Unknown effectiveness (limited evidence)

Add fertilizer to soil (alongside planting/seeding)

1A replicated, controlled study in Iceland found that adding fertilizer and sowing seeds increased cover of shrubs and trees in a majority of cases. The same study showed an increase in vegetation cover in two of three cases. One controlled study in the USA found that adding fertilizer increased the biomass of four-wing saltbush in a majority of cases. Assessment: unknown effectiveness (effectiveness 45 %; certainty 25 %; harms 0 %).

2https://www.conservationevidence.com/actions/1704

Add peat to soil (alongside planting/seeding)

3One replicated, randomized, controlled study in the UK found that adding peat to soil and sowing seed increased the cover of common heather in the majority of cases, compared to seeding alone. One replicated, randomized, controlled study in the UK found that adding peat to soil and sowing seed increased the density of heather seedlings, and led to larger heather plants than seeding alone, but that no seedlings survived after two years. Assessment: unknown effectiveness (effectiveness 42 %; certainty 20 %; harms 0 %).

4https://www.conservationevidence.com/actions/1705

Add mulch and fertilizer to soil (alongside planting/ seeding)

5A randomized, controlled study in the USA found that adding mulch and fertilizer, followed by sowing of seeds increased the abundance of seedlings for a minority of shrub species. The same study found that adding mulch and fertilizer, followed by sowing seeds had no significant effect on grass cover. Assessment: unknown effectiveness (effectiveness 35 %; certainty 15 %; harms 0 %).

6https://www.conservationevidence.com/actions/1707

Add gypsum to soil (alongside planting/seeding)

7One randomized, controlled study in South Africa found that adding gypsum to soils and sowing seeds increased survival of seedlings for one of two species. Assessment: unknown effectiveness (effectiveness 30 %; certainty 10 %; harms 0 %).

8https://www.conservationevidence.com/actions/1708

Add sulphur to soil (alongside planting/seeding)

9A randomized, replicated, controlled study in the UK found that adding sulphur to soil alongside sowing seeds did not increase heather cover in a majority of cases. One replicated, controlled study in the UK found that adding sulphur and spreading heathland clippings had mixed effects on cover of common heather, perennial rye-grass, and common bent. One randomized, controlled study in the UK found that adding sulphur to soil alongside planting of heather seedlings increased their survival, though after two years survival was very low. Assessment: unknown effectiveness (effectiveness 20 %; certainty 30 %; harms 0 %).

10https://www.conservationevidence.com/actions/1710

Strip/disturb topsoil (alongside planting/seeding)

11Two replicated, controlled studies in the UK found that removal of topsoil and addition seed/clippings increased cover of heathland plants or cover of heather and gorse. One controlled study in the UK found that soil disturbance using a rotovator and spreading clippings of heathland plants (alongside mowing) increased the number of heathland plants. One replicated, controlled study in the UK found that stripping the surface layers of soil and adding seed reduced the cover of perennial rye-grass. One randomized, replicated, paired, and controlled study in the UK found that removal of topsoil and addition of the clippings of heathland plants did not alter the cover of annual grasses but led to a decrease in cover of perennial grasses. Assessment: unknown effectiveness (effectiveness 60 %; certainty 35 %; harms 0 %).

12https://www.conservationevidence.com/actions/1711

Add topsoil (alongside planting/seeding)

13One randomized, replicated, paired, controlled study in the USA found that addition of topsoil alongside sowing of seed increased the biomass of grasses but reduced the biomass of forbs in comparison to addition of topsoil alone. Assessment: unknown effectiveness (effectiveness 0 %; certainty 10 %; harms 0 %).

14https://www.conservationevidence.com/actions/1857

Plant seed balls

15A randomized, replicated, controlled study in the USA found that planting seed balls resulted in lower seedling numbers than sowing seed. Assessment: unknown effectiveness (effectiveness 0 %; certainty 10 %; harms 0 %).

16https://www.conservationevidence.com/actions/1712

Plant/sow seeds of nurse plants alongside focal plants

17A randomized, replicated, controlled study in the UK found that sowing seeds of nurse plants and heathland plants did not increase the cover of common heather. One replicated, randomized, controlled study in the USA found that sowing seeds of nurse plants and California sagebrush seeds together reduced survival of shrubs in more than half of cases. The same study found that California sagebrush biomass was also reduced when its seeds were sown with those of nurse plants. Assessment: unknown effectiveness (effectiveness 0 %; certainty 20 %; harms 10 %).

18https://www.conservationevidence.com/actions/1713

Plant/seed under established vegetation

19A replicated, randomized, controlled study in the USA found that sowing seed under established shrubs had mixed effects on blackbrush seedling emergence. Assessment: unknown effectiveness (effectiveness 20 %; certainty 10 %; harms 0 %).

20https://www.conservationevidence.com/actions/1714

Plant shrubs in clusters

21A randomized, controlled study in South Africa found that when shrubs were planted in clumps more of them died than when they were planted alone. Assessment: unknown effectiveness (effectiveness 0 %; certainty 15 %; harms 1 %).

22https://www.conservationevidence.com/actions/1715

Add root associated bacteria/fungi to introduced plants

23Two controlled studies (one of which was randomized) in Spain found that adding rhizobacteria to soil increased the biomass of shrubs. One of these studies also found an increase in shrub height. Assessment: unknown effectiveness (effectiveness 60 %; certainty 15 %; harms 0 %).

24https://www.conservationevidence.com/actions/1716