Introduce nurse plants: brackish/saline swamps
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 to help naturally recolonizing vegetation (Padilla & Pugnaire 2006). Nurse plants may trap and stabilize sediments, trap propagules, reduce harsh environmental conditions (e.g. temperature fluctuations and strong sunlight), attract pollinators, deflect herbivory away from focal species, and/or limit 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).
To be summarized as evidence for this action, studies must have 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 summarized under other interventions if (a) the nurse plant is itself a desirable part of the final plant community, (b) if vegetation other than nurse plants is introduced, or (c) desirable vegetation is planted into existing nurse vegetation. Studies of the nursing effect of existing vegetation (e.g. Lewis & Dunstan 1975; McKee et al. 2007) are outside the scope of this synopsis.
Related actions: Introduce target marsh vegetation – Directly plant whole plants, Introduce vegetation fragments or Introduce seeds or propagules; Introduce nurse plants to complement planting of swamp vegetation.
Lewis R.R. & Dunstan F.M. (1975) The possible role of Spartina alterniflora Loisel in establishment of mangroves in Florida. Proceedings of the 2nd Annual Conference on Restoration of Coastal Vegetation in Florida, Tampa, Florida, 81–100.
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 study in 2013–2016 on an estuarine mudflat in northeast India (Begam et al. 2017) reported that an area planted with saltmarsh grasses trapped mangrove propagules, that the majority of these propagules established, and the average height of established propagules increased. In the two monsoon seasons approximately 18–30 months after planting, grassy vegetation patches trapped an average of 1,200–1,372 mangrove propagules/m2/week. Between 60 and 80 per cent of trapped propagules developed into seedlings (depending on species). The average height of established seedlings increased by 21–90% taller over the first month after establishment (depending on species). Methods: In 2013, four grass species were transplanted from nearby marshes to an estuarine mudflat (lower and middle intertidal zones; water salinity 19–34 ppt). There were mangrove forests elsewhere in the estuary as a source of propagules. The resulting grassy vegetation patches were surveyed weekly in the 2014–2015 and 2015–2016 monsoon seasons. Mangrove propagules were counted along 10 x 100 m transects. Seedlings were counted and measured in 100-m2 subplots as soon as they had established, then measured again one month later.Study and other actions tested
Referenced paperBegam M.M., Sutradhar T., Chowdhury R., Mukherjee C., Basak S.K. & Ray K. (2017) Native salt-tolerant grass species for habitat restoration, their acclimation and contribution to improving edaphic conditions: a study from a degraded mangrove in the Indian Sundarbans. Hydrobiologia, 803, 373-387.