Trade-offs between soil-based functions in wetlands restored with soil amendments of differing lability.

Soil amendments have been proposed as a means to speed the development of plant and soil processes that contribute to water quality, habitat, and biodiversity functions in restored wetlands. However, because natural wetlands often act as significant methane sources, it remains unknown if amendments will also stimulate emissions of this greenhouse gas from restored wetlands. In this study, we investigated the potential trade-offs of incorporating soil amendments into wetland restoration methodology. We used controlled field-scale manipulations in four recently restored depressional freshwater wetlands in western New York, USA to investigate the impact that soils amended with organic materials have on water-quality functions and methane production in the first three years of development. Results showed that amendments, topsoil in particular, were effective for stimulating the development of a suite of biological (microbial biomass increased by 106% and respiration by 26%) and physicochemical (cation exchange capacity increased by 10%) soil properties indicative of water-quality functions. Furthermore, increases in microbial biomass and activity lasted for a significantly longer period of time (years instead of days) than studies examining less recalcitrant amendments. However, amended plots also had 20% times higher potential net methane production than control plots three years after restoration. Wetlands restoration projects are implemented to achieve a variety of goals, commonly including habitat provision, biodiversity, and water-quality functions, but also carbon sequestration, flood abatement, cultural heritage and livelihood preservation, recreation, education, and others. Projects should strive to achieve their specific goals while also evaluating the potential tradeoffs between wetland functions.

Rewilding the small stuff: the effect of ecological restoration on prokaryotic communities of peatland soils.

To investigate the effect that restoration has on the microbiome of wetland soils, we used 16S amplicon sequencing to characterize the soil prokaryotic communities of retired cranberry farms that were restored to approximate the peat wetlands they once were. For comparison, we also surveyed the soil communities of active cranberry farms, retired cranberry farms and natural peat wetlands that were never farmed. Our results show that the prokaryotic communities of active cranberry farms are distinct from those of natural peat wetlands. Moreover, 4 years after restoration, the prokaryotic community structure of restored cranberry farms had shifted, resulting in a community more similar to natural peat wetlands than to active farms. Meanwhile, the prokaryotic communities of retired cranberry farms remained similar to those of active farms. The observed differences in community structure across site types corresponded with significant differences in inferred capacity for denitrification, methanotrophy and methanogenesis, and community composition was also correlated with previously published patterns of denitrification and carbon sequestration measured from the same soil samples. Taken together, these results suggest that ecological restoration efforts have the potential to restore ecosystem functions of soils and that they do so by 'rewilding' the communities of resident soil microbes.