The Facilitative Role of Kosteletzkya pentacarpos in Transitioning Coastal Agricultural Land to Wetland During Sea Level Rise

Rising sea level is increasing soil salinity and flooding frequency, directly impacting low-lying coastal farmlands. In response to reduced production of traditional crops, dikes may be built which will prevent inland migration of wetlands. Seashore mallow, Kosteletzkya pentacarpos, is being developed as an alternative crop for such areas. Eventually, when the crop can no longer be harvested because of flooding, we hypothesize that seashore mallow will facilitate the establishment of desirable wetland species by acting as a nurse crop through this transitional period. Four treatments were planted in flood-irrigated plots at an upland field site adjacent to a salt marsh. The control, Spartina patens, K. pentacarpos, and combined treatments were laid out in a complete randomized block design with replication. These were sampled for species percent vegetative cover, morphological traits, above-ground biomass, and leaf litter. The presence of seashore mallow enhanced S. patens and Baccharis halimifolia recruitment and did not negatively impact growth of planted S. patens. Communities established around K. pentacarpos were both productive and diverse, and leaf litter was increased by K. pentacarpos. Our findings support the use of K. pentacarpos as a low-cost nurse crop in salinized agro-ecosystems. Such a strategy would prolong agricultural function and minimize loss of ecological services by allowing gradual inland wetland migration.