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A major aim in invasion ecology is to understand the role of exotic species in plant communities. Whereas most studies have explored the traits of exotic species in the context of the introduced community, functional comparisons of entire assemblages of species in their native and introduced communities have rarely been analysed. Taking advantage of the unidirectional invasion of plant species of European origin (i.e. colonizers) into California, this study aims to investigate the relative importance of plant traits, environmental factors and invasion status in biological invasions. We compared the functional structure (i.e. trait composition and diversity) along resource availability gradients in recipient and native Mediterranean grassland communities in California and Spain, respectively. Traits were related to resource use in above-ground and below-ground organs and reproductive strategy. We also investigated how niche differences vary along environmental gradients between coexisting colonizer and native species assemblages within communities. There were clear differences in the functional structure of Mediterranean grassland communities between regions, which were associated with the resource availability gradient. Paradoxically, the most acquisitive communities occurred in resource-poor sites, highlighting that rapid acquisition and use of resources permit species to cope with environmental stress through stress avoidance. In Spain, colonizer species had greater specific leaf area than non-colonizers. Yet, differences between colonizer and non-colonizer species in Spain for other traits were mostly absent and did not change along the gradient. This might be a result of the greater native species richness as a consequence of the agricultural practices that have taken place in Europe for millennia and reflect that the entire species pool of grasslands is adapted to agricultural landscapes. In comparison, in California, colonizer species were more acquisitive in

Determining the factors that pre-adapt plant species to successfully establish and spread outside of their native ranges constitutes a powerful approach with great potential for management. While this source-area approach accounts for the bias associated with species’ regions of origin, it has been only implemented in pools of species known to be established elsewhere. We argue that, in regions with well-known introduction histories, such as the Mediterranean Biome, the consideration of co-dominant non-introduced species as a control group allows a better understanding of the invasion process. For this purpose, we used occurrence data from GBIF and trait data from previous studies to find predictors of establishment and invasion. We compare the frequency, climatic niche and functional traits of 149 co-dominant plant species in their native region in southern Spain, considering whether they have colonised other Mediterranean-climate regions or not and their level of invasion. We found that large native ranges and diverse climatic niches were the best predictors of species establishment abroad. Moreover, coloniser species had longer bloom periods, higher growth rates and greater resource acquisition, whereas coloniser species becoming invasive had also greater reproductive height and nitrogen use efficiency. This framework has the potential to improve prediction models and management practices to prevent the harmful impacts from species in invaded communities.

Invasions by plant species are an increasing threat which is reducing species diversity across regions, changing community composition and altering ecosystems functioning. While most investigations on impacts of exotic plants are conducted in their areas of introduction, the study of the assembly of exotic species in their native areas is emerging as a framework to better understand their roles in the invaded communities. In this regard, functional traits reflect the ecological strategy of plants and their interactions with coexistent species and the environment, therefore plant traits are a key tool to understand the rol of exotic plant species in the structure of their communities. One of the main objectives of this thesis is to identify the functional strategies of exotic species in invaded Mediterranean ecosystems and disentangle the rules that govern the assembly of invaded communities. For this, we analysed traits from several plant organs (i.e. leafs, seeds, roots) of 285 species from two vegetation types (woodlands and grasslands) at different spatial scales of resolution (i.e. Biome, environmental gradients, communities, plants). We used the Mediterranean biome as a study system because of the mostly unidirectional invasion of plants from the Mediterranean Basin to California, Chile, Australia and South Africa. Many exotic species were introduced with the arrival of the European settlers and their naturalisation was facilitated by the simultaneous intensification of agriculture and farming. Currently, these exotic species are locally very abundant and cause great impacts on the diversity and functioning of the invaded communities. We first investigated the assembly of exotic herbaceous species in their donor and recipient grassland communities in Spain and California, respectively. We found that exotic species were more abundant than other coexisting species in communities of both the donor and recipient regions (Chapter 1). The abundance of exotic species

Aim: Colonization of new areas may entail shifts in diversification rates linked to biogeographical movement (dispersification), which may involve niche evolution if species were not exapted to new environments. Scleria (Cyperaceae) includes c. 250 species and has a pantropical distribution suggesting an extraordinary capacity for long-distance dispersal and colonization. We investigate patterns of diversification in Scleria, and whether they are coupled with colonization events, climate niche shifts or both. Location: Tropics and subtropics. Taxon: Nutrushes Scleria (Cyperaceae). Methods: We used molecular data from three DNA regions sequenced for 278 accessions representing 140 Scleria taxa (53% of species) to develop a chronogram, model ancestral ranges and measure rates of diversification. Integrating data from 12,978 digitized and georeferenced herbarium records, we investigated niche evolution. Results: High dispersal rates in Scleria, a genus with multiple dispersal syndromes, make reconstruction of ancestral ranges at deep nodes in the phylogeny highly equivocal. Main dispersal and colonization events involve movements from South to Central America (c. 19), from Africa to Madagascar (c. 12), from Asia to Oceania (c. 7), from Africa to South America (c. 7) and Central America to South America (c. 6). The two main shifts in diversification rates happened during the warm period of the Miocene. Main conclusions: Dispersification from South America to Africa without climate niche shift seems to explain the diversification shift in section Hypoporum implying that species were exapted. Shifts in climate niche evolution predate the second shift in diversification rates suggesting lineages were exapted prior to biogeographical movements. Within subgenus Scleria, colonizations of Asia and Madagascar by sections Elatae and Abortivae, respectively, are coupled with niche shifts suggesting that these colonizations involved climate niche adaptation.

Functional segregation among species in a community depends on their mean trait values (i.e. functional distinctiveness), and the range of trait attributes exhibited by each species (i.e. functional diversity). Previous evidence suggests that invasive plants tend to display traits related to a more acquisitive resource-use strategy than natives. However, the contribution of intraspecific trait variation to functional diversity has received little attention in community ecology, and might provide interesting information about community processes. In this study, we used eight plant traits related to carbon and nutrient acquisition of coexisting dominant native and invasive plants in eight communities across the Mediterranean-climate biome to determine sources of functional segregation between native and invasive species. We found three major axes of functional variation, related to leaf economics, resource-use efficiency, and plant height. Invasive species across communities had leaf traits related to an acquisitive resource-use strategy in contrast to native species, whereas differences in the second and third axes were community dependent. Invasive species were more functionally diverse than native species across the dataset and in four out of the eight communities. Intraspecific variance accounted for 11%–27% of total trait variation and was on average greater in invasive species, and especially important in the axis related to resource use efficiency. These results, although dependent on the trait and community considered, offer interesting insights to the sources of functional trait diversity of native and invasive species within communities, indicating that intraspecific variation might not be equally distributed between native and invasive species.

Extensive research efforts are devoted to understand fine root trait variation and to confirm the existence of a belowground root economics spectrum (RES) from acquisitive to conservative root strategies that is analogous to the leaf economics spectrum (LES). The economics spectrum implies a trade-off between maximizing resource acquisition and productivity or maximizing resource conservation and longevity; however, this theoretical framework still remains controversial for roots. We compiled a database of 320 Mediterranean woody and herbaceous species to critically assess if the classic economics spectrum theory can be broadly extended to roots. Fine roots displayed a wide diversity of forms and properties in Mediterranean vegetation, resulting in a multidimensional trait space. The main trend of variation in this multidimensional root space is analogous to the main axis of LES, while the second trend of variation is partially determined by an anatomical trade-off between tissue density and diameter. Specific root area (SRA) is the main trait explaining species distribution along the RES, regardless of the selected traits. We advocate for the need to unify and standardize the criteria and approaches used within the economics framework between leaves and roots, for the sake of theoretical consistency

The introduction of exotic species to new regions offers opportunities to test fundamental questions in ecology, such as the context-dependency of community structure and assembly. Annual grasslands provide a model system of a major unidirectional introduction of plant species from Europe to North America. We compared the community structure of grasslands in two Mediterranean regions by surveying plots in Spain and in California with similar environmental and management conditions. All species found in Spanish grasslands were native to Spain, and over half of them (74 of 139 species) are known to have colonized California. In contrast, in California, over half of the species (52 of 95 species) were exotic species, all of them native to Spain. Nineteen species were found in multiple plots in both regions (i.e., shared species). The abundance of shared species in California was either similar to (13 species) or greater than (6 species) in Spain. In California, plants considered pests were more likely than non-pest species to have higher abundance. Co-occurring shared species tended to maintain their relative abundance in native and introduced communities, which indicates that pools of exotic species might assemble similarly at home and away. These findings provide interesting insights into community assembly in novel ecosystems. They also highlight an example of startling global and local floristic homogenization.

Functional segregation among species in a community depends on their mean trait values (i.e. functional distinctiveness), and the range of trait attributes exhibited by each species (i.e. functional diversity). Previous evidence suggests that invasive plants tend to display traits related to a more acquisitive resource-use strategy than natives. However, the contribution of intraspecific trait variation to functional diversity has received little attention in community ecology, and might provide interesting information about community processes. In this study, we used eight plant traits related to carbon and nutrient acquisition of coexisting dominant native and invasive plants in eight communities across the Mediterranean-climate biome to determine sources of functional segregation between native and invasive species. We found three major axes of functional variation, related to leaf economics, resource-use efficiency, and plant height. Invasive species across communities had leaf traits related to an acquisitive resource-use strategy in contrast to native species, whereas differences in the second and third axes were community dependent. Invasive species were more functionally diverse than native species across the dataset and in four out of the eight communities. Intraspecific variance accounted for 11%–27% of total trait variation and was on average greater in invasive species, and especially important in the axis related to resource use efficiency. These results, although dependent on the trait and community considered, offer interesting insights to the sources of functional trait diversity of native and invasive species within communities, indicating that intraspecific variation might not be equally distributed between native and invasive species.

Aim: Colonization of new areas may entail shifts in diversification rates linked to biogeographical movement (dispersification), which may involve niche evolution if species were not exapted to new environments. Scleria (Cyperaceae) includes c. 250 species and has a pantropical distribution suggesting an extraordinary capacity for long-distance dispersal and colonization. We investigate patterns of diversification in Scleria, and whether they are coupled with colonization events, climate niche shifts or both. Location: Tropics and subtropics. Taxon: Nutrushes Scleria (Cyperaceae). Methods: We used molecular data from three DNA regions sequenced for 278 accessions representing 140 Scleria taxa (53% of species) to develop a chronogram, model ancestral ranges and measure rates of diversification. Integrating data from 12,978 digitized and georeferenced herbarium records, we investigated niche evolution. Results: High dispersal rates in Scleria, a genus with multiple dispersal syndromes, make reconstruction of ancestral ranges at deep nodes in the phylogeny highly equivocal. Main dispersal and colonization events involve movements from South to Central America (c. 19), from Africa to Madagascar (c. 12), from Asia to Oceania (c. 7), from Africa to South America (c. 7) and Central America to South America (c. 6). The two main shifts in diversification rates happened during the warm period of the Miocene. Main conclusions: Dispersification from South America to Africa without climate niche shift seems to explain the diversification shift in section Hypoporum implying that species were exapted. Shifts in climate niche evolution predate the second shift in diversification rates suggesting lineages were exapted prior to biogeographical movements. Within subgenus Scleria, colonizations of Asia and Madagascar by sections Elatae and Abortivae, respectively, are coupled with niche shifts suggesting that these colonizations involved climate niche adaptation

The introduction of exotic species to new regions offers opportunities to test fundamental questions in ecology, such as the context-dependency of community structure and assembly. Annual grasslands provide a model system of a major unidirectional introduction of plant species from EuropetoNorthAmerica. WecomparedthecommunitystructureofgrasslandsintwoMediterranean regions by surveying plots in Spain and in California with similar environmental and management conditions. AllspeciesfoundinSpanishgrasslandswerenativetoSpain,andoverhalfofthem(74of 139species)areknowntohavecolonizedCalifornia. Incontrast,inCalifornia,overhalfofthespecies (52 of 95 species) were exotic species, all of them native to Spain. Nineteen species were found in multiple plots in both regions (i.e., shared species). The abundance of shared species in California was either similar to (13 species) or greater than (6 species) in Spain. In California, plants considered pests were more likely than non-pest species to have higher abundance. Co-occurring shared species tended to maintain their relative abundance in native and introduced communities, which indicates that pools of exotic species might assemble similarly at home and away. These findings provide interestinginsightsintocommunityassemblyinnovelecosystems. Theyalsohighlightanexampleof startling global and local floristic homogenization

Introduction to the flora of Valle de Valdebezana (Burgos, Spain). This article presents an introduction to the flora of Valdebezana forests. The checklist includes 327 species and 741 citations, which corresponds to 218 genera and 73 families. 299 citations were retrieved from previous references, and 442 are newly described. The fieldwork was performed during March, April and May of 2014 and consisted of different vegetation surveys from 28 plots across different forests in the valley. We cite 148 species for the first time in this region, and present new citations for another 92., El presente trabajo es una primera aproximación a la flora de los bosques del valle de Valdebezana (Las Merindades, Burgos). Incluye 741 citas y 327 especies, agrupadas en 218 géneros y 73 familias. Más de la mitad de las citas, hasta 442, corresponden a muestreos realizados en primavera y verano de 2014, mientras que 299 se han recuperado de la bibliografía. Hasta 148 taxones se citan por primera vez en los bosques de Valdebezana, y se incluyen citas nuevas para otros 92 taxones.

A taxonomic revision of the genus Scleria (Cyperoideae, Cyperaceae) in Madagascar is presented, supported by a phylogeny based on the markers ndhF, rps16 and ITS. Collections from K, P and MO have been examined and 424 specimens identified to species level. Our results recognise 25 species of Scleria from Madagascar, including two varieties: six endemics, one near endemic, 10 African species and eight tropical widespread taxa. Scleria achtenii is reported for the first time in Madagascar and S. rosea is taken out of synonym of S. trialata. Distribution maps, preliminary conservation assessments, and notes on synonymy, ecology and ethnobotany are provided. Nine species have been typified. Three rare endemic species: S. andringitrensis, S. madagascariensis and S. perpusilla, are assessed as threatened. The most diverse sections: Abortivae and Hypoporum, which include 13 species in total and 52% of the vouchers examined, showed strong differences in habitat preference

[EN] Introduction: Functional trait-based approaches are extensively applied to the study of mechanisms governing community assembly along environmental gradients. These approaches have been classically based on studying differences in mean values among species, but there is increasing recognition that alternative metrics of trait distributions should be considered to decipher the mechanisms determining community assembly and species coexistence. Under this framework, the main aim of this study is to unravel the effects of environmental conditions as drivers of plant community assembly in sub- Mediterranean ecotones. Methods: We set 60 plots in six plant communities of a sub-Mediterranean forest in Central Spain, and measured key above- and belowground functional traits in 411 individuals belonging to 19 species, along with abiotic variables. We calculated community-weighted mean (CWM), skewness (CWS) and kurtosis (CWK) of three plant dimensions, and used maximum likelihood techniques to analyze how variation in these functional community traits was driven by abiotic factors. Additionally, we estimated the relative contribution of intraspecific trait variability and species turnover to variation in CWM. Results and discussion: The first three axes of variation of the principal component analyses were related to three main plant ecological dimensions: Leaf Economics Spectrum, Root Economics Spectrum and plant hydraulic architecture, respectively. Type of community was the most important factor determining differences in the functional structure among communities, as compared to the role of abiotic variables. We found strong differences among communities in their CWMs in line with their biogeographic origin (Eurosiberian vs Mediterranean), while differences in CWS and CWK indicate different trends in the functional structure among communities and the coexistence of different functional strategies, respectively. Moreover, changes in functional composition were primaril

[EN] Background and aims Submediterranean areas are rich ecotones, where slight modifications in environmental conditions can lead to substantial changes in the composition of plant communities. They thus offer an ideal scenario to examine plant community assembly. In this study, we followed a trait-based approach including intraspecific variability to elucidate (1) the relationship between niche occupancy components and species richness, (2) the processes governing the assembly of these communities, and (3) the contribution of intraspecific trait variability in shaping the functional trait space. Methods We measured eight morphological and chemical traits in 405 individuals across 60 plots located in different forest communities (Mediterranean, Eurosiberian and Mixed) coexisting within a submediterranean ecosystem in central Spain. We calculated three niche occupancy components related to Hutchinson’s n-dimensional hypervolumes: the total functional volume of the community, the functional overlap between species within the community and the average functional volume per species, and then used null models to explore the relative importance of habitat filtering, limiting similarity and intraspecific variability as assembly patterns. Key Results Both habitat filtering and niche differentiation drive the community assembly of Mediterranean communities, whereas limiting similarity and hierarchical competition shape Eurosiberian communities. Intraspecific responses were mostly explained by shifts in species’ niches across functional space (changes in the position of the centroids of hypervolumes). Conclusions Different assembly mechanisms govern the structure of Mediterranean, Eurosiberian and Mixed plant communities. Combining niche occupancy components with a null model approach at different spatial scales offers new insights into the mechanisms driving plant community assembly. Considering intraspecific variability is indispensable for understanding the mechanisms gov

[EN] A major aim in invasion ecology is to understand the role of exotic species in plant communities. Whereas most studies have explored the traits of exotic species in the context of the introduced community, functional comparisons of entire assemblages of species in their native and introduced communities have rarely been analysed. Taking advantage of the unidirectional invasion of plant species of European origin (i.e. colonizers) into California, this study aims to investigate the relative importance of plant traits, environmental factors and invasion status in biological invasions. We compared the functional structure (i.e. trait composition and diversity) along resource availability gradients in recipient and native Mediterranean grassland communities in California and Spain, respectively. Traits were related to resource use in above-ground and below-ground organs and reproductive strategy. We also investigated how niche differences vary along environmental gradients between coexisting colonizer and native species assemblages within communities. There were clear differences in the functional structure of Mediterranean grassland communities between regions, which were associated with the resource availability gradient. Paradoxically, the most acquisitive communities occurred in resource-poor sites, highlighting that rapid acquisition and use of resources permit species to cope with environmental stress through stress avoidance. In Spain, colonizer species had greater specific leaf area than non-colonizers. Yet, differences between colonizer and non-colonizer species in Spain for other traits were mostly absent and did not change along the gradient. This might be a result of the greater native species richness as a consequence of the agricultural practices that have taken place in Europe for millennia and reflect that the entire species pool of grasslands is adapted to agricultural landscapes. In comparison, in California, colonizer species were more acquisitiv

[EN] Extensive research efforts are devoted to understand fine root trait variation and to confirm the existence of a belowground root economics spectrum (RES) from acquisitive to conservative root strategies that is analogous to the leaf economics spectrum (LES). The economics spectrum implies a trade-off between maximizing resource acquisition and productivity or maximizing resource conservation and longevity; however, this theoretical framework still remains controversial for roots. We compiled a database of 320 Mediterranean woody and herbaceous species to critically assess if the classic economics spectrum theory can be broadly extended to roots. Fine roots displayed a wide diversity of forms and properties in Mediterranean vegetation, resulting in a multidimensional trait space. The main trend of variation in this multidimensional root space is analogous to the main axis of LES, while the second trend of variation is partially determined by an anatomical trade-off between tissue density and diameter. Specific root area (SRA) is the main trait explaining species distribution along the RES, regardless of the selected traits. We advocate for the need to unify and standardize the criteria and approaches used within the economics framework between leaves and roots, for the sake of theoretical consistency.