Author(s):
Fabião, António 
; Madeira, M. ; Pereira, J.S. ; Araújo, M.C. ; Ribeiro, C.
Date: 2002
Persistent ID: http://hdl.handle.net/10400.5/1345
Origin: Repositório da UTL
Subject(s): eucalyptus globulus; carbon stocks; nutrients; water
Description
Changes in the carbon stocks under different soil water and nutrient conditions were studied in Eucalyptus globulus Labill.
stands in a field experiment, at O ´ bidos (central Portugal). The treatments were irrigation plus a complete fertiliser solution to
simulate ‘near optimal’ nutrition (IF), irrigation only (I), and fertilisers added to rain-fed plots (F). The control (C) received
neither water nor fertilisers (except a small amount at planting). The production of biomass (aboveground), the litterfall and the
soil chemical composition were evaluated regularly during the experiment. Root biomass was estimated at the end of the
experiment. Carbon in biomass, litterfall and soil, increased significantly when water and/or nutrients were supplied, in
comparison to the control. The amount of carbon accumulated in the system, 6 years after planting, was 8.22, 10.22, 11.23 and
13.76 kg C m 2 in the control, F, I and IF treatments, respectively. The increase of carbon in the system during the same period
was 5.86, 7.86, 8.87 and 11.40 kg C m 2 in the control, F, I and IF treatments, respectively. This rise in carbon resulted from the
accumulation of long-lived woody biomass, which represented between 77.7 (in IF) and 82.9% (in the control) of the total rise in
carbon. Although water was the main limiting factor for biomass accumulation, the allocation of carbon to the soil was mainly
related to nutrient supply, irrespective of water availability. The amount of carbon stored belowground, i.e. soil and forest floor,
plus stumps and roots, reached 4.2, 4.7, 4.8 and 6.3 kg C m 2 in the control, F, I and IF treatments, respectively. The increase in
C in the mineral soil regarding the initial state was, in the same order as above, 0.21, 0.75, 0.58 and 1.21 kg C m 2. These values
were 3.6, 9.6, 6.6 and 10.6% of the C accumulated in the whole system, during the experimental period.
