Wildfires can cause serious imbalances in ecosystems, primarily at the soil level, making it vulnerable to degradation processes such as erosion. During and after a fire, changes occur in soil properties, including pH, which affects the solubility and availability of nutrients. Currently, there is a great diversity of protocols, some involving normalized standards, to determine soil pH, but there is no consensual or universal analytical method for this parameter, especially in burned soils, in which mineral and organic fractions could have been modified. Therefore, the objective of the present work is to evaluate the effect that variations in these analytical protocols may have on pH results. For this, five methods commonly found in the international bibliography for the analysis of pH of soil in water (pH_H2O) were selected and compared to propose the most precise procedure. The analytical methods were applied to 43 soil samples, collected in a plot subjected to prescribed burning in the Parque Natural de Montesinho (Northern Portugal). The studied methods differ in the following protocol items: water suspension ratio (1:2.5 or 1:5), mechanical stirring time in the suspension (10 min or 1 h), and in the resting time for the solid particles to settle (15 min or 8 h). The obtained results point to the suitability of the five methods used for soil pH analysis, indicating that there are no statistically significant differences. However, results also allow suggesting a more appropriate method concerning practical reasons, such as labor in a lab. Thus, to make the analysis process more profitable, M2 is a good option because it uses a small amount of sample (5 g), short agitation (10 min) and settling time (15 min). In turn, M1 and M5, which use a lower proportion of soil (1:2.5) show lower pH variation in the measurements. This fact may be explained by a smaller dilution effect. Considering that these two methods differ in the settling time, it is suggested to apply M1, because only 15 min are required. Therefore, the main conclusion reached with this work is that the measurement of soil pH using M1, i.e., a soil:water ratio of 1:2.5, with agitation of 10 min and settling time of 15 min, is a robust and more expeditious protocol to be applied to soil samples after a fire.

Os lameiros exercem um papel de influência na regulação do ciclo hidrológico em pequenas bacias de drenagem em zonas de montanha. No Parque Natural de Montesinho (PNM), os lameiros estão em regressão de uso devido ao abandono da terra, principalmente por se situarem em zonas com alto declínio demográfico. Nestas condições, através do método SCS (Soil Conservation Service), estimaram-se caudais de ponta em dezasseis bacias hidrográficas ocupadas parcialmente por lameiros no PNM, sendo possível identificar diferenças significativas entre categorias de bacias associadas a presença ou não de rio próximo aos lameiros, bem como ao uso e abandono de terra. Além disso, baseando-se em previsões de precipitação, no contexto de alterações climáticas, simulou-se um aumento de até 86% de nos caudais de ponta até o ano de 2100. À vista das respostas hidrológicas obtidas, percebeu-se o impacto do processo de abandono dos lameiros, principalmente nos caudais de ponta, trazendo efeitos negativos e riscos hidrológicos através da falta ou inadequação do manejo dessas zonas