Action: Add mulch and fertilizer to soil
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- One randomized, controlled study in the USA found that adding mulch and fertilizer did not increase the seedling abundance of seven shrub species. The same study also reported no change in grass cover.
Adding mulch may help to retain moisture in soil at shrublands in arid sites, as well as reducing the germination of problematic/invasive species. Adding fertilizer may help to stimulate the growth of any shrubland plants already present.
Supporting evidence from individual studies
A randomized, controlled study in 1997–1999 in a sagebrush scrub shrubland that had been invaded by grass and burnt by wildfires in California, USA (Cione et al. 2002) found adding mulch, followed by addition of nitrogen fertilizer did not increase the seedling abundance of seven shrub species or reduce grass cover after one year. The areas where mulch and fertilizer were added did not differ in the number of shrub seedlings for seven of seven species (0 seedlings/m2) from areas where mulch and fertilizer were not added (0 seedlings/m2). There was also no significant difference in grass cover between areas where mulch and fertilizer had been added (83%) and areas where mulch and fertilizer were not added (84%). In 1997 mulch and fertilizer were added to five randomly located 5 m x 5 m plots, while in five other plots no mulch or fertilizer were added. In spring 1997 plots were surveyed for grasses using two 0.25 m x 0.5 m quadrats/plot and two 0.5 m x 1 m quadrats/plot for shrubs.