Add mulch to control grass

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

0%
Certainty

10%
Harms

0%

Calculating overall effectiveness category

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.

Study locations

Key messages

One randomized, controlled study in the USA found that areas where mulch was used to control grass cover had a similar number of shrub seedlings to areas where mulch was not applied. The same study found that mulch application 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 did not increase the seedling abundance of shrub species or reduce grass cover. After one year, the number of seedlings for seven of seven shrub species did not differ between areas where mulch had been added (0 seedlings/m²) and areas without mulch (0 seedlings/m²). There was also no significant difference in grass cover between areas where mulch had been added (85%) and areas where mulch was not added (84%). In 1997 seeds were sown in five randomly located 5 m x 5 m plots, while in five other plots no seeds were sown. 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
Add mulch to control grass Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Use herbicide to control bracken Action Link	Unknown effectiveness (limited evidence)	8	Synopsis Link