Beneficial

Prepare the ground before tree planting

1Six of seven studies, including five replicated, randomized, controlled studies, in Canada and Sweden found that ground preparation increased the survival or growth rate of planted trees. One study found no effect of creating mounds on frost damage to seedlings. Assessment: beneficial (effectiveness 78 %; certainty 73 %; harms 0 %).

2http://www.conservationevidence.com/actions/1263

Use mechanical thinning before or after planting

3Five of six studies, including two replicated, randomized, controlled studies, in Brazil, Canada, Finland, France and the USA found that thinning trees after planting increased survival or size of planted trees. One study found mixed effects on survival and size and one found it decreased their density. One replicated study in the USA found that seedling survival rate increased with the size of the thinned area. Assessment: beneficial (effectiveness 75 %; certainty 63 %; harms 10 %).

4http://www.conservationevidence.com/actions/1261

Likely to be beneficial

Fence to prevent grazing after tree planting

5Four of five studies, including two replicated, randomized, controlled studies, in Finland, Australia, Canada and the USA found that using fences to exclude grazing increased the survival, size or cover of planted trees. Two studies found no effect on survival rate and one found mixed effects on planted tree size. Assessment: likely to be beneficial (effectiveness 70 %; certainty 50 %; harms 0 %).

6http://www.conservationevidence.com/actions/1254

Use herbicide after tree planting

7Two of three studies, including two replicated, randomized, controlled studies, in Sweden and the USA found that using herbicide increased the size of planted trees. One study found no effect. One replicated, randomized, controlled study in Sweden found no effect of using herbicide on frost damage to seedlings. Assessment: unlikely to be beneficial (effectiveness 58 %; certainty 45 %; harms 0 %).

8http://www.conservationevidence.com/actions/1262

Trade-off between benefit and harms

Use prescribed fire after tree planting

9Two of four studies, including one replicated, randomized, controlled study, in Finland, France and the USA found that using prescribed fire after planting increased the survival and sprouting rate of planted trees. One study found fire decreased planted tree size and one found no effect on the size and survival rate. Assessment: trade-offs between benefits and harms (effectiveness 50 %; certainty 43 %; harms 20 %).

10http://www.conservationevidence.com/actions/1255

Unknown effectiveness (limited evidence)

Apply insecticide to protect seedlings from invertebrates

11One randomized, replicated, controlled study in the USA found that applying insecticide increased tree seedling emergence and survival. Assessment: unknown effectiveness (effectiveness 70 %; certainty 13 %; harms 0 %).

12http://www.conservationevidence.com/actions/1149

Add lime to the soil after tree planting

13One of two replicated, randomized, controlled studies in the USA found that adding lime before restoration planting decreased the survival of pine seedlings. One found no effect on seedling growth. Assessment: unknown effectiveness (effectiveness 0 %; certainty 30 %; harms 50 %).

14http://www.conservationevidence.com/actions/1259

Add organic matter after tree planting

15Two replicated, randomized, controlled studies in the USA found that adding organic matter before restoration planting increased seedling biomass, but decreased seedling emergence or survival. Assessment: unknown effectiveness (effectiveness 20 %; certainty 25 %; harms 50 %).

16http://www.conservationevidence.com/actions/1258

Cover the ground with straw after tree planting

17One replicated, randomized, controlled study in the Czech Republic found that covering the ground with straw, but not bark or fleece, increased the growth rate of planted trees and shrubs. Assessment: unknown effectiveness (effectiveness 75 %; certainty 20 %; harms 0 %).

18http://www.conservationevidence.com/actions/1266

Improve soil quality after tree planting (excluding applying fertilizer)

19Two randomized, replicated, controlled studies in Australia found that different soil enhancers had mixed or no effects on tree seedling survival and height, and no effect on diameter or health. Assessment: unknown effectiveness (effectiveness 25 %; certainty 23 %; harms 13 %).

20http://www.conservationevidence.com/actions/1153

Manage woody debris before tree planting

21One replicated, randomized, controlled study in Canada found that removing woody debris increased the survival rate of planted trees. One replicated, controlled study in the USA found mixed effects on the size of planted trees. Assessment: unknown effectiveness (effectiveness 40 %; certainty 25 %; harms 13 %).

22http://www.conservationevidence.com/actions/1257

Use shading for planted trees

23One replicated, controlled study in Panama found that shading increased the survival rate of planted native tree seedlings. Assessment: unknown effectiveness (effectiveness 85 %; certainty 23 %; harms 0 %).

24http://www.conservationevidence.com/actions/1269

Use tree guards or shelters to protect planted trees

25One replicated, randomized, controlled study in the USA found that using light but not dark coloured plastic tree shelters increased the survival rate of planted tree seedlings. One replicated, controlled study in Hong Kong found that tree guards increased tree height after 37 but not 44 months. Assessment: unknown effectiveness (effectiveness 60 %; certainty 28 %; harms 20 %).

26http://www.conservationevidence.com/actions/1268

Use weed mats to protect planted trees

27One replicated, controlled study in Hong Kong found no effect of using weed mats on seedling height. Assessment: unknown effectiveness (effectiveness 0 %; certainty 18 %; harms 0 %).

28http://www.conservationevidence.com/actions/1267

Water seedlings

29One replicated, randomized, controlled study in Spain found that watering seedlings increased or had no effect on seedling emergence and survival, depending on habitat and water availability. Assessment: unknown effectiveness (effectiveness 45 %; certainty 20 %; harms 0 %).

30http://www.conservationevidence.com/actions/1154

Unlikely to be beneficial

Mechanically remove understory vegetation after tree planting

31Four of five studies, including three replicated, randomized, controlled studies in France, Sweden, Panama, Canada and the USA found no effect of controlling understory vegetation on the emergence, survival, growth rate or frost damage of planted seedlings. One found that removing shrubs increased the growth rate and height of planted seedlings, and another that removing competing herbs increased seedling biomass. Assessment: unlikely to be beneficial (effectiveness 20 %; certainty 50 %; harms 0 %).

32http://www.conservationevidence.com/actions/1256

Use different planting or seeding methods

33Four studies, including one replicated, randomized study, in Australia, Brazil, Costa Rica and Mexico found no effect of planting or seeding methods on the size and survival rate of seedlings. One replicated, controlled study in Brazil found that planting early succession pioneer tree species decreased the height of other planted species. Assessment: unlikely to be beneficial (effectiveness 0 %; certainty 43 %; harms 13 %).

34http://www.conservationevidence.com/actions/1264

Use fertilizer after tree planting

35Two of five studies, including two randomized, replicated, controlled studies, in Canada, Australia, France and Portugal found that applying fertilizer after planting increased the size of the planted trees. Three studies found no effect on the size, survival rate or health of planted trees. One randomized, replicated, controlled study in Australia found that soil enhancers including fertilizer had mixed effects on seedling survival and height. Assessment: unlikely to be beneficial (effectiveness 38 %; certainty 45 %; harms 3 %).

36http://www.conservationevidence.com/actions/1260

No evidence found (no assessment)

37We have captured no evidence for the following interventions:

• Apply fungicide to protect seedlings from fungal diseases
• Infect tree seedlings with mycorrhizae
• Introduce leaf litter to forest stands
• Plant a mixture of tree species to enhance the survival and growth of planted trees
• Reduce erosion to increase seedling survival
• Transplant trees
• Use pioneer plants or crops as nurse-plants.