Uma visão multidisciplinar sobre ecologia

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Complexidade, dinâmica, gestão e sustentabilidade da paisagem: dos conceitos à aplicação nos mosaicos do Norte de Portugal

Apresentação no evento: Lançamento do Living-Lab Português do projeto ResAlliance. Data: 17 Novembro 2023 Local: Vila RealN/

Regeneration of Pinus pinaster forests after wildfire

Wildfires are of extreme importance in Pinus pinaster forests of central and northern Portugal. Reforestation plans after wildfires are generally made without consideration for the possibility of natural regeneration. This paper addresses the question of the factors responsible for the occurrence of natural regeneration and concludes that litter accumulation, rock outcrops, slope, aspect, harvest, fire characteristics, and stand age are well related to the regeneration observed. Limitations of the model proposed are discussed

Size-dependent pattern of wilfire ignitions in Portugal: when do ignitions turn into big fires ?

Not all wildfire ignitions result in burned areas of a similar size. The aim of this study was to explore whether there was a size-dependent pattern (in terms of resulting burned area) of fire ignitions in Portugal. For that purpose we characterised 71,618 fire ignitions occurring in the country in the period 2001–2003, in terms of population density in the local parish, land cover type and distance to roads. We then assigned each ignition into subsets of five classes according to the resulting burned area:[5 ha, [50 ha,[100 ha,[250 ha,[500 ha. The probability of an ignition resulting in different burned area classes was modelled using binary logistic regression, and the relative importance, strength and signal (positive or negative) of the three explanatory variables compared across the models obtained for the different classes. Finally, we explored the implications of land cover and population density changes during the period 1990–2000 in Portugal for the likelihood of ignitions resulting in wildfires[500 ha. Population density was the more important variable explaining the resulting burned area, with the probability of an ignition resulting in a large burned area being inversely related to population density. In terms of land cover, ignitions resulting in large burned areas were more likely to occur in shrubland and forest areas. Finally, ignitions farther away from roads were more likely to result in large burns. The current land cover trends (decrease of agricultural land and increase in shrublands) and population trends (decline in population densities except near the coast) are increasing the probability that ignitions will result in large fires in vast regions of the country

Characterizing and modelling the spatial patterns of wildfire ignitions in Portugal: fire initiation and resulting burned area

Modelling, Monitoring and Management of Forest FiresAccording to the statistics Portugal has the highest density of wildfire ignitions among southern European countries. The ability to predict ignition occurrence constitutes an important tool for managers, helping to improve the effectiveness of fire prevention, detection and fire fighting resources allocation. In this study we used a database with information about 127 490 fire ignitions that occurred in Portugal during a five year period. We performed frequency analysis to characterize the occurrence of wildfire ignitions in relation to both human and environmental variables and compared the spatial patterns of ignitions which originated fires larger or smaller than 500 ha. We also used logistic regression models to predict the relative probability of ignition occurrence, as a function of the resulting fire size. Results show that fire ignitions are strongly related to human presence and activity, and that the spatial patterns of ignitions are different for larger or smaller wildfires. Larger wildfires started in areas with lower population density, more distant from the main roads and at higher elevations, when compared to smaller fires, and also started more frequently in shrublands and forested areas. The results obtained can be useful in decision making for fire danger managementinfo:eu-repo/semantics/publishedVersio

Historical fire records at the two ends of Iberian Central Mountain system: Estrela massif and Ayllon massif

The Iberian Peninsula has a long history of fire, as the Central Mountain System, from the Estrela massif in Portugal to the Ayllón massif in Spain, is a major fire-prone area. Despite being part of the same natural region, there are different environmental, political and socio-economic contexts at either end, which might have led to distinct human causes of wildfires and associated fire regimes. The hypothesis for this research lies in the historical long-term relationship between wildfire risks and fire use practices within a context of landscape dynamics. In addition to conducting an analysis of the statistical period, a spatial and temporal multiscale approach was taken by reconstructing the historical record of prestatistical fires and land management history at both ends of the Central Mountain System. The main result is the different structural causes of wildland fires at either end of the Central Mountain System, with human factors being more important than environmental factors in determining the fire regimes in both contexts. The study shows that the development of the fire regime was non-linear in the nineteenth and twentieth centuries, due to broader local human context factors which led to a shift in fire-use practicesLa Península Ibérica cuenta con una larga historia de incendios forestales. Es el caso del Sistema Central, desde la Sierra de Estrela en Portugal a la Sierra de Ayllón en España, aunque las causas humanas y el régimen de incendios difieren en función del contexto ambiental, político y socioeconómico en uno y otro extremo de la cordillera. La validación de la hipótesis de trabajo, sobre la relación histórica entre el riesgo de incendios y el uso del fuego en las actividades humanas, se ha llevado a partir de la reconstrucción del registro histórico de incendios forestales y de la gestión del territorio, y mediante el análisis multiescalar espacio- temporal de los incendios históricos y estadísticos. Como principal resultado se han identificado las causas estructurales de incendios en las sierras de Estrela y Ayllón. Además, se ha demostrado la influencia mayor de los aspectos humanos que de los físicos en la evolución del régimen de fuego. En conclusión, este trabajo evidencia la evolución discontinua de los incendios forestales a lo largo de los siglos XIX y XX debido a los factores contextuales humanos que influyen en el manejo tradicional del fuego a escala localinfo:eu-repo/semantics/publishedVersio

Are drought and wilfires turning Mediterranean cork oak forests into persistent shrublands ?

In the Iberian Peninsula Mediterranean oak forests have been transformed into a mosaic landscape of four main patch-types: forests, savannas, shrublands and grasslands. We used aerial photographs over a period of 45 years (1958–2002) to quantify the persistence and rates of transitions between vegetation patch-types in southern Portugal, where cork oak is the dominant tree species. We used logistic regression to relate vegetation changes with topographical features and wildfire history. Over the 45 years, shrublands have been the most persistent patch-type (59%), and have been expanding; forests are also persistent (55%) but have been decreasing since 1985; savannas and grasslands were less persistent (33% and 15%, respectively). Shrublands persistence was significantly correlated with wildfire occurrence, particularly on southern exposures after 1995. In contrast, forest persistence decreased with wildfire occurrence, and forests were more likely to change into shrublands where wildfire had occurred after 1995

Influence of territorial variables on the performance of wildfire detection systems in the Iberian Peninsula

This article belongs to the Special issue: Fire use policies and practices in Europe: solving the Fire ParadoxWildfire detection systems planning is an essential component of national and regional wildfire management policies. The common resources usually used in wildfire detection are lookout towers, terrestrial mobile brigades, aerial reconnaissance and the general public. The objectives of this paper are (i) to analyse the relative importance of the different detection systems in Portugal and Spain, according to their spatial and temporal patterns, (ii) to assess the territorial variables related to the performance of fire detection systems in the Iberian Peninsula, and (iii) to develop an explanatory model aiming to inform fire detection policies. Pursuing this aim, a common wildfire and territorial database for the whole Iberian Peninsula was developed, thus enabling common cartographic and statistical analyses. Results show the importance of land cover variables and population density on the proportion of fire detections made by the different systems in both countries. Despite certain national specificities, many common features were found, allowing the identification of general patterns of fire detection distribution and performance for the Iberian Peninsula. Models developed at the regional and sub-regional levels indicate that high population density and high proportion of forestlands are associated with higher proportion of detection by population, whereas higher proportion of shrublands corresponds to higher proportions of detections by other systems, particularly lookout towers. The conclusions obtained and the approaches applied could be used with similar objectives in other countries and regions to inform policy decisions regarding the allocation of resources for wildfire detection

Selection of suitable species for bioengineering

Soil bioengineering was developed in central Europe after World War II and in Mediterranean Europe in the last twenty years; soil bioengineering has been recently applied also in Portugal suggesting its potential future development. Soil bioengineering, to consolidate and stabilize sliding down slopes, uses indigenous trees and shrubs with good vegetative propagation. A key feature of these species, employed as cuttings or as whole plants, is to not get damaged when their stems are buried in the ground about one meter. In this article is selected, from Mainland Portugal flora, a list of plant species, starting from scientific literature of Portugal, Central Europe and Central and Southern Europe, and using practical knowledge developed in Southern Italy. Afterwards groups of species are defined as (i) appropriate for soil bioengineering works to do in Portugal and (ii) probably adequate, requiring further researches to improve the knowledge about their feature. Tests are planned to assess the biotechnical features of this second group

Plant species richness in the Cape Verde islands - ecogeographical determinants

Plant species richness in the Cape Verde archipelago is examined relative to island eco-geographical factors. Species-area and species-area-habitat relationships are analysed using the classical species-area model and the recently proposed species-choros model. The number of Xoristic zones (used to estimate the choros parameter) provides an adequate estimate of the potential habitat diversity, and the species-choros model achieved a better Wt with both total Xora and endemic species. In addition to area and habitat diversity, longitude also emerges as an important determinant of species diversity, whereas latitude, minimum distance to the nearest island, and total rural population do not display any correlation. As in other insular ecosystems, the species richness (about 140 per 100 km2) is lower than in nearby mainland regions; the proximity to the desert areas of the Sahel can also be seen as related with this low value. The Xoristic heterogeneity in Cape Verde is high, as is usual in island ecosystems. In a comparative analysis of the species richness on the diVerent islands (using -values), Brava stands out as having the highest total Xora species densities, while for endemic Xora Brava and São Nicolau jointly occupy the leading position. The high diversity for both total and endemic species on Santo Antão, São Vicente, São Nicolau, Fogo and Brava reinforces their importance in conservation terms - in the case of most of them, something that is already recognized in the established network of protected area