SummaryConsiderable 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.

The fate of Northern peatlands under climate change is important because of their contribution to global carbon (C) storage. Peatlands are maintained via greater plant productivity (especially of Sphagnum species) than decomposition, and the processes involved are strongly mediated by climate. Although some studies predict that warming will relax constraints on decomposition, leading to decreased C sequestration, others predict increases in productivity and thus increases in C sequestration. We explored the lack of congruence between these predictions using single-species and integrated species distribution models as proxies for understanding the environmental correlates of North American Sphagnum peatland occurrence and how projected changes to the environment might influence these peatlands under climate change. Using Maximum entropy and BIOMOD modelling platforms, we generated single and integrated species distribution models for four common Sphagnum species in North America under current climate and a 2050 climate scenario projected by three general circulation models. We evaluated the environmental correlates of the models and explored the disparities in niche breadth, niche overlap, and climate suitability among current and future models. The models consistently show that Sphagnum peatland distribution is influenced by the balance between soil moisture deficit and temperature of the driest quarter-year. The models identify the east and west coasts of North America as the core climate space for Sphagnum peatland distribution. The models show that, at least in the immediate future, the area of suitable climate for Sphagnum peatland could expand. This result suggests that projected warming would be balanced effectively by the anticipated increase in precipitation, which would increase Sphagnum productivity.

Aim Hydroclimatic shifts and anthropogenic‐driven nitrogen deposition are major outcomes of global change that could compromise the functioning of many peatlands as a carbon sink. For Sphagnum‐dominated peatlands, an emerging hypothesis is that the change could be triggered by shifts in competitive dominance among plant functional groups, specifically from the currently predominant decay‐resistant Sphagnum to the more decomposable vascular plants. However, the relationship between Sphagnum and vascular plant occurrence is notably complex and also includes facilitative interactions that are crucial to the productivity of Sphagnum, and therefore, carbon sequestration. Location Global. Taxa Northern peatlands—Sphagnum moss and vascular plants. Time period Present day and the future. Methods We use a conceptual review to examine underlying mechanisms for the competitive exclusion hypothesis and the nature of facilitative interactions between Sphagnum and vascular plants under potential global change conditions. We complement the review with an empirical study of peatlands with contrasting hydrology to provide some critical insights into the potential effects of change in plant communities on carbon sequestration. We also propose a conceptual model that presents probable combinations of global change factors and their implications for carbon sequestration. Results Vegetation structure in Sphagnum‐dominated peatland appears to be driven largely by hydrology, rather than competition among plant functional groups. The peat deposit also exerts some controls (e.g., nutrient immobilization) on biotic structure, thereby acting as resistance against an abrupt shift in plant communities. Main conclusions Peatland controls that constrain vegetation shifts have developed over a millennial time‐scale in many peatlands, and the pace of climate change may not allow enough time for the establishment of those mechanisms in younger peatlands. Thus, the persistence of a given peatland as a carbon sink also likely depends on the successional stage of the peatland.

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