Plant/sow seeds of nurse plants alongside focal plants
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Nurse plants are plants which are thought to aid the growth of other species by providing relatively benign conditions below their canopy. Examples of these altered conditions may include increases in moisture and nutrients, and decreases in temperature and damage from herbivores (de Toledo Castanho & Prado 2014). Combining the planting or sowing of seeds of nurse plants with that of focal plants may help to increase focal plant survival and growth.
de Toledo Castanho, C. and P. I. Prado (2014). "Benefit of shading by nurse plant does not change along a stress gradient in a coastal dune." PLOS ONE 9(8): e105082.
Supporting evidence from individual studies
A replicated, randomized, controlled study in 1993–1994 in former shrubland in California, USA (Marquez & Allen 1996) found that sowing California sagebrush Artemisia californica seeds with the seeds of nurse plants reduced its survival in four of seven comparisons and reduced its biomass in seven of seven comparisons. In four of seven comparisons, California sagebrush seedlings showed lower survival where they were sown with seeds of nurse plants (5–75% survival) than when they were sown without seeds of nurse plants (100% survival). In seven of seven comparisons California sagebrush biomass was lower when sown with seeds of nurse plants (0-1 g/m2) than when sown without seeds of nurse plants (5 g/m2). In three 0.75 m2 plots California sagebrush seeds were sown, while in 18 plots a mixture of California sagebrush and succulent lupine Lupinus succulentus or rose clover Trifolium hirtum seeds were sown. Plant survival was recorded in May 1994 following which all plants were harvested and dried to calculate their biomass.Study and other actions tested
A randomized, replicated, controlled study in 1994–2003 in two agricultural fields in Suffolk, UK (Walker et al. 2007) found that sowing seeds of a nurse plant, followed by seeds of heathland species did not increase the cover of common heather Calluna vulgaris . After nine years, cover of common heather in areas where seeds of a nurse plant and heathland species were sown (0%) was not significantly different to that in areas where no seeds had been sown (0%). In 1994 seeds of the nurse plant Italian ryegrass Lolium multiflorum were sown, followed in 1995 by seeds of common heather, grasses, and herbs in four 80 m2 plots. In four other plots no seeds were sown. In April 2003 five 2500 cm2 quadrats were placed in each plot and the cover of all plant species was recorded.Study and other actions tested