Soil seed bank can complement restoration efforts in a coastal freshwater creek

Abstract

Abstract Riparian vegetation is a keystone ecosystem element heavily impacted by livestock grazing. Historically, regeneration approaches of the riparian vegetation use either active (planting) and passive (natural regeneration) strategies. Objective frameworks based on an understanding of the soil seed bank are needed to help guide the approach adopted. This study compared the soil seed bank composition to the extant riparian vegetation to assess the potential for natural regeneration to supplement active plantings, following livestock exclusion. Our results show that the proportions of species nativeness, growth forms, and life cycle was similar for both communities, but there was an inverse relationship between wetland specialist species in both communities. While invasive species in the soil seed bank are considered a challenge, there is potential that restoration efforts may not be overwhelmed when there is a persistent native seed bank combined with other basic management strategies. The high abundance of native grass-types (Cyperaceae, Juncaceae, Juncaginaceae, Asparagaceae, Poaceae, Typhaceae), can be relied upon to regenerate the understorey to complement the planting of the upper tree layer and accelerate the successional trajectories of recovery. However, in areas that are species-rich of all native plant growth forms, redirecting resources to sites that are species-poor (especially of native trees and shrubs) could be an efficiency option. Our findings have important implications for land managers in not only selecting appropriate growth forms for restoration, but also extending their funding resources further to additional sites across the landscape.