A comparison of some fast growing species suitable for woodlots in the wet tropics

• Autor(a) principal: Arkcoll, David B.
• Data de Publicação: 2014
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/17479
• topic: poor soils; legume trees; rain forest; solos pobres; leguminosas arbóreas; floresta trópico-úmida

An interest in ways of reducing the area of and cycle time for shifting cultivation has led to a brief look at some fast growing forestry species for fuel. The following three species obtained from our forestry department, Eucalyptus deglupta (Mirtaceae), Cedrelinga catenaeformis (Leguminosae) and Jacaranda copaia (Bignoniaceae), were compared on a poor ultisol with Inga edulis (Leguminosae) used Iocally as a quick growing cocoa shade. Trees were harvested at two years of age in the field when the biggest trees had a stem weight that could still allow a man to bring it home (75 kg). Mean dry stem wood yields per ha were 45.8 t for E. deglupta, 14.8 t for I. edulis, 8.9 t for J. copaia and 4.7 t for C. catenaeformis. There was no response to NPK in any species. I. edulis nodulated very well and N fixers were detected in the washed roots of E. deglupta. Only I. edulis regrew well because leaf cutting ants eliminated the succulent regrowth of E. deglupta and J. copaia inspite of several attempts of control. The low yields of the first crop of the latter were partly due to a similar attack by ants and many C. catenaeformis, and a few E. deglupta suffered fungal attacks. A few Eucalyptus were also slightly defoliated by bagworms (Psychidae). In a subsequent experiment, 99% of I. Edulis seedlings survived a very strong drought compared to 78% of E. deglupta and 46% of an acid tolerant cultivar of Leucaena leucocephala 70% of I. edulis seedlings from seed sown directly in the field also survived. Although E. deglupta is the obvious species of choice for large well managed plantations on better soils, I. edulis has many advantages as a woodlot species suitable for the shifting cultivator in this region. These include the ease of direct planting of seeds in the field, the ability to coppice, a tolerance to drought and leaf cutting ants, the fixation of N2 and the provision of wood of stove size, of good shade and of edible fruit. Yields could be improved rapidly by selection as some trees weighed twice the mean. Better form, less crown and higher density may be found amongst the 100 or more Ingas of Latin America. These now deserve more attention along with the problem of exhausting the nutrients in poor soils with quick growing species.