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The purpose of this study was to assess spatial wildfire risk in a typical Mediterranean wildland-urban interface (WUI) in Greece and the potential effect of three different burning condition scenarios on the following four major wildfire risk components: burn probability, conditional flame length, fire size, and source-sink ratio. We applied the Minimum Travel Time fire simulation algorithm using the FlamMap and ArcFuels tools to characterize the potential response of the wildfire risk to a range of different burning scenarios. We created site-specific fuel models of the study area by measuring the field fuel parameters in representative natural fuel complexes, and we determined the spatial extent of the different fuel types and residential structures in the study area using photointerpretation procedures of large scale natural color orthophotographs. The results included simulated spatially explicit fire risk components along with wildfire risk exposure analysis and the expected net value change. Statistical significance differences in simulation outputs between the scenarios were obtained using Tukey's significance test. The results of this study provide valuable information for decision support systems for short-term predictions of wildfire risk potential and inform wildland fire management of typical WUI areas in Greece. [ABSTRACT FROM AUTHOR]

Aim Although all five of the major mediterranean-climate ecosystems (MCEs) of the world are recognized as loci of high plant species diversity and endemism, they show considerable variation in regional-scale richness. Here, we assess the role of stable Pleistocene climate and Cenozoic topography in explaining variation in regional richness of the globe's MCEs. We hypothesize that older, more climatically stable MCEs would support more species, because they have had more time for species to accumulate than MCEs that were historically subject to greater topographic upheavals and fluctuating climates. Location South-western Africa (Cape), south-western Australia, California, central Chile and the eastern (Greece) and western (Spain) Mediterranean Basin. Methods We estimated plant diversity for each MCE as the intercepts of species-area curves that are homogeneous in slope across all regions. We used two down-scaled global circulation models of the Last Glacial Maximum (LGM) to quantify climate stability by comparing the change in the location of MCEs between the LGM and present. We quantified the Cenozoic topographic stability of each MCE by comparing contemporary topographic profiles with those present in the late Oligocene and the early Pliocene. Results The most diverse MCEs - Cape and Australia - had the highest Cenozoic environmental stability, and the least diverse - Chile and California - had the lowest stability. Main conclusions Variation in plant diversity in MCEs is likely to be a consequence not of differences in diversification rates, but rather the persistence of numerous pre-Pliocene clades in the more stable MCEs. The extraordinary plant diversity of the Cape is a consequence of the combined effects of both mature and recent radiations, the latter associated with increased habitat heterogeneity produced by mild tectonic uplift in the Neogene. [ABSTRACT FROM AUTHOR]

Pinus nigra (black pine) is an ecologically and economically important species widely distributed around the Mediterranean Basin. P. nigra ecosystems have recently been affected by high severity fires occurring over the mountainous forest ecosystems of Southern Europe. The aim of this study is to investigate the post-fire regeneration patterns of black pine after a high severity crown fire which occurred on Mt Taygetos in Southern Greece. A network of 18 sites was selected to study black pine natural post-fire regeneration. Regeneration density was higher at the edges of patches that have remained unburned within the periphery of fire (0.406 individuals/m²) as compared to isolated burned areas (0.007 individuals/m²) although a significant between sites heterogeneity was recorded. Boosted regression trees analysis was used to explore the effects of environmental and microhabitat variables on black pine post-fire regeneration. The number of fires a site has experienced had a negative effect on regeneration density, while the presence of recovering ferns had a positive effect. The most important variable related to the black pine post-fire regeneration was distance from unburned patches. The result of the current study substantiates the importance of maintaining fire-resistant stands with large trees that are more likely to survive after a surface fire and which can also serve as seed sources for the recolonization of the burned area after severe crown fires. [ABSTRACT FROM AUTHOR]

The objective of this work was to compare and contrast the patterns of alien plant invasions in the world’s five mediterranean-climate regions (MCRs). We expected landscape age and disturbance history to have bearing on levels of invasion. We assembled a database on naturalized alien plant taxa occurring in natural and semi-natural terrestrial habitats of all five regions (specifically Spain, Italy, Greece and Cyprus from the Mediterranean Basin, California, central Chile, the Cape Region of South Africa and Southwestern - SW Australia). We used multivariate (hierarchical clustering and NMDS ordination) trait and habitat analysis to compare characteristics of regions, taxa and habitats across the mediterranean biome. Our database included 1627 naturalized species with an overall low taxonomic similarity among the five MCRs. Herbaceous perennials were the most frequent taxa, with SW Australia exhibiting both the highest numbers of naturalized species and the highest taxonomic similarity (homogenization) among habitats, and the Mediterranean Basin the lowest. Low stress and highly disturbed habitats had the highest frequency of invasion and homogenization in all regions, and high natural stress habitats the lowest, while taxonomic similarity was higher among different habitats in each region than among regions. Our analysis is the first to describe patterns of species characteristics and habitat vulnerability for a single biome. We have shown that a broad niche (i.e. more than one habitat) is typical of naturalized plant species, regardless of their geographical area of origin, leading to potential for high homogenization within each region. Habitats of the Mediterranean Basin are apparently the most resistant to plant invasion, possibly because their landscapes are generally of relatively recent origin, but with a more gradual exposure to human intervention over a longer period. [ABSTRACT FROM AUTHOR]

The Mediterranean pine species of low-and mid-elevations, namelyPinus halepensisMill.,Pinus brutiaTen.,Pinus pineaL. andPinus pinasterAit., constitute an important component of forest vegetation in Mediterranean-type ecosystems around the Mediterranean basin. These forests are strongly influenced by wildfires, which have occurred for millennia in Mediterranean regions. In burned Mediterranean pine forests, the community composition and the population dynamics of soil arthropods are determined by their life history traits and the wildfire regime. In these ecosystems, the effects of fire regime on soil arthropods at the taxonomical level of order are similar to those recorded in other Mediterranean-type ecosystems. Severe wildfires cause a simplification of the structure of the soil community due to both the immediate mortality of soil animals and the structural alteration of the soil organic horizon. Frequent wildfires influence the soil arthropods indirectly, preventing the recovery processes of the vegetation and, consequently, of the organic horizon. Wildfires do not influence the phenology of soil arthropods, at least at the taxonomical level of order, and the seasonality of the Mediterranean climate remains the principal environmental factor controlling the dynamics of soil arthropod populations. The recovery patterns of soil arthropods vary in relation to species, fire regime, and the environmental characteristics of the forest under consideration. [ABSTRACT FROM PUBLISHER]

Water is the most critical limiting factor for decomposition processes in Mediterranean climate ecosystems. The aim of this study was to investigate the effects of increased soil moisture levels upon cellulose mass loss in an eastern Mediterranean ecosystem. We used a split plot experimental design to evaluate the effect of seasonality on the decomposition process by manipulating water availability in situ during different seasons. Nylon litterbags of mesh size 20 μm and 1 mm were filled with cellulose filter paper and placed on the plots during each season. The treatment consisted of a systematic uniform watering of the plots with 7 L/m2/week. Litterbags were randomly removed from each plot on a monthly basis. Cellulose mass loss showed differences between treatment and control plots and between seasons but was significant only in the spring. Cellulose mass loss was significantly affected by irrigation treatment, season, and their interaction, while moisture seemed to be affected only by season. There was no significant difference in cellulose mass loss due to different mesh sizes. [ABSTRACT FROM AUTHOR]

Every year approximately half a million hectares of land are burned by wildfires in southern Europe, causing large ecological and socio-economic impacts. Climate and land use changes in the last decades have increased fire risk and danger. In this paper we review the available scientific knowledge on the relationships between landscape and wildfires in the Mediterranean region, with a focus on its application for defining landscape management guidelines and policies that could be adopted in order to promote landscapes with lower fire hazard. The main findings are that (1) socio-economic drivers have favoured land cover changes contributing to increasing fire hazard in the last decades, (2) large wildfires are becoming more frequent, (3) increased fire frequency is promoting homogeneous landscapes covered by fire-prone shrublands; (4) landscape planning to reduce fuel loads may be successful only if fire weather conditions are not extreme. The challenges to address these problems and the policy and landscape management responses that should be adopted are discussed, along with major knowledge gaps. [Copyright &y& Elsevier]

This study aims to provide a quantitative framework to model the dynamics of Mediterranean coniferous forests by integrating existing ecological data within a generic mathematical simulator. We developed an individual-based vegetation dynamics model, constrained on long-term field regeneration data, analyses of tree-rings and seed germination experiments. The simulator implements an asymmetric competition algorithm which is based on the location and size of each individual. Growth is parameterized through the analysis of tree-rings from more than thirty individuals of each of the three species of interest. A super-individual approach is implemented to simulate regeneration dynamics, constrained with available regeneration data across time-since-disturbance and light-availability gradients. The study concerns an insular population of an endemic to Greece Mediterranean fir (Abies cephalonica Loudon) on the island of Cephalonia (Ionian Sea) and two interacting populations of a Mediterranean pine (Pinus brutia Ten.) and a more temperate-oriented pine (Pinus nigra Arn. ssp. pallasiana) on the island of Lesbos (NE Aegean Sea), Greece. The model was validated against plot-level observations in terms of species standing biomass and regeneration vigour and adequately captured regeneration patterns and overall vegetation dynamics in both study sites. The potential effects of changing climatic patterns on the regeneration dynamics of the three species of interest were subsequently explored. With the assumption that a warmer future would probably cause changes in the duration of cold days, we tested how this change would affect the overall dynamics of the study sites, by focusing on the process of cold stratification upon seed germination. Following scenarios of a warmer future and under the current model parameterization, changes in the overall regeneration vigour controlled by a reduction in the amount of cold days, did not alter the overall dynamics in all plant populations studied. No changes were identified in the relative dominance of the interacting pine populations on Lesbos, while the observed reduction in the amount of emerging seedlings of A. cephalonica on Cephalonia did not affect biomass yield at later stages of stand development. [Copyright &y& Elsevier]

Vascular plants have been found to align along globally-recognised resource-allocation trade-offs among specific functional traits. Genetic constrains and environmental pressures limit the spectrum of viable resource-use strategies employed by plant species. While conspecific plants have often been described as identical, intraspecific variation facilitates species coexistence and evolutionary potential. This study attempts to link an individual's phenotype to its environmental tolerance and ecosystem function. We hypothesised that: (1) seasonal variation in water availability has selected for tight phenotypic integration patterns that shape Mediterranean vegetation; however, (2) coexisting species employ alternative resource-use strategies to avoid competitive exclusion; specifically (3) species with smaller climatic niches (i.e. potential distributions) display higher functional diversity. We examined the interdependence among and the sources of variation within 11 functional traits, reflecting whole-plant economics (e.g. construction costs, hydraulics, defences, water storage capacity), from nine dominant, thermo-Mediterranean species measured across a wide environmental and geographic gradient. Furthermore, we delineated the phenotypic and climatic hypervolumes of each studied species to test for climatic niche overlap and functional distinctiveness. By adopting this multidimensional trait-based approach we detected fundamental phenotypic integration patterns that define thermo-Mediterranean species regardless of life history strategy. The studied traits emerged intercorrelated shaping a resource-allocation spectrum. Significant intraspecific variability in most measured traits allowed for functional distinctiveness among the measured species. Higher functional diversity was observed in species restricted within narrower climatic niches. Our results support our initial hypotheses. The studied functional traits collectively formed an integrated space of viable phenotypic expressions; however, phenotypic plasticity enables functionally distinctive species to succeed complementary in a given set of environmental conditions. Functional variability among coexisting individuals defined species' climatic niches within the trait-spectrum permitted by Mediterranean conditions. Ultimately, a species establishment in a locality depends on the extent that it can shift its trait values., (Copyright © 2019 Elsevier B.V. All rights reserved.)