Introduce nurse plants to aid focal non-woody plants: brackish/saline wetlands
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Nurse plants, also known as companion plants or pioneer plants, can be planted alongside focal plants to help the focal plants establish (Padilla & Pugnaire 2006). Nurse plants may benefit focal plants in variety of ways, including: trapping and stabilizing sediments, trapping propagules, mitigating harsh environmental conditions (e.g. temperature fluctuations and strong sunlight), attracting pollinators, deflecting herbivory away from focal species, and/or limiting weed establishment.
Caution: Nurse plant species must be chosen carefully. Species that spread easily or are very strong competitors can cause more harm than good. For example, the non-native mangrove apple Sonneratia apetala has been used to restore Chinese mangroves, but has spread into neighbouring forests (Ren et al. 2009). Use of non-native nurse plants may not always be ethically acceptable.
To be summarized as evidence for this action, studies must have (a) deliberately introduced nurse plants before planting target marsh or swamp vegetation, and (b) reported the effects of the nurse plants on other vegetation, not just the survival or growth of the nurse plants. Studies must have explicitly planted vegetation for its nursing effect. Studies are not summarized as evidence here if they planted target vegetation into existing nurse vegetation (e.g. Egerova et al. 2003; McKee et al. 2007), or examined spontaneous colonization amongst planted nurse vegetation.
Related actions: Introduce nurse plants without introducing target marsh or swamp vegetation.
Egerova J., Proffitt C.E. & Travis S.E. (2003) Facilitation of survival and growth of Baccharis halimifolia L. by Spartina alterniflora Loisel. in a created Louisiana salt marsh. Wetlands, 23, 250–256.
McKee K.L., Rooth J.E. & Feller I.C. (2007) Mangrove recruitment after forest disturbance is facilitated by herbaceous species in the Caribbean. Ecological Applications, 17, 1678–1693.
Padilla F.M. & Pugnaire F.I. (2006) The role of nurse plants in the restoration of degraded environments. Frontiers in Ecology and the Environment, 4, 196–202.
Ren H., Lu H., Shen W., Huang C., Guo Q., Li Z. & Jian S. (2009) Sonneratia apetala Buch.Ham in the mangrove ecosystems of China: an invasive species or restoration species? Ecological Engineering, 35, 1243–1248.
Supporting evidence from individual studies
A replicated, controlled study in 2001 in an estuary in California, USA (Zedler 2003) reported that planting nurse plants before sowing seeds of arrowgrass Triglochin concinna had no effect on its germination. In the growing season after sowing, no arrowgrass seedlings were found – whether seeds were sown under nurse plants or onto bare sediment. The study suggests that high temperatures, high salinities and thick mats of microorganisms may have limited germination across the site. Methods: In March 2001, sets of 25 arrowgrass seeds were sown onto an area of recently reprofiled intertidal sediment. Of these, 288 sets were sown under planted adult nurse plants (alkali heath Frankenia salina, salt marsh daisy Jaumea carnosa or California sea lavender Limonium californicum; single plants or single-species clusters). A further 144 sets were sown onto bare sediment. All seeds sets were covered with burlap fabric after sowing. Any nurse plants that died were replaced. Seedlings were counted over the 2001 growing season.Study and other actions tested