Effects of fire occurrence and recurrence on nitrogen and phosphorus losses by overland flow in maritime pine plantations in north-central Portugal

Geoderma ◽  
2017 ◽  
Vol 289 ◽  
pp. 97-106 ◽  
Author(s):  
Mohammadreza Hosseini ◽  
Violette Geissen ◽  
Oscar González-Pelayo ◽  
Dalila Serpa ◽  
Ana Isabel Machado ◽  
...  
2013 ◽  
Vol 61 (4) ◽  
pp. 261-268 ◽  
Author(s):  
Martinho A.S. Martins ◽  
Ana I. Machado ◽  
Dalila Serpa ◽  
Sergio A. Prats ◽  
Sílvia R. Faria ◽  
...  

Abstract The purpose of this study was to assess how terracing affected overland flow and associated sediment losses, at the micro-plot scale (0.25 m2), in recently burnt stands of the two principal forest types in north-central Portugal, i.e. mono-specific stands of Maritime Pine and Eucalypt. Terracing is an increasingly common practice of slope engineering in the study region but its impacts on runoff and erosion are poorly studied. Non-terraced plots at the Eucalypt and the Pine site revealed similar median runoff coefficients (rc: 20-30%) as well as comparable median sediment losses (15-25 g m-2) during the first seven months following wildfire. During the ensuing, slightly wetter 18-month period, however, non-terraced plots at the Pine site lost noticeably more sediments (in median, 90 vs. 18 g m-2), in spite the runoff response had remained basically the same (median rc: 33 vs. 28%). By contrast, terraced plots at the same Pine site lost hugely more sediments (in median, 1,200 g m-2) during this 18-month period. Terraced plots at the Eucalypt site even lost three times more sediments (in median, 3,600 g m-2). Ground cover and resistance to shear stress seemed to be key factors in the observed/inferred impacts of terracing.


2021 ◽  
Author(s):  
Dalila Serpa ◽  
Ana Machado ◽  
Martha Santos ◽  
Isabel Campos ◽  
Fátima Jesus ◽  
...  

<p>Wildfires constitute a diffuse source of contamination to aquatic ecosystems. In burnt hillslopes, ash and sediments transported by overland flow are a source of potentially hazardous substances, like metals, posing a risk for downstream water bodies. In the present study, post-fire metal mobilization by overland flow was evaluated in 16 m<sup>2 </sup>bounded plots at a eucalypt stand in Albergaria-a-Velha (Aveiro district, North-Central Portugal) that burnt with moderate severity in September 2019. Overland flow samples were collected on a weekly to bi-weekly basis, depending on the occurrence of rain, during the first 6 months after fire. Aside from overland flow samples collected at slope scale, water and sediment samples were also collected in a fire-affected stream within the Albergaria burned catchment, to assess the contamination risk posed by the fire. Samples were collected at three sites along the stream: one upstream, one within and another downstream from the burnt area, after major rainfall events. The metals analysed in this study included, vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb). Results showed that most metals exhibited a peak in exports immediately after the first significant post-fire rainfall event likely due to the wash-off of the ash layer and high sediment losses, but for some elements like Zn and Cu, exports were more or less constant over time. The fire seems to have had a low impact on the water quality of the affected stream, since metal concentrations were similar between the three study sites. The quality of stream sediments, on the other hand, was clearly affected by the fire, especially after the rainy season. As fire severity and frequency is forecasted to increase in the near future due to climate changes, the results of this work reinforce the importance of water managers to define adaptative strategies to effectively protect freshwater bodies.</p>


2016 ◽  
Vol 572 ◽  
pp. 1281-1288 ◽  
Author(s):  
R.V. Ferreira ◽  
D. Serpa ◽  
A.I. Machado ◽  
M.L. Rodríguez-Blanco ◽  
L.F. Santos ◽  
...  

2015 ◽  
Vol 524-525 ◽  
pp. 201-212 ◽  
Author(s):  
A.I. Machado ◽  
D. Serpa ◽  
R.V. Ferreira ◽  
M.L. Rodríguez-Blanco ◽  
R. Pinto ◽  
...  

1993 ◽  
Vol 130 (2) ◽  
pp. 145-153 ◽  
Author(s):  
R. J. Reavy ◽  
D. H. W. Hutton ◽  
A. A. Finch

AbstractThe Castanheira pluton in north-central Portugal is a small (1000 m × 600 m) granite body of Hercynian age which contains a remarkable abundance of granite-cored, biotite-rimmed nodules. The nodules are interpreted as representing original bubbles in the uppermost volatile-rich zone of a granitic pluton. Strong depletion in K and Rb in the host granite around the nodules suggests that the biotite is magmatic in origin. The nodules may have formed by reaction between chloroferrate(II) complexes in the vapour phase and silicate melt, possibly followed by condensation of the vapour phase to a small granitic core. Motion of the vapour bubble stabilized a gradient in chemical potential with respect to the host granite, giving rise to the nodules. Chemical, petrological and structural data suggest that the pluton was part of a larger granite body, which was forcefully emplaced during synchronous transcurrent shearing. The inferred presence of volatiles, in addition to the pervasive tourmalinization of the roof zone, suggest that the magma was halogen-rich; this may imply that the magma had low viscosity.


Sign in / Sign up

Export Citation Format

Share Document