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20 páginas.- 1 figura.- 105 referencias, Alien plant species have been essential for farming and agro-forestry systems and for their supply of food, fiber, tannins, resins or wood from antiquity to the present. They also contributed to supporting functions and regulating services (water, soil, biodiversity) and to the design of landscapes with high cultural and scenic value. Some of those species were intentionally introduced, others arrived accidentally, and a small proportion escaped, naturalized and became invasive in natural ecosystems—these are known as invasive alien species (IAS). Here, invasive means that these species have some significant negative impact, either by spreading from human-controlled environments (e.g. fields, gardens) to natural ecosystems, where they can cause problems to native species, or to other production systems or urban areas, impacting on agricultural, forestry activities or human health. Socio-environmental impacts associated with plant invasions have been increasingly recognized worldwide and are expected to increase considerably under changing climate or land use. Early detection tools are key to anticipate IAS and to prevent and control their impacts. In this chapter, we focus on crop and non-crop alien plant species for which there is evidence or prediction of invasive behaviour and impacts. We provide insights on their history, patterns, risks, early detection, forecasting and management under climate change. Specifically, we start by providing a general overview on the history of alien plant species in agricultural and agroforestry systems worldwide (Sect. 1). Then, we assess patterns, risks and impacts resulting from alien plants originally cultivated and that became invasive outside cultivation areas (Sect. 2). Afterwards, we provide several considerations for managing the spread of invasive plant species in the landscape (Sect. 3). Finally, we discuss challenges of alien plant invasions for agricultural and agroforest systems, in the light of climate change (Sect. 4). © 2019, Springer Nature Switzerland AG., Joana R. Vicente was supported by POPH/FSE and FCT (Post-Doc grant SFRH/BPD/84044/2012). Ana Sofia Vaz was supported by FSE/MEC and FCT (Ph.D. grant PD/BD/52600/2014). Ana Isabel Queiroz supported by FCT—the Portuguese Foundation for Science and Technology [UID/HIS/04209/2013 and IF/00222/2013/CP1166/CT0001]. This work received financial support from the European Union (FEDER funds POCI-01-0145-FEDER-006821) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/BIA/50027/2013.

6 páginas.-- 50 referencia.-- This article is Free access in the https://doi.org/10.1111/1365-2745.13040, The quest for understanding the maintenance of species diversity has matured in recent decades under the umbrella of species coexistence theory, founded by Chesson (2000). The central conclusion of the theory is that coexistence at local scales depends on two opposing forces: average fitness differences between species, which drive the best-adapted species to exclude others, and stabilizing mechanisms, which promote diversity via niche differentiation. Recent theoretical work has focussed on how interactions between plants and other organisms influence the equalizing and stabilizing forces. However, there is a lack of empirical information. Therefore, the next fundamental step is to assess the prevalence of these mechanisms for controlling plant coexistence across a wide range of interactions and systems. To that end, this special feature presents 10 theoretical, observational, or manipulative studies illustrating 9 different biotic interactions including mutualisms (pollinators, seed dispersers, soil microbes, and arbuscular mycorrhizal fungi) and antagonisms (leaf and seed herbivores, and leaf and root pathogens). All studies share a common question: how biotic interactions regulate plant coexistence? Comparisons across studies suggest that biotic interactions modify both stabilizing and average fitness differences. In those cases where biotic interactions promote stable coexistence between plant species, both mutualistic and antagonistic interactions act more frequently as an equalizing rather than as a stabilizing mechanisms. Besides these generalities, the studies of this special issue also present novel theoretical and empirical approaches to better understand the maintenance of species diversity over a wide variety of systems, environmental conditions, and organisms. Synthesis. The studies presented here constitutes a solid base to empirically explore how mutualistic and antagonistic interactions act upon the determinants of plant species competition, and open novel paths for future research. Collectively, these advances will serve to pave the road for a better theoretical and empirical understanding of how biotic interactions control biodiversity, We thank James Ross and Mark Rees for a swift editorial assistance. Ideas were develop edunderhe Lincx project (CGL2014‐61590‐EXP). O.G. acknowledges postdoctoral financial support provided by the European Union Horizon research and innovation program under the Marie Sklodowska‐Curie grant agreement no 661118‐BioFUNC.

13 páginas.-- 5 figuras.-- 1 tabla.-- 53 referencias.-- Additional supporting information may be found online in the Supporting Information section at the end of the article. https://doi.org/10.1111/1365-2745.13028, Competition–defence trade-offs have long been thought to promote plant coexistence and increase species diversity. However, insights from modern coexistence theory clarify that such trade-offs alone cannot sustain coexistence. Coexistence also requires stabilising niche differences and the ability of competitor populations to persist under consumer pressure. Despite the breadth of potential consequences of competition–defence trade-offs, we have little mechanistic understanding of how they affect diversity in natural communities. We investigated the effects of seed harvesting by ants on coexistence in an annual plant community. We parameterised a model of plant competitive population dynamics with data from two field experiments: (a) plant demographic rates and competition coefficients determined by growing plants alone and against intra- and interspecific competitor density gradients; (b) plant fitness losses to ant consumers determined by measuring seed removal from experimental depots. We tested for a trade-off between a plant species’ demographic potential and its susceptibility to consumption and then determined the bounds of ant effects on pairwise and multispecies coexistence by comparing model projections with and without seed consumption. Ants harvested seeds of all plant species, but they strongly preferred the competitively superior large seeded species, inducing a competition–defence trade-off. Unequal seed loss to ants changed competition-based fitness hierarchies, affecting both the number and identities of plant species pairs that were predicted to coexist compared to a scenario without ants. The trade-off most often prevented coexistence by severely disadvantaging the superior competitor or excluding species directly through overconsumption, and a simulated reduction in the overall consumption rate opened few additional opportunities for coexistence. Ant exacerbation of average fitness differences was particularly disruptive to multispecies coexistence, where niche differences were insufficient to stabilise the coexistence of plant triplets and quadruplets. Synthesis. Our results show that the presence of a competition–defence trade-off in a community with stabilising niche differences does not always increase diversity. Instead, the full range of diversity outcomes—positive and negative changes in species number and changes in the identity of the dominant—are possible. Taken together, our results support the emerging paradigm that consumers have wide-ranging impacts on plant diversity and suggest that variation in consumer pressure may be an important driver of large-scale diversity patterns, H2020 Marie Skłodowska‐Curie Actions, Grant/Award Number: 661118‐BioFUNC; National Science Foundation, Division of Environmental Biology, Grant/Award Number: 1644641

12 páginas.-- 3 figuras.-- 1 tabla.-- 58 referencias.-- Special Feature: Intransitive competition and species coexistence.-- Data available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.5d1s9 (Matías, Godoy, Gómez-Aparicio, & Pérez-Ramos, 2018)., El artículo esta en libre acceso en la revista.-- free access article in this review, Very little is known about how variation in environmental conditions alters the strength and the structure of competitive networks and what are the consequences of this for species coexistence. We performed a competition experiment with 10 annual plant species to parameterise a population model describing species’ dynamics according to their vital rates and pairwise competitive coefficients. Seeds from all species were sown under two different climatic scenarios: (1) right before the first major storm of the growing season and (2) after an imposed fall drought of 2 months simulating an extreme climatic event of intense aridity. Species’ demography and competitive responses were used to estimate pairwise stabilising niche differences and average fitness differences. In addition, we used tools from network theory to characterise the structure of multispecies competition from the determinants of species coexistence. Specifically, we evaluated changes in competitive dominance between species pairs, and the prevalence of intransitive competitive relationships for 120 triplets between these two climatic events. The experimental extreme event significantly reduced fitness differences between species pairs. Such an equalising mechanism promotes coexistence. However, niche differences were also reduced in such a way that the number of species pairs whose niche differences overcame their fitness differences was reduced from six to two. Contrary to our expectations, the extreme event did not increase the hierarchy of competitive dominance. Instead, and depending on the technique used, the prevalence of intransitivity remained marginally similar (17% to 22%) or significantly increased from 19.4% to 29.8%. This pattern was likely a consequence of the significant changes in competitive dominance between species pairs (26 changes out of 45; 58%). Although fitness differences were equalised and intransitive competition promoted, our model predicted a lower likelihood of coexistence under the extreme event for both species pairs and triplets, mainly because competitive interactions did not promote enough niche differences to balance the observed fitness asymmetries in our competitive networks. Synthesis. We empirically proved that an extreme climate results in communities with reduced niche and fitness differences in which species are less likely to coexist despite the increasing prevalence of intransitive competition., Was funded by a Juan de la Cierva grant (FPDI-2013-15867). O.G. acknowledges postdoctoral financial support provided by the Spanish Ministry for Education and Science (Juan de la Cierva, JCI-2012-12061), and by the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 661118-BioFUNC. Funding support to conduct the experiment was provided by the Spanish Ecological Terrestrial Society (AEET, Jóvenes Investigadores grant 2014/2). L.G.-A. acknowledges support from the MICINN project INTERCAPA (CGL-2014-56739-R) and European FEDER Funds. I.M.P.-R thanks the funding provided by the Ramón & Cajal Research Programme (RYC-2013-13937) and the Spanish MINECO project DECAFUN (CGL2015-70123-R).

16 páginas.-- 5 figuras.-- 1 tablas.-- 56 referencias.-- This article belongs to the Special Issue "Ecology and Management of Invasive Species in Forest Ecosystems"., There is growing recognition of the importance of soil fauna for modulating nutrient cycling processes such as litter decomposition. However, little is known about the drivers promoting changes in soil fauna abundance on a local scale. We explored this gap of knowledge in a mixed oak forest of Southern Spain, which is under decline due to the invasion of the exotic soil-borne pathogen Phytophthora cinnamomi. Meso-invertebrate abundance found in soil litter was estimated at the suborder level. We then explored their statistical correlations with respect to light availability, tree and litter characteristics, and P. cinnamomi abundance. Oribatida and Entomobryomporpha were the most abundant groups of Acari and Collembola, respectively. According to their trophic level, predator and detritivore abundances were positively correlated while detritivores were, in turn, positively correlated with pathogen abundance and negatively influenced by light availability and tree defoliation. These overall trends differed between groups. Among detritivores, Diplopoda preferred highly decomposed litter while Oribatida and Psocoptera preferred darker environments and Poduromorpha were selected for environments with lower tree defoliation. Our results show the predominant role of light availability in influencing litter fauna abundances at local scales and suggest that the invasive soil-borne pathogen P. cinnamomi is integrated in these complex relationships., O.G. acknowledges postdoctoral financial support provided by the European Union Horizon research and innovation program under the Marie Sklodowska-Curie grant agreement No 661118-BioFUNC. O. G. also thanks research support from the Spanish Ministry of Economy and Competitiveness through the IMPLANTIN project (CGL2015-65346-R). L.G.A. acknowledges support from the MICINN project INTERCAPA (CGL-2014-56739-R).

We thank A.J. Muñoz‐Pajares, L. Rodríguez and G. Rutten for their help and logistic support during field sampling and M.E. Sánchez, M. Serrano and M.A. Romero for pathogen analyses and interest‐ ing discussions., Data will be available from the Dryad Digital Repository upon acceptance., Aim: Impacts of different global change drivers are altering the performance of plant species worldwide. However, these pressures usually differ across the species’ distri‐ bution range. To properly assess the combined effect of global change at species level, we need to evaluate its consequences across their complete distribution. We focused on recent decline in Cork oak (Quercus suber L.) populations given its high ecological and economic relevance. Location: We selected 10 different sites (and two populations per site) separated about one degree in latitude across the core distribution of Q. suber, following a transcontinental aridity gradient. Methods: To evaluate the current trends in population dynamics across the species’ distribution and the factors implied on population decline, we evaluated the effect of latitude, aridity, pathogens (Phytophthora cinnamomi), stand density and tree size on seed and crop size, demographic structure, dominance of recruitment bank, defolia‐ tion and mortality. Results: We found an increase in seed weight as latitude decreased, with a homogene‐ ous low crop size across the complete distribution. Demographic structure was deter‐ mined by latitude, precipitation and pathogen abundance. We detected a trend towards reduced sapling densities towards the southern edge of the distribution, with a demo‐ graphic structure dominated by old trees. The low sapling density at the southern edge translates into a loss of dominance with respect to other woody species, suggesting an alteration of community structure in the mid‐term future. Tree density, precipitation and pathogen abundance determined tree mortality across the species distribution, with a higher abundance of pathogens in central‐latitude populations. Main conclusions: Our results allow the early detection of declining trends and the evaluation of the main risks for species’ conservation, suggesting potential for range displacement of the species driven by the recruitment failure at the southern edge of the distribution and a likely range expansion at northern populations., This research was funded by the Large Research Grant (6007210) awarded from the British Ecological Society to L.M. L.G.A. acknowledges support from the MICINN project INTERCAPA (CGL‐2014‐56739‐R) and European FEDER Funds