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Considerable progress has been made in ecological and evolutionary genetics with studies demonstrating how genes underlying plant and microbial traits can influence adaptation and even 'extend' to influence community structure and ecosystem level processes. Progress in this area is limited to model systems with deep genetic and genomic resources that often have negligible ecological impact or interest. Thus, important linkages between genetic adaptations and their consequences at organismal and ecological scales are often lacking. Here we introduce the Sphagnome Project, which incorporates genomics into a long-running history of Sphagnum research that has documented unparalleled contributions to peatland ecology, carbon sequestration, biogeochemistry, microbiome research, niche construction, and ecosystem engineering. The Sphagnome Project encompasses a genus-level sequencing effort that represents a new type of model system driven not only by genetic tractability, but by ecologically relevant questions and hypotheses.

Peatlands are found on all continents, covering 3% of the global land area. However, the spatial extent and causes of metal enrichment in peatlands is understudied and no attempt has been made to evaluate global patterns of metal enrichment in bog and fen peatlands, despite that certain metals and rare earth elements (REE) arise from anthropogenic sources. We analyzed 368 peat cores sampled in 16 countries across five continents and measured metal and other element concentrations at three depths down to 70 cm as well as estimated cumulative atmospheric S deposition (1850–2009) for each site. Sites were assigned to one of three distinct broadly recognized peatland categories (bog, poor fen, and intermediate-to-moderately rich fen) that varied primarily along a pH gradient. Metal concentrations differed among peatland types, with intermediate-to-moderately rich fens demonstrating the highest concentrations of most metals. Median enrichment factors (EFs; a metric comparing natural and anthropogenic metal deposition) for individual metals were similar among bogs and fens (all groups), with metals likely to be influenced by anthropogenic sources (As, Cd, Co, Cu, Hg, Pb, and Sb) demonstrating median enrichment factors (EFs) > 1.5. Additionally, mean EFs were substantially higher than median values, and the positive correlation (< 0.40) with estimated cumulative atmospheric S deposition, confirmed some level of anthropogenic influence of all pollutant metals except for Hg that was unrelated to S deposition. Contrary to expectations, high EFs were not restricted to pollutant metals, with Mn, K and Rb all exhibiting elevated median EFs that were in the same range as pollutant metals likely due to peatland biogeochemical processes leading to enrichment of these nutrients in surface soil horizons. The global patterns of metal enrichment in bogs and fens identified in this study underscore the importance of these peatlands as environmental archives of metal deposition, but also illustrates that biogeochemical processes can enrich metals in surface peat and EFs alone do not necessarily indicate atmospheric contamination. [ABSTRACT FROM AUTHOR]

Microtopography is a common attribute of wetlands, particularly boreal bog and fen peatlands. This self-organized patterning is primarily an autogenic process; however, the role of allogenic forces such as disturbance in the maintenance of microtopography is poorly understood. In this study, we quantify the effect of fire on the distribution of the microtopographic gradient in boreal bogs using a before-after wildfire natural experiment. We also quantify the change in spatial abundance of microforms in boreal treed peatlands over a 100-year successional chronosequence. Wildfire nearly doubled the range of the microtopographic gradient, increasing the relative abundance of low-elevation microforms (hollows), although the distribution of elevations was influenced by peatland ontogeny at the time of wildfire. Through succession, raised microforms (hummocks) became more abundant, presumably due to autogenic surface drying facilitating hummock species expansion into adjacent hollows. Although autogenic processes may be responsible for the development of self-organized spatial patterning in wetlands, disturbances such as wildfire are necessary for maintaining boreal peatland microtopography over extended time scales. Because of the tight linkage between microtopography, species diversity, and ecosystem function, these feedbacks between wildfire and microtopography are critical for understanding peatland dynamics and the potential impact of a changing environment. Key words: self-organized patterning, succession, diversity, carbon, ecosystem resilience. La microtopographie est un attribut commun des milieux humides, plus particulierement des tourbieres ombrotrophes et des tourbieres minerotrophes en zone boreale. Cette structuration auto-organisee est un processus principalement autogenique mais le role des forces allogeniques, comme une perturbation, dans le maintien de la microtopographie est mal compris. Dans cette etude, nous avons quantifie l'effet du feu sur la distribution du gradient microtopographique dans les tourbieres boreales a l'aide d'une experience naturelle avant et apres feu. Nous avons aussi quantifie le changement dans l'abondance spatiale des microformes dans des tourbieres boreales boisees au cours d'une chronosequence successionnelle de plus de 100 ans. Le feu a plus que double l'etendue du gradient microtopographique, augmentant ainsi l'abondance relative des microformes basses (depressions), bien que la distribution des hauteurs ait ete influencee par l'ontogenese de la tourbiere lorsque le feu est survenu. Au cours de la succession, les microformes surelevees (buttes) sont devenues plus abondantes, vraisemblablement a cause de l'assechement autogenique en surface qui a facilite l'expansion des especes associees aux buttes dans les depressions adjacentes. Meme si les processus autogeniques peuvent etre responsables du developpement de la structuration spatiale auto-organisee dans les milieux humides, les perturbations telles que les feux sont necessaires pour maintenir la microtopographie des tourbieres boreales a long terme. A cause du lien etroit entre la microtopographie, la diversite des especes et la fonction de l'ecosysteme, ces retroactions entre les feux et la microtopographie sont essentielles pour comprendre la dynamique des tourbieres et l'impact potentiel d'un environnement en mutation. [Traduit par la Redaction] Mots-cles : structuration auto-organisee, succession, diversite, carbone, resilience des ecosystemes., Introduction Self-organized spatial patterning is a common phenomenon in a variety of ecosystems and can play a key role in ecosystem stability (Rietkerk and van de Koppel 2008). Positive feedbacks [...]

Summary

We examined the water balance of a forested ombrotrophic peatland and adjacent burned peatland in the boreal plain of western Canada over a 3-year period. Complete combustion of foliage and fine branches dramatically increased shortwave radiation inputs to the peat surface while halting all tree transpiration at the burned site. End-of-winter snowpack was 7-25% higher at the burned site likely due to decreased ablation from the tree canopy at the unburned site. Shrub regrowth at the burned site was rapid post-fire, and shading by the shrub canopy in the burned site approached that of the unburned site within 3 years after fire. Site-averaged surface resistance to evaporation was not different between sites, though surface resistance in hollows was lower in the burned site. Water loss at both burned and unburned sites is largely driven by surface evaporative losses. Evaporation at the burned site marginally exceeded the sum of pre-fire transpiration and interception at the unburned site, suggesting that evapotranspiration during the growing season was 20-40 mm greater at the burned peatland. Although the net change in water storage during the growing season was largely unchanged by fire, the lack of low-density surface peat in the burned site appears to have decreased specific yield, leading to greater water table decline at the burned site despite similar net change in storage. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Boreal peatland ecosystems occupy about 3.5 million km2 of the earth's land surface and store between 250 and 455 Pg of carbon (C) as peat. While northern hemisphere boreal peatlands have functioned as net sinks for atmospheric C since the most recent deglaciation, natural and anthropogenic disturbances, and most importantly wildfire, may compromise peatland C sinks. To examine the effects of fire on local and regional C sink strength, we focused on a 12 000 km2 region near Wabasca, AB, Canada, where ombrotrophic Sphagnum-dominated bogs cover 2280 km2 that burn with a fire return interval of 123±26 years. We characterized annual C accumulation along a chronosequence of 10 bog sites, spanning 1–102 years-since-fire (in 2002). Immediately after fire, bogs represent a net C source of 8.9±8.4 mol m−2 yr−1. At about 13 years after fire, bogs switch from net C sources to net C sinks, mainly because of recovery of the moss and shrub layers. Subsequently, black spruce biomass accumulation contributes to the net C sink, with fine root biomass accumulation peaking at 34 years after fire and aboveground biomass and coarse root accumulation peaking at 74 years after fire. The overall C sink strength peaks at 18.4 mol C m−2 yr−1 at 75 years after fire. As the tree biomass accumulation rate declines, the net C sink decreases to about 10 mol C m−2 yr−1 at 100 years-since-fire. We estimate that across the Wabasca study region, bogs currently represent a C sink of 14.7±5.1 Gmol yr−1. A decrease in the fire return interval to 61 years with no change in air temperature would convert the region's bogs to a net C source. An increase in nonwinter air temperature of 2 °C would decrease the regional C sink to 6.8±2.3 Gmol yr−1. Under scenarios of predicted climate change, the current C sink status of Alberta bogs is likely to diminish to the point where these peatlands become net sources of atmospheric CO2-C. [ABSTRACT FROM AUTHOR]