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Most ecological studies that involve point pattern analyses are based on a single plot, which prevent the separation of the effects of various processes that could act simultaneously, as well as limiting the conclusions that can be extracted from these studies. However, considering the spatial distribution of individuals in several plots as replicates of the same process could help to differentiate its specific effects from those of other confounding processes. Thus, we introduce a new method for analyzing spatial point patterns that are replicated according to a two�factorial design. By summarizing the spatial patterns as K�functions, the proposed method computes the average K�functions for each level of the two factors (i.e., predictors) and for each combination of levels, before estimating the sum of squared deviations from the overall mean K�function. Inferences of the strength of the relationship between the predictors, their interaction, and the spatial structure are made based on a non�parametric bootstrap procedure, which considers the dependency among spatial scales. We illustrate the proposed approach based on an analysis of the effects of altitude (with two levels: low and high) and slope (with two levels: flat and steep slopes) on the spatial pattern of Croton wagneri, a dominant shrub in an Andean dry scrubland. Our method detected a significant effect of the interaction between slope and altitude, which could not have been detected using current point pattern analysis methodology. The prevalence of single�plot analysis in ecological studies may be due to a lack of familiarity with appropriate methods for replicated point patterns, as well as the greater complexity of these methods and the absence of appropriate software. Our approach can be applied to a significant number of ecological questions while maintaining a simple, understandable, and easily reportable methodological framework.

Escribano-Avila, G., Pias, B., Escudero, A., Virgos, E. 2015. Ecological relevance of frugivorous mammals in the regeneration dynamics of old fields in Mediterranean environments. Ecosistemas 24(3): 35-42. Doi.: 10.7818/ECOS.2015.24-3.06 Two opposite tendencies govern land use worldwide: intensification and abandonment. Land abandonment represents an opportunity for ecosystem recovery, an urgent need due to the current environmental crisis. Dispersal communities play a key role in the recovery of old fields, as they mobilize seeds that serve as the primary source for the regeneration of woody plants. Recent studies have pointed out the special relevance of frugivorous mammals for seed dispersal in degraded environments such as old fields. This is due to morphological and behavioural traits of frugivorous mammals which make this dispersal guild especially effective. Frugivorous mammals are generally bigger body-sized, use bigger home ranges and are able to perform longer dispersal distances than other frugivorous, thus dispersing a greater quantity of seeds in old fields. Once a seed arrives to an old field several stages until recruitment should be overcome (post-dispersal predation, germination, survival and growth). Seed dispersal by frugivorous mammals favors the success of dispersed seeds to be recruited due to: i. At the inter-specific level, frugivorous mammals do not present gape width limitations, thereby dispersing a wide range of fleshy fruited species. At the intra-specific level they are able to consume all fruit/seed size ranges while smaller frugivorous, like small to medium sized birds, usually select small fruits which may hamper recruitment, and ii Mammal frugivorous, specially carnivores, deposit seeds in microhabitats specially suitable for woody plants recruitment (e.g. shrubs). Overall, mammal frugivorous are key members of dispersal communities promoting regeneration dynamics in old fields thereby their ecological function should be considered from a management and restoration perspective.

The sensitivity of stomatal behavior and patterning (i.e., distribution, density, size) to environmental stimuli, renders them crucial for defining the physiological performance of leaves. Thus, assessing long-term modifications in stomatal traits in conserved specimens arises as a valuable eco-physiological approach to predict how the rising trend of warmer, drier summers could affect plant fitness, particularly in mountain areas already experiencing climate aggravation and lacking the related monitoring schemes like Mediterranean high-mountains. Variations in foliar and stomatal traits were studied in conserved specimens of Senecio pyrenaicus subsp. carpetanus from Sierra de Guadarrama over the past 71 years. Our findings revealed decreasing trends in leaf width, stomatal size, and increasing tendency in stomatal density, all correlated with the recent 30-year climate exacerbation in these mountains. This evidenced a positive selection favoring traits that allow safeguarding plant performance under drier, hotter weather conditions. The significant relation between stomatal traits and climatic variables upholds the role of stomatal patterning in sensing environmental cues in this species, feasibly optimizing physiological responses involved in the growth&ndash, water loss trade-off. The transition to smaller, densely packed stomata observed in recent decades could indicate local-adaptive plasticity in this species, enhancing stomatal response, as coarser environmental conditions take place in Sierra de Guadarrama.

1) Background: Neotropical montane forests represent one of the most diverse ecosystems; however, they are also the most threatened for deforestation. Our main goal is to evaluate the change in Basal Area (BA), Density and Species Composition of montane forests in the southern Ecuador and to determine the influence on some critical ecological and geomorphological factors. 2) Methods: One hundred thirty-two temporary plots of 400 m2 each were installed; we identified and measured all trees> 10 cm DBH. We modeled species diversity (Fisher’s alpha) change in relation to climatic, elevational and geomorphological gradients with GLM and Kruskall-Wallis analyses. The change in composition was determined using Cluster Analyses (BIOENV analysis followed by a LINKTREE procedure). Non-metric multidimensional scaling (NMDS) was used to analyze changes across climatic and geomorphological gradients. Finally, we used SIMPER analysis to identify the species that contributed most to the dissimilarity among the different elevations. 3) Results: Formation of floristic groups was influenced by altitude, temperature and Isothermality; physiographic province, great landscape, geological landscape and lithology. Plots located in low hills have higher alpha diversity with respect to the high hills and dissected mountains. 4) Conclusions: The elevation is first hierarchical factor responsible of the division of structural and floristic groups. Plots located on the whitish tuff have a higher alpha value diversity compared with plots in andesitic tuffs. Wettest quarter (> 839 mm) and Isothermality (> 90.5) are the climatic factors that driven de floristic divisions.

Crown architecture usually is heterogeneous as a result of foraging in spatially and temporally heterogeneous light environments. Ecologists are only beginning to identify the importance of temporal heterogeneity for light acquisition in plants, especially at the diurnal scale. Crown architectural heterogeneity often leads to a diurnal variation in light interception. However, maximizing light interception during midday may not be an optimal strategy in environments with excess light. Instead, long-lived plants are expected to show crown architectures and leaf positions that meet the contrasting needs of light interception and avoidance of excess light on a diurnal basis. We expected a midday depression in the diurnal course of light interception both at the whole-crown and leaf scales, as a strategy to avoid the interception of excessive irradiance. We tested this hypothesis in a population of guava trees (Psidium guajava L.) growing in an open tropical grassland. We quantified three crown architectural traits: intra-individual heterogeneity in foliage clumping, crown openness, and leaf position angles. We estimated the diurnal course of light interception at the crown scale using hemispheric photographs, and at the leaf scale using the cosine of solar incidence. Crowns showed a midday depression in light interception, while leaves showed a midday peak. These contrasting patterns were related to architectural traits. At the crown scale, the midday depression of light interception was linked to a greater crown openness and foliage clumping in crown tops than in the lateral parts of the crown. At the leaf scale, an average inclination angle of 45° led to the midday peak in light interception, but with a huge among-leaf variation in position angles. The mismatch in diurnal course of light interception at crown and leaf scales can indicate that different processes are being optimized at each scale. These findings suggest that the diurnal course of light interception may be an important dimension of the resource acquisition strategies of long-lived woody plants. Using a temporal approach as the one applied here may improve our understanding of the diversity of crown architectures found across and within environments.

Iberian Mediterranean forests are mainly dominated by Quercus species, which belong to different sections of the genus characterized by the condition of leaves, sclerophyllous vs. deciduous. There are also other Fagaceae-dominated forests such as beech forest, but they are considered relict and have a restricted distribution on mountains. Sclerophyllous oak forest covers the biggest part of the area, mainly in valleys or plateaus, while deciduous forests are distributed along mountain ranges where the higher amount of precipitation compensates for the typical dryness of Mediterranean climate. As examples we can mention Q. canariensis or Q. pyrenaica that have functional particularities, i.e. a marcescent leaves that only fall when the new ones appear, and have a quite restricted distribution so that they are considered endemic species. Although the widespread sclerophyllous forests of Quercus rotundifolia cover a large area, there are other types that are of ecological, chorological, and climatic interest. This is the case for cork oak forest (Q. suber) or olive woodlands (Olea sylvestris), that are also treated in this paper. We have also included some azonal vegetation types, mainly deciduous forests, present along riverbeds in extended areas of Mediterranean Iberia.

GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (relevés) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001; ... 1,000 m²) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetation-plot databases, such as the European Vegetation Archive (EVA) and the global database “sPlot”. Its main aim is to facilitate studies on the scale- and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board. Abbreviations: EDGG = Eurasian Dry Grassland Group; EVA = European Vegetation Archive; GrassPlot = Database of Scale-Dependent Phytodiversity Patterns in Palaearctic Grasslands; SAR = species-area relationship.

We assessed the relative importance of dispersal limitation, environmental heterogeneity and their joint effects as determinants of the spatial patterns of 229 species in the moist tropical forest of Barro Colorado Island (Panama). We differentiated five types of species according to their dispersal syndrome; autochorous, anemochorous, and zoochorous species with small, medium-size and large fruits. We characterized the spatial patterns of each species and we checked whether they were best fitted by Inhomogeneous Poisson (IPP), Homogeneous Poisson cluster (HPCP) and Inhomogeneous Poisson cluster processes (IPCP) by means of the Akaike Information Criterion. We also assessed the influence of species' dispersal mode in the average cluster size. We found that 63% of the species were best fitted by IPCP regardless of their dispersal syndrome, although anemochorous species were best described by HPCP. Our results indicate that spatial patterns of tree species in this forest cannot be explained only by dispersal limitation, but by the joint effects of dispersal limitation and environmental heterogeneity. The absence of relationships between dispersal mode and degree of clustering suggests that several processes modify the original spatial pattern generated by seed dispersal. These findings emphasize the importance of fitting point process models with a different biological meaning when studying the main determinants of spatial structure in plant communities.

Gypsum soils are among the most restrictive and widespread substrates for plant life. Plants living on gypsum are classified as gypsophiles (exclusive to gypsum) and gypsovags (non-exclusive to gypsum). The former have been separated into wide and narrow gypsophiles, each with a putative different ecological strategy. Mechanisms displayed by gypsum plants to compete and survive on gypsum are still not fully understood. The aim of this study was to compare the main chemical groups in the leaves of plants with different specificity to gypsum soils and to explore the ability of Fourier transform infrared (FTIR) spectra analyzed with neural network (NN) modelling to discriminate groups of gypsum plants. Leaf samples of 14 species with different specificity to gypsum soils were analysed with FTIR spectroscopy coupled to neural network (NN) modelling. Spectral data were further related to the N, C, S, P, K, Na, Ca, Mg and ash concentrations of samples. The FTIR spectra of the three groups analyzed showed distinct features that enabled their discrimination through NN models. Wide gypsophiles stood out for the strong presence of inorganic compounds in their leaves, particularly gypsum and, in some species, also calcium oxalate crystals. The spectra of gypsovags had less inorganic chemical species, while those of narrow gypsum endemisms had low inorganics but shared with wide gypsophiles the presence of oxalate. Gypsum and calcium oxalate crystals seem to be widespread amongst gypsum specialist plants, possibly as a way to tolerate excess Ca and sulphate. However, other mechanisms such as the accumulation of sulphates in organic molecules are also compatible with plant specialization to gypsum. While gypsovags seem to be stress tolerant plants that tightly regulate the uptake of S and Ca, the ability of narrow gypsum endemisms to accumulate excess Ca as oxalate may indicate their incipient specialization to gypsum. © 2014 Palacio et al., The authors thank M.J. Albert, R. Milla, P. Fustero and A. Lamana for help with plant sampling and processing, to R. Hill for running the FTIR spectrometer, to E. Pérez-Fernández for assistance with FTIR figures and to J. F. Mota and an anonymous Referee for helpful comments on earlier versions of the manuscript.

Biological soil crusts (or biocrusts) are widespread, diverse and important components of drylands sometimes threatened by global change drivers. However, their response to fragmentation processes is poorly known. The aim of this study was to assess the effects of changing landscape structure, given by land use change and the presence of linear infrastructure (e.g., roads), on the cover and diversity of lichen-biocrusts. We also evaluated the influence of several subrogates of fragment quality, such as soil properties, vascular plant community structure and topography. Biocrust cover and diversity were measured in 50 remnants of a Mediterranean shrubland. The fragments varied in size, connectivity and distance to a road, but also in plant and soil attributes, topography and fragment history. We applied general linear and mixed models to assess the effects of environmental variables on biocrust communities. Biocrust cover, richness and species composition were mostly unresponsive to changes in landscape structure, while connectivity and distance to the road decreased species diversity. Soil properties better explained the variation in biocrust cover and diversity. Changes in plant community and biocrust community composition were coupled. We also identified several biocrust species with strong capacity to reflect landscape structure. Our findings suggest that landscape structure needs to be evaluated jointly with other environmental factors to fully understand the consequences of fragmentation processes on biocrust communities and the subsequent implications for their functional role in drylands.

Planting of woody species is a commonly used method to restore road embankments. Given the importance of road verges as potential corridors and refuge for biodiversity, natural plant regeneration processes may also play an important role in establishing vegetation into these novel landscape elements. Most studies on woody colonization of roadsides have considered only a few sites covering a very limited environmental range. Therefore, it is unclear whether or not there are general patterns that may explain the development of woody vegetation. We analyzed woody vegetation colonization in embankments over a large and heterogeneous territory, using aerial photographs, available repositories of environmental and land management data sets and some embankment features. We addressed the following questions: (1) To what extent does the presence of planted woody plants influence patterns of natural recruitment in road embankments? and (2) What are the key factors underlying natural/passive plant colonization in road embankments? We used Multi-Model Inference (MMI) analysis to model woody vegetation cover. According to our results, woody-planted vegetation does not have a facilitating effect on natural colonization, questioning the efficiency of reforestation measures in the ecological integration of areas affected by road construction. Passive natural plant colonization occurs spontaneously in road verges and shows a highly site-dependent pattern, driven mainly by the age of embankments and the immediate surrounding vegetation. Therefore, we suggest that natural succession may be sufficiently effective as a passive restoration measure on embankments in the long term.

Questions Shrublands often exhibit very high levels of species richness. We ask which mechanisms underlie plant species co-existence in a hyper-diverse Mediterranean shrubland, and the scales at which individual species exert their effects during organization of diversity in these communities. Location Brea de Tajo, Madrid, Spain. Methods We computed the individual species–area relationships (ISARs) in a completely mapped Mediterranean dwarf shrubland. Using appropriate species-specific null models, we evaluated how diversity was organized around individual species, covering a wide array of spatial scales. Results We mapped 7858 individuals from 48 perennial species. Our analyses showed that most species (80%) acted as accumulators and exhibited more diversity than expected, whereas 20% were neutral at fine scales. At larger spatial scales, most species exhibited no significant effects in terms of diversity accumulation. Conclusions In contrast to other species-rich ecosystems such as tropical forests, our results suggest that positive interactions and niche complementarities are the main drivers of community assembly in these communities. The most important finding was the existence of non-hierarchical multi-specific clumping that was independent of the fine-scale environmental heterogeneity, which is a pattern that has not been described previously, to the best of our knowledge. The abundance of accumulator species and the similarity among the ISAR curves suggest that nurse-like species were not present, thereby indicating that a different ecological mechanism led to the emergence of this pattern.

Most habitat fragmentation studies have focused on the effects of population size on reproductive success of single species, but studies assessing the effects of both fragment size and connectivity, and their interaction, on several coexisting species are rare. In this study, we selected 20 fragments along two continuous gradients of size and degree of isolation in a gypsum landscape in central Spain. In each fragment, we selected 15 individuals of each of three dominant gypsophiles (Centaurea hyssopifolia, Lepidium subulatum and Helianthemum squamatum, 300 plants per species, 900 plants in total) and measured several reproductive traits: inflorescence number, fruit set, seed set and seed mass. We hypothesised that plant fitness would be lower on small and isolated fragments due to an interaction between fragment size and connectivity, and that response patterns would be species-specific. Overall, fragment size had very little effect on reproductive traits compared to that of connectivity. We observed a positive effect of fragment connectivity on C. hyssopifolia fitness, mediated by the increased seed predation in plants from isolated fragments, resulting in fewer viable seeds per capitulum and lower seed set. Furthermore, seed mass was lower in plants from isolated fragments for both C. hyssopifolia and L. subulatum. In contrast, few reproductive traits of H. squamatum were affected by habitat fragmentation. We discuss the implications of species-specific responses to habitat fragmentation for the dynamics and conservation of gypsum plant communities. Our results highlight the complex interplay among plants and their mutualistic and antagonistic visitors, and reinforce the often-neglected role of habitat connectivity as a key component of the fragmentation process.

Questions Does edaphic heterogeneity (i.e. switches between gypsum and calcareous soils) affect annual plant community assembly in highly restrictive soils? Our main hypothesis is that soil filtering is the main determinant of species assembly, subsequently modulated by climate and lastly by biotic interactions, such as Stipa tenacissima and the biological soil crust (BSC) at fine spatial scales. Our study system is highly suitable to test the importance of edaphic heterogeneity to the assembly of annual plant communities, since calcareous and gypsum soils are in close contact and freely receive propagules. Location Annual plant communities of semi-arid steppes in central Spain. Methods We built a soil affinity index (SAI) for each species to measure mean soil affinity (MSA; analogous to the community-weighted mean – CWM) in each local assemblage. Results Most species were able to establish in both substrates, but gypsum soils clearly exerted a stronger filtering effect. Stipa favoured an expansion of the niche space in calcareous soils but not in gypsum, and BSCs not only reduced annual species richness, diversity and cover, but also the range of SAI values of local assemblages. Conclusions This study highlights the importance of the probabilistic filtering (sensu From plant traits to vegetation structure, 2010, Cambridge University Press, Cambridge, UK) of soil characteristics to the assembly of annual plant communities, as opposed to an ‘all-or-nothing’ filter.

La publicacion de las lecciones de juventud permite, hoy en dia, reconstruir con exactitud el temprano itinerario filosofico de Heidegger. Nos hallamos ante un periodo filosofico original, cuyas diversas etapas no se pueden considerar aisladamente. Aqui podemos hablar de un autentico camino del pensar (Denkweg), en el que van entrando en juego los elementos primordiales del pensamiento heideggeriano. Nuestra tesis de fondo es que las lecciones de juventud de Friburgo (1919-1923) y, por extension, las de Marburgo (1924- 1928) pueden leerse desde el horizonte tematico, conceptual y metodologico de Ser y tiempo como un camino que desemboca en esta obra clave. Finalmente, se analiza la relevancia metodologica de estas lecciones para las teorias contemporaneas de la mismidad. Nowadays, the publication of Heidegger’s early lectures allows us to reconstruct his philosophical itinerary. We are in front of an extremely original philosophical period, whose stages cannot be read in isolation. We can speak of a true path of thinking, in which the primordial elements of his thought come into place. In our opinion, the lecture courses of Freiburg (1919-1923) and Marburg (1924-1928) can be interpreted in the thematic, conceptual and methodological horizon of Being and Time as a path that leads into this key book. Finally, the methodological relevance of these early lectures regarding contemporary theories of selfhood will be shown.

Journal of Vegetation Science 2016 Colonization in Mediterranean old-fields: The role of dispersal and plant-plant interactions ( Articles not published yet, but available online Article in press About articles in press (opens in a new window) ) García-Cervigón, A.I.ab , Velázquez, E.cd , Wiegand, T.de , Escudero, A.f , Olano, J.M.a a iuFOR - Department of Agroforestry Sciences Universidad de Valladolid ES-42004 Soria Spain b Department of Natural Sciences Universidad Técnica Particular de Loja 110107 Loja Ecuador c Centro Universitario de Coyhaique Universidad de Magallanes José Miguel Carrera 485 Coyhaique 5951380 Chile View additional affiliations Abstract Questions: How do the dominant species in a Mediterranean community (Juniperus sabina, Juniperus communis and Pinus sylvestris) colonize abandoned fields? At what rates? Does dispersal limitation shape species colonization patterns? Does J. sabina act as nurse plant for the other two species? If so, in which stages of development: seedlings and saplings or older individuals? Location: Abandoned crop fields in the Alto Tajo Natural Park, central-eastern Spain. Methods: We mapped all individuals of the three species in three 4-14-ha plots, and aged them using dendrochronology. Spatial patterns in 2000, 1980 and 1960 were reconstructed according to estimated ages in 2014. We used a battery of spatial point-pattern analyses to evaluate dispersal in junipers, dispersal in pines, and the role of J. sabina as nurse plant for the other two species. Results: Both junipers colonized earlier than pines, probably due to their more effective endozoochorous dispersal. Late-coming pines, once established, expanded faster due to their higher seed productivity. Recent recruits of J. communis and P. sylvestris showed a random relationship with J. sabina canopies, whereas spatial patterns of older individuals in relation to J. sabina canopies ranged from attraction (plot 2 and marginally plot 1), suggesting facilitation, to repulsion in plot 3. These differences in spatial patterns between plots could be related to a shift in dominant herbivores, from sheep (plots 1 and 2) to red deer (plot 3). Conclusions: Dispersal and plant-plant interactions drove colonization in Mediterranean old fields. The inclusion of a temporal perspective in the analysis of spatial patterns allowed the detection of shifting interactions between J. sabina and the other two species, depending on their life stage. This is a clear advance compared with the usual static analyses, as it provides additional clues to interpret the mechanisms and processes underlying their origin. © 2016 International Association for Vegetation Science.

The recent Global Drylands Assessment of forests is based on both an incomplete delimitation of dry forests distribution and on an old and incorrect delimitation of drylands. Its sampling design includes a large proportion of plots located in humid ecosystems and ignores critical areas for the conservation of dry forests. Therefore its results and conclusions are unreliable.

The study by Bastin et al . (Reports, 12 May 2017, p. 635) is based on an incomplete delimitation of dry forest distribution and on an old and incorrect definition of drylands. Its sampling design includes many plots located in humid ecosystems and ignores critical areas for the conservation of dry forests. Therefore, its results and conclusions may be unreliable.

Habitat fragmentation, i.e., fragment size and isolation, can differentially alter patterns of neutral and quantitative genetic variation, fitness and phenotypic plasticity of plant populations, but their effects have rarely been tested simultaneously. We assessed the combined effects of size and connectivity on these aspects of genetic and phenotypic variation in populations of Centaurea hyssopifolia, a narrow endemic gypsophile that previously showed performance differences associated with fragmentation. We grew 111 maternal families sampled from ten populations that differed in their fragment size and connectivity in a common garden, and characterized quantitative genetic variation, phenotypic plasticity to drought for key functional traits, and plant survival, as a measure of population fitness. We also assessed neutral genetic variation within and among populations using eight microsatellite markers. Although Centaurea hyssopifolia is a narrow endemic gypsophile, we found substantial neutral genetic variation and quantitative variation for key functional traits. The partition of genetic variance indicated that a higher proportion of variation was found within populations, which is also consistent with low population differentiation in molecular markers, functional traits and their plasticity. This, combined with the generally small effect of habitat fragmentation suggests that gene flow among populations is not restricted, despite large differences in fragment size and isolation. Importantly, population’s similarities in genetic variation and plasticity did not reflect the lower survival observed in isolated populations. Overall, our results indicate that, although the species consists of genetically variable populations able to express functional plasticity, such aspects of adaptive potential may not always reflect populations’ survival. Given the differential effects of habitat connectivity on functional traits, genetic variation and fitness, our study highlights the need to shift the focus of fragmentation studies to the mechanisms that regulate connectivity effects, and call for caution on the use of genetic variation and plasticity to forecast population performance.

Ecosystems are structured by networks of interactions among species, but this hypothesis has rarely been tested in plant communities. Indeed, the structure and functioning of plant interaction networks have remained elusive so far and the mechanisms underlying their origin and maintenance remain unknown. By developing a novel approach that integrates the ecology of plant interactions with network theory and using spatial pattern analysis, we show that plant communities are organised in spatially variable and complex networks. Specifically, we found that positive plant interactions promote the formation and cohesiveness of large networks. At small spatial scale, where positive mutual interactions prevailed, the network was characterised by a large connected component. With increasing scale, when negative interactions took over, network structure became more hierarchical with many detached components. These findings shade new light on the complex networks of interactions occurring in plant communities.

Mediterranean mountains are extraordinarily diverse and hold a high proportion of endemic plants, but they are particularly vulnerable to climate change, and most species distribution models project drastic changes in community composition. Retrospective studies and long-term monitoring also highlight that Mediterranean high-mountain plants are suffering severe range contractions. The aim of this work is to review the current knowledge of climate change impacts on the process of plant regeneration by seed in Mediterranean high-mountain plants, by combining available information from observational and experimental studies. We also discuss some processes that may provide resilience against changing environmental conditions and suggest some research priorities for the future. With some exceptions, there is still little evidence of the direct effects of climate change on pollination and reproductive success of Mediterranean high-mountain plants, and most works are observational and/or centred only in the post-dispersal stages (germination and establishment). The great majority of studies agree that the characteristic summer drought and the extreme heatwaves, which are projected to be more intense in the future, are the most limiting factors for the regeneration process. However, there is an urgent need for studies combining elevational gradient approaches with experimental manipulations of temperature and drought to confirm the magnitude and variability of species' responses. There is also limited knowledge about the ability of Mediterranean high-mountain plants to cope with climate change through phenotypic plasticity and local adaptation processes. This could be achieved by performing common garden and reciprocal translocation experiments with species differing in life history traits.

Heidegger reconoció en varios testimonios autobiográficos la importancia de sus raíces teológicas para el desarrollo de su pensamiento. Aquí nos interesa la relevancia filosófica que los orígenes teológicos tienen para el joven estudiante Heidegger desde la perspectiva de uno de los temas centrales de su escrito de habilitación sobre Duns Escoto: la cuestión de la historicidad del “espíritu vivo” y la dimensión vivencial de la vida fáctica.

Land abandonment due to increasing depopulation of rural areas is an ongoing trend in developed countries worldwide. Abandoned lands represent an opportunity for ecosystem recovery, an urgent need for biodiversity conservation. Seed dispersal services provided by animals are a key feature for this process. Different dispersers may differentially contribute to plant recruitment under different ecological conditions, leading to complementary dispersal services. We studied the dispersal services, quantified as the contribution to plant recruitment, provided by the main dispersal guilds of Spanish juniper Juniperus thurifera L.: small-to-medium-sized strongly frugivorous birds (thrushes) and medium-to-large-sized carnivorous mammals (red fox and stone marten). To do this, we studied seed fate from seed dispersal to seedling survival during 2 years and estimated seed dispersal effectiveness (seedlings recruited per m2) in two ecological contexts derived from ecosystem recovery after a historical period of degradation: remnant woodlands and old fields. Results showed a clear shift in the contribution to plant recruitment between these guilds, resulting in complementary and non-redundant dispersal services. Thrushes were the main contributors to plant recruitment in woodlands (73%), leading to population growth but with a reduced impact on the colonization of old fields where carnivores contributed to 80% of recruitment (42% red fox, 38% stone marten). The dispersal complementarity observed for thrushes and carnivores is a consequence of their functional diversity, mainly driven by their differences in feeding and movement behaviour. Synthesis and applications. The combination of short-distance, strongly frugivorous dispersers (e.g. passerine birds) together with big generalist frugivores with long-distance movements (e.g. carnivorous mammals) maintained (i) effective seed dispersal services in remnant woodlands and (ii) the connectivity between patches promoting old fields colonization and woodland expansion. Thus, it is in heterogeneous landscape mosaics ecosystems (e.g. agro-environments) where functionally diverse disperser communities play a key role in ecosystem recovery. By performing effective dispersal services across an array of habitat types, functionally diverse disperser communities assist natural restoration of human-impacted ecosystems all over the world. Thus, dispersal communities provide an important ecosystem service that may replace costly human-mediated restoration projects. The combination of short-distance, strongly frugivorous dispersers (e.g. passerine birds) together with big generalist frugivores with long-distance movements (e.g. carnivorous mammals) maintained (i) effective seed dispersal services in remnant woodlands and (ii) the connectivity between patches promoting old fields colonization and woodland expansion. Thus, it is in heterogeneous landscape mosaics ecosystems (e.g. agro-environments) where functionally diverse disperser communities play a key role in ecosystem recovery. By performing effective dispersal services across an array of habitat types, functionally diverse disperser communities assist natural restoration of human-impacted ecosystems all over the world. Thus, dispersal communities provide an important ecosystem service that may replace costly human-mediated restoration projects., Funding was provided by the Spanish Ministries for Education (FPU-MEC grant) and Innovation and Science (projects: CGL2010-16388/BOS, Consolider-Montes/CSD2008_00040; VULGLO/CGL2010-22180-C03-03 and CALCOFIS/CGL2009-13013), and by the Community of Madrid project REMEDINAL 2 (CM-S2009/AMB-1783).

Adaptive responses to past climate change may play an important role in the persistence of high-mountain plants, which are vulnerable to global warming. Armeria caespitosa is a high-mountain plant, endemic to the Iberian Central Range. Differences in abiotic environment along the elevational gradient impose two opposing stress gradients (i.e. water stress and duration of the growth season) on the species. Furthermore, the species is found in two interspersed, contrasting microhabitats (rocky outcrops and dry cryophilic grasslands) that have different effects on plants depending of the elevation. As a result of this, the species shows great among-population variation in many reproductive and vegetative traits. We used a common garden approach to determine whether this phenotypic variation has a genetic basis or is the result of plastic responses shaped by heterogeneous environmental conditions. Plants from the high-elevation edge and dry cryophilic grasslands flowered earlier and produced more viable fruits but were smaller. These results confirm that among-population variation in flowering phenology and reproductive performance traits in A. caespitosa is partially genetically based. The results also show that the stronger selection response in favour of early-flowering individuals in populations at the low-elevation edge did not correspond with the greater proportion of early-flowering individuals. Genetic variability associated with flowering onset may be relevant in coping with the impacts of ongoing global warming. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 384–395.

Grazing represents one of the most common disturbances in drylands worldwide, affecting both ecosystem structure and functioning. Despite the efforts to understand the nature and magnitude of grazing effects on ecosystem components and processes, contrasting results continue to arise. This is particularly remarkable for the biological soil crust (BSC) communities (i.e., cyanobacteria, lichens, and bryophytes), which play an important role in soil dynamics. Here we evaluated simultaneously the effect of grazing impact on BSC communities (resistance) and recovery after livestock exclusion (resilience) in a semiarid grassland of Central Mexico. In particular, we examined BSC species distribution, species richness, taxonomical group cover (i.e., cyanobacteria, lichen, bryophyte), and composition along a disturbance gradient with different grazing regimes (low, medium, high impact) and along a recovery gradient with differently aged livestock exclosures (short-, medium-, long-term exclusion). Differences in grazing impact and time of recovery from grazing both resulted in slight changes in species richness; however, there were pronounced shifts in species composition and group cover. We found we could distinguish four highly diverse and dynamic BSC species groups: (1) species with high resistance and resilience to grazing, (2) species with high resistance but low resilience, (3) species with low resistance but high resilience, and (4) species with low resistance and resilience. While disturbance resulted in a novel diversity configuration, which may profoundly affect ecosystem functioning, we observed that 10 years of disturbance removal did not lead to the ecosystem structure found after 27 years of recovery. These findings are an important contribution to our understanding of BCS dynamics from a species and community perspective placed in a land use change context.

Colonization of abandoned lands by woody vegetation may be a great opportunity for ecosystem recovery given the current and future trend of land abandonment. This may help to reverse the generalized condition of ecosystem degradation of developed countries which is an urgent need. However, ecosystem recovery in abandoned lands can be seriously limited by biotic and abiotic factors. Indentify such factors and determine the relevant spatial scales at which they operate will help to understand natural patterns of colonization of abandoned lands and may be useful to guide restoration activities. We used Spanish juniper remnant woodlands and old fields recently colonized by the species to assess the variation in post-dispersal seed predation and environmental suitability to plant recruitment. These biotic and abiotic factors are two of the most limiting for vegetation recovery in abandoned lands, at the regional and local spatial scale. We found that recruitment was controlled by factors operating at different spatial scales in a hierarchical manner along different stages of the process. The regional scale was determinant for post-dispersal seed predation and seedling abundance which was, in turn, controlled by environmental suitability at the local spatial scale. Post-dispersal seed removal was higher in old fields than in mature woodlands, hence increasing seed limitation, a pervasive constraint for plant recruitment in abandoned lands. Environmental suitability for plant recruitment did not decrease as a result of previous farming uses at the regional scale, a common pattern in areas not subjected to intensive farming practices. Abandoned lands in Mediterranean areas seem to have a strong potential for ecosystem recovery being the biotic factors (e.g. seed availability) more limiting than the abiotic ones when non-intensive farming practices have been performed. This together with predictions of increase in land abandonment in low productive areas makes old fields especially relevant from an ecosystem recovery perspective. © 2014 Elsevier B.V., Gema Escribano-Ávila was supported by a FPU-MEC doctoral grant from the Spanish Ministry of Education (http://www.educacion.gob.es/portadahtml). Funding was provided by the Spanish Ministry for Innovation and Science (http://www.idi.mineco.gob.es/) with research projects CGL2010-16388/BOS, Consolider Montes (CSD2008_00040), VULGLO (CGL2010-22180-C03-03), and CALCOFIS (CGL2009-13013), and by the Community of Madrid project REMEDINAL 2 (CM-S2009/AMB-1783).

© 2014, Springer-Verlag Berlin Heidelberg. Understanding community dynamics during early life stages of trees is critical for the prediction of future species composition. In Mediterranean forests drought is a major constraint for regeneration, but likely not the only factor determining the observed spatial patterns. We carried out a sowing experiment aimed at identifying main filters during seed-seedling transition. Specifically, we studied seed fate (predation, fungi infection, emergence) and subsequent seedling performance (mortality during the first summer and overall recruitment after 2 years) of four co-occurring Mediterranean tree species (Quercus ilex, Quercus faginea, Juniperus thurifera,Pinus nigra). We related these processes to the dominant species composition, microhabitat heterogeneity, herb cover and seed mass. The identity of the dominant species in the forest canopy was more important for recruitment than the forest canopy being dominated by conspecific vs. heterospecific species. The patterns we found suggest that biotic interactions such as facilitation (lower mortality under the canopies) and herb competition (during emergence of J. thurifera) are relevant during recruitment. Moreover, our results pointed to ontogenetic conflicts regarding the seed mass of Q. faginea and to density-dependent seed mortality for Q. ilex, rarely described in Mediterranean ecosystems. We propose that our study species experience population growth in forests dominated by heterospecifics where the recruitment success depends on habitat heterogeneity and on moderated biotic and abiotic stresses created by each species. Our results reveal patterns and mechanisms involved in recruitment constraints that add complexity to the well-known drought-related processes in Mediterranean ecosystems., This work was supported by the Spanish Ministry for Innovation and Science with the grants FPI (CGL2007-66066-C04-02) to E. G., Consolider Montes (CSD2008 00040), VULGLO (CGL2010 22180 C03 03) and MOUNTAINS (CGL-2012-38427), and by the Community of Madrid grant REMEDINAL 2 (CM S2009 AMB 1783).

7 p., tablas, gráf., Cold stratification provided by snow cover is essential to break seed dormancy in many alpine plant species. The forecast reduction in snow precipitation and snow cover duration in most temperate mountains as a result of global warming could threaten alpine plant populations, especially those at the edge of their species distribution, by altering the dynamics of early life stages. We simulated some effects of a reduction in the snow cover period by manipulating the duration of cold stratification in seeds of Silene ciliata, a Mediterranean alpine specialist. Seeds from three populations distributed along an altitudinal gradient were exposed to different periods of cold stratification (2, 4 and 6 months) in the laboratory and then moved to common garden conditions in a greenhouse. The duration of the cold stratification treatment and population origin significantly affected seed emergence percentage, emergence rate and seedling size, but not the number of seedling leaves. The 6-month and 4-month cold stratification treatments produced higher emergence percentages and faster emergence rates than seeds without cold stratification treatment. No significant cold stratification duration x seed population origin interactions were found, thus differential sensitivity to cold stratification along elevation is not supported., This work was supported by the projects AdAptA (CGL2012-33528), Mountains (CGL2012-38427), LÍMITES (CGL2009-07229) and REMEDINAL2. C.L-R. was supported by a F.P.I. fellowship (BES-2010-036503); A.G-F. was supported by a F.P.I. fellowship (CGL2006-09431/BOS) and a post-doctoral contract (CGL2010-22234-C02/BOS).

Ecological restoration aims to revitalize ecosystem integrity and functionality following severe damage or degradation. Often, however, efforts are hampered by an incomplete or flawed concept of historical ‘reference’ used when choosing or constructing a target ecosystem or landscape to restore ‘to’. This problem may stem from a culturally-skewed interpretation of history or from misunderstanding or underestimation of the role that humans have played in a given ecosystem’s historical development and dynamics. While strongly confirming the importance of the reference concept in restoration ecology, we argue for the need to refine it, and to broaden the ways it can be conceived, developed, and applied. Firstly, the historical reference system informing a given restoration project should be grounded in both latent and active ‘ecological memories’, encoded and stored across relevant geographical and temporal scales. Further, the generally neglected geomorphic component of reference-building should also be addressed, as well as the contributions of human cultures to current ecosystem and landscape condition. Thirdly, ecosystems are historically contingent and multi-layered. Pre- versus post-disturbance comparisons are insufficient. Instead, restoration scenarios should be seen as tapestries of multiple and successive states. In sum, a well-conceived reference model helps promote and ensure the recovery and subsequent maintenance of historical continuity, i.e., the reestablishment of an impaired ecosystem to its historic ecological trajectory. We use case studies from Spain and Peru to illustrate how this approach can provide better goalposts and benchmarks, and therefore better guide the planning, implementation, and evaluation of effective restoration projects.

QuestionsWhat changes have occurred in Mediterranean high-mountain communities during the last 50yr? Do these changes reflect upward shifts and decline in dry grassland specialists due to climate warming? LocationUpper belt (1900-2400m a.s.l.) in Sierra de Guadarrama, Spain. MethodsWe re-surveyed dry grassland communities in 50 summits that were previously sampled between the 1960s and 1980s. New plots were placed in the same localities and the same conditions as the original surveys. Changes at the species level were evaluated by comparing, between the two survey periods, species frequencies and optimal altitude estimated by local distribution models done with Maxent. Changes at the community level were assessed by comparing species richness and composition of the two surveys in relation to altitude, plot size and time between surveys. We evaluated observed changes in the whole data set and species groups by structuring the species into dry grassland specialists, other alpine species and generalists occurring at wider altitudinal ranges. ResultsThere was a general decline in the frequency of dry grassland specialists, an increase in frequency of generalists and no clear trends in the other species. Upward shifts were mainly detected in generalists, with significant increases in frequency. At the community level, we found a general increase in species richness that was mainly determined by the increase in generalists; coupled with a decline in number of dry grassland specialists. The structure of the communities evidenced changes between the historical surveys and the re-survey, which were mainly correlated with the number of years and the increasing dominance of generalists. ConclusionsIn contrast with trends observed in other Mediterranean high-mountain communities, our study reports a general increase in species richness, although this effect is concurrent with a decline in dry grassland specialists. The observed trends support on-going replacement of endemic species by low-altitude species, and associated changes in community assemblages. Despite the limitations of re-visitation studies for assessing climate-driven changes, our results highlight the necessity of developing more studies for assessing the effects of drought in Mediterranean high-mountain communities.

Whether or not it is time for germination is a dilemma for annuals since they have only a single opportunity to reproduce successfully. This is critical for species living in stressful and unpredictable environments such as Mediterranean habitats. In order to clarify the environmental cues of germination, four annuals of different families, all of them occurring very frequently on gypsum soils, were selected and their germination observed under 14 climate scenarios, mimicking temperature and photoperiod conditions from autumn to spring, at two levels of water availability (continuous irrigation versus an initial single irrigation event followed by a progressive soil desiccation). In spring scenarios, two seed-storage conditions were compared: dry cold and room conditions. In the absence of water limitation, germination decreased from early autumn to late spring. Water scarcity always reduced germination, especially in early spring. Our results suggest a facultative winter germination behaviour and highlight the crucial role of dry cold storage in reducing spring germination. In conclusion, Mediterranean ephemerals showed a very plastic germination response that allows them to take advantage of favourable environmental conditions from autumn to spring. This environmental cueing is combined with the ability to dilute the risk through a variable rate of seed dormancy that, according to bet-hedging strategies, increases from secure autumn to riskier spring.

Understanding functional diversity is critical to manage and preserve biodi- versity and ecosystem functioning in the face of global change. However, the efforts to characterize this functional component have been mostly directed to vascular vegetation. We sampled lichen-dominated biological soil crusts (BSCs) in semiarid grasslands along an environmental gradient in the Iberian Peninsula. We characterized five effect functional traits for 31 lichens species, and evaluated the influence of large scale (i.e. precipitation) and small scale factors (i.e. substrate type, shrub presence, Stipa tenacissima presence) on dominant trait values; i.e. community weighted means, and functional divergence; i.e. Rao quadratic entropy in 580 sampling quadrats. Across the gradient, we found multiple trait shifts and a general increase of functional divergence with increasing precipitation. We also observed that substrate type and small scale biotic factors determined shifts in all traits studied, while these factors affected less to functional divergence. Comparing functional diversity with taxonomic diversity, we found contrasting responses to both large and small scale factors. These findings suggest that BSC community trait composition is influenced by multi-scale abiotic and biotic factors with environmental filtering dominating at large spatial scales and limiting similarity at specific small scales. Also, our results emphasize the potential differences between taxonomic and functional diversity in response to environmental factors. We concluded that functional diversity of BSCs not only provides novel and critical knowledge of BSC community structure, but also it should be considered

The adaptation of plants to particular soil types has long intrigued biologists. Gypsum soils occupy large areas in many regions of the world and host a striking biological diversity, but their vegetation has been much less studied than that developing over serpentine or saline soils. Herein, we review all aspects of plant life on gypsum ecosystems, discuss the main processes driving their structure and functioning, and highlight the main conservation threats that they face. Plant communities in gypsum habitats typically show distinctive bands at very small spatial scales, which are mainly determined by topography. Plants living on gypsum soils can be classified into three categories: (i) wide gypsophiles are specialists that can penetrate the physical soil crust during early life stages and have physiological adjustments to cope with the chemical limitations imposed by gypsum soils; (ii) narrow gypsophiles are refugee plants which successfully deal with the physical soil crust and can tolerate these chemical limitations but do not show specific adaptations for this type of soils; and (iii) gypsovags are non-specialist gypsum plants that can only thrive in gypsum soils when the physical crust is absent or reduced. Their ability to survive in gypsum soils may also be mediated by below-ground interactions with soil microorganisms. Gypsophiles and gypsovags show efficient germination at low temperatures, seed and fruit heteromorphism within and among populations, and variation in seed dormancy among plants and populations. In gypsum ecosystems, spatio-temporal changes in the composition and structure of above-ground vegetation are closely related to those of the soil seed bank. Biological soil crusts (BSCs) dominated by cyanobacteria, lichens and mosses are conspicuous in gypsum environments worldwide, and are important drivers of ecosystem processes such as carbon and nitrogen cycling, water infiltration and run-off and soil stability. These organisms are also important determinants of the structure of annual plant communities living on gypsum soils. The short-distance seed dispersal of gypsophiles is responsible for the high number of very narrow endemisms typically found in gypsum outcrops, and suggests that these species are evolutionarily old taxa due to the time they need to colonize isolated gypsum outcrops by chance. Climate change and habitat fragmentation negatively affect both plants and BSCs in gypsum habitats, and are among the major threats to these ecosystems. Gypsum habitats and specialists offer the chance to advance our knowledge on restrictive soils, and are ideal models not only to test important evolutionary questions such as tolerance to low Ca/Mg proportions in soils, but also to improve the theoretical framework of community ecology and ecosystem functioning.

Concostrina-Zubiri, L., Martinez, I., Huber-Sannwald, E., Escudero, A. 2013. Biological Soil Crust effects and responses in arid ecosystems: recent advances at the species level. Ecosistemas 22(3):95-000. Doi.: 10.7818/ECOS.2013.22-3.13. Biological soil crusts (BSCs) constitute a complex component of the ecosystem formed by different organisms (lichens, mosses, liverworts, cyanobacteria, fungi, algae) associated with soil surface. These communities are present in a wide variety of ecosystems; however, their abundance is generally higher in arid environments with sparse vegetation cover. In these ecosystems, BSCs greatly contribute to biodiversity and ecosystem functioning. Due to technical difficulties in species identification, most studies on BSCs have been carried out at community and morphotype levels. These studies have emphasized the potential role of BSCs in defining ecosystem structure and functioning by: interacting with topsoil layers and other soil organisms, participating in carbon and nitrogen fixation, and also in hydrological and nutrient cycling. Notwithstanding, recent advances in our knowledge about BSCs show substantial and interesting differences in the ecology and functional roles of BSC species, with marked implications in the management and conservation of these communities and their ecosystems. Particularly, it has been observed that BSC presence, abundance and frequency respond differently to diverse environmental factors (climatic variables, soil type, presence of vascular plants, and grazing disturbance - natural recovery) at the species level, and also do BSC effects on topsoil properties.

Positive plant interactions have strong effects on plant diversity at several spatial scales, expanding species distribution under stressful conditions. We evaluated the joint effect of climate and grazing on the nurse effect of Croton wagneri, by monitoring several community attributes at two spatial scales: microhabitat and plant community. Two very close locations that only differed in grazing intensity were surveyed in an Ecuadorian dry scrub ecosystem. At each location, two 30 × 30-m plots were established at four altitudinal levels (1500, 2630, 1959 and 2100 m asl) and 40 microsites were surveyed in each plot. Croton wagneri acted as community hubs, increasing species richness and plant cover at both scales. Beneath nurses mean richness and cover values were 3.4 and 21.9%, and in open areas 2.3 and 4.5%, respectively. Magnitude of nurse effect was dependent on climate and grazing conditions. In ungrazed locations, cover increased and diversity reduced with altitude, while grazed locations showed the opposite trend. In ungrazed plots the interactions shifted from positive to negative with altitude, in grazed locations interactions remained positive. We conclude that the nurse effect is a key mechanism regulating community properties not only at microsite but also at the entire community scale.

Seed dispersal is typically performed by a diverse array of species assemblages with different behavioral and morphological traits which determine dispersal quality (DQ, defined as the probability of recruitment of a dispersed seed). Fate of ecosystems to ongoing environmental changes is critically dependent on dispersal and mainly on DQ in novel scenarios. We assess here the DQ, thus the multiplicative effect of germination and survival probability to the first 3 years of life, for seeds dispersed by several bird species (Turdus spp.) and carnivores (Vulpes vulpes, Martes foina) in mature woodland remnants of Spanish juniper (Juniperus thurifera) and old fields which are being colonized by this species. Results showed that DQ was similar in mature woodlands and old fields. Germination rate for seeds dispersed by carnivores (11.5%) and thrushes (9.12%) was similar, however, interacted with microhabitat suitability. Seeds dispersed by carnivores reach the maximum germination rate on shrubs (16%), whereas seeds dispersed by thrushes did on female juniper canopies (15.5) indicating that each group of dispersers performed a directed dispersal. This directional effect was diluted when survival probability was considered: thrushes selected smaller seeds which had higher mortality in the seedling stage (70%) in relation to seedlings dispersed by carnivores (40%). Overall, thrushes resulted low-quality dispersers which provided a probability or recruitment of 2.5%, while a seed dispersed by carnivores had a probability of recruitment of 6.5%. Our findings show that generalist dispersers (i.e., carnivores) can provide a higher probability of recruitment than specialized dispersers (i.e., Turdus spp.). However, generalist species are usually opportunistic dispersers as their role as seed dispersers is dependent on the availability of trophic resources and species feeding preferences. As a result, J. thurifera dispersal community is composed by two functional groups of dispersers: specialized low-quality but trustworthy dispersers and generalist high-quality but opportunistic dispersers. The maintenance of both, generalist and specialist dispersers, in the dispersal assemblage community assures the dispersal services and increases the opportunities for regeneration and colonization of degraded areas under a land-use change scenario. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd., Gema Escribano-Ávila was supported by a FPU-MEC doctoral grant from the Spanish Ministry for Education (http://www.educacion.gob.es/portadahtml). Funding was provided by the Spanish Ministry for Innovation and Science (http://www.idi.mineco.gob.es/) with the grants CGL2010-16388/BOS, Consolider Montes (CSD2008_00040), VULGLO (CGL2010-22180-C03-03), and CALCOFIS (CGL2009-13013), and by the Community of Madrid grant (http://www.madrimasd.org/) REMEDINAL 2 (CM-S2009/AMB-1783).

Morphological and physiological characteristics of biological soil crusts (BSCs) enhance soil stability and fertility, and influence soil chemistry. However, the effect of BSCs on soil physico-chemical properties may vary depending on taxa (cyanobacteria, lichen, bryophytes) and species, and be susceptible to soil surface disturbance. We examined a wide variety of soil physico-chemical properties associated with five BSC components (cyanobacteria crust, one moss species, three lichen species) naturally occurring in the study area, and bare soil along a disturbance gradient in a semiarid grassland ecosystem in Central Mexico. We addressed the following questions: 1) Do different BSC components create distinct soil microsites characterized by a particular combination of physico-chemical properties? 2) Do distinct soil properties change beneath different BSC components? 3) Does grazing disturbance modify or override species-specific BSC effects? We found that BSC components and bare soil generated distinct soil microsites, however, this effect diminished with increasing grazing pressure. Also, most of the soil variables examined differed between BSC components and bare soil along the gradient. While soil properties associated with cyanobacteria were relatively similar compared to bare soil along the gradient, Diploschistes diacapsis and Lecidella sp. showed decreases in pH and marked differences in mineral nutrient concentration (i.e. variations in Na, Fe and Zn concentration respect to other BSC components and bare soil). Grazing intensity and frequency changed species-specific effects of D. diacapsis, specially modifying its effect on soil texture, diminishing its effect on pH, K and Na concentration, and increasing its effect on Ca and Zn concentration. We conclude that BSC components contribute to natural small-scale soil heterogeneity, and that soil disturbance substantially modifies the nature and magnitude of this effect with potentially important implications on ecosystem processes. Because of the potential influence of other factors (i.e. climate, vascular plants, microbial activity) on BSCs' relation to soil properties, this assertion should be tested including these factors and in multiple ecosystems.

PREMISE OF THE STUDY Mountain plants are among the species most vulnerable to global warming, because of their isolation, narrow geographic distribution, and limited geographic range shifts. Stochastic and selective processes can act on the genome, modulating genetic structure and diversity. Fragmentation and historical processes also have a great influence on current genetic patterns, but the spatial and temporal contexts of these processes are poorly known. We aimed to evaluate the microevolutionary processes that may have taken place in Mediterranean high-mountain plants in response to changing historical environmental conditions. METHODS Genetic structure, diversity, and loci under selection were analyzed using AFLP markers in 17 populations distributed over the whole geographic range of Armeria caespitosa, an endemic plant that inhabits isolated mountains (Sierra de Guadarrama, Spain). Differences in altitude, geographic location, and climate conditions were considered in the analyses, because they may play an important role in selective and stochastic processes. KEY RESULTS Bayesian clustering approaches identified nine genetic groups, although some discrepancies in assignment were found between alternative analyses. Spatially explicit analyses showed a weak relationship between genetic parameters and spatial or environmental distances. However, a large proportion of outlier loci were detected, and some outliers were related to environmental variables. CONCLUSIONS A. caespitosa populations exhibit spatial patterns of genetic structure that cannot be explained by the isolation-by-distance model. Shifts along the altitude gradient in response to Pleistocene climatic oscillations and environmentally mediated selective forces might explain the resulting structure and genetic diversity values found.

Questions Environmental factors have been identified as strong modulators of plant community distribution and diversity, especially in arid and semi-arid ecosystems. Despite recent advances in the ecology of biological soil crusts (BSC) from a community perspective, much remains unknown at the species level. Do environmental factors at different scales influence species richness, diversity and composition of BSC communities? At the species level, what are the main predictors for species occurrence and frequency? Location A geographic gradient from southeast to central Spain. Methods In a geographic gradient, we characterized BSC communities based on species richness and diversity, species composition and species frequency. Using generalized linear mixed models (GLMMs) and multivariate analyses we evaluated the effect of precipitation, type of soil substrate, presence of shrubs and presence of Stipa tenacissima on community attributes. Results Precipitation positively influenced species richness and diversity, but had little effect on BSC occurrence at the species level. Type of substrate was a strong predictor for species composition, occurrence and frequency, gypsiferous soils being those with higher species richness and diversity. At the local scale, S. tenacissima had more effect on species occurrence and frequency, while shrub presence was a poor predictor of community attributes. Conclusions Environmental factors influence BSC diversity predominantly at a large scale, while local-scale factors influence both community diversity and species distribution.

We evaluated the net outcome of the interaction between the shrub Retama sphaerocarpa, our target plant, and different herbaceous neighbours in response to changes in the magnitude and frequency of rainfall events during three years. The experiment was conducted in natural and anthropogenic grasslands dominated by a perennial stress-tolerator and ruderal annual species, respectively. In spite of the neutral or positive effects of neighbours on water availability, neighbouring plants reduced the performance of Retama juveniles, suggesting competition for resources other than water. The negative effects of grasses on the photochemical efficiency of Retama juveniles decreased with higher water availabilities or heavier irrigation pulses, depending on the grassland studied; however, these effects did not extent to the survival and growth of Retama juveniles. Our findings show the prevalence of competitive interactions among the studied plants, regardless of the water availability and its temporal pattern. These results suggest that positive interactions may not prevail under harsher conditions when shade-intolerant species are involved. This study could be used to further refine our predictions of how plant-plant interactions will respond to changes in rainfall, either natural or increased by the ongoing climatic change, in ecosystems where grass-shrubs interactions are prevalent. © 2013 Elsevier Ltd., FTM acknowledges support from the European Research Council under the European Community’s Seventh Framework Programme [(FP7/2007-2013)/ERC Grant agreement n 242658].

a b s t r a c t Evaluation of the effectiveness of protected areas networks for conserving diversity is a demanding topic in biological conservation. In the last few years, there has been an increasing number of studies on species distribution modelling which can be easily used to test the efficiency of reserve networks. Unfortunately, this effort has been focused on the so called charismatic species. Our main goal is to test the effectiveness of the Natura 2000 network by using non-charismatic species. We determined potential distribution patterns for 18 lichen species in Spain and evaluated the effectiveness of the Natura 2000 network in protecting them. Models were implemented with ENFA (Ecological-Niche Factor Analysis) because this modelling approach only requires presence data since the reliability of absence data is really poor. Habitat suitability maps were obtained and high suitability areas were characterised using ten environmental predictors. Maps of areas of high suitability were overlaid with the Natura 2000 network cover, considering the different biogeographical regions present in mainland Spain. The effectiveness of the Natura 2000 was quite low in most species. The analysis per region showed that Mediterranean lichen species growing in forests are better protected than species found in coastal, drier and warmer areas. Our results indicate that the Natura 2000 network, a protection system based on vascular plants, does not guarantee the protection of Mediterranean lichen species. Thus, this type of gap analysis and especially the inclusion of “non-charismatic” organisms such as lichens should be considered in studies to define protected areas.