Direct seeding of woody plants as an alternative to traditional plantations

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN [Coll_IRSTEA]Forest and landscape working papers n° 35

International audience

anglais. Direct tree seeding is a potentially promising technique for the afforestation of large areas at relatively low cost. However, the technique is not yet widely practised due to a range of limiting biological factors and practical considerations. The techniques of sowing in themselves could lead to important problems, for example in the case of steep slopes, or when using mixtures with different seed sizes and weights. The manager also has to decide on optimum sowing date, bearing in mind the dormancy status of seed, and balancing the risks from predation over winter from early sowing with the danger of seed death due to extreme temperatures from later sowing dates. Invading weeds can also jeopardize tree seedling growth by competition for resources, particularly during the early stages of tree establishment. Finally, only few data exist on the quantity and quality of seeds available on the market and real costs associated with the technique. In Claye-Souilly, East of Paris, a twenty-ha site, property of the French Railway Company, was established in 2005. Using 120 plots of 800 m² in size, it compared different techniques of tree seed sowing, mixtures of seeds, and techniques of mulching to control weed species. Results from this experiment and data from the literature will be discussed with special emphasis on practical recommendations for the use of direct tree seeding.