A 13-year approach to understand the Effect of prescribed fires and livestock grazing on soil chemical properties in Tivissa, NE Iberian Peninsula

The high density of fuel accumulated in the Mediterranean ecosystems due to land abandonment results in high severity fires. Traditional fire practices and livestock grazing have played an important role in shaping the structure and composition of Mediterranean landscapes, and both can be e cient tools to manage them now that land abandonment is widespread. Attempts at controlling forest fires are essential for landscape management practices that, in their turn, seek to maintain a specific species composition. Against this backdrop, this study aims to determine the short- and long-term e ects of the combined management practices of prescribed fires and goat grazing on the chemical properties of soils in Tivissa, Tarragona (NE Iberian Peninsula). Forty-two samples were collected in a 4 18 m plot before the prescribed fire of 2002 (1), immediately after the 2002 prescribed fire (PF) (2), one year after the 2002 PF (3), three years after the 2002 PF (4), and thirteen years after the 2002 PF (5). Soil samples were taken at each sampling point from the top layer (0-5 cm), sieved to obtain a <2 mm fraction, and soil pH, EC, Total C, total N, available P, K+, Ca2+, and Mg2+ were determined. The results indicate that the short-term e ects of fire are more relevant than those attributable to the livestock over the long term due to the low grazing intensity of less than one goat per ha. The long-term e ects of prescribed fires were not visible in the research, suggesting that they recovered after burning with all their functions intact and with enhanced levels of natural fertility. Combined land management practices of prescribed fire and livestock grazing did not a ect soil chemical properties. The applied management enhanced soil fertility and boosted the ecosystem's resilience

Long-term impact of wildfire on soils exposed to different fire severities. A case study in Cadiretes Massif (NE Iberian Peninsula)

Wildfires affect ecosystems depending on the fire regime. Long-term studies are needed to understand the ecological role played by fire, especially as regards its impact on soils. The aim of this study is to monitor the longtermeffects (18 years) of awildfire on soil properties in two areas affected by lowand high fire severity regimes. The properties studied were total nitrogen (TN), total carbon (TC), C/N ratio, soil organic matter (SOM) and extractable calcium (Ca), magnesium (Mg), sodium (Na) and potassium (K). The study was carried out in three phases: short- (immediately after the wildfire), medium- (seven years after the wildfire) and long-term (18 years after the wildfire). The results showed that in both fire regimes TN decreased with time, TC and SOM were significantly lower in the burned plots than they were in the control in the medium- and long-terms. C/N ratiowas significantly lower at short-termin lowwildfire severity area. Extractable Ca andMgwere significantly higher in control plot than in the burned plots in themedium-term. In the long-term, extractable Ca andMgwere significantly lower in the area exposed to a high severity burning. No differences were identified in the case of extractable Na between plots on any of the sampling dates, while extractable K was significantly higher in the plot exposed to low wildfire than it was in the control. Some restoration measures may be required after the wildfire, especially in areas affected by high severity burning, to avoid the long-term impacts on the essential soil nutrients of TC, SOM, xtractable Ca and Mg. This long-term nutrient depletion is attributable to vegetation removal, erosion, leaching and post-fire vegetation consumption. Soils clearly need more time to recover from wildfire disturbance, especially in areas affected by high severity fire regimes

Soil quality of abandoned agricultural terraces managed with prescribed fires and livestock in the municipality of Capafonts, Catalonia, Spain (2000-2017)

The abandonment of the economic activities of agriculture, livestock, and forestry since the second half of the 20th century, in conjunction with the exodus of inhabitants from rural areas, has resulted in an increase in the forest mass as well as an expansion of forest areas. This, in turn, has led to a greater risk of forest fires and an increase in the intensity and severity of these fires. Moreover, these forest masses represent a fire hazard to adjacent urban areas, which is a problem illustrated here by the village of Capafonts, whose former agricultural terraces have been invaded by shrubs, and which in the event of fire runs the risk of aiding the propagation of the flames from the forest to the village's homes. One of the tools available to reduce the amount of fuel in zones adjoining inhabited areas is prescribed burns. The local authorities have also promoted measures to convert these terraces into pasture; in this way, the grazing of livestock (in this particular instance, goats) aims to keep fuel levels low and thus reduce the risk of fire. The use of prescribed fires is controversial, as they are believed to be highly aggressive for the soil, and little is known about their long-term e ects. The alternation of the two strategies is more acceptable¿that is, the use of prescribed burning followed by the grazing of livestock. Yet, similarly little is known about the e ects of this management sequence on the soil. As such, this study seeks to examine the impact of the management of the abandoned terraces of Capafonts by means of two prescribed fires (2000 and 2002), which were designed specifically to prevent forest fires from reaching the village. Following these two prescribed burns, a herd of goats began to graze these terraces in 2005. Here, we report the results of soil analyses conducted during this period of years up to and including 2017. A plot comprising 30 sampling points was established on one of the terraces and used to monitor its main soil quality properties. The data were subject to statistical tests to determine whether the recorded changes were significant. The results show modifications to the concentration of soil elements, and since the first prescribed burn, these changes have all been statistically significant. We compare our results with those reported in other studies that evaluate optimum soil concentrations for the adequate growth of grazing to feed goats, and conclude that the soil conditions on the terrace after 17 years are optimum for livestock use

How clear-cutting affects fire severity and soil properties in a Mediterranean ecosystem

Forest management practices in Mediterranean ecosystems are frequently employed to reduce both the risk and severity of wildfires. However, these pre-fire treatments may influence the effects of wildfire events on soil properties. The aim of this study is to examine the short-term effects of a wildfire that broke out in 2015 on the soil properties of three sites: two exposed to management practices in different years e 2005 (site M05B) and 2015 (site M15B) e and one that did not undergo any management (NMB) and to compare their properties with those recorded in a plot (Control) unaffected by the 2015 wildfire. We analyzed aggregate stability (AS), soil organic matter (SOM) content, total nitrogen (TN), carbon/ nitrogen ratio (C/N), inorganic carbon (IC), pH, electrical conductivity (EC), extractable calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K), microbial biomass carbon (Cmic) and basal soil respiration (BSR). In the managed plots, a clear-cutting operation was conducted, whereby part of the vegetation was cut and left covering the soil surface. The AS values recorded at the Control site were significantly higher than those recorded at M05B, whereas the TN and SOM values at NMB were significantly higher than those recorded at M05B. IC was significantly higher at M05B than at the other plots. There were no significant differences in C/N ratio between the analyzed sites. Soil pH at M05B was significantly higher than the value recorded at the Control plot. Extractable Ca was significantly higher at NMB than at both M05B and the Control, while extractable Mg was significantly lower at M05B than at NMB. Extractable K was significantly lower at the Control than at the three fire-affected plots. Cmic was significantly higher at NMB than at the Control. BSR, BSR/C and BSR/Cmic values at the fire-affected sites were significantly lower than those recorded at the Control. No significant differences were identified in Cmic/C. Overall, a comparison of the pre-fire treatments showed that NMB was the practice that had the least negative effects on the soil properties studied, followed by M15B, and that fire severity was highest at M05B due to the accumulation of dead plant fuelThis study was supported by the POSTFIRE Project (CGL2013-47862-C2-1 and 2-R) and the POSTFIRE_CARE Project (CGL2016-75178-C2-2-R [AEI/FEDER, UE]),financed by the Spanish Research Agency (AIE) and the European Union through European Funding for Regional Development (FEDER) and the FPU Program (FPU 014/00037) of the Ministry of Education, Cultureand Sports and Program 2014SGR825 of the Generalitat de Catalunya

How clear-cutting affects fire severity and soil properties in a Mediterranean ecosystem

Forest management practices in Mediterranean ecosystems are frequently employed to reduce both the risk and severity of wildfires. However, these pre-fire treatments may influence the effects of wildfire events on soil properties. The aim of this study is to examine the short-term effects of a wildfire that broke out in 2015 on the soil properties of three sites: two exposed to management practices in different years e 2005 (site M05B) and 2015 (site M15B) e and one that did not undergo any management (NMB) and to compare their properties with those recorded in a plot (Control) unaffected by the 2015 wildfire. We analyzed aggregate stability (AS), soil organic matter (SOM) content, total nitrogen (TN), carbon/ nitrogen ratio (C/N), inorganic carbon (IC), pH, electrical conductivity (EC), extractable calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K), microbial biomass carbon (Cmic) and basal soil respiration (BSR). In the managed plots, a clear-cutting operation was conducted, whereby part of the vegetation was cut and left covering the soil surface. The AS values recorded at the Control site were significantly higher than those recorded at M05B, whereas the TN and SOM values at NMB were significantly higher than those recorded at M05B. IC was significantly higher at M05B than at the other plots. There were no significant differences in C/N ratio between the analyzed sites. Soil pH at M05B was significantly higher than the value recorded at the Control plot. Extractable Ca was significantly higher at NMB than at both M05B and the Control, while extractable Mg was significantly lower at M05B than at NMB. Extractable K was significantly lower at the Control than at the three fire-affected plots. Cmic was significantly higher at NMB than at the Control. BSR, BSR/C and BSR/Cmic values at the fire-affected sites were significantly lower than those recorded at the Control. No significant differences were identified in Cmic/C. Overall, a comparison of the pre-fire treatments showed that NMB was the practice that had the least negative effects on the soil properties studied, followed by M15B, and that fire severity was highest at M05B due to the accumulation of dead plant fuel

Ubiquitination of CXCR7 Controls Receptor Trafficking

The chemokine receptor CXCR7 binds CXCL11 and CXCL12 with high affinity, chemokines that were previously thought to bind exclusively to CXCR4 and CXCR3, respectively. Expression of CXCR7 has been associated with cardiac development as well as with tumor growth and progression. Despite having all the canonical features of G protein-coupled receptors (GPCRs), the signalling pathways following CXCR7 activation remain controversial, since unlike typical chemokine receptors, CXCR7 fails to activate Gαi-proteins. CXCR7 has recently been shown to interact with β-arrestins and such interaction has been suggested to be responsible for G protein-independent signals through ERK-1/2 phosphorylation. Signal transduction by CXCR7 is controlled at the membrane by the process of GPCR trafficking. In the present study we investigated the regulatory processes triggered by CXCR7 activation as well as the molecular interactions that participate in such processes. We show that, CXCR7 internalizes and recycles back to the cell surface after agonist exposure, and that internalization is not only β-arrestin-mediated but also dependent on the Serine/Threonine residues at the C-terminus of the receptor. Furthermore we describe, for the first time, the constitutive ubiquitination of CXCR7. Such ubiquitination is a key modification responsible for the correct trafficking of CXCR7 from and to the plasma membrane. Moreover, we found that CXCR7 is reversibly de-ubiquitinated upon treatment with CXCL12. Finally, we have also identified the Lysine residues at the C-terminus of CXCR7 to be essential for receptor cell surface delivery. Together these data demonstrate the differential regulation of CXCR7 compared to the related CXCR3 and CXCR4 receptors, and highlight the importance of understanding the molecular determinants responsible for this process

Impact of an intense rainfall event on soil properties following a wildfire in a Mediterranean environment (North-East Spain)

Intense rainfall events after severewildfires can have an impact on soil properties, above all in theMediterranean environment. This study seeks to examine the immediate impact and the effect after a year of an intense rainfall event on a Mediterranean forest affected by a high severity wildfire. The work analyses the following soil properties: soil aggregate stability, total nitrogen, total carbon, organic and inorganic carbon, the C/Nratio, carbonates, pH, electrical conductivity, extractable calcium, magnesium, sodium, potassium, available phosphorous and the sodium and potassium adsorption ratio (SPAR). We sampled soils in the burned area before, immediately after and one year after the rainfall event. The results showed that the intense rainfall event did not have an immediate impact on soil aggregate stability, but a significant difference was recorded one year after. The intense precipitation did not result in any significant changes in soil total nitrogen, total carbon, inorganic carbon, the C/N ratio and carbonates during the study period. Differences were only registered in soil organic carbon. The soil organic carbon content was significantly higher after the rainfall than in the other sampling dates. The rainfall event did