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MS-M was supported by the Spanish Ministry of Science and Innovation (FPU predoctoral grant and the project PROPIFEN PGC2018-101773-B-I00). MM acknowledges a grant from the Swiss National Science Foundation (project n.175101) and funding from the Canada Research Chairs Program. PS was funded by the project "Ecologia Funcional de los Bosques Andaluces y Predicciones Sobre Sus Cambios Futuros" (ForChange) (UCO-27943) by Junta de Andalucia (Spain), the project "Funcionalidad y servicios ecosistemicos de los bosques andaluces y normarroquies: relaciones con la diversidad vegetal y edafica ante el cambio climatico" by "Ayudas a la I CD del Plan Andaluz de Investigacion, Desarrollo e Innovacion (PAIDI) 2020," Junta de Andalucia (Spain) and European FEDER funds. JQ and RN-C were funded by the project ESPECTRAMED (CGL2018-86161-R) from Spanish Research Agency, Ministry of Science and Innovation. RN-C was funded by the projects ISOPINE (UCO-1265298) and SilvAdpat Network RED2018-102719., We acknowledge the E-OBS dataset from the EU-FP6 project UERRA (http://www.uerra.eu) and the Copernicus Climate Change Service, and the data providers in the ECA&D project (https://www.ecad.eu). We thank Robert Scheller, Brian Miranda, Rafael Villar, and Núria Aquilué for useful insights on project conceptualization during the initial steps of this work. We also thank two reviewers for the comments and suggestions made to earlier versions of this manuscript., The use of spatially interactive forest landscape models has increased in recent years. These models are valuable tools to assess our knowledge about the functioning and provisioning of ecosystems as well as essential allies when predicting future changes. However, developing the necessary inputs and preparing them for research studies require substantial initial investments in terms of time. Although model initialization and calibration often take the largest amount of modelers' efforts, such processes are rarely reported thoroughly in application studies. Our study documents the process of calibrating and setting up an ecophysiologically based forest landscape model (LANDIS-II with PnET-Succession) in a biogeographical region where such a model has never been applied to date (southwestern Mediterranean mountains in Europe). We describe the methodological process necessary to produce the required spatial inputs expressing initial vegetation and site conditions. We test model behaviour on single-cell simulations and calibrate species parameters using local biomass estimations and literature information. Finally, we test how different initialization data-with and without shrub communities-influence the simulation of forest dynamics by applying the calibrated model at landscape level. Combination of plot-level data with vegetation maps allowed us to generate a detailed map of initial tree and shrub communities. Single-cell simulations revealed that the model was able to reproduce realistic biomass estimates and competitive effects for different forest types included in the landscape, as well as plausible monthly growth patterns of species growing in Mediterranean mountains. Our results highlight the importance of considering shrub communities in forest landscape models, as they influence the temporal dynamics of tree species. Besides, our results show that, in the absence of natural disturbances, harvesting or climate change, landscape-level simulations projected a general increase of biomass of several species over the next decades but with distinct spatio-temporal patterns due to competitive effects and landscape heterogeneity. Providing a step-by-step workflow to initialize and calibrate a forest landscape model, our study encourages new users to use such tools in forestry and climate change applications. Thus, we advocate for documenting initialization processes in a transparent and reproducible manner in forest landscape modelling., Spanish Government PROPIFEN PGC2018-101773-B-I00, Swiss National Science Foundation (SNSF) European Commission 175101, Canada Research Chairs, Junta de Andalucia European Commission UCO-27943, project "Funcionalidad y servicios ecosistemicos de los bosques andaluces y normarroquies: relaciones con la diversidad vegetal y edafica ante el cambio climatico" by "Ayudas a la I CD del Plan Andaluz de Investigacion, Desarrollo e Innovacion (PAIDI) 2020, European Commission, project ESPECTRAMED from Spanish Research Agency, Ministry of Science and Innovation CGL2018-86161-R, project ISOPINE UCO-1265298, Project SilvAdpat Network RED2018-102719, Spanish Ministry of Science and Innovation (FPU predoctoral grant)

Phytophthora root rot is considered one of the main factors associated with holm oak (Quercus ilex L.) mortality. The effectiveness and accuracy of soilborne pathogen and management could be influenced by soil spatial heterogeneity. This factor is of special relevance in many afforestation of southwestern Spain, which were carried out without phytosanitary control of the nursery seedlings. We selected a study area located in a 15 year-old afforestation of Q. ilex, known to be infested by Phytophthora cinnamomi Rands. Soil samples (ntotal = 132) were taken systematically from a grid under 4 trees, and analysed to quantify 12 variables, the colony forming units (cfu) of P. cinnamomi plus 11 physical and chemical soil properties. The combined analysis of all variables was performed with linear mixed models (GLMM), and the spatial patterns of cfu were characterised using an aggregation index (Ia) and a clustering index (&nu, ) by SADIE. Cfu values ranged from 0 to 211 cfu g&minus, 1, and the GLMM built with the variables silt, P, K and soil moisture explained the cfu distribution to the greatest extent. The spatial analysis showed that 9 of the 12 variables presented spatial aggregation (Ia &gt, 1), and the clustering of local patches (&nu, i&ge, 1.5) for organic matter, silt, and Ca. The spatial patterns of the P. cinnamomi cfu under planted holm oak trees are related to edaphic variables and canopy cover. Small-scale spatial analysis of microsite variability can predict which areas surrounding trees can influence lower oomycetes cfu availability.

14 páginas.-- 5 figuras.-- 2 tablas.-- 83 referencias.-- Electronic supplementary material The online version of this article https://doi.org/10.1007/s00468-017-1646-z) contains supplementary material, which is available to authorized users, Key message This study reinforces the existence of the leaf economics spectrum in Mediterranean woody species, and demonstrates the strong influence of phylogeny, leaf habit and environmental context as main drivers of variability in structural and nutrient traits of leaves. Abstract Leaf structural and nutrient traits are key attributes of plant ecological strategies, as these traits are related to resource-use strategies and plant growth. However, leaf structure and nutrient composition can vary among different habitats, leaf habits or phylogenetic groups. In this study, we measured 13 leaf traits (one structural—leaf mass per area, LMA—and 12 nutrient traits) in 98 Mediterranean woody species growing over a wide range of environmental conditions, with the final aim of discerning the main causes of leaf trait variability. The variance decomposition results show that phylogeny, leaf habit and habitat type affected in several ways the structural and nutrient traits studied. Leaf nutrient concentrations are strongly positively correlated amongst themselves, and negatively correlated with LMA, in accordance with the “leaf economics spectrum”. We found that leaf habit and phylogeny were important causes of variation in LMA and in a broad number of leaf nutrients (i.e., C, N, Mg, S, K), while other micronutrients seemed to be more dependent on the environment (i.e., Cu and Mn). In summary, our study reinforces the existence of the leaf economics spectrum in a broad pool of Mediterranean woody species, and demonstrates the strong influence of phylogeny, leaf habit and environmental context as the main drivers of variability in some leaf structural and nutrient traits., This study was funded by the Spanish MEC coordinated project DIVERBOS (CGL2011-30285-C02-01 and C02-02), the Andalusian ANASINQUE project (PGC2010-RNM-5782), the Life+Biodehesa Project (11/BIO/ES/000726), ECO-MEDIT (CGL2014-53236-R), RESTECO (CGL2014-52858-R) and European FEDER funds.

International audience; Despite their importance, how plant communities and soil microorganisms interact to determine the capacity of ecosystems to provide multiple functions simultaneously (multifunctionality) under climate change is poorly known. We conducted a common garden experiment using grassland species to evaluate how plant functional structure and soil microbial (bacteria and protists) diversity and abundance regulate soil multifunctionality responses to joint changes in plant species richness (one, three and six species) and simulated climate change (3 degrees C warming and 35% rainfall reduction). The effects of species richness and climate on soil multifunctionality were indirectly driven via changes in plant functional structure and their relationships with the abundance and diversity of soil bacteria and protists. More specifically, warming selected for the larger and most productive plant species, increasing the average size within communities and leading to reductions in functional plant diversity. These changes increased the total abundance of bacteria that, in turn, increased that of protists, ultimately promoting soil multifunctionality. Our work suggests that cascading effects between plant functional traits and the abundance of multitrophic soil organisms largely regulate the response of soil multifunctionality to simulated climate change, and ultimately provides novel experimental insights into the mechanisms underlying the effects of biodiversity and climate change on ecosystem functioning.

Widespread tree mortality caused by forest decline in recent decades has raised concern among forest managers about how to assess forest fuels in these conditions. To investigate this question, we developed and tested an objective, consistent approach to the characterization of canopy fuel metrics – such as fuel load (FL), live fuel moisture content (LFMC), and live-dead ratio (LDR) – by integrating airborne laser scanning (ALS) and hyperspectral data to produce more-accurate estimates at the stand level. Regression models were developed for Pinus sylvestris and P. nigra stands representative of pine plantations in southern Spain, using field data acquired for different spatial fuel types and distributions as well as high resolution airborne hyperspectral data (AHS) and ALS datasets. Strong relationships were found between ALS and FL using a density of 2 points m−2 (R2 = 0.64) and between LFMC and Temperature/NDVI index at a spatial resolution of 5 m (R2 = 0.91). The red edge normalized index provided the highest separability (Jeffries-Matusita distance = 1.83) between types of LDR. The plot-aggregate ALS and AHS metrics performed better at spatial resolutions of 5 m and 2 points m−2 than at other scales. Cartography of the estimations of FL, LFMC, and LDR made using the empirical models from the ALS and AHS data showed a mean FL value of 65.87 Mg ha−1, an average LFMC content of 57.51%, and 30.75% of the surface classified as dead fuel (≥60% defoliation). The results suggest that our remote sensing approach could improve the estimation of canopy fuels characteristics at higher spatial resolutions as well as estimations of fuel cartography, to assist the planning and management of fuel reduction treatments.

Drought stress is known to limit plant performance in Mediterranean-type ecosystems. We have investigated the dynamics of the hydraulics, gas exchange and morphology of six co-existing Mediterranean woody species growing under natural field conditions during a drought that continued during the entire summer. Based on the observed minimum leaf water potentials, our results suggest that the six co-existing species cover a range of plant hydraulic strategies, from isohydric to anisohydric. These differences are remarkable since the selected individuals grow within several meters of each other, sharing the same environment. Surprisingly, whatever the leaf water potentials were at the end of the dry period, stomatal conductance, photosynthesis and transpiration rates were relatively similar and low across species. This result contradicts the classic view that anisohydric species are able to maintain gas exchange for longer periods of time during drought stress. None of the plants showed the expected structural acclimation response to the increasing drought (reduction of leaf-to-sapwood area ratio), thereby rejecting the functional equilibrium hypothesis for our study system. Instead, three of the six species increased photosynthetic area at the branch level. The observed dissimilar patterns of gas exchange, hydraulics and morphology across species seem to be equally successful given that photosynthesis at the leaf level was maintained at similar rates over the whole dry period.

Here, we investigate small-scale spatial variation of environmental factors potentially influencing woody-plant establishment for 3 years (2004, 2005 and 2006) along a heterogeneous landscape. Environmental variables of over 2883 potential microsites were sampled in different landscape units with a spatially explicit design, and seeds of four tree species were sown at the different microsites. We used spatial-analysis techniques to quantify spatial heterogeneity of the environment surrounding the seeds, and to relate seedling and sapling survival to the spatial structure of environmental factors studied. Most environmental variables showed aggregated spatial patterns among landscape units. However, survival showed random spatial patterns in most of the cases, although it may depend on year-to-year variation of precipitation. Thus, spatial patterns of survival were random under both wet and dry conditions, while aggregated patterns emerged under intermediate conditions. Aggregated survival, if detected, was better explained by the environmental variables studied as plant age increased. In addition, the spatial consistency found across demographic stages, represents hotspots of recruitment, for which direct identification would be critical for restoration activities. Our results showed a balance between stochasticity at early stages and environmental determinism at later stages, showing, behind the idiosyncratic character of plant recruitment, stronger general rules at sapling stages.

La luz y el agua son dos de los principales factores que regulan el crecimiento y la supervivencia de las plantas leñosas mediterráneas. El objetivo de este estudio es conocer el nivel de respuesta plástica de plántulas de cuatro especies de Quercus a tratamientos de sombra y sequía. Además queremos evaluar qué variables son más plásticas a uno u otro factor, y probar la hipótesis de que los rasgos fisiológicos son más plásticos que los rasgos estructurales. Se cultivaron en condiciones controladas plántulas de Quercus ilex subsp. ballota, Q. súber, Q. pyrenaica y Q. canariensis en tres tratamientos de luz (100, 27 y 3 % de luz incidente) y con agua abundante. A partir de mediados de primavera, a la mitad de las plántulas se les suprimió el agua, de forma que recibieron dos tratamientos de agua (riego versus no riego) dentro de cada tratamiento de luz. Se analizaron distintos rasgos fisiológicos como la tasa de fotosíntesis y respiración, el punto de compensación y de saturación a la luz, la conductancia estomática, la eficiencia en el uso del agua y de nitrógeno y la eficiencia fotosintética a la luz. También se estudiaron distintos rasgos morfológicos o estructurales, como el área foliar, el área específica foliar, las concentraciones foliares de N y C, y un índice de clorofila. En general, la respuesta plástica de las variables estructurales al factor agua fue muy baja, mientras que la respuesta de las fisiológicas fue relativamente alta. Con la luz, no se detectaron diferencias significativas en la respuesta plástica entre las variables estructurales y fisiológicas. En estas especies de Quercus mediterráneos, la mayor respuesta plástica a la luz podría estar ligada con una estrategia de tolerancia a la sombra, mientras que la baja respuesta plástica al agua (i.e., canalización) respondería a una estrategia de tolerancia a la sequía, indicando que la tolerancia a bajos niveles de recursos puede ser alcanzada mediante diferentes estrategias.Light and water availability are two of the main factors that regulate growth and survival of Mediterranean woody plants. The objective of this study is to investigate the plastic response of seedlings of four Mediterranean Quercus species to these factors, as well as to determine what traits are more plastic to one or another factor. Our hypothesis was that physiological variables are more plastic than structural variables. We cultivated in controlled conditions seedlings of Quercus ilex ssp. ballota, Q. súber, Q. pyrenaica and Q. canariensis in three treatments of light (100, 27 and 3 % of incident light) and with abundant water. On late spring, watering was stopped for half of the seedlings, so there were two water treatments (irrigation versus no-irrigation) within each treatment of light. Several physiological traits were studied: photosynthetic and respiration rate, light compensation and saturation points, stomatal conductance, water use and nitrogen use efficiency. We also evaluated different structural traits were studied such as leaf area, specific leaf area, leaf nitrogen and carbon concentrations, and a chlorophyll index. Changes in water availability induced low plastic responses of structural traits, whereas responses of physiological traits were relatively higher. On the other hand, there were not significant differences in the plastic response of structural or physiological traits to changes in light availability. In these Mediterranean oak species, the higher response to light could be linked to a shade tolerance strategy and the low response to water (i.e., canalization) could be related to drought tolerant strategy, thus indicating that tolerance to low-resources may be attained through different strategies.

Intransitive competition networks, those in which there is no single best competitor, may ensure species coexistence. However, their frequency and importance in maintaining diversity in realworld ecosystems remain unclear. We used two large data sets from drylands and agricultural grasslands to assess: (1) the generality of intransitive competition, (2) intransitivity–richness relationships and (3) effects of two major drivers of biodiversity loss (aridity and land-use intensification) on intransitivity and species richness. Intransitive competition occurred in > 65% of sites and was associated with higher species richness. Intransitivity increased with aridity, partly buffering its negative effects on diversity, but was decreased by intensive land use, enhancing its negative effects on diversity. These contrasting responses likely arise because intransitivity is promoted by temporal heterogeneity, which is enhanced by aridity but may decline with land-use intensity. We show that intransitivity is widespread in nature and increases diversity, but it can be lost with environmental homogenisation.

We used a functional trait-based approach to assess the impacts of aridity and shrub encroachment on the functional structure of Mediterranean dryland communities (functional diversity and community-weighted mean trait values [CWM]), and to evaluate how these functional attributes ultimately affect multifunctionality (i.e., the provision of several ecosystem functions simultaneously).Shrub encroachment (the increase in the abundance/cover of shrubs) is a major land cover change that is taking place in grasslands worldwide. Studies conducted on drylands have reported positive or negative impacts of shrub encroachment depending on the functions and the traits of the sprouting or non-sprouting shrub species considered.Functional diversity and CWM were equally important as drivers of multifunctionality responses to both aridity and shrub encroachment. Size traits (e.g., vegetative height or lateral spread) and leaf traits (e.g., specific leaf area and leaf dry matter content) captured the effect of shrub encroachment on multifunctionality with a relative high accuracy (r2=0.63). Functional diversity also improved the resistance of multifunctionality along the aridity gradient studied.Maintaining and enhancing functional diversity in plant communities may help to buffer negative effects of ongoing global environmental change on dryland multifunctionality.

Aim: Geographical, climatic and soil factors are major drivers of plant beta diversity, but their importance for dryland plant communities is poorly known. The aim of this study was to: (1) characterize patterns of beta diversity in global drylands; (2) detect common environmental drivers of beta diversity; and (3) test for thresholds in environmental conditions driving potential shifts in plant species composition. Location: Global. Methods: Beta diversity was quantified in 224 dryland plant communities from 22 geographical regions on all continents except Antarctica using four complementary measures: the percentage of singletons (species occurring at only one site); Whittaker's beta diversity, ?(W); a directional beta diversity metric based on the correlation in species occurrences among spatially contiguous sites, ?(R2); and a multivariate abundance-based metric, ?(MV). We used linear modelling to quantify the relationships between these metrics of beta diversity and geographical, climatic and soil variables. Results: Soil fertility and variability in temperature and rainfall, and to a lesser extent latitude, were the most important environmental predictors of beta diversity. Metrics related to species identity [percentage of singletons and ?(W)] were most sensitive to soil fertility, whereas those metrics related to environmental gradients and abundance [(?(R2) and ?(MV)] were more associated with climate variability. Interactions among soil variables, climatic factors and plant cover were not important determinants of beta diversity. Sites receiving less than 178 mm of annual rainfall differed sharply in species composition from more mesic sites (> 200 mm). Main conclusions: Soil fertility and variability in temperature and rainfall are the most important environmental predictors of variation in plant beta diversity in global drylands. Our results suggest that those sites annually receiving c. 178 mm of rainfall will be especially sensitive to future climate changes. These findings may help to define appropriate conservation strategies for mitigating effects of climate change on dryland vegetation

[EN] Pine seedling survival and growth in eastern Spain have often been related to site preparation, planting date and seedling stock. However, in spite of the acknowledged importance of spatial heterogeneity in seedling performance, little is understood about how topography-related spatial patterns may modify seedling response to plantation, particularly on dry sites. We tested the hypotheses that growth and survival of Pinus halepensis seedlings are related to stock quality, plantation date and topographic conditions, as well as the spatial pattern of environmental variables using a spatially explicit design. The plantation treatment consisted of three seedling stocks, two plantation dates and two contrasted quality sites. Topographic features, such as slope, aspect, Compound Topographic Index and flow accumulation, were measured using GPS and low density LiDAR, with growth and survival monitored over a period of one and two years, respectively. The spatial pattern of the study variables was examined via spatial analysis by distance indices (SADIE). The relative importance of each topographic variable explaining the spatial pattern (local aggregation indices, v) of seedling response was examined using ordinary least squares (OLS) regressions. P. halepensis seedlings showed higher survival and growth in better sites and early plantations, but they were very similar between seedling stocks. A significantly greater proportion of seedlings survived in early date of plantation (54%) compared to medium date (36%), and in the favorable site (51%) versus the restrictive site (38%). Seedlings also grew significantly faster for those treatments during the first year. However, stock quality had few effects on survivorship and growth. All the topographic and seedling response variables exhibited an aggregated spatial pattern. Seedling survival was clearly associated with topographic patterns, particularly to those related to water availability (CTI and flow accumulation), indicating that on topographic-spatial scales, seedling response is driven by soil-water dynamics in Mediterranean ecosystems. The topographic morphology described by LiDAR was also closely linked to seedling response, thus suggesting the potential of these data to evaluate reforestation success. Accurate maps of topographic factors may indicate whether a plantation has a higher survival and growth potential and with routine reforestation planning activities such as soil preparation. (C) 2014 Elsevier B.V. All rights reserved., We are grateful to the Generalitat of Valencia for its assistance in using the experimental forests. Our thanks also to VAERSA for their help with the field work, especially to Antonio Ibanez, and Martha Gaustad for revising the English. Financial support was received from DIVERBOS (CGL2011-30285-C02-02) project. We also acknowledge the financial support from University of Cordoba-Campus de Excelencia CEIA3 and the Sustainable Forest Restoration Management Research Program.

The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. Wefind a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition1. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems. Fil: Delgado Baquerizo, Manuel. Universidad Pablo de Olavide; España. Universidad Rey Juan Carlos. Departamento de Biología y Geología. Área de Biodiversidad y Conservación; España Fil: Maestre, Fernando T.. Universidad Pablo de Olavide; España. Universidad Rey Juan Carlos. Departamento de Biología y Geología. Área de Biodiversidad y Conservación; España Fil: Gallardo, Antonio. Universidad Pablo de Olavide; España Fil: Bowker, Matthew A.. Northern Arizon University/school Of Forestry; Fil: Wallenstein, Matthew D.. Northern Arizona University; Estados Unidos Fil: Bran, Donaldo Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; Argentina. Universidad Rey Juan Carlos. Departamento de Biología y Geología. Área de Biodiversidad y Conservación; España Fil: Gatica, Mario Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina Fil: Hepper, Estela Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina Fil: Prina, Anibal Oscar. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina Fil: Pucheta, Eduardo Raúl. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina Fil: Huber Sannwald, Elisabeth. Instituto Potosino de Investigación Científica y Tecnológica; México Fil: Jankju, Mohammad. Ferdowsi University of Mashhad; Irán Fil: Liu, Jushan. Northeast Normal University. Institute of Grassland Science,; China Fil: Mau, Rebecca L.. Northern Arizona University; Estados Unidos Fil: Miriti, Maria. Ohio State University; Estados Unidos Fil: Monerris, Jorge. Université du Québec a Montreal; Canadá Fil: Naseri, Kamal. Ferdowsi University of Mashhad; Irán Fil: Noumi, Zouhaier. Université de Sfax; Túnez Fil: Polo, Vicente. Universidad Rey Juan Carlos. Departamento de Biología y Geología. Área de Biodiversidad y Conservación; España Fil: Ramírez Collantes, David A.. International Potato Center; Perú Fil: Romão, Roberto. Universidade Estadual de Feira de Santana. Departamento de Ciencias Biológica, Herbario; Brasil Fil: Tighe, Matthew. University of New England; Australia Fil: Torres, Duilio. Universidad Centroccidental ‘‘Lisandro Alvarado’’; Venezuela Fil: Torres Díaz, Cristian. Universidad del Bio Bio. Facultad de Ciencias. Departamento de Ciencias Básicas. Laboratorio de Genómica y Biodiversidad; Chile Fil: Ungar, Eugene D.. The Volcani Center. Agricultural Research Organization. Institute of Plant Sciences; Israel Fil: Val, James. Office of Environment and Heritage; Australia Fil: Wamiti, Wanyoike. National Museums of Kenya. Zoology Department; Kenia Fil: Wang, Deli. Northeast Normal University. Institute of Grassland Science; China Fil: Zaady, Eli. Gilat Research Center; Israel

Drylands occupy large portions of the Earth, and are a key terrestrial biome from the socio-ecological point of view. In spite of their extent and importance, the impacts of global environmental change on them remain poorly understood. In this introduction, we review some of the main expected impacts of global change in drylands, quantify research efforts on the topic, and highlight how the articles included in this theme issue contribute to fill current gaps in our knowledge. Our literature analyses identify key under-studied areas that need more research (e.g. countries such as Mauritania, Mali, Burkina Faso, Chad and Somalia, and deserts such as the Thar, Kavir and Taklamakan), and indicate that most global change research carried out to date in drylands has been done on a unidisciplinary basis. The contributions included here use a wide array of organisms (from micro-organisms to humans), spatial scales (from local to global) and topics (from plant demography to poverty alleviation) to examine key issues to the socio-ecological impacts of global change in drylands. These papers highlight the complexities and difficulties associated with the prediction of such impacts. They also identify the increased use of long-term experiments and multidisciplinary approaches as priority areas for future dryland research. Major advances in our ability to predict and understand global change impacts on drylands can be achieved by explicitly considering how the responses of individuals, populations and communities will in turn affect ecosystem services. Future research should explore linkages between these responses and their effects on water and climate, as well as the provisioning of services for human development and well-being.

13 pages, 5 figures, 1 table, 66 references. We thank Wageningen University for facilitating the stay of Lorena Gómez-Aparicio and José Luis Quero., The combined effects of shade and drought on plant performance and the implications for species interactions are highly debated in plant ecology. Empirical evidence for positive and negative effects of shade on the performance of plants under dry conditions supports two contrasting theoretical models about the role of shade under dry conditions: the trade-off and the facilitation hypotheses. We performed a meta-analysis of field and greenhouse studies evaluating the effects of drought at two or more irradiance levels on nine response variables describing plant physiological condition, growth, and survival. We explored differences in plant response across plant functional types, ecosystem types and methodological approaches. The data were best fit using quadratic models indicating a humped-back shape response to drought along an irradiance gradient for survival, whole plant biomass, maximum photosynthetic capacity, stomatal conductance and maximal photochemical efficiency. Drought effects were ameliorated at intermediate irradiance, becoming more severe at higher or lower light levels. This general pattern was maintained when controlling for potential variations in the strength of the drought treatment among light levels. Our quantitative meta-analysis indicates that dense shade ameliorates drought especially among drought-intolerant and shade-tolerant species. Wet tropical species showed larger negative effects of drought with increasing irradiance than semiarid and cold temperate species. Non-linear responses to irradiance were stronger under field conditions than under controlled greenhouse conditions. Non-linear responses to drought along the irradiance gradient reconciliate opposing views in plant ecology, indicating that facilitation is more likely within certain range of environmental conditions, fading under deep shade, especially for drought-tolerant species., This study was partly supported by the postdoctoral grant MCINN (Spain) to J.L.Q. (ref 2007-0572).

In pharmaceutical industries, the validation of analytical methods is used to demonstrate that the method is fitted for its purpose; it must follow a plan which includes scope, performance characteristics, and acceptance limits. Analytical methods need to be validated or revalidated prior to their introduction into routine analyses (release of batch). The overarching philosophy in current good manufacturing practices (cGMPs) of the twenty first century and robust modern quality systems is the quality that it has to be built into the product, and testing alone cannot be relied to ensure the quality of the product. From the analytical perspective, it will mean that analytical methods used to test products should have quality attributes built into them. In order to apply quality attributes into the analytical method, fundamental quality attributes have to be applied by the bench level scientist. This is a paradigm shift that requires the bench level scientist to have a scientific and technical understanding, product knowledge, process knowledge, and/or risk assessment ability to appropriately execute the quality functions of analytical method validation. In addition, it requires the following procedures: (a) an appropriate training of the bench level scientist to understand the principles involved with method validation, validate an analytical method, and understand the principles involved with the method validation, (b) proper documentation and understanding and interpreting data, and (c) cross – an understanding functional of the effect of their activities on the product and to customers (the patient). Management has a responsibility of verifying that gained skills from the training are implemented in routine analyses performance. This chapter gives a review and strategy for the validation of analytical methods in-house, recommendation in documentation and completion of method validation in the pharmaceutical environmental.

The great spatial and temporal heterogeneity of Mediterranean ecosystems can influence establishment success in woody species, whose natural regeneration occurs to a very small extent. In this work, the effect of the spatial pattern of environmental variables (light availability, soil moisture and herbaceous production) on seedling emergence, growth, survival and establishment success was examined by using a spatially explicit approach. Seeds of four Quercus species differing in leaf longevity (Quercus ilex, Quercus suber, Quercus faginea and Quercus pyrenaica) were sown in two plots located in a holm oak forest (southern Spain). The spatial pattern of the studied variables was examined by Spatial Analysis by Distance Indices. All environmental variables exhibited an aggregated spatial pattern. There was no clear spatial association between the environmental variables and emergence and survival. Only soil moisture during the dry season was spatially associated with the establishment success of all the species. Species also differed in survival and establishment success, with evergreens having higher percentages than deciduous. No aggregated spatial pattern for growth and morphological traits was apparent, these being more dependent on seed mass than on environmental factors. Identifying which microsites facilitate regeneration may provide useful hints with a view in focusing restoration endeavours on microenvironments with high survival percentage.

Soil compaction and light availability influence plant growth via different mechanisms. In general, soil compaction has a direct effect on roots, whereas light affects leaves and stems. Although plants in nature are exposed to variable levels of soil compaction and light, no study on the potential mutual interactions of these limiting factors in woody plants has to the authors' knowledge been reported to date. The aim of this work was therefore to elucidate the effects of soil compaction and light availability on growth and biomass allocation in the deciduous oak Quercus pyrenaica. To this end, a study was conducted at two light levels (viz. 3% and 100% of incident light, designated as low-light and high-light, respectively) under a wide range of soil compaction (0.02-3 MPa as penetration resistance) in a greenhouse. Total biomass was found to be positively affected by both light and soil compaction. There was marginally significant interaction between the effects of the two factors on total biomass, which was positively affected by soil compaction only under high-light conditions. Soil compaction had a strong, negative effect on the length of the main root; thus, at maximum soil compaction, such a length was roughly one-half that observed at lower compaction levels. Also, the specific root length of main root (root length to root mass ratio) was reduced by roughly one-half in highly compacted soils. These results suggest that an unfavourable combination of soil compaction and light availability may have severely adverse effects on woody plant performance in drought periods since plants with short roots can hardly access water at deep soil levels. The strength of this effect may be modulated by light availability.

16 pages, 6 figures, 2 tables, 75 references. We thank to SCAI of University of Cordoba for greenhouse facilities, and F. Conde, M. A. Calero, C. Sánchez-Casimiro, L. Bejarano, A. Murillo J. Rubio, F. J. Morilla and M. A. Núñez for their help during the experiment. G. Quero gave logistic support., Understanding the impacts of combined resource supplies on seedlings is critical to enable prediction of establishment growth, and forest dynamics. We investigated the effects of irradiance and water treatments on absolute growth, and relative growth rate (RGR) and its components, for seedlings of four Quercus species differing in leaf habit and with a wide variation in seed mass. Plants were grown for 6.5 months at three levels of irradiance (100, 27, and 3% daylight), and treated during the last 2.5 months with two watering treatments (frequent watering v. suspended watering). Both shade and drought reduced seedling growth rates, with a significant interaction: under full irradiance the drought treatment had a stronger impact on RGR and final biomass than under deep shade. For three species, seed mass was positively related to absolute growth, with stronger correlations at lower irradiance. The evergreen species grew faster than the deciduous species, though leaf habit accounted for a minor part of the interspecific variation in absolute growth. Seedling biomass was determined positively either by RGR or seed mass; RGR was positively linked with net assimilation rate (NAR) and leaf mass fraction (LMF), and seed mass was negatively linked with RGR and LMF, but positively linked with NAR. Seedling RGR was not correlated with light-saturated net photosynthetic rate, but was strongly correlated with the net carbon balance estimated, from photosynthetic light-response curves, considering daily variation in irradiance. These findings suggest an approach to applying short-term physiological measurements to predict the RGR and absolute growth rate of seedlings in a wide range of combinations of irradiance and water supplies., This study was supported by the grant FPI-MEC to JLQ (BES-2003 1716), and by the coordinated Spanish MEC projects HETEROMED (REN2002 04041) and DINAMED (CGL2005 05830). This research is part of the REDBOME and GLOBIMED networks on forest ecology (http://www.ugr.es/~redbome/; http://www.globimed.net/).

12 pages, 6 figures, 1 table, 78 references. We thank the Consejería de Medio Ambiente, Junta de Andalucía, and the Direction of the Sierra Nevada National Park, for permission for the field work, constant support and facilities. We are also especially grateful to Sergio de Haro for his help during the field work. Martin F. Quigley made valuable comments on an earlier version of the manuscript. David Nesbitt looked over the English version of the manuscript., Spatial heterogeneity of abiotic factors influences patterns of seedling establishment at different scales. In stress-prone ecosystems such as Mediterranean ones, heterogeneity generated by shrubs has been shown to facilitate the establishment of tree species. However, how this facilitation is affected by spatial scale remains poorly understood. We have experimentally analysed the consequences of the abiotic heterogeneity generated by pioneer shrubs on survival, growth and physiology of seedlings of three important tree species from Mediterranean mountains (Acer opalus ssp. granatense, Quercus pyrenaica and Quercus ilex). Patterns of abiotic heterogeneity and seedling performance were studied at two scales differing in grain: 1) the microhabitat scale, by using open interspaces as controls of the effect of different shrub species, and 2) the microsite scale, analysing the effects of fine-grain heterogeneity (within-microhabitat heterogeneity). Results showed that, at the microhabitat scale, seedling establishment of the three tree species significantly benefited from the modification of the abiotic environment by nurse shrubs. However, we found shrub-seedling interactions to be species-specific, due to differential modification of both aboveground (light availability) and belowground (soil compaction, water content, and fertility) abiotic factors by nurse shrub species. Heterogeneity at the within-microhabitat scale was rather high, although it did not significantly affect seedling performance of any of the tree species. The study demonstrates that the effects of the abiotic heterogeneity generated by shrubs are not consistent across the range of spatial scales considered. The regeneration niche of tree species becomes very complex at fine spatial scales, and thereby estimators of abiotic heterogeneity are valuable descriptors of spatial patterns of seedling establishment only when microsite ‘‘noise’’ is averaged out at greater scales., This study was supported by a PFPU-MECD grant to L.G.A., and projects REN2001- 4552-E and HETEROMED REN2002-04041-CO2-01/GLO from the Spanish Ministry of Science and Technology (MCYT). This collaborative research was favoured by the thematic network GLOBIMED, also supported by MCYT.

Dryland vegetation is characterized by discrete plant patches that accumulate and capture soil resources under their canopies. These “fertile islands” are major drivers of dryland ecosystem structure and functioning, yet we lack an integrated understanding of the factors controlling their magnitude and variability at the global scale. EEA Bariloche Fil: Ochoa-Hueso, Raúl. Universidad Autónoma de Madrid. Department of Ecology; España Fil: Eldridge, David J. University of New South Wales. School of Biological, Earth and Environmental Sciences; Australia Fil: Delgado-Baquerizo, Manuel. University of Colorado. Cooperative Institute for Research in Environmental Sciences; Estados Unidos. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España Fil: Soliveres, Santiago. University of Bern. Institute of Plant Sciences; Suiza Fil: Bowker, Matthew A. Northern Arizona University. School of Forestry; Estados Unidos Fil: Gross, Nicolás. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España. Institut Nationale de la Recherche Agronomique; Francia. Université La Rochelle. Centre d’étude biologique de Chizé; Francia Fil: Le Bagousse-Pinguet, Yoann. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España Fil: Quero, José L. Universidad de Córdoba. Escuela Técnica Superior de Ingeniería Agronómica y de Montes. Departamento de Ingeniería Forestal: España Fil: García-Gómez, Miguel. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España Fil: Valencia, Enrique. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España Fil: Arredondo, Tulio. Instituto Potosino de Investigación Científica y Tecnológica. División de Ciencias Ambientales; México Fil: Beinticinco, Laura. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina Fil: Bran, Donaldo Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentina Fil: Cea, Alex. Universidad de La Serena. Departamento de Biología; Chile Fil: Coaguila, Daniel. Instituto de Ensino Superior de Rio Verde; Brasil Fil: Dougill, Andrew J. University of Leeds. School of Earth and Environment; Gran Bretaña Fil: Espinosa, Carlos I. Universidad Técnica Particular de Loja. Departamento de Ciencias Naturales; Ecuador Fil: Gaitan, Juan Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; Argentina Fil: Guuroh, Reginald T. University of Cologne. Botanical Institute. Range Ecology and Range Management Group; Alemania. CSIR-Forestry Research Institute of Ghana; Ghana Fil: Guzmán, Elizabeth. Universidad Técnica Particular de Loja. Departamento de Ciencias Naturales; Ecuador Fil: Gutiérrez, Julio R.. Universidad de La Serena. Departamento de Biología; Chile. Centro de Estudios Avanzados en Zonas Áridas (CEAZA); Chile. Instituto de Ecología y Biodiversidad; Chile Fil: Hernández, Rosa M. Universidad Experimental Simón Rodríguez. Centro de Agroecología Tropical. Laboratorio de Biogeoquímica; Venezuela Fil: Huber-Sannwald, Elisabeth. Instituto Potosino de Investigación Científica y Tecnológica. División de Ciencias Ambientales; México Fil: Jeffries, Thomas. Western Sydney University. Hawkesbury Institute for the Environment; Australia Fil: Linstädter, Anja. University of Cologne. Botanical Institute. Range Ecology and Range Management Group; Alemania Fil: Mau, Rebecca L. Northern Arizona University. Center for Ecosystem Science and Society: Estados Unidos Fil: Monerris, Jorge. Université du Québec à Montréal. Pavillon des Sciences Biologiques. Département des Sciences Biologiques; Canadá Fil: Prina, Anibal. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina Fil: Pucheta, Eduardo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Biología; Argentina Fil: Stavi, Ilan. Dead Sea and Arava Science Center, Israel Fil: Thomas, Andrew. Aberystwyth University. Department of Geography and Earth Sciences; Gran Bretaña Fil: Zaady, Eli. Agricultural Research Organization. Gilat Research Center. Natural Resources; Israel Fil: Singh, Brajesh K. Western Sydney University. Hawkesbury Institute for the Environment; Australia. Western Sydney University. Global Centre for Land-Based Innovation; Australia Fil: Maestre, Fernando T. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España