0537-B1

Potential Forest Species for Plantations in Brazilian Amazonia

Luiz Marcelo Brum Rossi^[1], Celso Paulo de Azevedo, Cintia Rodrigues de Souza and Roberval M. B. de Lima

Abstract

The purpose of this research was to test the performance and growth of forest species in homogeneous experimental plantations, in modified and abandoned areas in Amazonia. Fifteen species (including natives and exotics) were tested, in plots with 81 plants each, being 49 measurable ones. The height and diameter at breast height (DBH) were evaluated at 6, 12, 18, 24, 38 and 48 months of age. The results, at 48 months, showed that the species with better performance and growth were Acacia mangium and the hybrid Eucalyptus grandis x Eucalyptus urophylla clone 0321. The mean annual increments (MAI) reached 34 and 45 m³ ha^-1 yr^-1 and the average volumes, with four years of age, were 133 and 181 m³ ha^-1 for the Eucalyptus hybrid clone 0321 and Acacia mangium, respectively. Among the native species, Schizolobium amazonicum was found to perform better, reaching a MAI of 32.5 m³ ha^-1 yr^-1 and volume of 130 m³ ha^-1, at four years of age.

Introduction

The Amazonian region presents a great potential for plantations in modified, abandoned and degraded areas (by agricultural and cattle ranch activities). In Brazilian Amazonia, those lands represent about 40 million hectares. The surface deforested in the Legal Amazonia was 588.000 km² until 2000 (INPE 2002), representing about 15 percent of total area (MMA 2000). Another factor that reinforces the importance of the reforestation is the crescent scarcity of wood of the more utilized species, like Ceiba pentandra, Schizolobium amazonicum and Virola surinamensis. These species respond for over than 50 percent of the plywood market, and they are found only in long distances, raising the exploration costs. The utilization of abandoned areas for forest plantations provides reduction in the raw material cost due to concentration of same species plants or plants groups through plantations and because of the proximity of the wood manufacturing process centers. The availability of technology for plantations in degraded areas will motivate the reduction of the pressure over the native tropical forest in the region, the increase of the plantations productivity and the consequent increase of the landowner incomes, by the wood and seeds sale.

However, the commercial plantations in the Amazonian region are still rare, due to the lack of scientific knowledge about native and exotic species behaviour in the region, besides the unavailability of good quality seeds. The major limitation is the necessity of more adequate species selection for the different ecologic conditions in the region, since the quality of this recommendation depends on experimental results in similar environmental conditions. Incorrect species selection can be disastrous at worst or significantly reduce productivity at best (Tilki & Fisher 1998).

The forest species plantation represents an efficient alternative for the degraded lands in tropical regions with elevated precipitation, like Amazonia. Plantations contribute with erosion control, soil moisture conservation and with creation of a microclimate propitious to the other cultures development. Information about adaptability of the species more utilized by the wood sector and about potential species for future use, in the several ecosystems in the region, will be a fundamental instrument for the species selection for each site, contributing, in this manner, for the success of the forest plantations, at industrial and small scale.

According to Haggar et al. (1998), the high natural biodiversity of tropical timber species should represent a substantial resource for the production of timber under the variety of conditions and management regimes in the lowland humid tropics. Nevertheless, tropical forestry has concentrated on a few well-known species, like Pinus spp. and Eucalyptus spp. These species have been tested, and seed sources selected and genetically improved to produce stocks of very high productive potential, but they may not be the best adapted to the lowland per humid tropics where large areas of land are now becoming available for reforestation. These traditional plantation forest species need to be evaluated together with species native to the lowland humid tropics to test their adaptability before large scale planting begins. In this study, the adaptation of 14 exotic (proven plantation species in other tropical regions) and 66 potential native plantation timber species to these conditions was tested in a 6-years-old trial in the lowland humid tropics of Costa Rica. Two exotic species, Gmelina arborea and Acacia mangium, has the highest growth rates, but both were subject to pest attacks that limited the life of the stand. Of the native species tested, only about 10 species had sufficiently high growth rates and good form to be attractive as potential plantation species, these included Vochysia spp., Stryphnodendron excelsum and Terminalia amazonia.

Alder (1999) compared the volume growth of five major plantation species of the lowland tropics. These are: Cedrelinga catenaeformis, Parkia multijuga, Jacaranda copaia, Cordia alliodora and Schizolobium parahybum. Maximum MAI’s of 20 cm underbark volume are about 23 m³ ha^-1 yr^-1 at 15 years for Cedrelinga, 16 m³ ha^-1 yr^-1 at 15 years for Jacaranda, 15 m³ ha^-1 yr^-1 at 25 years for Parkia, and 8 m³ ha^-1 yr^-1 at 10 years for Cordia. Schizolobium yields are currently between 10 and 20 m³ ha^-1 yr^-1, but very dependent on the health of the stand.

The aim of the present study was to indicate potential species (in performance and growth) for forest plantations in modified, abandoned and degraded areas in the Brazilian Amazonia and quantify this information.

Materials and methods

This work takes part at a large-scale experiment that involves 25 forest species and plantations in 15 sites from five Brazilian States in the Amazonian region, totalizing more than 300 experimental plots.

The tested species were selected based in some criteria, like rapid growth (empiric information), adequate growth in full sun and for pulpmill, sawmill or plywood and energy production.

The Table 1 shows the species utilized in the experiment, the usual utilization and the tree spacing. The seeds of native species were obtained in several Amazonian regions. To the collection, special precautions with regard to the minimum number of ten original trees represented in the seeds lots, and that these original trees were located in a minimum distance of two times the tree height. With the exception of the five hybrids Eucalyptus grandis x Eucalyptus urophylla clones, those were obtained with Copener (a Brazilian reforestation company). The others species were arranged to germination, in accordance with the dormancy break necessities of each species, and transplanted to plastic bags. The substrate was composed by organic soil and sand. The plantation occurred in 1998, after the soil preparation and fertilization in the hole using 60 g of super phosphate triple per plant. Trees were planted at 3 x 4 m spacing for species that will be destined to sawmills (slow growth) and 3 x 2 m spacing for species that will be destined to energy production or to plywood (fast growth, like Schizolobium, Sclerolobium, A. mangium and Eucalyptus). It was planted, for each species, 81 trees, with edge formed by one plant, totalizing 49 measurable plants.

The study area was located in Embrapa Amazônia Ocidental Experimental Station, in Manaus, Amazonas, 2º54’ S and 59º58’ W. The climatic type is Ami, in according to Köppen classification, with annual average temperature of 25,9ºC and annual average precipitation of 2551 mm. The soil is a xanthic Ferralsol (FAO-UNESCO 1990) with clavey texture, kaolinitic mineralogy, acidic, poor in phosphorus and nutrient cations (Table 2).

The variables height and diameter at breast height (DBH) were evaluated at ages of 6, 12, 18, 24, 38 and 48 months. With regard to the cultural tracts, weedings and plants coronation were made twice a year, to eliminate the competition against weed.

Results and discussion

The species presented, at 4 years, values (Table 3) of DBH, height (H), basal area (G), volume (Vol), and the mean annual increments in diameter at breast height (MAI DBH), height (MAI H), basal area (MAI G) and volume (MAI Vol). With regard to the DBH, the better values, at 4 years, were reached by Schizolobium amazonicum (11.6 cm) and the Eucalyptus clones 1270 (10.6 cm), 0321 (10.4 cm) and 0103 (10.3 cm). Concerning to mean annual increment in DBH (MAI DBH), the three species were S. amazonicum (2.9 cm) and the Eucalyptus clones 1270 (2.7 cm) and 0321 (2.6 cm).

Regarding to the total height values, the following species presented satisfactory values, at age of 4 years: Eucalyptus clones 0321 (18.6 m), 1232 (18.2 m) and 1270 (17.7 m), S. amazonicum (15.1 m) and Acacia mangium (14.0 m). The clones 0321 (4.7 m), 1232 (4.6 m) and 1270 (4.5 m) had the better MAI performance, followed by S. amazonicum (3.8 m), A. mangium (3.5 m) and the clone 0103 (3.5 m).

Acacia mangium presented superior value of basal area, with 25.5 m² ha^-1, with age of 4 years. S. amazonicum (18.8 m² ha^-1), the Eucalyptus clones 0321 (15.1 m² ha^-1), 1270 (14.5 m² ha^-1) and 0103 (13.4 m² ha^-1) and S. paniculatum presented satisfactory values too (13.8 m² ha^-1). A. mangium presented superior value of MAI in basal area too, with 6.4 m² ha^-1, followed by S. amazonicum (4.7 m² ha^-1), Eucalyptus clones 0321 (3.8 m² ha^-1), 1270 (3.7 m² ha^-1) and 0103 (3.4 m² ha^-1) and S. paniculatum (3.4 m² ha^-1).

The main parameters in this study were the volume and the MAI in volume. In the first case, A. mangium had superior performance, with 181.25 m³ ha^-1, at 4 years, followed by S. amazonicum and the Eucalyptus clones 0321, 1270, 1232 and 0103 (volumes varying from 94.2 to 133.2 m³ ha^-1). In the case of the MAI in volume, two species can be detached: A. mangium (45.3 m³ ha^-1 yr^-1) and the Eucalyptus clone 0321 (34 m³ ha^-1 yr^-1). The following species presented intermediary values: S. amazonicum (32.5 m³ ha^-1 yr^-1), Eucalyptus clone 1270 (32.5 m³ ha^-1 yr^-1), clone 1232 (25.1 m³ ha^-1 yr^-1), clone 0103 (24.1 m³ ha^-1 yr^-1) and S. paniculatum (21.2 m³ ha^-1 yr^-1).

The analysis of the mathematical models tested with the six better species (Figure 1) to the prognosis of the periodic increment for DBH and height showed an excellent adjustment, presenting R² values above of 90 percent (Table 4).

Table 1. List of species used in the experiment, main utilization and tree spacing.

Table 2. Soil chemical characteristics at different depths.

Table 3. Dendrometric variables of the species at 4 years.

Common letters indicate means that are not significantly different from one another at 5% significance level.

Table 4. Regression models of periodic increment in DBH and height for the better performance species.

Where: y periodic increment, and x age in months.

Figure 1. Periodic increment in diameter and total height for the six best performance species.

Conclusion

The species with best performance and growth were Acacia mangium and the Eucalyptus hybrid clone 0321. The mean annual increments (MAI) reached 34 and 45 m³ ha^-1 yr^-1 and the average volumes, with 4 years of age, were 133 and 181 m³ ha^-1 yr^-1 the Eucalyptus hybrid clone 0321 and Acacia mangium, respectively. Acacia mangium, due to its rapid growth and volumetric production, is a species indicated to substitute the use of native species at firewood production. The Eucalyptus are important to the firewood production too, with the advantage of sprout after the harvest, reducing the wood production costs. Among the native species, the best performance concerns to Schizolobium amazonicum, that reached the mean annual increment of 32.5 m³ ha^-1 yr^-1 and volume of 130 m³ ha^-1, at 4 years. The Schizolobium would be very important in reforestation in Amazonia, because it’s a native specie, presented good performance in this study and has assured trade in plywood production.

Literature cited

Alder, D., 1999. Growth and yield of some plantation species of the lowland tropics in Ecuador. Paper presented to Conferencias sobre las Investigaciones y Experiencias de 20 Años de La Fundacion Forestal Juan Manual Durini, Ecuador, 9 p.

FAO-UNESCO, 1990. Soil map of the world. Food and Agriculture Organization of the United Nations. Rome, 119 p. (revised).

Haggar, J. P., Briscoe, C. B., Butterfield, R. P., 1998. Native species: a resource for the diversification of forestry production in the lowland humid tropics. Forest Ecology and Management, 106: 195-203.

Instituto Nacional de Pesquisas Espaciais (INPE)., 2002. Monitoramento da Floresta Amazônica Brasileira por Satélite: Relatório 2000-2001. Available on the Internet at http://www.inpe.br.

Ministério do Meio Ambiente (MMA), 2000. Programa Nacional de Florestas - PNF. Brasília: MMA/SBF/DIFLOR, 52 p.

Tilki, F. & Fisher, R. F., 1998. Tropical leguminous species for acid soils: studies on plant form and growth in Costa Rica. Forest Ecology and Management, 108: 175-192.