Add mulch to control grass and sow seed

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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Background information and definitions

Mulch is usually an organic material such as leaves, grass cuttings, or wood chips that is applied to the top layer of soils. Using mulch directly on unwanted plants can reduce the amount of light they receive and therefore may reduce their abundance. Combining this with the addition of seeds of shrubland plants may aid on the establishment of shrubland species.

Study locations

Key messages

One randomized, controlled study in the USA found that adding mulch, followed by seeding with shrub seeds, increased the seedling abundance of one of seven shrub species but did not reduce grass cover.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A randomized, controlled study in 1997–1999 in sagebrush scrub habitat that had been invaded by grass and burnt by wildfires in California, USA (Cione et al. 2002) found that adding mulch, followed by seeding with shrub seeds, increased the seedling abundance of one of seven shrub species but did not reduce grass cover. After one year, areas where mulch and shrub seeds were added did not have a significantly higher number of shrub seedlings for two of seven species (1 seedlings/m²) than areas where mulch and seed were not added (0 seedlings/m²). There was also no significant difference in grass cover between areas where mulch and seeds had been added (76%) and areas where neither mulch, nor seeds were added (84%). In 1997 mulch was added to five randomly located 5 m x 5 m plots which were subsequently sown with seeds from native shrubs, while in five other plots no mulch or seeds 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.
Study and other actions tested
Referenced paper
Cione N.K., Padgett P.E. & Allen E.B. (2002) Restoration of a native shrubland impacted by exotic grasses, frequent fire, and nitrogen deposition in southern California. Restoration Ecology, 10, 376-384.

Please cite as:

Martin, P.A., Rocha, R., Smith, R.K. & Sutherland, W.J. (2020) Shrubland and Heathland Conservation. Pages 483-525 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Shrubland and Heathland Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Apply herbicide and sow seeds of shrubland plants to control grass Action Link	Unknown effectiveness (limited evidence)	2	Synopsis Link
Cut and use prescribed burning to control grass Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Add mulch to control grass and sow seed Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link