suggests that climate warming effects on plant community composition in boreal peatlands may be more unpredictable than the literature suggests. Furthermore, this study demonstrates that plant community shifts occur even under modest warming scenarios.

In the past, most sunflower research was conducted in tilled cropping systems and was based on wide row configurations established using precision planters. Little agronomic information is available for the no-till systems predominant in Saskatchewan, where crops are typically seeded in narrow rows using an air drill. Two studies were conducted in Saskatchewan to determine the optimum seeding and nitrogen (N) rates for short-season sunflowers in a no-till cropping system. The N rate study used 5 N rates (10, 30, 50, 70, and 90 kg N ha−1) with the hybrid 63A21. The seeding rate study used 7 seeding rates (37 000, 49 000, 61 000, 74 000, 86 000, 98 000, and 111 000 seeds ha−1) with two cultivars, AC Sierra (open pollinated) and 63A21 (hybrid). There was a linear yield increase as the N rate increased from 10 to 90 kg N ha−1. Based on the N rates tested in this study and current N fertilizer costs below $1 kg−1, sunflower yields and gross returns were most favorable at 90 kg N ha−1. Future N response research with a wider range of N rates is warranted to best determine the optimum N rate. The optimum seeding rate was between 98 000 and 111 000 seeds ha−1 for AC Sierra and between 74 000 and 86 000 seeds ha−1 for 63A21. The optimum plant density, approximately 70 000 to 75 000 plants ha−1, was similar for both cultivars. These results are higher than the current recommended seeding rates for wide-row precision planting systems in areas with a longer growing season.