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Comunicación oral presentada en BES Annual Meeting 2018 16-19 December 2018, Birmingham UK

Comunicación oral presentada en the XIV MEDECOS & XIII AEET meeting, Seville, Spain, 31st January - 4th February 2017, Ecologists have argued for decades that exist a parallelism between the mechanisms determining species diversity and those driving functioning in a community: stabilizing niche differences underlies the positive complementary effects of diversity on community function, and differences in species’ fitness are related to differences in species’ selection effects. However, recent theoretical advances suggest that this parallelism does not occur, instead, complementarity effects results from the interaction of niche and fitness differences and the same is true for selection effects. We empirically tested these novel predictions by coupling a competition experiment to a diversity-multifunctioning experiment with ten annual plant species. We additionally included an extreme drought treatment to explore how abiotic conditions changes these relationships. We clearly found that more diverse communities produced more biomass, litter was decomposed faster, and soil nutrients were more abundant. Moreover, drought reduced this overall functioning as well as niche and fitness differences between species. Could we then establish that this reduction in multifunctionality was caused by lower niche and fitness differences between species? The answer is no as results revealed a diverse range of relationships. For biomass and soil nutrients, complementarity effects between species pairs were explained only by niche differences and differences in selection effects only by fitness differences, supporting the classical parallelism. For litter decomposition, only complementarity effects were explained by the interaction of niche and fitness differences, partly supporting the novel predictions. Our results suggest that common linkages between the species’ differences modulating diversity and functioning across multiple functions do not occur, This meeting is co-organized and supported by the Spanish Association for Terrestrial Ecology (AEET), the Doñana Biological Station (EBD-CSIC) and the University of Seville (US)

The increase of species richness with area is a universal phenomenon on Earth. However, this observation contrasts with our poor understanding of how these species-area relationships (SARs) emerge from the collective effects of area, spatial heterogeneity, and local interactions. By combining a structuralist approach with five years of empirical observations in a highly-diverse Mediterranean grassland, we show that spatial heterogeneity plays a little role in the accumulation of species richness with area in our system. Instead, as we increase the sampled area more species combinations are realized, and they coexist mainly due to direct pairwise interactions rather than by changes in single-species dominance or by indirect interactions. We also identify a small set of transient species with small population sizes that are consistently found across spatial scales. These findings empirically support the importance of the architecture of species interactions together with stochastic events for driving coexistence- and species-area relationships, MINECO (RYC-2017-23666) RTI2018-098888-A-I00, MICINN (RTI2018-098888-A-I00)

8 páginas.- 5 figuras.- 2 tablas.- 60 referencias, Climate change and exotic pests and pathogens are causing alarming forest declines worldwide. However, we still lack a comprehensive understanding of how damage caused by exotic pests and pathogens might vary under the different scenarios of water availability imposed by a changing climate, particularly in water-limited forests as those that occupy Mediterranean areas. In this paper we aimed to experimentally analyse the interactive effects of the aggressive exotic pathogen Phytophthora cinnamomi and climate change-related reductions in soil moisture on seedling performance of the Mediterranean host Quercus suber. We conducted a full-factorial greenhouse experiment where the physiology and growth of Q. suber seedlings was measured in soils with different combinations of P. cinnamomi inoculum density (0, 30, 60 and 120 colony forming units per gram of dry soil) and soil moisture (15%, 40%, 50% and 100% soil water holding capacity) simulating different invasion and climate change scenarios. We found additive effects of P. cinnamomi and drought on Q. suber performance aboveground, although these effects were not always negative. In fact, seedlings showed a compensatory physiological response to P. cinnamomi infection by increasing their net photosynthetic rates. Our results also supported important interactive effects of pathogens and soil moisture on belowground performance. Thus, the inoculum density in the soil required to cause significant root damage in experimental seedlings decreased as soil moisture increased. From a climate change perspective, these results suggest that an average drier climate might imply sub-optimal conditions for P. cinnamomi infections allowing for a slower advance of the disease in invaded areas. However, this effect will be modulated by the also predicted more frequent extreme climatic events. A higher frequency of extreme rain events that saturate the soil might be particularly beneficial for P. cinnamomi, boosting its soil density beyond any possible response capacity of susceptible hosts. © 2019, This study was funded by the MICINN project INTERCAPA ( CGL2014-56739-R ). P.H. was supported by a FPI-MICINN grant, L.M. by an “Acción 6 UJA” fellowship (EI_RNM4_2017), O.G. by a Marie Sklodowska-Curie grant agreement ( No 661118-BioFUNC ), and I.M.P.R by a “Ramón & Cajal” contract ( RYC-2013-13937 ).

10 páginas.- 6 figuras.- 1 tabla.- 60 referencias.- Supplementary material related to this article can be found, in the online version, at doi:https://doi.org/10.1016/j.envexpbot.2019.103852.- This article is part of a special issue entitled “The climatic challenge: learning from past survivors and present outliers”., Understanding why co-occurring plant species show differential phenological sensitivities to climate fluctuations, and more specifically to the joint variation in temperature and precipitation, is critical to make accurate predictions on how climate change could alter community dynamics and ecosystem functioning. However, the role that some relevant functional traits involved in resource uptake and/or stress tolerance could play on these inter-specific differences in phenological sensitivity remains largely unknown. In this study we evaluated experimentally how five co-occurring herbaceous species with contrasting functional strategies respond to current and ongoing climatic scenarios of increased temperature, decreased water availability and both abiotic changes acting interactively. To decompose the direct effect of climate change and the indirect effect of neighbors on plant performance and reproductive phenology, each of the five species was exposed to a density gradient of competitor species. Although the study species were more sensitive to changes in temperature than in water availability, the combined effect of both abiotic cues triggered very heterogeneous responses. Species with higher SLA values were particularly sensitive to climate change, delaying their reproduction and lengthening their flowering period under warmer scenarios while maintaining a high plant growth rate. In contrast, the species with the lowest SLA values exhibited less phenological variability to climate alterations, but they were more strongly affected by neighbor density compared to species with opposite trait values. These species-specific responses to climatic shifts altered the synchrony of phenological events at the community level. The most important changes appeared under the two scenarios of increased temperature, where 4 out of 5 species overlapped their flowering periods. Our findings indicate that the ongoing scenarios of increasing temperature and aridity could disrupt the phenological asynchrony within communities, and highlight the necessity of considering the interactive effects of temperature and precipitation to obtain an overall picture of climate change predictions on plant phenology and population dynamics., This study was entirely funded by the MICINN project DECAFUN (CGL2015-70123-R). I.M.P.R was funded by a “Ramón and Cajal” contract (RYC-2013-13937) and LM by a Plan 6-UJA fellowship (EI_RNM4_2017).

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.

31 páginas.-- 7 figuras.-- 33 referencias.-- 6 Apéndices, Much of the recent work on species coexistence is based on studying per-capita growth rates of species when rare (invasion growth rates) in deterministic models where populations have continuous densities and extinction only occurs as densities approach zero over an infinite time horizon. In nature, extinctions occur in finite time and rarity corresponds to small, discrete populations whose dynamics are not well approximated by deterministic models. To understand whether the biological significance of these discrepancies, we parameterized a stochastic counterpart of a classical deterministic model of competition using data from annual plants competing on serpentine soils. While the minimum of the invasion growth rates explained up to 60% of the variation in the predicted coexistence times, species pairs with similar invasion growth rates had coexistence times that differed by several orders of magnitude. By integrating the deterministic invasion growth rates and coexistence equilibrium population sizes, a simplified stochastic model explained over 99% of the variation in the coexistence times. This simplified model corresponds to uncoupled single species models whose parameters are determined from the two species model. This simplified model shows that coexistence times are approximately one-half of the harmonic mean of these single species’ persistence times. Furthermore, coexistence times increase and saturate with invasion growth rates, but increase exponentially with equilibrium population sizes. When the minimum of the invasion growth rate is sufficiently greater than one, coexistence times of 1, 000 years occur even when the inferior species has < 50 individuals at the deterministic coexistence equilibrium. When the fitness inferior has the lower equilibrium population size (which occurs for 6 out of 8 of the deterministically coexisting pairs), niche overlap and fitness differences negatively impact coexistence times, which is consistent with the deterministic theory. However, when the fitness inferior has the higher equilibrium population size (2 species pairs), coexistence times can exhibit a humped shaped relationship with fitness differences–increasing and then decreasing with fitness differences. Collectively our results support the use of deterministic theory to infer the controls over coexistence in finite systems, while also highlighting when ecologists must look beyond invasion growth rates and consider species equilibrium population sizes

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

5 figuras.- 1 tabla.- This article is in Press, Journal Pre-proof, Climate change is a fundamental process affecting terrestrial ecosystems. However, there is relatively little knowledge about its impacts on soil communities, with a large degree of uncertainty regarding their resistance to predicted alterations in temperature and, particularly, precipitation. Moreover, most studies exploring the response of soil biota to predicted rainfall reduction have focused on mesic environments and soil microbes, which limit our ability to find general patterns across ecosystems and soil organisms. In this study, we analysed the impact of predicted climate change scenarios of rainfall reduction on soil food webs of Mediterranean water-limited forests using nematodes as bioindicators. We took advantage of replicated rainfall exclusion infrastructures (30% exclusion) established in Quercus forests of southern Spain in 2016 (2-year exclusion) and of southern France in 2003 (15-year exclusion) to explore the sensitivity of the soil food web to predicted reductions at short- and long-term scales. Rainfall reduction had large negative short-term effects on nematode abundance, particularly of lower trophic groups (bacterivores and fungivores). Rainfall reduction had also consistent short- and long-term impacts on community composition (decrease of fungivores, marginal increase of omnivores) and nematode-based indicators of soil food web structure (higher maturity and structure index, lower prey:predator ratio). These results can be considered indicative of a low resistance of the soil food web to rainfall reductions predicted by climate change. Overall, our findings demonstrate the sensitivity of water-limited forests to further reductions in soil water availability, which might substantially alter their soil communities and likely affect the many ecosystem processes that they control., This study was funded by the MICINN projects INTERCAPA (CGL2014-56739-R) and MICROFUN (RTI2018-094394-B-I00). P.H. was supported by a FPI-MICINN grant. L.M. was supported by the fellowship IV2 from VI-PPIT (Univ. Sevilla) and the project PID2019-108288RA-I00 (MINECO). OG acknowledges financial support provided by the Spanish Ministry of Economy and Competitiveness (MINECO) and by the European Social Fund through the Ramón y Cajal Program (RYC-2017-23666). Puéchabon is supported by the OSU OREME (UMS 3282) and the French national research infrastructure ANAEE-France (ANR-11-INBS-0001).