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| Author(s): |
Ingo Isernhagen
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2010-08-20 |
| Examining board members: |
Ricardo Ribeiro Rodrigues;
Pedro Henrique Santin Brancalion;
Flávio Bertin Gandara Mendes;
Adriana de Fatima Rozza;
Ricardo Augusto Gorne Viani
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| Advisor: | Ricardo Ribeiro Rodrigues |
| Abstract | |
The number of restoration projects in the Atlantic Forest biome is increasing, and direct seeding has been identified as a complement technique to the planting of tree seedlings, especially considering the possibility of reducing the costs of the activity. This experiment sought to test the large scale use of this technique, by proposing the fast occupation and coverage (filling) of two degraded agricultural lands with low resilience through direct seeding of fast growing and wide canopy tree species. In a second moment, it was tested the use of direct seeding to increase plant richness of these areas. The experiment was set at the Usina São João, Araras, São Paulo state, in two Permanent Preservation Areas (riparian areas) abandoned after agricultural use (Area 1 and Area 2). For the filling direct seeding, 16 native tree species were used, in which seed germination tests were carried out in laboratory. The experimental design was the completely randomized in Area 1 (48 plots of 200m² 0,96ha) and the randomized blocks in Area 2 (30 plots of 300m² 0,90ha). Three treatments were tested in the field, based on three different densities of seed sowing, calculated according to an expected projection of individuals number (Area 1 16 repetitions / Area 2 10 repetitions). The number of surviving individuals was monitored over 15 months after seeding (A.S.) in Area 1 and 6 months A.S. in Area 2. Tree height and canopy cover were also monitored in Area 1 in the seeded lines (CL) during 34 months A.S. Emergence rates were about 70-90% lower than those obtained in laboratory. Even so, the densities of individuals were elevated and directly related to the different densities of seeds used, reaching a projected density on the experimental plots of 1,215 ind.ha-1 to 13,002 ind.ha-1. In one to three months A.S., the density of individuals had already reached levels close to those obtained at the end of monitoring. Thirty four months A.S., individuals of <0.50m to 7.0m-8.0m high were recorded, with the largest percentage (29.05%) in the range of 3.01m-4.0m. In this evaluation, over 70% of seeded lines showed CL above 101%. The expenses with seed acquisition to obtain a single seedling in the field from direct seeding of most species used was two to three times lower than the price of an individual seedling in nurseries. After covering the two experimental areas, direct seeding was implanted to increase plant richness, with 30 species in Area 1 and 35 species in Area 2. Problems related to weed infestation, soil disturbance by animals and predation by ants hindered seedling emergence. Direct seeding of native tree species was both technically and economically effective to the initial occupation of agricultural lands through restoration. However, effectiveness is dependent on the species used and the local site conditions, such as soils, being necessary a pre-implantation diagnosis and even the need of seedling plantation as a complementary technique. (AU) | |