Browsing by Author "Rego, Francisco C."
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- Fire effects on litter chemistry and early development of Eucalyptus globulusPublication . Águas, Ana; Incerti, Guido; Saracino, Antonio; Lanzotti, Virginia; Silva, Joaquim S.; Rego, Francisco C.; Mazzoleni, Stefano; Bonanomi, GiulianoBackground and aim Fires affect what happens to litter in ecosystems. Biological and chemical effects of burnt litter on plants are not as of yet fully understood. We aimed to assess the effects of heat-treated leaf litter on germination and seedling root growth of Eucalyptus globulus. Methods Litter from E. globulus, Acacia dealbata, Pinus pinaster, and Quercus suber was collected in Portugal, on Humic Cambisol, and heated between 25 °C and 600 °C. Those materials were then characterized by: 13C CPMAS NMR spectroscopy, proximate lignin and cellulose, and elemental analyses. Afterwards, they were used as substrate in bioassays with Eucalyptus seeds. Results Heating changed litter composition (P < 0.05), consistently across species: alkyl C, O-alkyl C, and methoxyl + N-alkyl C decreased more than 50%; and aromatic C increased more than 5-fold. Unheated and lightly heated litters inhibited germination and growth, with maximum inhibition by Quercus and Eucalyptus litters, down to 17% of the control (P < 0.05). Severely charred materials had neutral or stimulatory effects, up to 191% of the control (P < 0.05). These responses were associated with concentrations of dominant C types in litters (P < 0.05). Conclusion Litter charring, as it occurs during wildfires, is potentially critical for the success of E. globulus’s regeneration from seeds.
- Understanding the naturalization of Eucalyptus globulus in Portugal: a comparison with Australian plantationsPublication . Águas, Ana; Larcombe, Matthew J.; Matias, Hugo; Deus, Ernesto; Potts, Brad M.; Rego, Francisco C.; Silva, Joaquim S.Despite the potential utility of a biogeographical approach to understanding the naturalization of exotic species, studies using this approach are scarce. Eucalyptus globulus is an economically important Australian tree species that has become naturalized in a number of countries where it was introduced. Portugal is an ideal territory to study the naturalization of E. globulus owing to: a long introduction history, the antipodal location compared to Australia and the large cultivated area. Wildling density was assessed in 116 E. globulus plantations in central Portugal through 213 transects established along plantation borders. Boosted regression trees were used to model the influence of plantation-scale variables. Results from this survey were compared with data obtained in plantations from seven Australian regions, where a similar sampling protocol had been used. In Portugal, wildlings were more abundant in plantations that were: located in moist aspects, coppiced, with older tree stems and corresponding to intermediate site growth indexes. The overall density (127 plants ha-1) was 14.9 times higher than in the Australian estate, but this ratio was reduced to 3.1 in a more comparable subset of unburnt, first rotation plantations. A generalized linear model fitted using a dataset combining the two surveys showed that country influenced wildling density, together with plantation rotation and stem age. These results provide insights into the naturalization of a widely cultivated tree species, pointing to a fundamental role of the introduction history, possibly acting along with the biogeographical characteristics of the introduced range.