Vegetation Responses to Restoration of Massachusetts Cranberry Bogs

After a decade of vegetation monitoring across more than 30 actively farmed, passively retired, and actively restored cranberry farm sites, what are the big takeaways?

• Active restoration of former cranberry farmland to wetlands consistently promoted biodiverse plant communities dominated by native, wetland-adapted plant species with very few non-native or invasive species, indicating widespread success in these important restoration goals.
• By 1-3 years after active restoration, the average plant species richness (or number of different species) in our monitoring plots had consistently doubled or tripled from pre-restoration levels, indicating that this metric of plant biodiversity at sites was greatly enhanced by restoration. The richness of wetland-adapted plant species also roughly doubled in this period. Afterwards, species richness consistently declined from this peak over time, but always remained higher than pre-restoration.
• By 6-8 years after active restoration, the abundance of upland-adapted plant species (or the area that they cover) had increased at several sites, indicating that the sites were becoming drier over time. The plant communities at several sites were also becoming more similar to their pre-restoration communities over time since restoration. These are concerns because a major goal of these restoration efforts is to create self-sustaining wetlands.
• All but one of the monitored restored sites, Eel River, was restored in the last decade. Longer-term monitoring of older restored sites and building in experiments during restoration planning for prospective sites would allow for better understanding of the site conditions and restoration practices which best allow biodiverse wetland communities to sustain themselves over time.
• Although they are generally not abundant at restored sites, invasive species such as Salix cinerea (gray willow) and Phragmites australis (common reed) must be continually monitored and treated or they will almost certainly spread and adversely affect biodiversity.