Need to Seed? Ecological, Genetic, and Evolutionary Keys to Seed-Based Wetland Restoration

Abstract

As we approach the Decade of Ecosystem Restoration (2021-2030), there is renewed focus on improving wetland restoration practices to reestablish the habitat and climate mitigation functions and services that wetlands provide. A first step in restoring these functions and services is to reestablish the native vegetation structure and composition through strategic seed-based approaches. These approaches should be driven by ecological, genetic, and evolutionary principles, along with consideration for economics, logistics, and other social constraints. Effective seed-based approaches must consider the chosen species, seed sourcing, dormancy break and germination requirements, seed enhancement technologies, potential invaders, seeding densities, and long-term monitoring. Choice of species should reflect historical plant communities and future environmental conditions, species that support functional goals including invasion resistance, and seed availability constraints. Furthermore, seeds should be sourced to ensure ample genetic diversity to support multifunctionality and evolutionary capacity while also considering the broad natural dispersal of many wetland species. The decision to collect wild seeds or purchase seeds will also impact species choice and genetic diversity, which can have cascading effects for functional goals. To ensure seedling establishment, seed dormancy should be addressed through dormancy breaking treatments and the potentially narrow germination requirements of some species will require targeted sowing timing and location to align with safe sites. Other seed enhancements such as priming and coatings are poorly developed for wetland restoration and their potential for improving establishment is unknown. Because wetlands are highly invasion prone, potential invaders and their legacies should be addressed. Seeding densities should strike a balance between outcompeting invaders and preserving valuable seed resources. Invader control and long-term monitoring is key to improving revegetation and restoration. Here, we review scientific advances to improve revegetation outcomes, and provide methods and recommendations to help achieve the desired goals. Gaps in knowledge about seed-based wetland restoration currently exist, however, and untested practices will certainly increase risks in future efforts. These efforts can be used to better understand the ecological, genetic, and evolutionary processes related to wetland seeds, which will bring us one step closer to seed-based restoration of functions and services needed for human and ecological communities.

Wetland Restoration with Hydrophytes: A Review

“…As seen above, both in Europe and the United States, but also in China, there has been a large tradition of aquatic ecosystems restoration [ 31 , 32 , 33 , 34 ]. For example, important native seed banking initiatives have been developed to improve the access to genetically diverse native wetland seeds for research, conservation, and restoration (European Native Seed Conservation Network (ENSCONET) and Seeds of Success (SOS)) (see references in [ 1 ]). China, with 68.5 million hectares of wetlands (36.2 and 32.3 million ha natural and constructed wetlands, respectively [ 26 ]), is one of the countries where many attempts at submerged macrophyte restoration and bioremediation have been made since the 1980s, despite the unfavorable results in some of the cases (references in [ 35 ]; reviewed in [ 36 ]).…”

“…The need to seed in wetland restoration has been widely and recently reviewed by Kettenring and Tarsa [ 1 ]. Employing strategic seed-based approaches in wetland restoration is a first step to more quickly and completely recover the underlying vegetation structure and composition that supports the vital functions and services of wetlands.…”

“…Employing strategic seed-based approaches in wetland restoration is a first step to more quickly and completely recover the underlying vegetation structure and composition that supports the vital functions and services of wetlands. Seed-based approaches are less expensive and more logistically feasible in treating larger areas than other wetland revegetation techniques (e.g., planting plugs, transplanting rhizomes and installing sod mats) despite the high cost of native seed (see [ 1 ] and references therein). However, frequently a deficiency of submerged macrophyte propagules is faced.…”

“…Hence, an effective seed-based approach should be driven by ecological, genetic and evolutionary principles, along with consideration for economics, logistics and other social constraints. Moreover, best practices for seed-based restoration must address limiting environmental factors and inform strategic management interventions for improving revegetation outcomes [ 1 ].…”

“…), and inland freshwater and saline wetlands (emergent wetlands, sedge meadows, wet prairies, fens, vascular plants in bogs, and temporary or seasonal wetlands, such as vernal pools and mudflats). Wetlands in the world provide essential ecosystem functions and services [ 1 ]: support biodiversity for conservation, improve water quality for downstream waters, combat sea-level rise, protect coastlines, mitigate the effects of flooding, drought and climate change, and provide habitat for recreation and other activities [ 2 , 3 , 4 , 5 ]. However, historically wetlands have been heavily impacted by humans, resulting in a loss of more than half of the wetlands globally, with significant impacts and risks to wildlife, humans and economies.…”