Xavier Úbeda

Mediterranean ecosystems are increasingly affected by the rising frequency and intensity of wildfires, requiring proactive management strategies such as grazing or prescribed burns to control post-fire biomass. Despite an extensive body of literature addressing the individual effects of these two disturbances, their combined and sequential effects on soil properties remain poorly understood and heterogeneous. This highlights the need to synthesise extant evidence on fire–grazing interactions and to identify associated knowledge gaps. This study aims to map and synthesise evidence of the effects of fire and grazing on Mediterranean ecosystem soil properties and associated ecosystem functioning. It also seeks to characterise management regimes, identify research gaps, and inform sustainable soil management and conservation strategies. Peer-reviewed studies published in English between 2005 and 2025 focusing on Mediterranean ecosystem soils affected by fire–grazing sequences were included. Both quantitative and qualitative studies assessing physical, chemical, or biological soil properties were considered. A systematic search was conducted in Scopus, Web of Science, and Google Scholar using Boolean search terms related to fire, grazing, livestock, Mediterranean ecosystems, and soils for the period 2005–2025. Data were charted in ATLAS.ti using a standardised coding framework following pilot testing. Three independent reviewers extracted and agreed on study characteristics, soil variables, and fire–grazing regime information. Fourteen studies met the inclusion criteria, primarily conducted in Spain and Israel. The evidence shows a strong emphasis on biological variables and short-term responses, with reported positive outcomes mainly related to vegetation and biodiversity. Research on fire–grazing practices is predominantly oriented towards management and conservation objectives, while physical and chemical soil properties remain underrepresented. This indicates substantial knowledge gaps in the current literature. Fire–grazing research remains fragmented and dominated by biological approaches, limiting a comprehensive understanding of soil processes. Despite its management potential, there is a clear need for more standardised, long-term, and multidisciplinary studies across diverse Mediterranean ecosystem regions to support resilient ecosystem management.

Rural land abandonment means that some rural areas fall into disuse or are taken over by forest stands. In this context, prescribed burning is a widely used forest management tool, but few studies have analyzed the influence of pre-burn land use on post-burn soil recovery. This study seeks to determine the impact of prescribed burning on soil chemical properties and to examine any differences in these parameters based on prior land use. The study is conducted in two plots – one, a forest plot (TV2); the other an abandoned agricultural terrace (TV3) – located in Tivissa (southern Catalonia), both dominated by Pinus halepensis Mill. and Quercus ilex L., and situated on Lithic Calcixerept soils. The plots, located 3 km apart, share a similar topography, exposure, and vegetation structure. Low-intensity prescribed burns were conducted in 2001, and soil samples (0–5 cm depth) were collected in five campaigns: just before the fire (BPF), immediately after the fire (APF), and at 1-, 3-, and 13-years post-burn (1YAPF, 3YAPF, and 13YAPF, respectively). In each sampling period, 30 samples were collected from an experimental plot of 72 m2 (4 x 18 m). The soil properties analyzed included total carbon (TC), total nitrogen (TN), pH, electrical conductivity (EC), and extractable calcium (Ca), magnesium (Mg), potassium (K), and available phosphorus (P) concentrations. In TV2 soil, TC and TN increase at short and medium term, soil pH increases after fire and decreases gradually, EC decreases at short and medium term, and increases at long-term, and extractable major cations increase until medium term and are reduced at long-term. In TV3 soil TC decreases and TN increases gradually over time, pH increases at short and decreases at long-term, EC decreases from short to long-term with a slight increase at medium-term, and extractable major cations (except P which decrease over time) increase until long-term. Changes caused by different pre-fire land use and consequently differences caused by different vegetation cover minor over time. Despite differences in soil properties in the short and medium term due to land use prior to prescribed fire, after 13 years, soil conditions had largely stabilized, and there was no evidence of horizontal or vertical continuity in plant fuel. These findings suggest that prescribed burning does not result in long-term soil degradation and, thus, remains a viable tool for sustainable forest management under different land uses.

Wildfires pose one of the greatest threats to the world’s forests soils. After exposure to fire, forests lose many of their ecological functions; moreover, the repercussions can extend well beyond the forest itself, as the erosive processes attributable to the combustion of vegetation and the soil’s lack of protection against rainfall are likely to impact any areas of a catchment, contaminating reservoirs, estuaries and aquifers. A forest fire is not solely, therefore, an environmental issue, but also a social and economic problem. The recovery of a forest is heavily dependent on just how the soil has been affected and how rapidly the latter can be restored. Fire intensity is critical in understanding the temporal evolution of the forest, while its location—a clear determinant of its climate and the ecosystem it occupies—can undermine the functionality of the forest system and is critical in determining the duration of the effects of the fire episode. This paper undertakes a review of the literature with the aim of understanding what might be understood when studies speak of the long-term effects of fire on the soil and when a soil might be considered to have recovered from these effects. What is evident is that many variables have a role to play and that not all soil properties recover at the same rate; indeed, some may never be restored to pre-fire levels.

Purpose: Urban agriculture is expanding worldwide and is being promoted by the FAO as a strategic activity because of its environmental, socio-economic, and educational benefits for citizens. In Spain, it is estimated that there are more than 20,000 urban gardens. There are many variables to take into account when starting to cultivate an urban garden, among which the quality of the soil is crucial. Nevertheless, some studies have shown high levels of contamination in soils dedicated to urban horticulture. The sources of contamination can be various, such as previous unrecognized management and irrigation with poor quality water, or the addition of polluted compost and other soil improvers. Soil contamination can migrate to vegetables and fruits, thus entering the food chain. Materials and methods: In this study, we analyzed the soils from ten urban gardens in the city of Barcelona, with a special focus on possible contaminants. Based on the possibility that irrigation water is a source of pollution, this was also analyzed in all investigated gardens. Results and discussion: Some of the waters analyzed for irrigation have a high concentration of salts, and a few of them contain nitrites, which are listed as a pollutant. The dominant texture of the soils was sandy clay loam and loamy sand, the pH was generally high, between 7.87 and 8.41, clearly carbonated, with Ca generally being the dominant exchangeable cation, but without the risk of a high percentage of active carbonates that could make it difficult to grow vegetables. The content in organic matter was very variable, but in all cases it appeared to be potentially incrementable. The three tests used to check possible soil contamination from heavy metals, do not attest to significant pollution. Conclusions: The soil quality overall is suitable for growing vegetables and allowing growers to work in these areas in complete safety. Although it would be necessary to analyze also other toxic elements, not considered in this study, some of the measured ones could come from the gases of road transport or even from the port of Barcelona.

High-severity wildfires have a major impact on vegetation and soil properties. Moreover, recently burned areas are susceptible to extreme rainfall events and post-fire management. However, little is known about the impact of extreme rainfall and salvage logging on the relationship between soil properties and vegetal recovery and their spatial distribution. This study examines the effects of intense rainfall and post-fire management on soil properties and vegetal recovery and their spatial distribution in a small area using principal component analysis (PCA) medium-term after the fire. The vegetal recovery was measured using the index as Richness (S), Evenness (It), Density (D) and Diversity (H'). The soil variables studied were aggregate stability (AS), total nitrogen (TN), soil organic matter (SOM), inorganic carbon (IC), C/N ratio, calcium carbonates (CaCO3), pH, electrical conductivity (EC), available phosphorus (P), extractable calcium (Ca), extractable magnesium (Mg), extractable sodium (Na) and extractable potassium (K). Each PCA for vegetation and soil (one year after fire and four years after fire) allowed us to extract five factors and carry out the variograms with each factor for each moment. The preliminary results showed an increase in factors that mainly explain the results at the time four years after the fire compared to one year after. The PCA score maps illustrated a marked change in the spatial distribution of the variables one year and four years after the wildfire.

Forest management is a common practice to reduce wildfire risk, furthermore in ecosystems prone to fire and where wildfires are recurrent as is the Mediterranean ecosystem. However, few studies were carried out about the effects of pre-fire management in wildfire affected areas and the effectivity of these managements decreasing soil nutrients depletion. The aim of this study is to examine the effectivity of this treatment (clear-cutting operation whereby part of the vegetation was cut and left covering soil surface) carried out before a wildfire that broke out in 2015 and evaluate if the management had influence on wildfire severity of three sites: two exposed to management practices in 2005 (site M05B) and in 2015 (site M15B)–and one that did not undergo any management (NMB) and to compare their properties with those recorded in a Control area unaffected by 2015 wildfire. The fourth areas were sampled and compared 2, 10 and 18 months after wildfire. The study area is located in Ódena (NE Spain). The wildfire occurred at July 27th of 2015 and burned 1237 ha. In each area and in each sampling moment we collected 9 topsoil samples (0-5 cm depth) and analyzed: aggregate stability (AS), soil organic matter (SOM) content, total nitrogen (TN), pH, electrical conductivity (EC), extractable calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K). Two-way ANOVA statistical analysis was carried out to check the differences between managements and time. Results show significant differences (p value < 0.05) between managements 2 months after wildfire in AS, TN, SOM, pH, EC, Ca and Mg; 10 months after wildfire in AS, SOM, pH, EC, Ca, Mg and Na; and 18 months after wildfire in AS, SOM, pH, EC, Ca and Mg. Differences between sampling time were registered in M05B, M15B and NMB for each soil analyzed property. Control did not vary significantly (p value > 0.05) over time due to the absence of fire or manage perturbation. The vegetation removal in M05B decreased the wildfire impact on soil, perhaps due to the fuel load reduction and consequent low fire severity. In this case if forest management is carried out few months before the fire, the impact is strongly reduced as occurs in M15B. High fuel density that we found in NMB site should be managed to avoid high wildfire severity. Overall, the time of forest management previous to fire is a crucial aspect that influence on fire severity and the consequent impact on soil properties. Therefore, this type of studies and knowledge should be taken into account and incorporated when carrying out forest management plans to periodically manage certain areas.

Urban complexity can be measured by the numerical and spatial diversity of activities in a territory. Just as biodiversity can be measured in a natural ecosystem, diversity indices can be applied to urban settings. Urban diversity presents higher values in areas where there is a greater number of (economic, institutional, and social) activities with a high degree of differentiation between them. This study seeks to investigate the potential of applying an urban diversity index in a specific case study: namely, the city of Barcelona (Spain), known for the orthogonal grid plan of its Eixample district. Results show that the municipal territory of Barcelona as a whole is characterized by highly differentiated spaces according to their urban diversity values. Specifically, it is the Eixample district that presents the highest values of urban diversity, reflecting the densification of its morphology and its urban commercial policies.

Durante siglos los incendios forestales han tenido lugar en España y han configurado el paisaje vegetal del país. Lo que se plantea en este artículo es analizar si ha habido un cambio de régimen de incendios en las últimas décadas. Los resultados indican que parece ser que sí hay un cambio de régimen, aunque la respuesta es diferente dependiendo de la ubicación geográfica de los bosques en España. El abandono de las prácticas forestales, la despoblación de las áreas rurales y los efectos del cambio climático, pueden ser las causas de este cambio de régimen de incendios.