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Phenological studies have a crucial role in the global change context. The Mediterranean basin constitutes a key study site since strong climate change impacts are expected, particularly in mountain areas such as Sierra Nevada, where we focus. Specifically, we delve into phenological changes in endemic vascular plants over time by analysing data at three scales: entire massif, altitudinal ranges, and particular species, seeking to contribute to stopping biodiversity loss. For this, we analysed 5262 samples of 2129 herbarium sheets from Sierra Nevada, dated from 1837 to 2019, including reproductive structure, complete collection date, and precise location. We found a generalized advancement in phenology at all scales, and particularly in flowering onset and flowering peak. Thus, plants flower on average 11 days earlier now than before the 1970s. Although similar trends have been confirmed for many territories and species, we address plants that have been studied little in the past regarding biotypes and distribution, and which are relevant for conservation. Thus, we analysed phenological changes in endemic plants, mostly threatened, from a crucial hotspot within the Mediterranean hotspot, which is particularly vulnerable to global warming. Our results highlight the urgency of phenological studies by species and of including ecological interactions and effects on their life cycles. [ABSTRACT FROM AUTHOR]

Soil water erosion is one of the most important environmental problems for the sustainability of Mediterranean olive groves on hillsides. Governments and public agencies recognize the need to control this process in order to improve soil conservation, especially in vulnerable areas. In the present study, a simple, inexpensive method using Structure-from-motion (SfM) and Unmanned Aerial Vehicle (UAV) technology was applied to quantify the soil loss rates provoked by water erosion and tillage in mountain olive groves, according to a reconstruction of their historical surface features. Specifically, the main study aims were: i) to quantify the historical soil loss in olive groves, by analysing residual tree mounds; ii) to consider how soil relief and management can influence the erosion process; iii) to determine the degree to which the proposed method achieves the above aims.Analysis revealed a mean erosion rate in the study area of 127.69 t ha−1 years−1, with a linear relationship between soil truncation and slope (R2 = 0.64, p

Phenological studies have a crucial role in the global change context. The Mediterranean basin constitutes a key study site since strong climate change impacts are expected, particularly in mountain areas such as Sierra Nevada, where we focus. Specifically, we delve into phenological changes in endemic vascular plants over time by analysing data at three scales: entire massif, altitudinal ranges, and particular species, seeking to contribute to stopping biodiversity loss. For this, we analysed 5262 samples of 2129 herbarium sheets from Sierra Nevada, dated from 1837 to 2019, including reproductive structure, complete collection date, and precise location. We found a generalized advancement in phenology at all scales, and particularly in flowering onset and flowering peak. Thus, plants flower on average 11 days earlier now than before the 1970s. Although similar trends have been confirmed for many territories and species, we address plants that have been studied little in the past regarding biotypes and distribution, and which are relevant for conservation. Thus, we analysed phenological changes in endemic plants, mostly threatened, from a crucial hotspot within the Mediterranean hotspot, which is particularly vulnerable to global warming. Our results highlight the urgency of phenological studies by species and of including ecological interactions and effects on their life cycles.

The tree has been a constant feature in the structure and sustainability of agrarian landscapes in Mediterranean mountain regions. Our research focuses on trees that grow outside forests, important resources which due to their heterogeneity and multi-functionality have been studied from a variety of methodological perspectives without a clear integrated vision. In this context we have used the concept of ‘Trees Outside Forest’ (TOF) and the standardized methodological and assessment criteria proposed by the FAO in the Global Forest Resources Assessment (FRA) as a benchmark for our research, which deals above all with the current situation of the TOF in Mediterranean mountain regions. To this end, and always from a landscape perspective, we have carried out a diachronic analysis and an integrated assessment of the multi-functionality of these resources within the agricultural system of the Mediterranean mountainside, exemplified in the coastal massif of the Contraviesa in southern Spain.

Historic irrigation systems have been an invariant in the landscapes of an arid Mediterranean mountain such as the Sierra de la Contraviesa (southeast Spain). These irrigated spaces have contributed, despite their meager size, to diversify the mountain agrarian mosaic and the local economy, presenting constant relatively stable landscapes for centuries. Despite everything, since 1950, the socioeconomic marginality of this area within the current territorial dynamics of the region has triggered profound changes. The purpose of this work is to interpret in a landscape key the historical evolution and multiplicity of functions of these systems and their current role in the mosaic of agrosystems present in the massif. In order to do this, it is delved, first of all, into the physical bases that sustain irrigation and the process of historical-geographical conformation (IV-XX Centuries) of these inherited structures. Second, and starting from the cadastral historical cartography, a diachronic analysis of its extension and configuration is carried out in the main irrigated perimeters for the last 70 years. The results obtained reveal how the recent disarticulation of the traditional management model compromises the continuity of these systems and their various associated values, determining a progressive impoverishment and homogenization of the landscape. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted increments in rainfall erosivity along the Cordilleras Béticas Litorales. Thus, it is recommended to move forward the soil loss estimation caused by water erosion, which is the main geomorphic agent in that region. This study deals with the application of RUSLE equation in two-watershed characterised by different rainfall regimes (one semiarid/dry and other subhumid) from 1997-2018. Both watersheds present ecogeomorphic features typical from Mediterranean mountains under those rainfall regimes. The application of RUSLE was made introducing some methodological modifications in the calculation of soil loss: (a) 10 minutes periods (I10) to calculate rainfall erosivity (Factor R); (b) vegetation cover (factor C) estimated from NDVI; (c) soil loss evaluation from soil surface components inventory. The results indicated significant differences between both watersheds due to difference in ecogeomorphology and rainfall erosivity. The use of I10 contributed to a better approach to the soil loss estimation and its spatial and temporal variability. The mean soil loss was of 244.4 t h-1 year-1 and 547.0 t h-1 year-1 in the rainier watershed and the drier one, respectively. The inventory and analysis of soil surface component was better related to higher soil losses in the more humid watershed, where the biotic components of soil surface were dominant (moss, annual plants, and litter). These results may contribute to detect more appropriately critical areas to increase vegetation cover and reduce soil loss by water erosion in the framework of future reforestation. [ABSTRACT FROM AUTHOR]

Vegetation expansion following farmland abandonment is a complex process that depends on multiple natural and human-induced factors, resulting in differences in the evolution of land cover on former cultivated fields, with various environmental implications. To assess the complexity of the hydrogeomorphological consequences of farmland abandonment, the Instituto Pirenaico de Ecología (CSIC) and the University of La Rioja monitored three small catchments, representative of different post land abandonment scenarios, in the Pyrenees and Iberian Range respectively. In the Pyrenees, a fourth small catchment, covered by natural forest, was monitored as a reference for an undisturbed environment. This study describes the evolution of land use in the abandoned catchments and examines its implications on catchment hydrological connectivity. It also analyses the hydrological responses of the three abandoned scenarios to similar rainfall events, and compares them to that of natural forested areas. .Vegetation tended to increase in the three catchments, but there were important differences in the characteristics of the current land cover. Arnás, the catchment left to a process of natural revegetation, contained a mosaic of shrubs (64%) and forest (27%) at different stages of succession, largely conditioned by the topography and soil properties. Araguás_afforestation was extensively afforested in the 1960s, with 75% of this catchment currently covered by forest, most of it planted artificially. In Munilla, occupied by terraced fields, vegetation recovery was partly restrained by the introduction of cattle, and 80% of the catchment was covered by sparse shrubs. Land abandonment resulted in a general reduction in computed hydrological connectivity in the three studied catchments, except in localized areas close to the main channel, new forest roads and trails, and upstream of terrace wall collapses, all areas of increased hydrological connectivity. The decrease in hydrological connectivity was much lower in Munilla, characterized by an absence of dense vegetation and still dominated by a terraced topography. The hydrological responses of the catchments to similar rainfall events differed significantly, showing the influence of not only vegetation cover but of the properties of soil remaining after previous agricultural activities. Significant storm-flow discharge was observed in Arnás, even under dry conditions, with high peakflows and fast responses. Lower streamflow response was observed in Araguás_Afforestation under dry conditions; however, once the soils were wet the hydrological response was notable and was characterized by high peakflow. The response under afforested trees differed greatly from that of a catchment covered by natural forest, with the latter characterized by gentler hydrographs. The hydrological response in Munilla was the lowest, with long response times and recessions, associated with the thick soils of the terraced fields. These results demonstrated the large variability of post land abandonment scenarios and associated hydrological implications, and highlighted the need to consider these differences to reduce future uncertainties in forecasting water resources and soil conservation.

Agricultural terraces are an essential element in the mountains of the European Mediterranean. The construction and maintenance of these structures consumes requires considerable energy and gave rise to cultures based on the careful and complex use of these slopes. Entire terraced slopes have now been abandoned and are suffering intense erosion and revegetation processes that threaten to ruin valuable cultural landscapes. One of the best terraced landscapes in the Central Pyrenes was configured in the Bestué Valley (Aragonese Central Pyrenees). The terraces occupy 13.1% of the area of the valley. The terraces were built for the cultivation of cereals to feed the local population. They were cultivated until the 1950-70s and later used as meadows. Since the last decade of the 20th century they have been abandoned. The end of cultivation and the lack of grazing ha meant that these terraces have been covered by forests (which occupied 13.7% of the area in 1956 and 48.7% in 2015). Between the same dates, the landscape lost heterogeneity and cultural value. There are some remaining areas of the terraced landscape that should be preserved as they form a compendium of agricultural uses and soil conservation. [ABSTRACT FROM AUTHOR]

Genista longipes Pau is part of orophile pulvinular baetic scrubs, one of the one of the plant communities most vulnerable to global warming. Its easternmost distribution in the Iberian Peninsula is located at the culmination of the Serra d'Aitana (Alicante), considered a refuge of extreme fragility in the face of any climatic alteration. In 2004, a detailed corological cartography was made with the distribution of the species in the eastern sector of the sierra, preferably from 1475 mamsl, registering a small isolated subpopulation at 1300 mamsl. To try to understand this disjunct location, the Thermicity Index has been calculated for squares of 200 m on each side in order to determine the extension and subdivision of the supra-Mediterranean level, modeling a scenario of increased temperatures that would cause its extinction. To verify this hypothesis, since 2014 a follow-up is carried out through an exhaustive fieldwork with centimeter accuracy GPS. The results show controversial data, since the population increased significantly between 2004 and 2014 and is in a sustained decline from 2014 to 2018. The value of temperature is discussed as the only variable to be treated and the need to analyze the role of wind and the historical management of vegetation to understand its dynamics. [ABSTRACT FROM AUTHOR]

As an important process regulating the water cycle, forest evapotranspiration (ET) also reflects vegetation and moisture conditions in response to a changing environment. For mountains in a Mediterranean climate and precipitation largely in winter, inconsistent seasonal variations between water stress and forest growth complicate remote-sensing-based ET modeling. Focusing on the Mediterranean-climate forests of California's Sierra Nevada, this regional study presents an NDWI-CWS (Normalized Difference Water Index-Canopy Water Stress) model to estimate daily ET in a globally important, representative region using MODIS NDWI and NDVI (normalized difference vegetation index) data, plus ground-based meteorological data. Specifically, to account for the important yet less-studied role of root-zone water storage in supporting the growth of deep-rooted woody vegetation (i.e. forest tree and shrub) during dry seasons and droughts, we proposed to use water availability based on NDWI in modeling woody ET. In contrast, given the predominant role of surface soil moisture for non-woody vegetation (e.g. grass) with shallow roots, the model calculated non-woody ET using water availability based on the ratio of cumulative precipitation to potential ET (denoted as P/PET). With ET measurements from 18 flux towers and long-term water-balance measurements at 58 catchments in the relatively data-rich California study area, we compared ET estimates from four modeling experiments with different water availability combinations, and six global and regional ET products. Overall, our NDWI-CWS ET estimates generally agreed best with field measurements, with R2 of 0.74 for point-scale woody-ET comparison and R2 of 0.42 for catchment-scale comparison. The mean annual woody ET (634 mm) during water year 2003–2020 was larger than that (353 mm) in non-woody areas. Further, with NDWI-CWS ET estimates and snow data, we estimated that the mean root-zone water storage capacity (601 mm) in forests is double that (285 mm) in non-woody (e.g. grassland) vegetated areas in the Sierra Nevada. We found that remote-sensing NDWI-based water availability is highly correlated with deep root-zone water storage, and much so (correlation R of 0.74) during dry summers. However, P/PET-based water availability reflects surface soil moisture (R of 0.66) modulated by short-term precipitation. Together, explicitly accounting for the distinct roles of root-zone water storage and soil moisture for woody versus non-woody vegetated areas improves MODIS-based ET estimation, which is critical for regional water resources and forest management, in addressing water cycle in a warming climate. [Display omitted] • An ET model accounts for distinct water stresses in Mediterranean vegetation • NDWI is used to estimate woody-vegetation ET supported by root-zone water storage • Non-woody ET relies on surface soil moisture regulated by short-term precipitation • Model was evaluated against flux-tower ET and catchment water-balance measurements • NDWI-based water availability is highly correlated with root-zone water storage [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos de Investigación Geográfica is the property of Universidad de la Rioja, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Numerous authors from various disciplines have underlined the importance of Indigenous Peoples' and Community Conserved Territories and Areas (ICCAs) for assuring the livelihoods of local populations whilst conserving the environment. The agdal is probably Morocco's best example of such an institution. Nevertheless they have always existed within the context of change and currently are experiencing major transitions. Detailed ethnographic studies of the socio-ecological drivers of these processes of change in agdals are scarce. Based on the particular case of the agdal of Yagur in the Mountain Mesioui tribal territory (High Atlas of Morocco), this article will analyse contemporary transformations. These dynamics are inherent to small-scale societies' ICCAs, even if they have most often been described as isolated, autarchic and mutable only under external pressure. From the case of the agdal of Yagur, we show how non-local processes are only part of the picture, and that the transformation of agdal forms are also related to key internal drivers, entailing a greater degree of agency by local actors than is usually given in the literature. At the same time, placing our analysis within a broader social anthropological framing, we provide a detailed actor-centred analysis that situates agents and local power relations within their institutional and cultural context while explaining how these same micropolitics of natural resource management articulate with and within wider global scales. [ABSTRACT FROM AUTHOR]

In Midelt high plain, alfa (Stipa tenacissima L.) is formed by mean to high density good state of health and tall tufts that can sometimes reach up to 1.2 m height. It there builds up a spontaneous steppic intramountain ecosystem, characterized by a good regeneration that attests topo-edapho-climatic conditions are favorable to its growth and reproduction. Climatic approach used for characterizing this plain steppe (in contrast with slope steppe) is based on two climatic criteria: raininess (and more generally rainfalls) and temperature. Each of these two parameters has been analysed from different points of view using different indicators. These criteria are not the only climatic factors that act on the life conditions of alfa and its accompanying steppic vegetal species; but they are predominant. Indeed, these factors have close correlations with other climatic parameters such as relative humidity, wind and insolation. Finally, the P/2T ratio of H. GAUSSEN has been used to delimit the modalities of dryness.

Pinus leucodermis Antoine (= Pinus heldreichii var. leucodermis) is a species of the Balkan flora which in Italy grows in a small area between the Regions of Basilicata and Calabria, in the Pollino National Park. A relict of the oro-Mediterranean Tertiary forests, it is found from the lower vegetation belt, where it is mixed with evergreen sclerophyllous vegetation, up to the alpine vegetation belt beyond the closed formations of Fagus sylvatica, where it makes up stands with very old, isolated and big trees growing in open spaces between rocks. The ecophysiological and dendrochronolgy features of the P. leucodermis stands growing on the west slope of Serra di Crispo (Monte Pollino), between 1800 and 2000 m a.s.l., have been studied during recent years and some of the results are presented in this work. Ecophysiological measurements in situ show that reduced atmospheric vapour pressure deficit conditions, due to humid currents from the western Tyrrhenian Sea, allow the trees to escape from summer drought. When day summer weather conditions are optimal P. leucodermis exhibits a remarkable photosynthetic activity and adaptation to high irradiance. The tree ring width chronology documents a marked reduction of radial growth from 1950 to 1985, followed by a strong recovery, still continuing. In the same period differences between the annual minimum and maximum temperatures tend to increase. Anthropic and grazing pressure is reduced markedly after the institution of the National Park of Pollino.

The effects of land use changes on soil carbon stocks are a matter of concern stated in international policy agendas on the mitigation of greenhouse emissions. Afforestation is increasingly viewed as an environmental restorative land use change prescription and is considered one of the most efficient carbon sequestration strategies currently available. Given the large quantity of CO 2 that soils release annually, it is important to understand disturbances in vegetation and soil resulting from land use changes. The main objective of this study is to assess the effects of land abandonment, land use change and afforestation practices on soil organic carbon (SOC) dynamics. For this aim, five different land covers (bare soil, permanent pastureland, secondary succession, Pinus sylvestris ( PS ) and Pinus nigra ( PN ) afforestation), in the Central Spanish Pyrenees, were analysed. SOC dynamics have been studied in the bulk soil, and in the fractions separated according to two methodologies: (i) aggregate size distribution, and (ii) density fractionation, and rates of carbon mineralization have been determined by measuring CO 2 evolution using an automated respirometer. The results showed that: (i) SOC contents were higher in the PN sites in the topsoil (10 cm), (ii) when all the profiles were considered no significant differences were observed between pastureland and PN , (iii) SOC accumulation under secondary succession is a slow process, and (iv) pastureland should also be considered due to the relative importance in SOC stocks. The first step of SOC stabilization after afforestation is the formation of macro-aggregates promoted by large inputs of SOC, with a high contribution of labile organic matter. However, our respiration experiments did not show evidence of SOC stabilization. SOC mineralization was higher in the top layers and values decreased with depth. These results gain insights into which type of land management is most appropriate after land abandonment for SOC. [ABSTRACT FROM AUTHOR]

The perception of the population linked to Cameros Viejo (Iberian System) about the revegetation process and its impacts on the natural environment is studied. We carried out 40 depth semi-structured interviews. The interviewee' answers are corroborated with the results of scientific works carried out in the study area and in other nearby areas of the Mediterranean mountains. Moreover, it is observed that the local population shows a more realistic perception than the foreign population about the changes in the natural environment. [ABSTRACT FROM AUTHOR]

This paper evaluates the response of streamflow and other components of the water balance to changes in climate and land use in a Pyrenean watershed. It further provides a measure of uncertainty in water resources forecasts by comparing the performance of two hydrological models: the Soil and Water Assessment Tool (SWAT) and Regional Hydro-ecological Simulation System (RHESSys). Regional climate model outputs for the 2021-2050 time frame and hypothetical (but plausible) land-use scenarios considering re-vegetation and wildfire processes were used as inputs to the models. Results indicate an overall decrease in river flows (up to 30%, depending on the combination of scenarios) when the scenarios are considered, except for the post-fire vegetation scenario, in which streamflows are simulated to increase (between 2% and 10%). However, the magnitude of these projections varies between the two models used, as SWAT tends to produce larger hydrological changes under climate change scenarios and RHESSys shows more sensitivity to changes in land cover. The final prediction will therefore depend largely on the combination of the land-use and climate scenarios and on the model used. [ABSTRACT FROM AUTHOR]

Rural abandonment in mountainous regions is a habitual process that occurs in many countries and has socioeconomic and environmental implications. Land cover changes in Mediterranean mountains resulting from farming abandonment have been associated with certain processes of land degradation. This study employed Landsat satellite images for mapping the land cover changes in 1984 and 2007, south of the Iberian Range (region of Sierra de Albarracín, Teruel, Spain). A neural network classification was used to achieve sufficient land cover accuracy. The land cover change analysis revealed an expansion of forestland at the expense of pastureland and abandoned rainfed cropland. These changes were associated with demographic and economic shifts that resulted from a continuous process of rural abandonment. Population reduction has been the natural trend for a century, characterized by massive internal migrations to nearby cities. The dynamic displacement of the population centroid was used to identify the migratory processes in the last century. The primary sector and the associated secondary sector (farming and forestry) were diminished and resulted in a decrease in natural resource exploitation. Economic activity moved towards the tertiary sector, which focuses on rural tourism. The current socioeconomic scenario has unknown future implications for land cover dynamics and their associated ecosystem services values. Thus, monitoring of land cover changes and ecosystem services is required to promote sustainable development in an area that is highly dependent on the conservation of natural resources and ecological services. [ABSTRACT FROM AUTHOR]

In 1974, Valdezcaray ski resort was built. It is located in the Sierra de la Demanda, which is crossed by the rivers Oja and Najerilla (Iberian System, in La Rioja, Spain). It is a small ski resort (22.6 Km of ski area) sponsored by the Town Hall of Ezcaray (Oja Valley), in order to boost tourism and break the regressive process that had been dragging on for decades in the Demanda area. This paper examines: i) the influence of Valdezcaray in the evolution of the population as well as in the demographic structure, and ii) the impact of the touristic sector development in primary activities (development of farms, agricultural livestock census and farmland) of the region. The results obtained indicate that the ski resort affects only a small area: the Oja Valley, especially the village of Ezcaray, but not the Najerilla Valley. In the first one, demographic trends and primary sector evolution have been positive and both of them have helped to improve the population structure. However, in the Najerilla Valley, population, livestock and farmland are still going down further. [ABSTRACT FROM AUTHOR]

Drought-induced events of massive tree mortality appear to be increasing worldwide. Species-specific vulnerability to drought mortality may alter patterns of species diversity and affect future forest composition. We have explored the consequences of the extreme drought of 2005, which caused high sapling mortality (approx. 50 %) among 10-year-old saplings of two coexisting pine species in the Mediterranean mountains of Sierra Nevada (Spain): boreo-alpine Pinus sylvestris and Mediterranean P. nigra. Sapling height growth, leaf δ 13C and δ 18O, and foliar nitrogen concentration in the four most recent leaf cohorts were measured in dead and surviving saplings. The foliar isotopic composition of dead saplings (which reflects time-integrated leaf gas-exchange until mortality) displayed sharp increases in both δ 13C and δ 18O during the extreme drought of 2005, suggesting an important role of stomatal conductance (g s) reduction and diffusional limitations to photosynthesis in mortality. While P. nigra showed decreased growth in 2005 compared to the previous wetter year, P. sylvestris maintained similar growth levels in both years. Decreased growth, coupled with a sharper increase in foliar δ 18O during extreme drought in dead saplings, indicate a more conservative water use strategy for P. nigra. The different physiological behavior of the two pine species in response to drought (further supported by data from surviving saplings) may have influenced 2005 mortality rates, which contributed to 2.4-fold greater survival for P. nigra over the lifespan of the saplings. This species-specific vulnerability to extreme drought could lead to changes in dominance and distribution of pine species in Mediterranean mountain forests. [ABSTRACT FROM AUTHOR]

Over the past century, the ecologically-diverse, braided Magra River in Italy has narrowed, incised, and lost many gravel bars due to the riparian vegetation encroachment following the decrease in bedload supply and channel degradation. Motivated by the European Water Framework Directive, river scientists and managers are beginning to plan projects to conserve and restore these dynamic mosaics of rare habitats and processes. To support this objective, a study was conducted to assess how braided rivers are perceived by different social groups in the area. In June, 2006, 127 people were surveyed using a photo-questionnaire consisting of ten photographs that depicted riverscapes with different proportions of water, vegetation, and bed material. Respondents were asked to score each photograph in terms of aesthetic value, beneficial uses, and river management needs. Results showed that the photographs depicting gravel bars were perceived as less aesthetically pleasing, so therefore they need an active management. However, these perceptions differed amongst groups of participants, reflecting their interests and objectives. This paper identifies a distance between scientific and popular attitudes and discusses implications for public participation, support for braided river restoration policy, and environmental education. [Copyright &y& Elsevier]

Question To what extent do small-scale biotic interactions and local variations determine the spatial pattern and plant performance of three Mediterranean subshrubs growing under contrasting climatic conditions? Location Three sites subjected to climatically contrasting conditions in Aragón (Javalambre, cold site; Bernués, mesic site; Monegros, xeric site), NE Spain. Methods The three species studied were Hormathophylla spinosa, Ononis fruticosa and Linum suffruticosum in the cold, mesic and xeric sites, respectively. Two transects (100 × 5 m) were located in each site, one in the upper part and another in the north-oriented slope of a hill. All adult individuals located within each transect of each species were tagged, spatially located and their size measured (height and crown diameter). We also estimated visually the cover of other woody species around each subshrub individual to study inter-specific interactions. We estimated the age of all subshrub individuals by counting annual rings in basal wood sections. To investigate the spatial patterns and plant performance of the three species we used spatial point pattern analyses and structural equation modelling. Results The density of individuals and the spatial pattern of the species varied greatly among and within sites. H. spinosa and L. suffruticosum showed higher variability in density among transects and a more aggregated spatial pattern than O. fruticosa. Similarly, the three subshrubs presented different architecture and performed differently in the two transects studied for each species. All three species presented higher growth rates in the upper part of the hill than in the north-oriented slope. Inter-specific interactions were more important than intra-specific ones in determining the performance of the three subshrubs, and were more intense in the case of H. spinosa and L. suffruticosum than in the case of O. fruticosa. Conclusions Our results demonstrate that the spatial patterns of the three species studied varied within sites as a function of local environmental conditions. Moreover, plant-plant interactions can play an important role in explaining subshrub spatial patterns and performance in Mediterranean ecosystems. Inter- and intra-specific interactions acting at local scales should be considered for understanding the responses of Mediterranean subshrubs to regional climate. [ABSTRACT FROM AUTHOR]

Herbivores can affect future forest composition by feeding selectivity. At temperature-sensitive treelines, herbivory can exacerbate or constrain climate-driven distributional shifts in tree species. This study analyses the impact of herbivory in a Mediterranean treeline of widespread Pinus sylvestris and P. nigra pinewoods, testing whether herbivory damage reinforces or inhibits the climatic responses of these trees. We used naturally occurring sapling pairs of similar size and age of both species, thereby isolating plant characteristics from environmental effects in herbivore behaviour. Herbivory damage by ungulates proved higher than that caused by insects in saplings of both species. Low plant density and extreme abiotic conditions at the treeline could in part be responsible for the observed low incidence of insect herbivory. Ungulates preferred P. sylvestris over P. nigra, implying heavier browsing damage for a large number of P. sylvestris saplings, suffering reduced internode growth as a consequence. In addition, P. sylvestris could not compensate height-growth reductions due to browsing with higher growth rate than P. nigra. In fact, P. sylvestris showed similar or lower relative height growth with respect to P. nigra. Under a scenario of increasing aridity and maintenance of ungulate populations, the upward migration of P. sylvestris in its southern range could be restricted by higher drought vulnerability than P. nigra, a situation exacerbated by ungulate herbivory. Our results indicate that ungulate herbivory reinforces climatic response of coexisting P. sylvestris and P. nigra at treeline, favouring a potential change in community dominance towards Mediterranean P. nigra. [ABSTRACT FROM AUTHOR]

Abstract: We compared soil organic carbon (SOC) stocks and stability under two widely distributed tree species in the Mediterranean region: Scots pine (Pinus sylvestris L.) and Pyrenean oak (Quercus pyrenaica Willd.) at their ecotone. We hypothesised that soils under Scots pine store more SOC and that tree species composition controls the amount and biochemical composition of organic matter inputs, but does not influence physico-chemical stabilization of SOC. At three locations in Central Spain, we assessed SOC stocks in the forest floor and down to 50cm in the mineral in pure and mixed stands of Pyrenean oak and Scots pine, as well as litterfall inputs over approximately 3 years at two sites. The relative SOC stability in the topsoil (0–10cm) was determined through size-fractionation (53μm) into mineral-associated and particulate organic matter and through KMnO4-reactive C and soil C:N ratio. Scots pine soils stored 95–140Mgha−1 of C (forest floor plus 50cm mineral soil), roughly the double than Pyrenean oak soils (40–80Mgha−1 of C), with stocks closely correlated to litterfall rates. Differences were most pronounced in the forest floor and uppermost 10cm of the mineral soil, but remained evident in the deeper layers. Biochemical indicators of soil organic matter suggested that biochemical recalcitrance of soil organic matter was higher under pine than under oak, contributing as well to a greater SOC storage under pine. Differences in SOC stocks between tree species were mainly due to the particulate organic matter (not associated to mineral particles). Forest conversion from Pyrenean oak to Scots pine may contribute to enhance soil C sequestration, but only in form of mineral-unprotected soil organic matter. [Copyright &y& Elsevier]

Abstract: Since the 1950s the Spanish Mediterranean mountains have undergone a process of population decline, abandonment of land by farmers, and a reduction in livestock pressure. These changes have involved pasture loss as a result of the spread of scrub and an increase in the incidence of fires. To avoid these negative outcomes the regional administration of La Rioja (Spain) has implemented scrub clearance programs. Between 1986 and 2005 a total of 23,668ha were cleared, particularly on abandoned fields where the processes of vegetation succession had led to the dominance of Genista scorpius and Cistus laurifolius. Pasture regeneration as a result of scrub clearing of areas dominated by G. scorpius has resulted in a productivity rise from 6666 to 12,983 Mj/ha/year, whereas productivity of areas dominated by C. laurifolius has risen from 2435 to 9741 Mj/ha/year. The clearing of scrub needs to be recognized as a significant factor contributing to the control of fire. Scrub clearing has had positive results in La Rioja, leading to a reduced incidence of fires in recent years. Between 1996 and 2005 only 155ha/year was burnt, compared with 1541ha/year over the period from 1976 to 1985. Scrub clearing appears to be an appropriate means of management in marginal mountainous areas without the need for large investments of time and money. [Copyright &y& Elsevier]

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Question: Positive interactions are predicted to be common in communities developing under high physical stress or high herbivory pressure due to neighbour amelioration of limiting physical and consumer stresses, respectively. However, when both stress sources meet in the same community, the relative importance of the two facilitation mechanisms is poorly understood. We ask: What is the relative importance of abiotic vs. biotic mechanisms of facilitation of tree saplings by shrubs in Mediterranean mountain forests? Location: Sierra Nevada, SE Spain (1800-1850 m a.s.l.) Methods: Saplings of four tree taxa (Acer opalus ssp. granatense, Quercus hex, Pinus nigra ssp. salzmanii and P. sylvestris var. nevadensis) were planted following a 2 x 2 factorial design: two levels of herbivory (control and ungulate exclusion) and two microhabitats (under shrubs and in open areas). Sapling survival and growth were monitored for five years. Results: Shrubs had positive effects on sapling survival both in control and ungulate excluded plots. This effect was species-specific, with shrubs increasing the survival of Acer opalus and Quercus ilex three and twofold, respectively, but having a minor effect on the Pinus species. Herbivory damage was also species-specific, being much higher for Acer opalus than for any other species. Shrubs did not protect saplings of any species against ungulates. Thus, all Acer saplings (the most damaged species) suffered herbivory outside the exclosures, which largely reduced sapling height. Conclusions: Protection from abiotic stress (summer drought and winter frost) was much more relevant than protection from biotic stress (herbivory). However, we propose that the final balance between the two mechanisms can be expected to vary strongly between sites, depending on the relative magnitude of the different sources of stress and the intrinsic traits (e.g. palatability) of the species interacting. [ABSTRACT FROM AUTHOR]

1 Spatial patterns of seedling establishment have been shown to be largely affected by differences at the microhabitat scale. However, it is far from clear whether such differences are consistent both in space and time, and how they influence the spatial structure of plant populations. 2 We analyse the spatiotemporal variability in microhabitat quality for seedling emergence and survival of the Mediterranean tree Acer opalus ssp. granatense, examining seedling dynamics at the microhabitat scale in two maple populations intermingled in pine forests and two established on stony slopes during three consecutive years with different climatic conditions. 3 Seedling establishment varied markedly between microhabitats. In general, seedlings benefited from the presence of pre-established vegetation, with lower emergence and survival of maple seedlings in open interspaces than under adult maples, non-conspecific trees and shrubs. 4 However, the quality of most microhabitats depended on both habitat type and year. Emergence and survival under adult maples, heterospecific trees and in open interspaces was higher in forest than in stony-slope populations, and increased significantly with summer rainfall. Shrubs, on the contrary, showed relatively high values of seedling emergence and survival at all sites and in both dry and wet years. Consequently, the benefits of living under shrubs were comparatively greater at lower precipitation levels. 5 The different microhabitats found in heterogeneous landscapes such as Mediterranean forests vary, over relatively large spatiotemporal scales, in quality for seedling establishment. Shrubs showed the highest consistency in patterns of both seedling emergence and survival. This finding, together with the predominance of dry years in Mediterranean areas, may explain why Acer opalus ssp. granatense has a stable spatial distribution at a geographical scale with most saplings associated with shrubs. Spatiotemporal patterns of seedling dynamics at the microhabitat scale may cascade through later demographic stages, eventually impacting the spatial structure of plant populations. [ABSTRACT FROM AUTHOR]

The concentration of suspended sediment and discharge generated during flood events are not normally homogenous, and the curve representing sediment concentration vs. discharge through time is often a hysteretic loop. Three types of hysteretic loops were found at Arna´s, a Mediterranean headwater catchment in the Central Spanish Pyrenees: clockwise (the most frequent), counter-clockwise and eight-shaped. They are associated with different levels of humidity and rainfall and therefore indicators of different processes of runoff and sediment transport. Clockwise loops are generated under ‘normal’ stormflow conditions, when the catchment is very moist and runoff generation and sediment supply is limited to areas next to the channel (i.e. sediments are removed, transported and depleted rapidly). Counter-clockwise curves occur under very high moisture and high antecedent rainfall conditions. In this case, flood propagation occurs as a kinematic wave. Sediment sources are incorporated all over the catchment. In both cases, saturation excess overland flow generates the superficial runoff. The eight-shaped loop (partial clockwise followed by counter-clockwise) occurs with low water content. Here, the runoff generation process is supposed to be infiltration excess overland flow, which causes a rapid extension of the contributing areas both near the channel and over the whole catchment. [Copyright &y& Elsevier]

Air and shallow ground temperatures from two monitoring sites at the Serra da Estrela (Portugal) are analysed. The Caˆntaro Gordo site is located at 1875 m ASL and the Fraga das Penas at 1640 m ASL. The climate of the study area is Mediterranean and very irregular, both on a yearly and monthly basis. This is particularly significant during winter, when differences in snow cover have direct influence on the ground thermal regimes and therefore on geocryological processes. To assess the significance of the ground thermal regimes for the geomorphological dynamics, bi-hourly records of temperature are studied at a daily basis. Eight types of daily regime were identified: isothermal unfrozen, non-isothermal unfrozen, surficial freeze–thaw, surficial freeze–thaw and subsurficial frost, surficial and subsurficial freeze–thaw, subsurficial frost, surficial and subsurficial frost and surficial frost but no daily rhythm. The occurrence of these regimes is analysed and their geomorphological significance is presented. Based on the altitudinal differences of the two monitoring sites, on the occurrence of the different regimes and on field observations, a conceptual model for the altitudinal and seasonal zoning of the daily thermal regimes of the ground is presented. This model was prepared for the Serra da Estrela, but it can be used in other Mediterranean or tropical areas if altitude and seasonal precipitation differences are taken in explanation. [Copyright &y& Elsevier]

Facilitation by dispersal occurs if the nurse plant acts as a focus which is actively selected by seed dispersers and enhances the fitness of the facilitated plant. Sex-biased facilitation may be produced if seed dispersers tend to concentrate the seeds under female, fruit-bearing plants of dioecious species more often than under conspecific males. Juniperus sabina is a dioecious shrub with a prostrate growth form from Mediterranean high mountains that modifies many microhabitat characteristics related to seedling establishment and survival. Soil water availability, maximum soil temperature in summer, organic matter and total nitrogen content, were different on open ground as compared with beneath J. sabina shrubs, irrespective of its sex. Other studied characteristics such as soil bulk density and soil compaction after rain did not differ between the microhabitats considered. Some species, such as Juniperus communis, Pinus nigra, Helleborus foetidus and Euphorbia nicaeensis, are spatially associated to J. sabina shrubs, strongly suggesting a facilitative role. The anemochorous P. nigra and myrmechorous H. foetidus and E. nicaeensis did not associate preferentially to any sex of J. sabina. Only J. communis, an endozoochorous species sharing the same bird dispersers as J. sabina, presented a female-biased spatial association with the nurse plant. Seed dispersal mediated by birds attracted by the fruit-rewarding females of J. sabina explains the sex-biased spatial pattern of Juniperus communis. [ABSTRACT FROM AUTHOR]