Author(s):
Fabião, António 
; Madeira, M. ; Herraez, L. ; Dighton, J. ; Gonzalez-Rio, F. ; Tomé, Margarida ; Fernandez Marcos, M.
Date: 1999
Persistent ID: http://hdl.handle.net/10400.5/1342
Origin: Repositório da UTL
Subject(s): eucalyptus globulus; sustainable forestry; organic matter management; decomposition rates
Description
Sustainable management of forest resources, including nutrient retention and protection of the soil structure, is required to
ensure long-term soil fertility and productivity of later rotations. Potential depletion of soil nutrients is particularly likely in
production systems based on fast-growing trees, such as eucalypts. We have studied production of second rotation Eucalyptus
globulus stands at two sites in northern Spain and two in central Portugal, after replanting or coppicing, under four treatments,
in which plant residues from the ®rst crop were utilised. The residues were either removed from the sites (Treatment R),
spread over the soil surface (Treatments S, uniform spreading, and W, in which the woody debris was con®ned to rows
between the trees) or incorporated into the soil by harrowing to 15-cm depth (Treatment I). We measured tree height and girth
at intervals over three growing seasons, and root biomass at the Portuguese sites. Decomposition of three residue components:
leaves-plus-bark, twigs and branches, was measured in litter bags placed in the position corresponding to the placement of the
organic residues.
By the end of the experiment, tree height was signi®cantly greater in Treatment I than in Treatment R at both Spanish sites,
if planted as seedlings, with intermediate growth in S and W. In Portugal, tree height was smaller in R, though not
signi®cantly. DBH showed similar trends, although treatment differences were not signi®cant. Coppiced trees grew faster than
seedling trees, but a signi®cant treatment effect on the growth was only observed at the inland Portuguese site, where it was
better in Treatment I by the end of the experiment.
The residues decomposed signi®cantly faster in I than S or W at the Portuguese sites, but not in Spain. Leaves-plus-bark
decomposed faster than twigs, and twigs faster than branches.
The results are discussed in relation to recommended management options
