Action: Add mulch to soil (alongside planting/seeding)
Key messagesRead our guidance on Key messages before continuing
- A replicated, randomized, controlled study in the USA found that using mulch did not increase the number of shrubs, or the height of California sagebrush. A randomized, controlled study in South Africa found that applying mulch and sowing seeds increased the number of seedlings, but not their survival.
Adding mulch to soil alongside planting and seeding may help to increase survival of shrubland plants by increasing the amount of moisture in the soil.
Supporting evidence from individual studies
A randomised, controlled study in 1994–1998 in a succulent karoo shrubland in Western Cape, South Africa (Beukes & Cowling 2003) found that applying mulch, followed by sowing seeds of shrubland species increased the number of seedlings of these species, but did not increase seedling survival. Applying mulch followed by seeding with the seeds of the species Karoo bietou Tripteris sinuata, Spiny ruschia Ruschia spinosa and Gha grass Chaetobromus dregeanus increased the number of seedlings of these species compared with unmulched, unseeded plots (data not provided). However, applying mulch followed by seeding did not increase the survival of seedlings relative to unmulched, unseeded plots (data not provided). In 1994 eight 12.5 m2 plots were established. In four plots mulch was applied, followed by sowing with the seeds of shrubland species. In the other four plots no mulch was applied, and no seeds were sown. Seedlings in each plots were counted annually between 1994 and 1998.
A replicated, randomized, controlled study in 2008–2009 in sagebrush scrub shrubland that had been burnt in wildfires in California, USA (McCullough & Endress 2012) found that using a hydromulch did not increase the number of shrubs, forb cover, or the height of California sagebrush Artemisia californica and common deerweed Lotus scoparius and did not reduce the cover of non-native forbs and grasses. After one year, California sagebrush (32-37 cm) and common deerweed (50-51 cm) were not significantly taller in areas where hydromulch had been used than areas where it had not (California sagebrush: 33 cm; common deerweed: 48 cm). In January 2008 in eight 8 m x 20 m plots hydromulch was applied, while in four other plots no hydromulch was applied. In July 2009 vegetation was surveyed by placing three 20 m transects in each plot and recording vegetation every 1 m.
- Beukes P.C. & Cowling R.M. (2003) Evaluation of restoration techniques for the Succulent Karoo, South Africa. Restoration Ecology, 11, 308-316
- McCullough S.A. & Endress B.A. (2012) Do Postfire Mulching Treatments Affect Plant Community Recovery in California Coastal Sage Scrub Lands? Environmental Management, 49, 142-150