Suchergebnisse

What is all this fuss about ethnic studies? -- Mainstream curriculum as (multicultural) white studies -- What the research says about ethnic studies -- Ethnic studies curriculum as counter-narrative -- Ethnic studies teachers' reflections on their praxis -- Research and the movement for ethnic studies.

13 pages, 4 figures, 2 tables, 70 references. We are grateful to the Andalusian Government (Consejería de Medio Ambiente), and to Felipe Oliveros and the staff of Los Alcornocales Park for the facilities to compile forest inventory information and for visit permits. We thank Javier Quijada and José Manuel Moreira of REDIAM, and José A. Villanueva of the Ministry of Environment, for providing, respectively, environmental and SSFI data, as well as Francisco Rodríguez, Sara Rodríguez, and Carlota Martínez for assistance at various stages. Daniel Montoya, Drew Purves, James Aronson. Historical forest management plans were consulted in the archive of the Dirección General para la Biodiversidad (Madrid). ; Aims Both human and non-human determinants have shaped Mediterranean forest structure over the last few millennia. The effects of recent human activities on forest composition, however, remain poorly understood. We quantified changes in forest composition during the past century in the mixed forests of Quercus suber (cork oak) and Q. canariensis (Algerian oak), and explored the effects of forest management and environmental (climate, topography) factors on forest structure at various spatial and temporal scales. Location Mountains north of the Strait of Gibraltar (southern Spain). Methods First, we quantified 20th-century changes in species composition from a series of inventories in nine mixed forests (c. 40,000 ha), and examined them in terms of the management practices and environmental conditions. Second, we analysed present-day Q. suber and Q. canariensis stand structure along environmental gradients at two spatial scales: (1) that of the forest landscape (c. 284 ha), combining local inventories and topographic variables and using a digital elevation model; and (2) regional (c. 87,600 km2), combining data from the Spanish Forest Inventory for the Andalusia region and estimates of climatic variables. Results Historical data indicate anthropogenic changes in stand composition, revealing a sharp increase in the density of cork oaks over the last century. Forest management has favoured this species (for cork production) at the expense of Q. canariensis. The impact of management is imprinted on the present-day forest structure. The abundance of both species increases with annual mean precipitation, and they coexist above 800 mm (the minimum threshold for Q. canariensis). Quercus suber dominates in most of the stands, and species segregation in the landscape is associated with the drainage network, Q. canariensis being clearly associated with moister habitats near streams. Main conclusions Our study quantitatively exemplifies a recent humanmediated shift in forest composition. As a result of forest management, the realized niche of the cork oak has been enlarged at the expense of that of Q. canariensis, providing further evidence for humans as major drivers of oak forest composition across the Mediterranean. Recent regeneration problems detected in Q. suber stands, a reduced demand for wood products, conservation policies, and climate change augur new large-scale shifts in forest composition. ; This study was supported by grant FPI-MEC to I.R.U. and project grants REN2002-04041-C02 and CGL2005-05830-C03. This research is part of REDBOME (http://www.ugr.es/~redbome/) and GLOBIMED (http:// www.globimed.net) networks on forest ecology ; Peer reviewed

Recent forest expansion in Euro‐Mediterranean countries predominantly results from secondary succession in abandoned farmland, rather than from artificial afforestation. This major forest transition involves the delivery of both ecosystem services and disservices, which must be balanced through new land‐use planning and policy approaches. Ecosystem services arising from this expansion of forests include increased carbon sequestration, water infiltration, provision of forest products, soil retention, and forest coalescence. Nevertheless, ecosystem disservices such as reductions in water yield, landscape homogenisation, increased wildfire risk, and/or the loss of high nature value managed habitats caution against generalisation of the benefits of such expansion. Most EU funds related to forests are being allocated to conservation, restoration, or fire prevention and extinction efforts, whereas sustainable forest management and the maintenance of multifunctional agro‐silvo‐pastoral mosaics are hampered by the lack of financial incentives and by environmental regulations. Policy implications. We advocate for more‐targeted policies based on landscape planning that favours multifunctionality while reducing environmental and economic uncertainties and maximizing the ecosystem service/disservice ratio. The following recommendations follow from this approach: (1) a climate‐smart policy favouring fire‐resistant landscapes and enhancing value chains that stimulate active forest management; (2) the adoption of a territorial perspective, beyond forest and farm‐based measures and payments, that relies on management actions and minimizes socio‐ecological tensions; (3) re‐focusing CAP Pillar II grants from afforestation and forest protection measures to sustainable forest management; (4) transforming the CAP direct payments to support multifunctional farming systems (e.g. agroforestry); (5) a more balanced inclusion of different land uses in the Natura 2000 network and intensification of the support for High Nature Value ...

Ruiz Benito, P. et al. 14 páginas.-- 3 figuras.-- 2 tablas.-- 50 referencias.-- Additional supporting information may be found in the online version of this article at the publisher's web-site: http://dx.doi.org/10.1111/geb.12515 ; Aim: Biodiversity loss and climate-driven ecosystem modification are leading to substantial changes in forest structure and function. However, the effects of diversity on demographic responses to the environment are poorly understood. We tested the diversity hypothesis (measured through functional diversity) and the mass ratio hypothesis (measured through functional identity) in relation to tree growth, tree mortality and sapling abundance. We sought to determine whether functional diversity underlies demographic responses to environmental variation in European forests. Location: Europe (Spain, Germany, Wallonia, Finland and Sweden). Methods: We used data from five European national forest inventories from boreal to Mediterranean biomes (c. 700,000 trees in 54,000 plots and 143 tree species) and the main forest types across Europe (i.e. from needle-leaved evergreen forests to broad-leaved deciduous forests). For each forest type, we applied maximum likelihood techniques to quantify the relative importance of stand structure, climate and diversity (i.e. functional diversity and functional identity) as determinants of growth, mortality and sapling abundance. We also tested whether demographic responses to environmental conditions (including stand density, evapotranspiration and temperature anomalies) varied with functional diversity. Results: Our results suggest that functional diversity has a positive effect on sapling abundance and growth rates in forests across Europe, while no effect was observed on tree mortality. Functional identity has a strong effect on mortality and sapling abundance, with greater mortality rates in forests dominated by needle-leaved individuals and a greater abundance of saplings in forests dominated by broad-leaved individuals. Furthermore, we observed that functional diversity modified the effects of stand density on demographic responses in Mediterranean forests and the influence of evapotranspiration and temperature anomalies in forests widely distributed across Europe. Main conclusion: Our results suggest that functional diversity may play a key role in forest dynamics through complementarity mechanisms, as well as by modulating demographic responses to environmental variation. ; The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement nos 265171 (FunDivEUROPE) and PCOFUND-GA-2010-267243 (Plant Fellows), The Leverhulme Trust (no. IN-2013-004), the University of Stirling and MINECO (FUNDIVER, no. CGL2015-69186-C2-2-R) ; Peer Reviewed

18 pages, 6 figures, 2 tables, 1 plate, 93 references. This research is part of REDBOME (www.ugr.es/;redbome/) and GLOBIMED (www.globimed.net) networks on forest ecology. ; The ecological impacts of forest plantations are a focus of intense debate, from studies that consider plantations as "biological deserts" to studies showing positive effects on plant diversity and dynamics. This lack of consensus might be influenced by the scarcity of studies that examine how the ecological characteristics of plantations vary along abiotic and biotic gradients. Here we conducted a large-scale assessment of plant regeneration and diversity in plantations of southern Spain. Tree seedling and sapling density, plant species richness, and Shannon's (H0) diversity index were analyzed in 442 pine plantation plots covering a wide gradient of climatic conditions, stand density, and distance to natural forests that act as seed sources. Pronounced variation in regeneration and diversity was found in plantation understories along the gradients explored. Low- to mid-altitude plantations showed a diverse and abundant seedling bank dominated by Quercus ilex, whereas high-altitude plantations showed a virtually monospecific seeding bank of Pinus sylvestris. Regeneration was null in plantations with stand densities exceeding 1500 pines/ha. Moderate plantation densities (500–1000 pines/ha) promoted recruitment in comparison to low or null canopy cover, suggesting the existence of facilitative interactions. Quercus ilex recruitment diminished exponentially with distance to the nearest Q. ilex forest. Richness and H0 index values showed a hump-shaped distribution along the altitudinal and radiation gradients and decreased monotonically along the stand density gradient. From a management perspective, different strategies will be necessary depending on where a plantation lies along the gradients explored. Active management will be required in highdensity plantations with arrested succession and low diversity. Thinning could redirect plantations toward more natural densities where facilitation predominates. Passive management might be recommended for low- to moderate-density plantations with active successional dynamics (e.g., toward oak or pine–oak forests at low to mid altitudes). Enrichment planting will be required to overcome seed limitation, especially in plantations far from natural forests. We conclude that plantations should be perceived as dynamic systems where successional trajectories and diversity levels are determined by abiotic constraints, complex balances of competitive and facilitative interactions, the spatial configuration of native seed sources, and species life-history traits. ; Financial support was provided by a Juan de la Cierva contract (2006-1342) to L. Gómez-Aparicio and the GESBOME project (RNM 1890) from the Excellence Research Group Programme of the Andalusian Government. ; Peer reviewed

10 pages, 2 figures, 26 references. We thank the Consejería de Medio Ambiente (Andalusian Government) and Felipe Oliveros, Director of Los Alcornocales Natural Park, for the facilities and support to carry out the field work. We also thank to Maite Domínguez and Carmen Navarro for field assistance. Regeneration Models were carried out by IRU, with the advice of Dr. Richard Kobe, during a short-time grant in Michigan State University. El libro referenciado ha sido publicado con motivo de Conference Proceedings: Conference held at the University of Huelva on 20-22 october, 2005. Organised bay: Departamento de Ciencias Agroforestales, Universidad de Huelva, Spain. Centro de Estudos Florestais, Universidade Técnica de Lisboa, Portugal. ; The success of natural regeneration in forests depends on the sequential and complete achievement of several connected life-history stages of tree species. The collapse of any stage results in the limitation of the overall recruitment process. In this study, we focus on several regeneration stages of the cork oak (Quercus suber) tree species: seed production, pre-dispersal and post-dispersal predation rates, and establishment of seedlings. The fieldwork was carried out at three forest plots located within Los Alcornocales Natural Park (Southern Spain) where Q. suber is dominant. We have monitored seed production of 50 adult trees during three consecutive years, estimating the proportion of crop loss due to abortions and to damage by insect larvae. We have also studied the impact of predators (rodents and large herbivores) on seed survival in different types of microsites. Finally, we have studied the effect of microsite types and environmental factors (light, soil moisture and soil compaction) on the germination of sown seeds and the subsequent emergence and survival of seedlings. Results suggest that the high acorn predation rates (both pre-dispersal and post-dispersal) and the high mortality of seedlings (during the summer drought) are main causes of limitation in the natural regeneration of Q. suber in the study area. These factors act on a microsite-depending scale, altering acorns and seedlings probability of survivorship. The scientific knowledge of natural regeneration requirements of Q. suber will help to develop ecological restoration programs in disturbed areas caused by fire, tree disease, or changes of land use. ; This study was supported by the coordinated project Heteromed (REN2002-04041-CO2). This research is part of REDBOME and GLOBIMED networks on forest ecology. ; Peer reviewed

A numerical assessment of different thermal conditions for an impinging flame configuration is investigated using large-eddy simulation. The cases of study correspond to a turbulent methane flame at equivalence ratio ER = 0.8 and temperature T = 298 K exiting at 30 m/s with a nozzle-to-plate distance over diameter of H/D = 2. Computational cases based on different thermal conditions are compared to a conjugate case, in which fluid and solid domains are solved simultaneously. A solid material defined with enhanced conductivity properties is used to represent the wall in the conjugate case, so that the characteristic time scales of the solid are reduced. The results indicate that the heat transfer condition influences not only the mean temperature and gradients, but also the temperature fluctuations in the near-wall region. It is found that adiabatic, isothermal and more sophisticated Robin-type boundary conditions contribute to underpredict/overpredict the temperature field near the wall. As the time scales of fluid and solid are of the same order, the use of conjugate approaches is required to predict the correct flow fields near the wall and the skin temperature. ; The research leading to these results has received funding through the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7, 2007-2013) under the grant agreement No. FP7-290042 for the project COPA-GT. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Red Espa~nola de Supercomputación (RES). ; Peer Reviewed ; Postprint (author's final draft)

A numerical assessment of different thermal conditions for an impinging flame configuration is investigated using large-eddy simulation. The cases of study correspond to a turbulent methane flame at equivalence ratio ER = 0.8 and temperature T = 298 K exiting at 30 m/s with a nozzle-to-plate distance over diameter of H/D = 2. Computational cases based on different thermal conditions are compared to a conjugate case, in which fluid and solid domains are solved simultaneously. A solid material defined with enhanced conductivity properties is used to represent the wall in the conjugate case, so that the characteristic time scales of the solid are reduced. The results indicate that the heat transfer condition influences not only the mean temperature and gradients, but also the temperature fluctuations in the near-wall region. It is found that adiabatic, isothermal and more sophisticated Robin-type boundary conditions contribute to underpredict/overpredict the temperature field near the wall. As the time scales of fluid and solid are of the same order, the use of conjugate approaches is required to predict the correct flow fields near the wall and the skin temperature. ; The research leading to these results has received funding through the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7, 2007-2013) under the grant agreement No. FP7-290042 for the project COPA-GT. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Red Espa~nola de Supercomputación (RES). ; Peer Reviewed ; Postprint (author's final draft)

Neglecting tree size and stand structure dynamics might bias the interpretation of the diversity-productivity relationship in forests. Here we show evidence that complementarity is contingent on tree size across large-scale climatic gradients in Europe. We compiled growth data of the 14 most dominant tree species in 32,628 permanent plots covering boreal, temperate and Mediterranean forest biomes. Niche complementarity is expected to result in significant growth increments of trees surrounded by a larger proportion of functionally dissimilar neighbours. Functional dissimilarity at the tree level was assessed using four functional types: i.e. broad-leaved deciduous, broad-leaved evergreen, needle-leaved deciduous and needle-leaved evergreen. Using Linear Mixed Models we show that, complementarity effects depend on tree size along an energy availability gradient across Europe. Specifically: (i) complementarity effects at low and intermediate positions of the gradient (coldest-temperate areas) were stronger for small than for large trees; (ii) in contrast, at the upper end of the gradient (warmer regions), complementarity is more widespread in larger than smaller trees, which in turn showed negative growth responses to increased functional dissimilarity. Our findings suggest that the outcome of species mixing on stand productivity might critically depend on individual size distribution structure along gradients of environmental variation. ; This manuscript was funded by the European Union Seventh Framework Program (FP7/2007–2013) under grant agreement no. 265171, project FUNDIV-Europe, and from project FUNDIVER (MINECO, Spain; CGL2015-69186-C2-2-R). ; J.C. holds a Spanish FPU PhD Grant (FPU12/00575). ; PR-B was granted by the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 265171 (project FunDivEUROPE) and No. PCOFUND-GA-2010-267243 (Plant Fellows). ; Peer reviewed

This global study, which has been coordinated by the World Meteorological Organization Global Atmospheric Watch (WMO/GAW) programme, aims to understand the behaviour of key air pollutant species during the COVID-19 pandemic period of exceptionally low emissions across the globe. We investigated the effects of the differences in both emissions and regional and local meteorology in 2020 compared with the period 2015–2019. By adopting a globally consistent approach, this comprehensive observational analysis focuses on changes in air quality in and around cities across the globe for the following air pollutants PM2.5, PM10, PMC (coarse fraction of PM), NO2, SO2, NOx, CO, O3 and the total gaseous oxidant (OX = NO2 + O3) during the pre-lockdown, partial lockdown, full lockdown and two relaxation periods spanning from January to September 2020. The analysis is based on in situ ground-based air quality observations at over 540 traffic, background and rural stations, from 63 cities and covering 25 countries over seven geographical regions of the world. Anomalies in the air pollutant concentrations (increases or decreases during 2020 periods compared to equivalent 2015–2019 periods) were calculated and the possible effects of meteorological conditions were analysed by computing anomalies from ERA5 reanalyses and local observations for these periods. We observed a positive correlation between the reductions in NO2 and NOx concentrations and peoples' mobility for most cities. A correlation between PMC and mobility changes was also seen for some Asian and South American cities. A clear signal was not observed for other pollutants, suggesting that sources besides vehicular emissions also substantially contributed to the change in air quality. As a global and regional overview of the changes in ambient concentrations of key air quality species, we observed decreases of up to about 70% in mean NO2 and between 30% and 40% in mean PM2.5 concentrations over 2020 full lockdown compared to the same period in 2015–2019. However, PM2.5 exhibited complex signals, even within the same region, with increases in some Spanish cities, attributed mainly to the long-range transport of African dust and/or biomass burning (corroborated with the analysis of NO2/CO ratio). Some Chinese cities showed similar increases in PM2.5 during the lockdown periods, but in this case, it was likely due to secondary PM formation. Changes in O3 concentrations were highly heterogeneous, with no overall change or small increases (as in the case of Europe), and positive anomalies of 25% and 30% in East Asia and South America, respectively, with Colombia showing the largest positive anomaly of ~70%. The SO2 anomalies were negative for 2020 compared to 2015–2019 (between ~25 to 60%) for all regions. For CO, negative anomalies were observed for all regions with the largest decrease for South America of up to ~40%. The NO2/CO ratio indicated that specific sites (such as those in Spanish cities) were affected by biomass burning plumes, which outweighed the NO2 decrease due to the general reduction in mobility (ratio of ~60%). Analysis of the total oxidant (OX = NO2 + O3) showed that primary NO2 emissions at urban locations were greater than the O3 production, whereas at background sites, OX was mostly driven by the regional contributions rather than local NO2 and O3 concentrations. The present study clearly highlights the importance of meteorology and episodic contributions (e.g., from dust, domestic, agricultural biomass burning and crop fertilizing) when analysing air quality in and around cities even during large emissions reductions. There is still the need to better understand how the chemical responses of secondary pollutants to emission change under complex meteorological conditions, along with climate change and socio-economic drivers may affect future air quality. The implications for regional and global policies are also significant, as our study clearly indicates that PM2.5 concentrations would not likely meet the World Health Organization guidelines in many parts of the world, despite the drastic reductions in mobility. Consequently, revisions of air quality regulation (e.g., the Gothenburg Protocol) with more ambitious targets that are specific to the different regions of the world may well be required. ; World Meteorological Organization Global Atmospheric Watch programme is gratefully acknowledged for initiating and coordinating this study and for supporting this publication. We acknowledge the following projects for supporting the analysis contained in this article: Air Pollution and Human Health for an Indian Megacity project PROMOTE funded by UK NERC and the Indian MOES, Grant reference number NE/P016391/1; Regarding project funding from the European Commission, the sole responsibility of this publication lies with the authors. The European Commission is not responsible for any use that may be made of the information contained therein. This project has received funding from the European Commission's Horizon 2020 research and innovation program under grant agreement No 874990 (EMERGE project). European Regional Development Fund (project MOBTT42) under the Mobilitas Pluss programme; Estonian Research Council (project PRG714); Estonian Research Infrastructures Roadmap project Estonian Environmental Observatory (KKOBS, project 2014-2020.4.01.20-0281). European network for observing our changing planet project (ERA-PLANET, grant agreement no. 689443) under the European Union's Horizon 2020 research and innovation program, Estonian Ministry of Sciences projects (grant nos. P180021, P180274), and the Estonian Research Infrastructures Roadmap project Estonian Environmental Observatory (3.2.0304.11-0395). Eastern Mediterranean and Middle East—Climate and Atmosphere Research (EMME-CARE) project, which has received funding from the European Union's Horizon 2020 Research and Innovation Programme (grant agreement no. 856612) and the Government of Cyprus. INAR acknowledges support by the Russian government (grant number 14.W03.31.0002), the Ministry of Science and Higher Education of the Russian Federation (agreement 14.W0331.0006), and the Russian Ministry of Education and Science (14.W03.31.0008). We are grateful to to the following agencies for providing access to data used in our analysis: A.M. Obukhov Institute of Atmospheric Physics Russian Academy of Sciences; Agenzia Regionale per la Protezione dell'Ambiente della Campania (ARPAC); Air Quality and Climate Change, Parks and Environment (MetroVancouver, Government of British Columbia); Air Quality Monitoring & Reporting, Nova Scotia Environment (Government of Nova Scotia); Air Quality Monitoring Network (SIMAT) and Emission Inventory, Mexico City Environment Secretariat (SEDEMA); Airparif (owner & provider of the Paris air pollution data); ARPA Lazio, Italy; ARPA Lombardia, Italy; Association Agréée de Surveillance de la Qualité de l'Air en Île-de-France AIRPARIF / Atmo-France; Bavarian Environment Agency, Germany; Berlin Senatsverwaltung für Umwelt, Verkehr und Klimaschutz, Germany; California Air Resources Board; Central Pollution Control Board (CPCB), India; CETESB: Companhia Ambiental do Estado de São Paulo, Brazil. China National Environmental Monitoring Centre; Chandigarh Pollution Control Committee (CPCC), India. DCMR Rijnmond Environmental Service, the Netherlands. Department of Labour Inspection, Cyprus; Department of Natural Resources Management and Environmental Protection of Moscow. Environment and Climate Change Canada; Environmental Monitoring and Science Division Alberta Environment and Parks (Government of Alberta); Environmental Protection Authority Victoria (Melbourne, Victoria, Australia); Estonian Environmental Research Centre (EERC); Estonian University of Life Sciences, SMEAR Estonia; European Regional Development Fund (project MOBTT42) under the Mobilitas Pluss programme; Finnish Meteorological Institute; Helsinki Region Environmental Services Authority; Haryana Pollution Control Board (HSPCB), IndiaLondon Air Quality Network (LAQN) and the Automatic Urban and Rural Network (AURN) supported by the Department of Environment, Food and Rural Affairs, UK Government; Madrid Municipality; Met Office Integrated Data Archive System (MIDAS); Meteorological Service of Canada; Ministère de l'Environnement et de la Lutte contre les changements climatiques (Gouvernement du Québec); Ministry of Environment and Energy, Greece; Ministry of the Environment (Chile) and National Weather Service (DMC); Moscow State Budgetary Environmental Institution MOSECOMONITORING. Municipal Department of the Environment SMAC, Brazil; Municipality of Madrid public open data service; National institute of environmental research, Korea; National Meteorology and Hydrology Service (SENAMHI), Peru; New York State Department of Environmental Conservation; NSW Department of Planning, Industry and Environment; Ontario Ministry of the Environment, Conservation and Parks, Canada; Public Health Service of Amsterdam (GGD), the Netherlands. Punjab Pollution Control Board (PPCB), India. Réseau de surveillance de la qualité de l'air (RSQA) (Montréal); Rosgydromet. Mosecomonitoring, Institute of Atmospheric Physics, Russia; Russian Foundation for Basic Research (project 20–05–00254) SAFAR-IITM-MoES, India; São Paulo State Environmental Protection Agency, CETESB; Secretaria de Ambiente, DMQ, Ecuador; Secretaría Distrital de Ambiente, Bogotá, Colombia. Secretaria Municipal de Meio Ambiente Rio de Janeiro; Mexico City Atmospheric Monitoring System (SIMAT); Mexico City Secretariat of Environment, Secretaría del Medio Ambiente (SEDEMA); SLB-analys, Sweden; SMEAR Estonia station and Estonian University of Life Sciences (EULS); SMEAR stations data and Finnish Center of Excellence; South African Weather Service and Department of Environment, Forestry and Fisheries through SAAQIS; Spanish Ministry for the Ecological Transition and the Demographic Challenge (MITECO); University of Helsinki, Finland; University of Tartu, Tahkuse air monitoring station; Weather Station of the Institute of Astronomy, Geophysics and Atmospheric Science of the University of São Paulo; West Bengal Pollution Control Board (WBPCB). ; Peer reviewed

Many experiments have shown that local biodiversity loss impairs the ability of ecosystems to maintain multiple ecosystem functions at high levels (multifunctionality). In contrast, the role of biodiversity in driving ecosystem multifunctionality at landscape scales remains unresolved. We used a comprehensive pan-European dataset, including 16 ecosystem functions measured in 209 forest plots across six European countries, and performed simulations to investigate how local plot-scale richness of tree species (α-diversity) and their turnover between plots (β-diversity) are related to landscape-scale multifunctionality. After accounting for variation in environmental conditions, we found that relationships between α-diversity and landscape-scale multifunctionality varied from positive to negative depending on the multifunctionality metric used. In contrast, when significant, relationships between β-diversity and landscape-scale multifunctionality were always positive, because a high spatial turnover in species composition was closely related to a high spatial turnover in functions that were supported at high levels. Our findings have major implications for forest management and indicate that biotic homogenization can have previously unrecognized and negative consequences for large-scale ecosystem multifunctionality. ; We thank the Hainich National Park administration as well as Felix Berthold and Carsten Beinhoff for support of this study and Gerald Kaendler and the Johann Heinrich von Thünen-Institut for providing access to the German National Forest Inventory data. The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 265171. ; This is the final version of the article. It first appeared from the National Academy of Sciences via https://doi.org//10.1073/pnas.1517903113

There is considerable evidence that biodiversity promotes multiple ecosystem functions (multifunctionality), thus ensuring the delivery of ecosystem services important for human well-being. However, the mechanisms underlying this relationship are poorly understood, especially in natural ecosystems. We develop a novel approach to partition biodiversity effects on multifunctionality into three mechanisms and apply this to European forest data. We show that throughout Europe, tree diversity is positively related with multifunctionality when moderate levels of functioning are required, but negatively when very high function levels are desired. For two well-known mechanisms, 'complementarity' and 'selection', we detect only minor effects on multifunctionality. Instead a third, so far overlooked mechanism, the 'jack-of-all-trades' effect, caused by the averaging of individual species effects on function, drives observed patterns. Simulations demonstrate that jack-of-all-trades effects occur whenever species effects on different functions are not perfectly correlated, meaning they may contribute to diversity-multifunctionality relationships in many of the world's ecosystems. ; The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 265171. ; This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/ncomms11109