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Background Plant communities of fragmented agricultural landscapes, are subject to patch isolation and scale-dependent effects. Variation in configuration, composition, and distance from one another affect biological processes of disturbance, productivity, and the movement ecology of species. However, connectivity and spatial structuring among these diverse communities are rarely considered together in the investigation of biological processes. Spatially optimised predictor variables that are based on informed measures of connectivity among communities, offer a solution to untangling multiple processes that drive biodiversity. Results To address the gap between theory and practice, a novel spatial optimisation method that incorporates hypotheses of community connectivity, was used to estimate the scale of effect of biotic and abiotic factors that distinguish plant communities. We tested: (1) whether different hypotheses of connectivity among sites was important to measuring diversity and environmental variation among plant communities; and (2) whether spatially optimised variables of species relative abundance and the abiotic environment among communities were consistent with diversity parameters in distinguishing four habitat types; namely Crop, Edge, Oak, and Wasteland. The global estimates of spatial autocorrelation, which did not consider environmental variation among sites, indicated significant positive autocorrelation under four hypotheses of landscape connectivity. The spatially optimised approach indicated significant positive and negative autocorrelation of species relative abundance at fine and broad scales, which depended on the measure of connectivity and environmental variation among sites. Conclusions These findings showed that variation in community diversity parameters does not necessarily correspond to underlying spatial structuring of species relative abundance. The technique used to generate spatially-optimised predictors is extendible to incorporate multiple variables of interest along with a priori hypotheses of landscape connectivity. Spatially-optimised variables with appropriate definitions of connectivity might be better than diversity parameters in explaining functional differences among communities.

Questions: The human-related spread of alien plants has serious environmental and socioeconomic impacts. Therefore, it is important to know which habitats are most threatened by invasion and why. We studied a wide range of European grasslands to assess: (a) which alien species are the most successful invaders in grasslands; (b) how invasion levels differ across European regions (countries or their parts) and biogeographical regions; and (c) which habitat types are the most invaded. Location: Europe. Methods: We selected 97,411 grassland vegetation plots from the European Vegetation Archive (EVA) and assigned a native or alien status to each of the 8,212 vascular plant species found in these plots. We considered only neophytes (alien species introduced after 1500 AD), which we further divided according to their origin. We compared the levels of invasion using relative neophyte richness in the species pool, relative neophyte richness and cover per plot, and percentages of invaded plots among regions and habitats. Results: Only 536 species, representing 6.5% of all grassland vascular plant species, were classified as neophytes. These were mostly therophytes or hemicryptophytes with low habitat specificity. Most of them were present in very few plots, while only three species were recorded in more than 1% of all plots (Onobrychis viciifolia, Erigeron annuus and Erigeron canadensis). Although invasion levels were generally low, we found more invaded plots in the Boreal and Continental regions. When considering only non-European neophytes, the Pannonian region was the most invaded. Among different grassland habitats, sandy grasslands were most invaded, and alpine and oromediterranean grasslands least invaded. Conclusions: In general, natural and semi-natural European grasslands have relatively low levels of neophyte invasions compared with human-made habitats or alluvial forests, as well as with grasslands on other continents. The most typical neophytes invading European grasslands are species with broad ecological niches., IA, VK, JDa, MV, IK and MC were supported by the Czech Science Foundation (EXPRO grant no. 19-28491X), PP and JP by the Czech Science Foundation (EXPRO grant no. 19-28807X), JDa, PP and JP by the Czech Academy of Sciences (long-term research development project RVO 67985939), IB by the Basque Government (IT936-16), RGG by REMEDINAL network (S2018/EMT-4338), AL by Komarov Botanical Institute, RAS (AAAA-A19-119031290052-1) and AK by the National Research Foundation of Ukraine (grant no. 2020.01/0140). JCS considers this work a contribution to his VILLUM Investigator project “Biodiversity Dynamics in a Changing World” funded by VILLUM FONDEN (grant 16549).

Albeit the remarkably high Ultraviolet B loads, high temperatures, and drought stress substantiate the need for efficient photoprotective strategies in Mediterranean high-mountain plants, these remain understudied. Considering the sensitivity of photosystems to extreme conditions, we evaluated an environmental gradient’s weight on the photoprotection of five high-mountain specialists from Central Spain. Diurnal and seasonal variations in chlorophyll, chlorophyll fluorescence, carotenoids, and xanthophylls in consecutive and climatically contrasting years were taken to evaluate the effect of the impending climate coarsening at the photosystem level. Our results revealed significant differences among species in the xanthophyll cycle functioning, acting either as a continuous photoprotective strategy enhancing photochemistry-steadiness, or prompted only to counteract the cumulative effects of atypically adverse conditions. The lutein cycle’s involvement is inferred from the high lutein content found in all species and elevations, acting as a sustained photoprotective strategy. These findings added to high de-epoxidation state (DEPS) and minor seasonal changes in the chlorophyll a/b ratio, infer the xanthophyll and Lutein cycles are crucial for upkeeping the photosystems’ optimal functioning in these plants heightening their photoprotective capacity during periods of more unfavorable conditions. Nevertheless, an atypically dry growing season’s detrimental effect infers the feasible surpassing of stress-thresholds and the precariousness of the communities’ functional diversity under climate change.

Pouteau, R., et al., [Aim] The number of naturalized (i.e. established) alien species has increased rapidly over recent centuries. Given the differences in environmental tolerances among species, little is known about what factors determine the extent to which the observed size of the naturalized range of a species and hence the extent to which the observed richness of naturalized species of a region approach their full potential. Here, we asked which region- and species-specific characteristics explain differences between observed and expected naturalizations. [Location] Global. [Time period] Present. [Major taxa studied] Vascular plants. [Methods] We determined the observed naturalized distribution outside Europe for 1,485 species endemic to Europe using the Global Naturalized Alien Flora (GloNAF) database and their expected distributions outside Europe using species distribution models. First, we investigated which of seven socio-economic factors related to introduction pathways, anthropogenic pressures and inventory effort best explained the differences between observed and expected naturalized European floras. Second, we examined whether distributional features, economic use and functional traits explain the extent to which species have filled their expected ranges outside Europe. Results: In terms of suitable area, more than 95% of expected naturalizations of European plants were not yet observed. Species were naturalized in only 4.2% of their suitable regions outside of Europe (range filling) and in 0.4% of their unsuitable regions (range expansion). Anthropogenic habitat disturbance primarily explained the difference between observed and expected naturalized European floras, as did the number of treaties relevant to invasive species. Species of ornamental and economic value and with large specific leaf area performed better at filling and expanding beyond their expected range. Main conclusions: The naturalization of alien plant species is explained by climate matching but also by the regional level of human development, the introduction pressure associated with the ornamental and economic values of the species and their adaptation to disturbed environments., Robin Pouteau was supported by the National Natural Science Foundation of China (grant number 31901176) and Taizhou University (2018YQ001). Carsten Meyer acknowledges funding by the Volkswagen Foundation through a Freigeist Fellowship (A118199), and additional support by iDiv, funded by the German Research Foundation (DFG–FZT 118, 202548816). Petr Pyšek and Jan Pergl were supported by the Czech Science Foundation (EXPRO grant 19-28807X) and the Czech Academy of Sciences (long-term research development project RVO 67985939). Idoia Biurrun and Juan Antonio Campos were supported by the Basque Government (IT936-16). Gianmaria Bonari, Milan Chytrý, Ilona Knollová, Anna Kuzemko and Corrado Marcenò were supported by the Czech Science Foundation (19-28491X). Rosario G. Gavilán was supported by Madrid Government project REMEDINAL (P2018/EMT-4338). Jens-Christian Svenning considers this work a contribution to his VILLUM Investigator project ‘Biodiversity Dynamics in a Changing World’ funded by VILLUM FONDEN (16549). Mark van Kleunen was supported by the German Research Foundation DFG (264740629). The authors appreciate the helpful comments by three anonymous referees and the Handling Editor, Melodie A. McGeoch.

© 2021 The Authors., Aims: Understanding fine-grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine-grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location: Palaearctic biogeographic realm. Methods: We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results: Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi-natural) grasslands and natural grasslands are the richest vegetation type. The open-access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions: The GrassPlot Diversity Benchmarks provide high-quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation-plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology., GrassPlot development has been supported by the Bavarian Research Alliance (BayIntAn_UBT_2017_58), the Eurasian Dry Grassland Group (EDGG) and the International Association for Vegetation Science (IAVS); IB, CorM, JAC, IGM, DGM, MHe, DL and MTo were supported by the Basque Government (IT936‐16); CorM, IAx, MCh, JDa, PD, MHá, ZL, ZPr, EŠ and LT were supported by the Czech Science Foundation (19‐28491X); TR was supported by the Estonian Research Council (PUT1173); RJP was funded by the Strategic Research Programme of the Scottish Government’s Rural and Environmental Science and Analytical Services Division”; SBa was supported by the GINOP‐2.3.2‐15‐2016‐00019 project; GFi was partially supported by the MIUR initiative “Department of excellence” (Law 232/2016)"; BJA was funded by the Spanish Research Agency (grant AEI/ 10.13039/501100011033); AK, VB, IM, DS, IV and DV were supported by the National Research Foundation of Ukraine (2020.01/0140); MP and AH were supported by the Estonian Research Council (PRG874, PRG609), and the European Regional Development Fund (Centre of Excellence EcolChange); Data collection of HCP was funded by FORMAS (Swedish Research Council for Environment, Agricultural Science and Spatial Planning) and The Swedish Institute; JR was supported by the Czech Science Foundation (grant No. 20‐09895S) and the long‐term developmental project of the Czech Academy of Sciences (RVO 67985939); ATRA was funded by the Grant of Excellence Departments, MIUR‐Italy (ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016); JMA was supported by Carl Tryggers stiftelse för vetenskaplig forskning and Qatar Petroleum; AAli was supported by the Jiangsu Science and Technology Special Project (Grant No. BX2019084), and Metasequoia Faculty Research Startup Funding at Nanjing Forestry University (Grant No. 163010230), and he is currently supported by Hebei University through Faculty Research Startup Funding Program; ZB was supported by the NKFI K 124796 grant; The GLORIA‐ Aragón project of JLBA was funded by the Dirección General de Cambio Climático del Gobierno de Aragón (Spain); MCs and LDem were supported by DG Environment through the European Forum on Nature Conservation and Pastoralism and Barbara Knowles Fund, in collaboration with Pogány‐havas Association, Romania; JDa was partially supported by long‐term research development project no. RVO 67985939 of the Czech Academy of Sciences; BD and OV were supported by the NKFI KH 126476, NKFI KH 130338, NKFI FK 124404 and NKFI FK 135329 grants; BD, OV and AKe were supported by the Bolyai János Scholarship of the Hungarian Academy of Sciences; BE was funded by the Environmental Department of the Tyrolean Federal State Government, the MAB Programme of the Austrian Academy of Science, the Mountain Agriculture Research Unit and the Alpine Research Centre Obergurgl of Innsbruck University. The GLORIA projects of BE were funded by the EU project no. EVK2‐CT‐2000‐00056, the Earth System Sciences Program of the Austrian Academy of Sciences (project MEDIALPS), the Amt für Naturparke, Autonome Provinz Bozen‐Südtirol, the Südtiroler Wissenschaftsfonds and the Tiroler Wissenschaftsfonds; RGG was supported by the Spanish Ministry of Research to sample GLORIA sites in central Spain (CGL 2008‐00901/BOS) and present works by the Autonomous Region of Madrid (REMEDINAL TE‐CM, S2018/EMT‐4338); MJ was supporteLatviaed by Latvia Grant No. 194051; NP and SŠ were partly supported by the Slovenian Research Agency, core fundings P1‐0403 and J7‐1822.

[Aim] Alpine habitats support unique biodiversity confined to high-elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups., [Location] European mountains below 50° N., [Time period] Between 1928 and 2019., [Major taxa studied] Vascular plants., [Methods] We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non-alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed-effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions., [Results] Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non-alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non-alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions., [Main conclusions] Besides area effects, edaphic, topographic and spatio-temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post-glacial environmental filtering, while non-alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles., The authors thank Daniela Gaspar for support in GIS analyses. B.J.-A. thanks the Marie Curie Clarín-COFUND program of the Principality of Asturias-EU (ACB17-26), the regional grant IDI/2018/000151, and the Spanish Research Agency grant AEI/ 10.13039/501100011033. J.V.R.-D. was supported by the ACA17-02FP7 Marie Curie COFUND-Clarín grant. G.P.M. was funded by US National Science Foundation award 1853665. C.M. was funded by grant no. 19-28491 of the Czech Science Foundation.

Aim The EUNIS Habitat Classification is a widely used reference framework for European habitat types (habitats), but it lacks formal definitions of individual habitats that would enable their unequivocal identification. Our goal was to develop a tool for assigning vegetation-plot records to the habitats of the EUNIS system, use it to classify a European vegetation-plot database, and compile statistically-derived characteristic species combinations and distribution maps for these habitats. Location Europe. Methods We developed the classification expert system EUNIS-ESy, which contains definitions of individual EUNIS habitats based on their species composition and geographic location. Each habitat was formally defined as a formula in a computer language combining algebraic and set-theoretic concepts with formal logical operators. We applied this expert system to classify 1,261,373 vegetation plots from the European Vegetation Archive (EVA) and other databases. Then we determined diagnostic, constant and dominant species for each habitat by calculating species-to-habitat fidelity and constancy (occurrence frequency) in the classified data set. Finally, we mapped the plot locations for each habitat. Results Formal definitions were developed for 199 habitats at Level 3 of the EUNIS hierarchy, including 25 coastal, 18 wetland, 55 grassland, 43 shrubland, 46 forest and 12 man-made habitats. The expert system classified 1,125,121 vegetation plots to these habitat groups and 73,188 to other habitats, while 63,064 plots remained unclassified or were classified to more than one habitat. Data on each habitat were summarized in factsheets containing habitat description, distribution map, corresponding syntaxa and characteristic species combination. Conclusions EUNIS habitats were characterized for the first time in terms of their species composition and distribution, based on a classification of a European database of vegetation plots using the newly developed electronic expert system EUNIS-ESy. The data provided and the expert system have considerable potential for future use in European nature conservation planning, monitoring and assessment. The previous versions of the expert system and related reports were produced within a contract from the European Environment Agency to Wageningen Environmental Research and Masaryk University. The opinions expressed are those of the contractor and do not represent the Agency's official position. EVA data management and preparation of this paper were supported by the Czech Science Foundation (project no. 19-28491X to MC, LT, IK, TP, CM, JDa, MH, PN, DZ, GB, AJ, AKu, ZL and DV). IB and JAC were supported by the Basque Government (project no. T936-16). TB, ET, and LK were supported by the Ministry of Science and Higher Education of the Russian Federation (TB and ET project no. AAAA-A18-118052590019-7; LK project no. AAAA-A19-119012490096-2).

The composition and distribution of the vegetation in the subtropical montane forests of the Serranias de Zapla Multiple Use Ecology Reserve was determined using the phytosociological methodology of the Zurich-Montpellier school (Braun-Blanquet 1979) adapted to the study area, which allowed the identification and delimitation of the different plant communities along the altitudinal gradient in the Reserve.

The flora of the province of Jujuy is one of the most diverse in the Republic of Argentina. It comprises a total of 170 families, 972 genera and 2831 species distributed in the various ecological belts and plant formations throughout the region. According to these figures, the study area contains a representation of 39% the families, 20% of the genera and 9.1% of the species in the province. Specifically, for the subtropical mountain woodlands or Yungas in northwest Argentina, and especially in the province of Jujuy, a complete floristic catalogue has yet to be compiled. Many of the studies have focused on the tree layer and very few have undertaken the combined analysis of the three main vegetation layers; added to this is the fact that practically none has employed a theoretical approach and the phytosociological methodology. In this regard, and specifically for the province of Jujuy, only two phytosociological studies have recently been done in these forests, one of which analyses the vegetation at the level of the three layers, while the other focuses solely on arboreal vegetation.

Serranias de Zapla Multiple Use Ecology Reserve is located in the Department of Palpala, in Jujuy province. It is delimited by the geographic coordinates 24°09′–24°21’S and 65°1′–65°14’W, and has an area of 37,139 ha, with altitudes ranging from 834 to 2183 m asl. Within this altitudinal range, the forest extends along an altitudinal gradient of 600 m at between 1015 and 1620 m asl. This Reserve is included in the sub-Andean mountain ranges that descend from Peru, crosses Bolivia and penetrates into Argentina as a narrow belt running north to south and covering part of Jujuy and Salta provinces. It has approximately 100 km wide and 500 km long, increasing in altitude from east to west. It represents approximately 23% of the total area of Jujuy province.

Vegetation is the most easily recognisable component of the ecosystem, and is the result of the joint action of environmental factors: it reflects climate, the nature of the soil, the availability of water and nutrients, and biotic and anthropic factors. It therefore acts as an indicator of the characteristics and status of ecosystems (Whittaker 1975; Matteucci and Colma 1982). The study of vegetation is of exceptional importance as it is a vital part of the ecological system: it captures, transforms and stores solar energy, protects the soil, regulates the local climate and serves as sustenance and refuge for fauna; it is the origin of raw materials for humans and a source of spiritual and cultural well-being thanks to its aesthetic, recreational and educational value. It is the essential basis for obtaining information on the composition, structure, dynamic and distribution of plant communities within a specific plant formation (Braun-Blanquet 1964; Whittaker 1975; Matteucci and Colma 1982). Vegetation studies serve numerous purposes, basically for research and development, and are closely linked to the conservation of the environment. The information obtained from these studies can be used to assess the vegetation for the purposes of conservation and to reach a diagnosis on its current state, with a view to designing strategies and programmes for conservation, ordination and territorial management and for planning the use of the territory (Whittaker 1973; Mueller-Dombois and Ellenberg 1974; Meaza Rodriguez 2000). These studies serve as the basis for creating maps of vegetation distribution within a given area, delimiting homogeneous ecological units and determining the degree of priority of its conservation. They also provide indicators on the environment, the effects of management (livestock, forestry production and so on) and different treatments (fertilisation, irrigation, reforestation and others), and supply valuable information for studies on environmental impact and the sustainable management of natural resources (forestry, management of wild fauna, etc.), among others. The detailed study of the composition, structure, dynamic and distribution of vegetation is therefore the cornerstone of a greater understanding and a balanced management of ecosystems, of which humans also form part. The increasing anthropic pressure to which natural ecosystems are subject today makes this type of study absolutely essential (Matteucci and Colma 1982; Barbour et al. 1998).

The study of ecological succession to determine how plant communities re-assemble after a natural or anthropogenic disturbance has always been an important topic in ecology. The understanding of these processes forms part of the new theories of community assembly and species coexistence, and is attracting attention in a context of expanding human impacts. Specifically, new successional studies provide answers to different mechanisms of community assemblage, and aim to define the importance of deterministic or stochastic processes in the succession dynamic. Biotic limits, which depend directly on biodiversity (i.e., species competition), and abiotic filtering, which depends on the environment, become particularly important when they are exceeded, making the succession process more complicated to reach the previous disturbance stage. Plant functional traits (PFTs) are used in secondary succession studies to establish differences between abandonment stages or to compare types of vegetation or flora, and are more closely related to the functioning of plant communities. Dispersal limitation is a PFT considered an important process from a stochastic point of view because it is related to the establishing of plants. Related to it the soil seed bank plays an important role in secondary succession because it is essential for ecosystem functioning. Soil compounds and microbial community are important variables to take into account when studying any succession stage. Chronosequence is the best way to study the whole process at different time scales. Finally, our objective in this review is to show how past studies and new insights are being incorporated into the basis of classic succession. To further explore this subject we have chosen old-field recovery as an example of how a number of different plant communities, including annual and perennial grasslands and shrublands, play an important role in secondary succession.

Aims Our objective was to study the high-mountain grasslands growing on siliceous substrata on the Iberian Peninsula to determine the floristic patterns and affinities that best define the structure and the phytosociological classification of this vegetation. Location Cantabrian Range, Sierra Nevada, Sistema Central, Sistema Iberico and the Pyrenees. Methods We analysed 1484 phytosociological releves representing 25 phytosociological associations of high-mountain grasslands on siliceous substrata previously described in the study area. A first classification by noise clustering produced a large noise group containing over 50% of the releves. We then carried out a DCA to check the relative position of the noise group components respect to the whole pool and a K-means combined with species indicator analysis to obtain a more precise delimitation of clusters through their representative species. Results We considered 17 groups as the optimum number of clusters by considering K-means and the corresponding indicators species. Pyrenean alpine vegetation separated first, showing a homogeneous pattern with a set of diagnostic taxa organised around two groups that coincide with one European class (Juncetea trifidi) and two alliances: Festucion eskiae in chionophilous environments, and Festucion supinae in chionophobous habitats. The rest of the data correspond to the Iberian class Festucetea indigestae, recognized in three alliances corresponding to three territories: the Cantabrian Range, Central Iberian Peninsula (Sistema Central and Sistema Iberico) and Sierra Nevada. Four groups have been extracted from the Cantabrian Range, which correspond to temperate plant communities (2 groups, alpine and subalpine) and to Mediterranean plant communities (2 groups, oromediterranean). All of them are included in Teesdalio-Luzulion. Two groups for Sierra Nevada – one oro- (Thymion serpylloidis) and another cryoromediterranean (Ptilotrichion purpurei) – were separated later on. Some relationships were found between the oromediterranean communities in the Central Mountains (Sierra de Guadarrama) and Sierra Nevada. This highlights the Mediterranean character of this central Iberian mountain, compared to the rest of central ranges (4 groups representing cryoromediterranean plant communities from ranges that are part of the Sistema Central and Sistema Iberico) that were independently separated by the analysis and have a more submediterranean character. All are included in Jasionion carpetanae. Conclusions The Pyrenees and the Cantabrian Range show relationships in these communities but also differences since the Cantabrian Range has a major influence of Mediterranean taxa in their plant communities. Central Iberian mountains showed relationships with the other Mediterranean mountains through the presence of species of the Festuca indigesta gr. and other endemic taxa. The particular pattern of Sierra Nevada – very patchy and with lower cover values – hindered the separation of groups, but two groups were finally detected in the analysis based on the altitudinal gradient. This article is protected by copyright. All rights reserved.

Increasing evidence indicates that in wild ecosystems plant viruses are important ecological agents, and with potential to jump into crops, but only recently have the diversity and population dynamics of wild plant viruses begun to be explored. Theory proposes that biotic factors (e.g., ecosystem biodiversity, host abundance, and host density) and climatic conditions would determine the epidemiology and evolution of wild plant viruses. However, these predictions seldom have been empirically tested. For 3 years, we analyzed the prevalence and genetic diversity of Potyvirus species in preserved riparian forests of Spain. Results indicated that potyviruses were always present in riparian forests, with a novel generalist potyvirus species provisionally named Iberian hop mosaic virus (IbHMV), explaining the largest fraction of infected plants. Focusing on this potyvirus, we analyzed the biotic and climatic factors affecting virus infection risk and population genetic diversity in its native ecosystem. The main predictors of IbHMV infection risk were host relative abundance and species richness. Virus prevalence and host relative abundance were the major factors determining the genetic diversity and selection pressures in the virus population. These observations support theoretical predictions assigning these ecological factors a key role in parasite epidemiology and evolution. Finally, our phylogenetic analysis indicated that the viral population was genetically structured according to host and location of origin, as expected if speciation is largely sympatric. Thus, this work contributes to characterizing viral diversity and provides novel information on the determinants of plant virus epidemiology and evolution in wild ecosystems.

High-mountain areas provide excellent opportunities to study the effects of combined abiotic stresses on plant physiology given their variety of steep ecological gradients, low anthropogenic disturbance and remarkable levels of taxonomic diversity. Efficient photoprotective and antioxidant scavenging mechanisms are vital for survival in high-mountain plants, having its altitudinal and seasonal variations determined by environmental or ontogenetic factors such as the decrease in mean temperatures and water availability. A number of stress indicators have been described in order to rapidly assess plant fitness in high-mountain environments. For instance, carbon isotope (δ13 C) and proline content as drought and temperature stress indicators, because of their link to water-use efficiency and osmotic adjustment; photosynthetic pigments, related to phenology, nutrient status, light and temperature stress; and non-structural carbohydrate accumulation in response to mild or brief drought conditions. The present review unveils the wide research opportunities available for the study of adaptive responses in high-mountain plants via stress indicators, and calls attention to the substantial knowledge gap existing between alpine zones and other mountainous regions, such as Mediterranean high-mountains. The aim is to grant a more holistic understanding of the physiological mechanisms driving plant life in high altitudes and improve the predictions of the effects of changing environments in these species and across ecological scales.

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.

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.

BACKGROUND: High-mountain pine forests and broom communities in central Spain today have led to contrasting interpretations of their natural or human-induced origin. AIMS: We evaluated the vulnerability and resilience of high-mountainPinus sylvestris/P. nigra forests and derivedCytisusbroom scrub communities to climate and anthropogenic disturbances. METHODS: We assessed historical transitions from forest to scrub and their relation to climate and human influences, using a multi-proxy paleoenvironmental study (pollen, non-pollen palynomorphs, charcoal, magnetic susceptibility) in three mires in the Gredos Range, western Iberian Central System. RESULTS: High percentages of Pinus sylvestris/nigrapollen and the identification of their macro remains demonstrated that high-mountain pine forests have been present in the oromediterranean bioclimatic belt of the Gredos Range since the mid-Holocene. After that, a major human-induced decline, enhanced by climate conditions, has led to their gradual replacement by broom communities. CONCLUSIONS: Broom communities are derived from ancient pine forests that were intensively transformed by human activities after 700 cal year BP, and largely disappeared byca. 500 cal yr BP. Today’s landscape, dominated by broom scrub and grasslands with scattered stands of pines, shows high resilience and provides suitable refugia for a rich mountain biodiversity which deserves a further protection.

Through litter decomposition enormous amounts of carbon is emitted to the atmosphere. Numerous large-scale decomposition experiments have been conducted focusing on this fundamental soil process in order to understand the controls on the terrestrial carbon transfer to the atmosphere. However, previous studies were mostly based on site-specific litter and methodologies, adding major uncertainty to syntheses, comparisons and meta-analyses across different experiments and sites. In the TeaComposition initiative, the potential litter decomposition is investigated by using standardized substrates (Rooibos and Green tea) for comparison of litter mass loss at 336 sites (ranging from -9 to +26 °C MAT and from 60 to 3113 mm MAP) across different ecosystems. In this study we tested the effect of climate (temperature and moisture), litter type and land-use on early stage decomposition (3 months) across nine biomes. We show that litter quality was the predominant controlling factor in early stage litter decomposition, which explained about 65% of the variability in litter decomposition at a global scale. The effect of climate, on the other hand, was not litter specific and explained

Aims The introduction of potentially invasive species through ornamental cultivation or for rehabilitation purposes is a serious environmental problem. They cause damage to biodiversity through loss, increased mortality or ‘in situ’ selection phenomena in natural flora. Spartium junceum is a Mediterranean shrub that is not native in most areas of the Iberian Peninsula, although it is extensively grown for the rehabilitation of roadsides. We have investigated the effect on the native vegetation of an old S. junceum (Fabaceae) plantation in a conservation area in the centre of the Iberian Peninsula: the Cuenca Alta del Manzanares nature reserve in Madrid. Methods We compared S. junceum stands with the native nanophanerophytic Cistus ladanifer community at different ecosystem properties: soil properties, temporal soil seed bank contents, standing vegetation and net primary production of annual grasslands growing in these shrublands. Important Findings The results highlighted S. junceum’s ability to become established in the new environment (marginal areas of the nature reserve) and ensure its successful growth. This is more apparent in northern and eastern exposures where this formation contacts with the core of the best conserved native vegetation in the nature reserve. Soils under Spartium showed a higher nitrogen content, indicating its capacity—in common with other legumes—to fix N, and conferring an advantage over Cistus, which is N-limited. Other soil nutrients such as phosphorus, magnesium and calcium and water availability are also higher in Spartium soils than in Cistus. Phosphorus is usually a constraint for N-fixers, but in our study, it is the most significant soil variable in both shrub formations and is important to the success of Spartium. Water availability is a key factor for Mediterranean vegetation, and particularly in autumn when soils are recharged. The Spartium formation is able to retain water as its growth produces a closer canopy than Cistus, thereby preventing water evaporation and contributing to the success of this species. Perennials are more frequent in the standing vegetation than in the seed bank, whereas therophytes are similar. The standing vegetation has therophytes and chamaephytes as the predominant growth forms in Spartium sites, and hemicryptophytes and phanerophytes in Cistus. Therophytes are dominant in Spartium and Cistus seed banks, although the first formation has more species. Spartium has a higher number of hemicryptophytes and Cistus is higher in phanerophytes. Northern and eastern aspects show significant differences in richness—with a predominance of annual weed species in Spartium—and in aboveground net primary production, probably as a consequence of the nutrients present in the soils. Ruderal annual species under Spartium (Bromus tectorum, Chenopodium album) have higher germination rates in the greenhouse than in the standing vegetation, suggesting they are at potential risk if environmental conditions change.

The aim of this work was to study the sensibility to warming of soil organic matter (SOM) decomposition in Mediterranean high mountain areas. Thus, we investigated the effects of temperature, C availability and vegetation in a Mediterranean high-mountain area in relation to SOM decomposition patterns. Along an altitudinal gradient (from 2100 to 2380 m a.s.l.) in Central Spain mountains, we assessed the altitudinal shifts in soil organic C (SOC), soil nitrogen (N), dissolved organic carbon (DOC), microbial biomass C (MBC), microbial respiration, microbial respiration sensitivity to temperature (Q10) and C availability index (CAI). Furthermore, we tested the differences in SOM decomposition rates between grasslands and shrub vegetation. SOC, DOC, N content, MBC, microbial respiration and CAI decreased, while Q10 increased with increasing altitude. In the grassland, MBC and microbial respiration were positively correlated to SOM. Q10 was positively correlated to pH and negatively correlated to substrate-induced microbial respiration. Soils below shrubs showed lower microbial respiration rates, lower CAI, and higher Q10 than soils below grassland. However MBC, DOC and soil N content were higher below shrubs. The results suggest that a rise in temperature would enhance SOM decomposition rates in grasslands more dramatically at higher altitudes, since they are more sensitive to temperature increases. The SOC accretion observed below shrubs may be due to the lower respiration rate of soil microorganisms, possibly determined by lower C substrate availability below shrubs. This result suggests a higher recalcitrance of shrub litter compared to grassland litter. Nevertheless, SOC in shrubland may be released at a higher rate due to its higher temperature sensitivity.

The Sistema Central or Central Range has an overall length of 600 km and is the most extensive mountain range on the Iberian Peninsula. It has an alpine orogeny and is located in the centre of the peninsula running northeast-southwest in its eastern part (Ayllon and Guadarrama ranges), and east-west in its western part (Guadarrama, Gredos and Estrela ranges). The whole system comprises a continuous series of smaller mountain ranges, including valleys and various natural areas. It occupies a vast territory from the middle of Portugal (Serra da Estrela) to the Sierra de Ayllon range in the east, and acts as a natural division of the Castilian central plateau, separating the northern plateau (Castile and Leon) from the southern plateau (Madrid, Castile-La Mancha and Extremadura). It generally represents the watershed between two of the most important Iberian rivers: the Duero and the Tagus. The highest point of the whole Iberian Central Range is the Almanzor Peak (2592 m) in the central massif of the Gredos mountains. Its characterisation and location on the Iberian Peninsula have interesting phytogeographical and geobotanical implications. These mountains are noteworthy for their bioclimatic, geomorphological and lithological features. Their remarkable bioclimatic complexity is a result of the dissymmetry between the northern and southern slopes (with average values of 1200 vs. 500 m), and their lithological homogeneity, dominated by plutonic igneous and –to a lesser extent– metamorphic rocks. All these factors condition the landscape in these territories. The natural vegetation in these mountains has a woodland character, except in the summit areas above the tree line, which are characterised by Mediterranean alpine grasslands. However other types of vegetation grow in these siliceous high-mountain areas, in the rocky places, peatland, meadows and shrubland that conform the landscape here. Natural Iberian Scots pine (Pinus sylvestris var. iberica) and Spanish black pine (Pinus nigra subsp. salzmannii) forests are distributed throughout the high- and mid-mountain territories respectively in spite of extensive deforestation –more pronounced in the westernmost mountain areas–, in addition to oak forests (Quercus pyrenaica and Quercus rotundifolia) in the rest of the mountain landscape, where natural forests have often been eliminated in order to cultivate several strains of pines, and to encourage the spread of meadows and grasslands which support an important livestock population. Some interesting small relict forests such as beech (Fagus sylvatica), birch (Betula celtiberica) and juniper woodlands (Juniperus thurifera and Juniperus oxycedrus subsp. lagunae) are scattered within the mountain areas. Also significant are the riparian and hygrophilous forests and other vegetation, and the seral vegetation complexes –both forest fringe vegetation and shrub communities– which often predominate throughout vast mountain areas in the landscape.

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.

The Mediterranean area is a natural biodiversity hotspot that has also been influenced by humans for millennia. Especially the grasslands of Southern Europe have long been known for their diversity and beauty. However, several gaps remain in our knowledge about these grasslands, e.g. for some regions such as the southern Balkans, or taxonomic groups such as cryptogams. Here we introduce a Special Issue with contributions from the 9th European Dry Grassland Group meeting held in Prespa, Greece, 2012. The topic of this meeting was “Dry grasslands of Europe: grazing and ecosystem services” with special focus on Southern European regions. The Special Issue, apart from this Editorial, consists of eight contributions arranged according to the three major topics: syntaxonomy (5 articles), management (2) and conservation (1). The classification papers include descriptions of four new associations and four subassociations. Data about management practices are provided as well. We conclude that dry grassland vegetation in Southern Europe exhibits transitions between different higher syntaxa and thus requires further studies at broader scales to allow better understanding at the supranational scale.

Mediterranean high-mountain ecosystems are considered to be among the most vulnerable to global change. Nevertheless Mediterranean high-mountain ecosystems are still relatively little known and their structure and function have only been elucidated in last decade. High-mountain environments are also currently target ecosystems for monitoring the changes caused by global change. Specifically the GLORIA project has developed a common long-term survey protocol of plant biodiversity changes in these habitats. Other short-term studies can be combined with long-term protocols and make use of the data already available in order to increase the understanding of these habitats and to predict the future responses of communities to global change. We summarized the most relevant results already achieved with short-term studies using the data recorded with GLORIA protocols in Sistema Central.

About 19% of European population lives in the mountainous regions – a notably more than the global average. The 50% of the Earth’s population depends on the mountain resources, mainly on drinking and industrial water and energy. However, the role of the mountain regions as place of recreation and leisure should not be underestimated as it is a major source economic force in some countries but also one of sources of problems creating pressure on mountain biota and landscapes. Lazaroa, Journal of Botany, through this feature presents a collection of papers focused on biodiversity of South Europe and Northern Africa mountain ranges. Geographically, it covers the main mountain chains of Europe and of North Africa, including those of the Balkans, Dinarides, Apennines, Pyrennees, Cantabrian Mts, Sierra Nevada and a whole array of other Mediterranean mountain ranges such as the Sistema Central in the Iberian Peninsula and those of Portugal and Sicily, and finally the Atlas of North Africa.

Background: The relationship between plant traits and environmental factors will be of value in understanding of functional strategies that plants have developed to cope with the environmental constraints on plant life in Mediterranean high mountain ecosystems. Aims: The aims of this study were (1) to explore the variation in plant traits in relation to environmental variability; (2) to analyse the functional strategies of species; and (3) to assess the habitat constraints for the species in the study area. Methods: We sampled the floristic composition of 76 1 m × 1 m plots on five summits over 2,100 m above sea level in the mountains of the Sistema Central, Spain. Soil properties and temperature and grazing disturbance parameters were recorded. Eight plant traits were assessed in 21 species. Environmental variability and the co-variation of functional traits were analysed by RDA and PCA, respectively. Plant traits and environmental variability were related using fourth-corner analysis. Results: Traits re...

We assessed the temporal changes on microbial biomass in relation to changes in soil moisture, dissolved organic carbon and plant biomass during the summer season in a Mediterranean high-mountain grassland. Temporal variations were tested by two-way ANOVA. The relationships among microbial biomass, plant biomass, soil water content, soil organic carbon, dissolved organic carbon and total soil nitrogen during the summer season were assessed by means of structural equation modeling. Microbial biomass did not show variation, while dissolved organic carbon and root biomass decreased throughout the summer. Aboveground plant biomass peaked in the middle of the summer, when soil water content was at its minimum. Soil water content directly and negatively affected soil microbial biomass, and positively affected dissolved organic carbon. Moreover soil microbial biomass and dissolved organic carbon were negatively related. Plant biomass effects on soil microbial biomass were driven by root biomass, which indirectly affected soil microbial biomass through effects on soil organic carbon and soil nitrogen. The temporal dynamic of microbial biomass during the summer season appeared to differ from previous observations in temperate alpine communities, and indicated the drought resistance of the microbial community during the summer in Mediterranean high-mountain grasslands. During the dry period, microbial biomass may play an alternative role in soil carbon conservation.

The degraded state, scattered distribution and substrate type of Quercus pyrenaica forests in eastern Spain make them a subject of particular interest, as well as a priority for conservation efforts. An extension of Dufrene and Legendre's indicator value (IndVal) analysis was applied to one hundred releves. This extension of the IndVal method allowed us, by considering the preference of species for combinations of releve groups, to obtain those species that represent local, but also regional, characteristics (as a new practical use). Our objective was to identify the species that best indicate the main ecological features of these broad-leaved oak forests. The usefulness of our analysis was evidenced at two levels: local indicator species, showing the characteristic species of individual sites and including the presence of endemics in the area; and indicator species of combinations of two or more sites, reflecting the affinities or relationships between these scattered forests. Most singular forests showed a higher number of local indicator species. The indicator species of each site combination represent the main ecological traits shared by these groups – such as proximity to the coast, land uses or postglacial migration pathways – thereby defining their relationships. Indicator value analysis with site group combinations ( Multipatt function) proved to be a useful tool for the identification of different species that could serve both to determine the local forest conservation status and aid in its preservation, as well as contributing to an understanding of the life history of larger territories.