Direct Seeding

Some tree species can be established in the field directly from seed. Direct seeding involves:

• collecting seeds from native trees in the target forest ecosystem and if necessary storing them until sowing;
• sowing them in the restoration site at the optimal time of year for seed germination;
• manipulating field conditions to maximise germination.

Advantages of direct seedling:

• Inexpensive because there are no nursery and planting costs
• Transporting seeds to the site is obviously easier and cheaper than trucking in seedlings
• Trees that are established usually have better root development and grow faster than nursery-raised saplings because their roots are not constrained within a container.
• Implemented in combination with accelerated natural regeneration  and conventional tree planting, direct seeding can be used to increase both the density and species richness of regenerants.

In addition to establishing framework tree species, direct seeding can be used with the maximum diversity method or to establish ‘nurse tree’ plantations, but it does not work with all tree species.

Potential obstacles to direct seeding

In nature, a very low percentage of dispersed tree seeds germinate and even fewer seedlings survive to become mature trees. The biggest threats to sown seeds and seedlings are:

1. Desiccation
2. Seed predation, particularly by ants and rodents
3. Competition from herbaceous weeds

Burying can also reduce seed predation by making the seeds more difficult to find. Pre-sowing seed treatments that accelerate germination can reduce the time available for seed predators to find the seeds. Once germination commences, the nutritional value of seeds and their attractiveness to predators decline rapidly. But treatments that break the seed coat and expose the cotyledons sometimes increase the risk of desiccation or make seeds more attractive to ants. It could also be worth exploring the possibility of using chemicals to repel seed predators. Any carnivores that prey on rodents (e.g. raptors or wild cats) should be regarded as valuable assets on ANR sites. Preventing the hunting of such animals can help to control rodent populations and reduce seed predation.

Seedlings that germinate from seeds are tiny compared with planted, nursery-raised saplings, so weeding around the seedlings is especially important and it must be carried out with extra care. Such meticulous weeding can greatly increase the cost of direct seeding.

Directions for performing direct seeding are in "How to Plant a Forest" pages 58 to 62. For a broad discussion of the technique, please read "Restoring Tropical Forests: a practical guide" starting on page 140. For really detailed advice on direct seeding, click on the publications tab at the top of the page to access our research papers on the subject. Finally if you are considering using the technique, please send us details of your restoration site and we can probably recommend species suitable for direct seeding for your project.