Southeast Iberian Peninsula Research Articles

Mediterranean pine forest decline: A matter of root-associated microbiota and climate change

Forest ecosystems worldwide currently face worrying episodes of forest decline, which have boosted weakening and mortality of the trees. In the Mediterranean region, especially in the southeast Iberian Peninsula, Pinus sylvestris forests are severely affected by this phenomenon, and it has been commonly attributed to drought events. Remarkably, the role of root microbiota on pine decline has been overlooked and remains unclear. We therefore used metabarcoding to identify the belowground microbial communities of decline-affected and unaffected pine trees. Taxonomic composition of bacterial and fungal rhizosphere communities, and fungal populations dwelling in root endosphere showed different profiles depending on the health status of the trees. The root endosphere of asymptomatic trees was as strongly dominated by ‘Candidatus Phytoplasma pini’ as the root of decline-affected pines, accounting for >99 % of the total bacterial sequences in some samples. Notwithstanding, the titer of this phytopathogen was four-fold higher in symptomatic trees than in symptomless ones. Furthermore, the microbiota inhabiting the root endosphere of decline-affected trees assembled into a less complex and more modularized network. Thus, the observed changes in the microbial communities could be a cause or a consequence of forest decline phenomenon. Moreover, ‘Ca. Phytoplasma pini’ is positively correlated to Pinus sylvestris decline events, either as the primary cause of pine decline or as an opportunistic pathogen exacerbating the process once the tree has been weaken by other factors.

Comparative Analysis and Evaluation of Seismic Response in Structures: Perspectives from Non-Linear Dynamic Analysis to Pushover Analysis

This study presents a detailed comparative analysis of different methods for evaluating seismic response in structures, focusing on maximum displacements and collapse assessment. The results obtained through modal spectral analysis, non-linear dynamic analysis, and the incremental pushover analysis applied to a specific structure are compared. It has been found that the choice of time step and the consideration of ductility are critical for obtaining accurate predictions. The results of the non-linear dynamic analysis of the building’s response indicate that an earthquake equivalent to the one that affected the city of Lorca (southeast Iberian Peninsula) in 2011 would have a devastating impact on the studied structure, highlighting the importance of the finite element method modelling in predicting the formation of plastic hinges and assessing structural safety. These findings highlight the importance of utilising multiple analysis approaches and detailed modelling to fully understand the seismic behaviour of structures and ensure adequate resistance and stability to extreme events.

Teucrium × gutierrezii a new hybrid from Southeast Iberian Peninsula, a hotspots of natural hybridization of subfamily Ajugoideae (Lamiaceae)

A new nothospecies, Teucrium × gutierrezii, is described as result of the natural hybridization processes between two species of T. sect. Polium: T. eriocephalum subsp. almeriense (subsect. Simplicipilosa) and Teucrium lusitanicum subsp. lusitancum (subsect. Polium) both endemic from Iberian Peninsula. A morphological description with the diagnostic taxonomic differences between the new hybrid and the parental is provided as well as information about distribution, ecology and phenology for the new hybrid. In this paper we highlight the importance of hybridization in Teucrium in the Southeast Iberian Peninsula as drivers of diversity for Ajugoideae in the temperate Mediterranean regions.

Applying Remote Sensing Methods to Estimate Alterations in Land Cover Change and Degradation in the Desert Regions of the Southeast Iberian Peninsula

Numerous drylands worldwide have experienced degradation of both soil and vegetation in proximity to watering areas. Degradation can be observed in satellite imagery as fading radial brightness belts extending away from the water sources. The main objective of this study was to examine the spatio-temporal patterns of land degradation and rehabilitation in the drylands of the southeast Iberian Peninsula. The brightness index of tasseled cap was discovered to be the best form of spectral transformation for enhancing the contrast between the bright-degraded areas near the points and the darker surrounding areas far from and in between these areas. To comprehend the spatial structure present in spaceborne imagery of two desert sites and three key time periods, semi-variograms were created (mid-late 2000s, around 2015 and 2020). To assess spatio-temporal land-cover patterns, a kriging was used to smooth the brightness index values extracted from 30 m spatial resolution images. To assess the direction and intensity of changes between study periods, a change detection analysis based on kriging prediction maps was performed. These findings were linked to the socioeconomic situation prior to and following the EU economic crisis. The study discovered that degradation occurred in some areas as a result of the region’s agricultural activities being exploited.

Understanding the microbial biogeography of ancient human dentitions to guide study design and interpretation.

The oral cavity is a heterogeneous environment, varying in factors such as pH, oxygen levels, and salivary flow. These factors affect the microbial community composition and distribution of species in dental plaque, but it is not known how well these patterns are reflected in archaeological dental calculus. In most archaeological studies, a single sample of dental calculus is studied per individual and is assumed to represent the entire oral cavity. However, it is not known if this sampling strategy introduces biases into studies of the ancient oral microbiome. Here, we present the results of a shotgun metagenomic study of a dense sampling of dental calculus from four Chalcolithic individuals from the southeast Iberian peninsula (ca. 4500-5000 BP). Interindividual differences in microbial composition are found to be much larger than intraindividual differences, indicating that a single sample can indeed represent an individual in most cases. However, there are minor spatial patterns in species distribution within the oral cavity that should be taken into account when designing a study or interpreting results. Finally, we show that plant DNA identified in the samples is likely of postmortem origin, demonstrating the importance of including environmental controls or additional lines of biomolecular evidence in dietary interpretations.

Bioclimatic habitat limitations for argan trees (Argania spinosa (L.) Skeels) in Northern Africa and Spain

Argania spinosa L. Skeels is an Algerian-Moroccan endemic tree. This species is part of various plant communities consisting of Mediterranean, Macaronesian and Saharan floristic elements. It has been introduced and perhaps sometimes naturalized in various regions of the Mediterranean basin. Due to its role in combating desertification, high socio-economic value, and traditional use as fodder and food, the southwestern Moroccan argan grove (Arganeraie) was declared Biosphere Reserve. It had already been subject to conservation and reforestation programs a century earlier. Its cultivation for oil production could be, besides an economic objective, an effective method to conserve its genetic diversity. Therefore, this study aims to estimate its potential distribution and establish efficient breeding programs by determining its ecological requirements, identifying its different habitats, and predicting habitat suitability models for Morocco, Algeria, Tunisia, and Spain. Using 53 occurrence points, wind speed and direction data, and 29 bioclimatic variables, multivariate methods were applied to describe the ecological profiles and characterize the heterogeneity of its habitat to subsequently, train a Maxent model that establishes, besides Morocco and Algeria, suitable cultivation areas in Tunisia and Spain. The North African potential area is limited to the western Mediterranean coast of Algeria and flat and coastal areas of eastern Tunisia. The increased likelihood of suitability remains in the southeast Iberian Peninsula. A high probability of argan cultivation is also evident in the Canary Islands. These results provide possibilities for future expansion of argan crop and a window of opportunity to improve its genetic diversity and conservation.

Esparto crafting under empire: Local technology and imperial industry in Roman Iberia

Drawing on scholarship in postcolonial archaeology that emphasizes the place of indigenous technology in colonial and imperial contexts, this article explores the role of local communities in esparto grass weaving and basketry in the southeast Iberian Peninsula in antiquity. Esparto crafting became essential to Phoenician and Carthaginian colonial economies of the 1st millennium BCE and, later, to the production equipment for mining and other industries under Roman imperial rule. This paper uses ethnographic studies alongside archaeological evidence of esparto objects, particularly esparto mining equipment, to reconstruct the chaîne opératoire of ancient esparto crafting. It argues that local communities developed landscape learning and tactile technical knowledge surrounding esparto crafting over many generations. In supplying equipment essential to Roman mining, these communities used their technical knowledge to maintain agency and construct their identities under imperial rule. Ultimately, understanding esparto crafting helps elucidate the relationship between resources, technology, and imperial or colonial encounters.

Enhancing the Resilience of a Mediterranean Forest to Extreme Drought Events and Climate Change: Pinus—Tetraclinis Forests in Europe

The southeast Iberian Peninsula is the only place in the European Community where Tetraclinis articulata (Vahl) Masters populations are native. In this area, the optimal ecological niche for this species is occupied by Pinus halepensis (Miller). The increasing intensity of extreme drought events induced by climate change causes severe declines in pine forests, while providing expansion opportunities for established Tetraclinis populations. Within the framework of the LIFE-TETRACLINIS project, a study has been designed to simulate the pine forest decline effects on the population dynamics of this protected species. This work investigates the effects of decreasing competition on T. articulata specimens with limited reproductive activity. To induce the reproductive activity of these specimens through increasing the availability of light, the surrounding pines were removed within a 15 m radius. Increased light availability was modelled using “Light Detection And Ranging” (LiDAR) data, and changes in the main reproductive parameters were registered throughout the study period. A significant increase in the reproductive population was achieved, as well as the cones produced per specimen and the recruitment. Findings obtained are promising for the habitat management in continental Europe and enhancing this forest system’s resilience to extreme drought events and climate change.

Massive Aggregations of Serpulidae Associated With Eutrophication of the Mar Menor, Southeast Iberian Peninsula

For decades, inputs of nutrients and organic matter into the Mar Menor coastal lagoon have favored the change from an original oligotrophic to a eutrophic state. The lagoon reached a stage of severe eutrophication and “environmental collapse” during the spring of 2016. This paper describes the massive growth of Serpulidae (Annelida, Polychaeta) forming large aggregations and reef structures after the environmental collapse caused by the eutrophic crisis. Four species belonging to the genera Hydroides and Serpula were identified; the identified species are Hydroides elegans, Hydroides dianthus, Serpula concharum, and Serpula vermicularis. The presence of bi-operculate and tri-operculate specimens is also documented in this study.

Processes driving seagrass soils composition along the western Mediterranean: The case of the southeast Iberian Peninsula

Seagrasses are distributed all along the coast of the Mediterranean Sea being Posidonia oceanica and Cymodocea nodosa the most common species. They promote sedimentation, leading to the formation of well-structured soils. Over the last decade, a growing attention has been paid to their role as CO2 sinks in the form of organic carbon (Corg) and to their use as environmental archives. However, most of the knowledge about pedogenetic processes in these soils refer to the rhizosphere. This study aims to understand seagrass soils biogeochemistry in the rhizosphere and below, which in turn can help to understand their long term formation processes. Fifteen cores were strategically sampled along a 350 km stretch of the Southeast Iberian coast, and analyzed for elemental composition (XRF core-scanning), magnetic susceptibility, Corg content and gran size distribution. The cores were dated by 210Pb and 14C-AMS techniques to estimate soil accretion. Principal component analysis was used to explore the main geochemical processes linked to soil formation. The results showed that terrestrial runoff plays a key role in meadow soil composition. Furthermore, Corg accumulation did not follow any general depth trend in our soil records, suggesting that temporal variation in Corg inputs is an important factor in determining carbon depth distribution within the soil. We obtained evidence that the establishment of well-developed, stable C. nodosa meadows in the Mediterranean Sea may be promoted by adverse environmental conditions to P. oceanica settlement. Metal's behavior within the meadow deposit and their interaction with organic matter and carbonates is unclear. The results presented in this paper highlight the importance of the influence of land-based inputs in the characteristics of seagrass meadow deposits, highly determining their Corg content, as well as the need for further studies on metal behavior, to understand their full potential as environmental records.

Fossil leaf wax hydrogen isotopes reveal variability of Atlantic and Mediterranean climate forcing on the southeast Iberian Peninsula between 6000 to 3000 cal. BP.

Many recently published papers have investigated the spatial and temporal manifestation of the 4.2 ka BP climate event at regional and global scales. However, questions with regard to the potential drivers of the associated climate change remain open. Here, we investigate the interaction between Atlantic and Mediterranean climate forcing on the south-eastern Iberian Peninsula during the mid- to late Holocene using compound-specific hydrogen isotopes from fossil leaf waxes preserved in marine sediments. Variability of hydrogen isotope values in the study area is primarily related to changes in the precipitation source and indicates three phases of increased Mediterranean sourced precipitation from 5450 to 5350 cal. BP, from 5150 to 4300 cal. BP including a short-term interruption around 4800 cal. BP, and from 3400 to 3000 cal. BP interrupted around 3200 cal. BP. These phases are in good agreement with times of prevailing positive modes of the North Atlantic Oscillation (NAO) and reduced storm activity in the Western Mediterranean suggesting that the NAO was the dominant modulator of relative variability in precipitation sources. However, as previously suggested other modes such as the Western Mediterranean Oscillation (WeMO) may have altered this overall relationship. In this regard, a decrease in Mediterranean moisture source coincident with a rapid reduction in warm season precipitation during the 4.2 ka BP event at the south-eastern Iberian Peninsula might have been related to negative WeMO conditions.

Long-term monitoring of the Iberian ibex population in the Sierra Nevada of the southeast Iberian Peninsula

This dataset provides long-term information on the presence of the Iberian ibex (Capra pyrenaica hispanica Schimper, 1848) in Sierra Nevada (SE Iberian Peninsula). Data on the abundance and demographic structure of the Iberian ibex population were compiled over the last three decades. Transects were laid out to record different variables such as the number of individuals sighted, the perpendicular distance of each group of Iberian ibex to the transect line and sex as well as age of individuals in the case of males. These data enabled the calculation of population parameters such as density, sex ratio, birth rate, and age structure. These parameters are key for Iberian ibex conservation and management, given that Sierra Nevada harbours the largest population of this species in the Iberian Peninsula. The data set we present is structured using the Darwin Core biological standard, which contains 3,091 events (582 transect walk events and 2,509 group sighting events), 5,396 occurrences, and 2,502 measurements. The occurrences include the sightings of 11,436 individuals (grouped by sex and age) from 1993 to 2018 in a total of 88 transects distributed along Sierra Nevada, of which 33 have been continuously sampled since 2008.

Concentración parcelaria, puesta en riego y desarrollo rural: el caso de Yéchar (Mula-Región de Murcia). De 1973 a 2016

La pedanía muleña de Yéchar, en el interior de la Región de Murcia, puede ser estudiada desde la geografía regional como un modelo de iniciativas para el desarrollo rural, al haber superado diversas crisis socioeconómicas mediante diferentes actuaciones agrarias. Durante los últimos cincuenta años sus vecinos han debido hacer frente al éxodo rural de los secanos del Sureste de la Península Ibérica con actuaciones de agentes locales y de las Administraciones Públicas, entre las que sobresalen la Declaración de Zona de Interés Nacional, la concentración parcelaría de las explotaciones, y la transformación en regadío con aguas del trasvase Tajo-Segura de más de 800 hectáreas. Las entrevistas realizadas a pie de parcela explican cómo los agricultores de Yéchar cambian los cultivos para hacer frente a los problemas del mercado hortofrutícola, y buscan otras políticas de gestión del agua por la excesiva dependencia de los recursos hídricos foráneos del Trasvase Tajo-Segura.

Comprehensive Analysis of Territorial Uses for the Development of Mining Degraded Areas: The Surrounding of Portmán (La Unión).

The Portman Bay, Southeast Iberian Peninsula, is home to one of the largest environmental disasters on the Mediterranean coast: the silting of the bay caused by the dumping of million tonnes of mining waste to the sea, over more than thirty years. The analysis of the values of the surroundings, and the assessment of the potential for the development of the bay arises with the aim of obtaining alternatives for planning a sustainable local development and respectful with the environment. Two phases of analysis have been carried out: the first through a partial, more detailed, study; followed by a second phase of analysis, with an overall assessment of land uses to determine the constraints and development opportunities of the surroundings of Portman. The integral analysis provides a vision of the space as a whole, and allows defining territorial categories in relation to possible developments in the form of residential and tourism projects, which are defined as: limitations, main constraints and additional constraints.

Buried marine-cut terraces and submerged marine-built terraces: The Carchuna-Calahonda coastal area (southeast Iberian Peninsula)

The Carchuna-Calahonda coastal area is located between the onshore Betic Cordillera and the Alboran Sea. Its onshore sector is formed by detrital sediments that cover a metamorphic basement mostly composed of marbles, contiguous to an offshore shelf setting. New onshore gravity data allow us to characterize the location of flat marine-cut terraces carved into the metamorphic bedrock, which are covered by detrital sediments. In addition, multibeam bathymetry data, 3.5kHz and sparker reflection seismic profiles, reveal offshore flat features linked to marine terraces that are related with the onshore buried marine-cut terraces. Gravity data are newly used to detect marine-cut terraces covered by sediments, enhancing the integration of onshore and offshore data. The marine terraces are distinguished based on the relative sea-level trend (regressive versus transgressive) and on the dominant sedimentary regime (erosional versus depositional). These data help constrain the ages of the marine terraces younger than 150ka, using available Late Quaternary sea-level curves. Although previous geodetic research suggests a rapid sinking of the Carchuna-Calahonda coast, the heights of the marine-cut terraces and depositional terraces are mainly driven by sea-level changes, not tectonics.

The isotopic footprint of irrigation in the western Mediterranean basin during the Bronze Age: the settlement of Terlinques, southeast Iberian Peninsula

The isotopic composition of the remains of cereals and pine has been studied, from three different chronological phases from 2140 to 1500 cal bc at the Terlinques site, southeast Iberian Peninsula. The δ13C values range between −24.91 and −21.19 ‰ (V-PDB), with an average of −23.05 ‰ (STD = 0.69). The archaeological cereals show an average isotopic discrimination (Δ13C) with the past atmospheric CO2 of 16.96 ‰, which is much greater than the average Δ13C of 13.89 ‰ of the rainfed Triticeae (wheat and barley) in modern times. However, considering the effect of the atmospheric CO2 concentration, which is included in the WUEi (intrinsic water-use efficiency), this difference is even greater, 77 for archaeological samples versus 144 for present-day rainfed cereals. This could represent some of the earliest evidence of the use of irrigation techniques in Europe. Modern cereals which have been irrigated show a general Δ13C average of 17.17 ‰, very similar to those of the middle Holocene. However, when the WUEi is calculated, the value of 108 indicates that present-day irrigated cereals are more stressed than the archaeological samples. For comparison, we have included pine trees, since these have an extensive root development which is capable of reaching the water table. In the past, both cereals and pine present similar WUEi values (77 vs. 72), however at present only irrigated cereals show similar WUEi values to pine (108 vs. 107). This again suggests irrigation of cereals in the past. The processes of climatic degradation towards drier conditions which started in the middle Holocene could be responsible for the use of land near water sources, on riverbanks and near shallow lakes. According to the isotopic and plant macrofossil data, irrigation or water management techniques were used at the Terlinques site, located close to the Laguna de Villena, a lake which has now dried out.

Multi-proxy evidence of rainfall variability recorded in subaqueous deltaic deposits off the Adra River, southeast Iberian Peninsula

The Adra River deltaic system, southeast Iberian Peninsula, shows a steep topography and is subjected to strong climatic seasonality. This system has been affected by alternating wet and dry periods, and it has also undergone numerous anthropogenic activities such as deforestation, mining activities, river channel deviations and dam construction, particularly during the last two centuries. Two sediment cores were retrieved off the Adra River, from the western (MS_V9) and eastern (MS_V4) lobes of the subaqueous deltaic deposit. A multi-proxy study was carried out, including grain size, benthic foraminiferal assemblages, magnetic susceptibility and geochemical element analyses, in order to understand the sedimentary expression of recent climatic cycles and anthropogenic interventions in the river basin.Periods of increased deposition of coarse-grained sediments, low absolute abundance of benthic foraminifera and high elemental ratios indicative of terrigenous contributions, were interpreted as periods of increased sediment supply to the shelf. Four flooding events were recorded in core MS_V9 and three events on core MS_V4, of which two were observed in both cores. They were related to periods with major floods that were documented on the southern Iberian Peninsula around 1770–1810 and 1860–1870 AD. On the other hand, sediment core intervals exhibiting increasing proportion of fine-grained sediments and higher abundances of foraminiferal species assigned as successful colonizers (Textularia earlandi) and opportunistic species that feed on bacteria or terrestrial organic matter (Bolivina ordinaria, Bulimina elongata, Eggerelloides scaber and Ammonia beccarii or tepida), indicate the establishment of new environments with new ecological constraints. They were related to significant decreases of terrigenous sediment input during low rainfall or dry periods. The increase of opportunistic species feeding on fresh phytodetritus (Nonionella iridea, Nonionella stella, Nonionella sp., Brizalina dilatata, Epistominella vitrea and Bolivinellina pseudopuntata), under more stable environmental conditions, also point to a stronger marine influence on the prodeltaic environments during these periods. The human interventions on the river basin after 1872 AD, with the deviation of the main river channel to the east, led to a drastic reduction of the sediment exported to the western delta lobe. This study showed that the sedimentation on the Adra subaqueous deltaic deposit was mainly controlled by rainfall variability from 1663 to 1872 AD, and afterwards by anthropogenic interventions.

Seismic scenario including site-effect determination in Torreperogil and Sabiote, Jaén (Spain), after the 2013 earthquake sequence

The recent seismic activity recorded in Jaen province in the south-east Iberian Peninsula has triggered great alarm among the people of the towns of Torreperogil and Sabiote despite the low magnitude of the events. The main objective of this paper is to examine why these low-magnitude events are responsible for such a high degree of concern in this area of low seismicity. Of all possible explanations, including directivity effects and local geology, we found that the site effect was the most important candidate for clarifying this phenomenon. An earthquake scenario was considered for the maximum 5.2 Mw shock that could occur in the event of the rupture of the identified responsible blind fault. In order to simulate the strong motion derived from such as extreme event, a stochastic finite-fault simulation was generated using the standard values of the different media parameters for the region and a stress drop of 130 bar, deduced from the simulation of the greatest shock of the sequence. In order to include the site effect, which was considered to be very important in this study, a local survey using refraction micro-tremor (ReMi) techniques was performed in both towns (at 33 and 35 sites in Torreperogil and Sabiote, respectively) to determine the Vs30 values. The site response results obtained were taken into account in the simulation process, and the results are shown on peak ground acceleration (PGA) and peak ground velocity (PGV) contour maps for each town, with 200–500 cm/s2 as PGA extreme values. A map of intensities obtained from the PGV map is also shown; for the extreme event, macroseismic EMS98 intensities in the range of V–VII were obtained for those towns. The deterministic earthquake scenario developed here will be of great interest in planning civil defence responses in the event of an earthquake emergency and in regional development.

Effects of Dry Olive Residue Transformed by Coriolopsis floccosa (Polyporaceae) on the Distribution and Dynamic of a Culturable Fungal Soil Community

Dry olive residue (DOR) is an abundant waste product resulting from a two-phase olive oil extraction system. Due to its high organic and mineral content, this material has been proposed as an organic soil amendment; however, it presents phytotoxic and microtoxic properties. Thus, a pretreatment is necessary before its application to soil. Among the strategies for the bioremediation of DOR is treatment with ligninolytic fungi, e.g. Coriolopsis floccosa. This work aimed to assess the diversity of culturable fungi in a soil of the southeast Iberian Peninsula and to evaluate the short-term impact of untransformed and C. floccosa-transformed DOR on soil mycobiota. A total of 1,733 strains were isolated by the particle filtration method and were grouped among 109 different species using morphological and molecular methods. The majority of isolates were ascomycetes and were concentrated among three orders: Hypocreales, Eurotiales and Capnodiales. The soil amendment with untransformed DOR was associated with a depression in fungal diversity at 30 days and changes in the proportions of the major species. However, when C. floccosa-transformed DOR was applied to the soil, changes in fungal diversity were less evident, and species composition was similar to unamended soil.

Time trend in the viability of pollen grains in the ‘Picual’ olive (Olea europaea L.) cultivar

The aim of this study was to evaluate the viability and longevity of the pollen grains of the olive cultivar ‘Picual’, the most extensive and important olive cultivar in the Iberian Peninsula. Over a 3-year period (2007–2009), viability of the pollen grains of 15 ‘Picual’ cultivar trees was measured using the Fluorochromatic Reaction (FCR). These olive trees were distributed along different altitudinal areas of the province of Jaen (southeast Iberian Peninsula). The percentages of viability did not show any geographical variability. In general, the percentage of viability did not vary from one year to another. With an average value of 49%, the viability of the pollen in the cultivar ‘Picual’ could be classified as medium-range. ‘Picual’ pollen grains have the highest viability after 24 hours of anther dehiscence. Viability declines rapidly with time. The longevity of the pollen grains was about seven days. The first three days after anthesis are the most important for fertilisation. A rapid decline in pollen viability may considerably reduce effective fertilisation and could negatively influence fruit production. For this reason, these findings should be considered for the improvement of olive fruit yields.