Diversos estudos teóricos, experimentais e observacionais têm demonstrado que as relações entre a biodiversidade e as funções ecossistêmicas (BEF) são determinadas pela estrutura funcional da comunidade (ou seja, pela distribuição dos atributos das suas espécies constituintes). Isso pode ocorrer por meio de dois mecanismos mutuamente não exclusivos: (1) a hipótese de dominância (também denominada de efeito de relação de massa), na qual os processos ecossistêmicos são influenciados pela média ponderada na comunidade de um dado atributo funcional (CWM) considerado relevante; (2) a hipótese de complementaridade, na qual a maior variabilidade de um atributo funcional na comunidade (FD) é uma expressão da complementariedade de nicho, o que beneficia o desempenho dos processos ecossistêmicos. Embora ambos os mecanismos já tenham sido amplamente estudados em comunidades de plantas em pequenas escalas espaciais, análises globais considerando distintos biomas ainda são necessárias. Neste estudo, a relação entre biodiversidade e funcionamento dos ecossistemas foi avaliada com base na integração entre uma base de dados global de parcelas de vegetação (sPlot), uma base de dados de atributos de espécies de plantas (TRY) e dados do Índice de Vegetação por Diferença Normalizada (NDVI) obtidos por sensoriamento remoto. O objetivo foi verificar, simultaneamente, os efeitos de dominância e de complementaridade sobre a produção de biomassa vegetal em ecossistemas campestres em todo o mundo. Os dados sobre a estrutura funcional das comunidades (CWM e FD) foram obtidos a partir da base de dados sPLOT e TRY, utilizando para isso atributos funcionais de plantas ecologicamente relevantes. O NDVI, considerado como aproximação da produtividade da vegetação, representa uma medida do funcionamento do ecossistema e foi obtido a partir do produto MOD13Q do sensor MODIS, com resolução espacial de 250m. Para garantir que as medidas de NDVI fossem derivadas apenas de ecossistemas campestres, sem a interferência de outras fisionomias vegetais, foram descartadas as parcelas do sPlot com presença de paisagens heterogêneas no seu entorno mediante consulta a um mapa global de cobertura e uso da terra (Globcover2009). Para quantificar os efeitos independentes da dominância e da complementariedade sobre as variações no NDVI , com controle das variáveis climáticas, foi utilizada uma análise de regressão múltipla do tipo commonality. Os resultados demonstraram que o principal preditor da variação no NDVI correspondeu a um conjunto de atributos funcionais das espécies dominantes relacionados com o espectro de economia da comunidade vegetal (atributos fast-slow), indicando a prevalência da hipótese de dominância (R2 ajustado = 0,65). Os efeitos evidentes da dominância e os efeitos potenciais da complementariedade são discutidos no contexto da sua relação com os fatores abióticos, sendo que a precipitação pluviométrica, em particular, parece ter maior influência tanto sobre a composição de atributos quanto sobre a produtividade. Apesar de algumas limitações metodológicas, a abordagem inovadora utilizada neste trabalho pode ajudar a esclarecer as relações entre biodiversidade e funções ecossistêmicas em escala global, dentro de uma perspectiva integradora e baseada em dados. / Theoretical, experimental and observational studies show that biodiversity ecosystem functioning (BEF) relationships are determined by functional community structure (i.e. trait distributions in a community) through two mutually non-exclusive mechanisms: (1) The dominance hypothesis (a.k.a. mass ratio effect) links ecosystem processes to the community weighted mean (CWM) of a relevant effect trait. (2) The complementarity hypothesis states that higher variability of a trait value within a community (FD) reflects niche complementarity enhancing ecosystem processes. While both mechanisms have been extensively studied in plant communities at small spatial scales, there is a need for global analyses across biomes. Here, a data driven approach to the BEF question is presented integrating a global vegetation plot database with a trait database and remotely sensed NDVI. The objective of this study was to simultaneously evaluate dominance and complementarity effects in grassland systems worldwide. Data on functional community structure (CWM and FD) were obtained from the global vegetation plot database sPlot in combination with the plant trait database TRY using 18 ecologically relevant plant traits. Ecosystem functioning at the selected sPlot sites (n = 2941) was measured as NDVI at a spatial resolution of 250m using the MODIS product MOD13Q (annual peak NDVI being a proxy of productivity). The landcover map Globcover2009 was used for characterization of landscape heterogeneity and landcover at each site, and plots in heterogeneous non-grassland pixels were discarded. Multiple regression commonality analysis was used to disentangle the contributions of complementarity and dominance effects to the variation in NDVI, while controlling for climate variables (adjusted R2 = 0.65). The results show that a plant community economics spectrum referring to the “fast-slow traits” of the dominant species in the community was the strongest predictor of the NDVI values in the grassland systems (dominance effect). Both, evident dominance and potential complementarity effects are discussed against the background of their interplay with abiotic factors and it is noted that especially precipitation seems to drive trait composition and productivity. Despite methodological shortcomings, the novel approach presented in this paper is considered a step towards a more integrative data-driven BEF debate at the global scale

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-09-19T21:47:36Z No. of bitstreams: 1 LeonardoHenriqueTeixeiraPinto_TESE.pdf: 6347370 bytes, checksum: 7e4c7fd1b6d9c592bdf652c6591c248c (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-09-22T19:20:30Z (GMT) No. of bitstreams: 1 LeonardoHenriqueTeixeiraPinto_TESE.pdf: 6347370 bytes, checksum: 7e4c7fd1b6d9c592bdf652c6591c248c (MD5) / Made available in DSpace on 2017-09-22T19:20:30Z (GMT). No. of bitstreams: 1 LeonardoHenriqueTeixeiraPinto_TESE.pdf: 6347370 bytes, checksum: 7e4c7fd1b6d9c592bdf652c6591c248c (MD5) Previous issue date: 2017-05-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A biodiversidade afeta positivamente diversas fun??es ecossist?micas. No entanto, os mecanismos pelos quais a biodiversidade afeta os ecossistemas ainda s?o pouco compreendidos e requerem novos estudos experimentais destinados a identificar seus componentes. Estudos anteriores sugeriram que comunidades de plantas mais diversas podem proporcionar mais estabilidade aos ecossistemas, devido aos efeitos de complementaridade e redund?ncia. A diversidade das esp?cies de plantas pode atuar em diferentes n?veis das propriedades de um ecossistema. Um exemplo claro ? o efeito da diversidade de plantas sobre a din?mica de nutrientes nos ecossistemas terrestres. A diversidade de plants pode alterar as taxas de ac?mulo de nutrientes no solo e, tamb?m, a carga de nutrientes para os sistemas aqu?ticos. No entanto, os impactos antr?picos nos ecossistemas t?m causado a perda de habitats e, tamb?m, de biodiversidade. Tais perdas acabar?o por comprometer as fun??es dos ecossistemas e seus servi?os associados, que s?o vitais para o bem-estar humano. Portanto, o desenvolvimento de projetos de restaura??o ? fundamental para mitigar os impactos antr?picos e para a conserva??o da biodiversidade. Projetos de restaura??o oferecem a possibilidade de desenvolver um conhecimento s?lido sobre o funcionamento dos ecossistemas diante diferentes tipos de perturba??es. Para alcan?ar esse conhecimento, precisamos realizar experimentos de restaura??o baseados no conhecimento cient?fico para avaliar a variabilidade, a previsibilidade e a confiabilidade do funcionamento dos ecossistemas restaurados. Neste contexto, esta tese de doutorado ? baseada em tr?s experimentos que testaram como a diversidade de plantas e suas caracter?sticas funcionais poderiam influenciar o funcionamento dos ecossistemas restaurados. Os objetivos dessa tese foram: (i) investigar quais esp?cies de plantas e caracter?sticas funcionais s?o mais eficientes paraa reten??o de nutrientes no solo, reduzindo assim as perdas por lixivia??o e seu consequente impacto nos ecossistemas aqu?ticos; (ii) testar os efeitos da riqueza de esp?cies vegetais e da diversidade filogen?tica para o sucesso da restaura??o de uma floresta rip?ria rec?m restaurada (i.e. o sucesso foi medido como produ??o de biomassa e sobreviv?ncia das plantas); e (iii) avaliar a influ?ncia de uma esp?cie de planta invasora sobre as din?micas de nutrientes no solo e na ?gua do solo em comunidades de pastagem com diferentes n?veis de diversidade funcional. Os experimentos realizados para esta tese est?o de acordo com estudos recentes que investigam como diferentes medidas de biodiversidade e, tamb?m, diferentes fontes de estresse podem afetar o funcionamento dos ecossistemas. Os principais resultados desta tese revelam que (i) apenas uma esp?cie de planta (Mimosa tenuiflora) influenciou a limpeza da ?gua e a reten??o de nutrientes do solo. Al?m disso, tra?os funcionais relacionados ao conte?do de mat?ria seca da parte a?rea (SDMC) e ao teor de ?gua da raiz (RWC) foram mais importantes para o controle de fun??es ecossist?micas individuais relacionadas ? reten??o de ?gua e nutrientes no solo. De outro modo, somente tra?os funcionais relacionados ? produ??o de biomassa nas plantas afetaram a multifuncionalidade do ecossistema; (ii) o uso de esp?cies filogeneticamente distantes pode aumentar o sucesso da restaura??o afetando positivamente a produ??o de biomassa nas plantas; e (iii) a diversidade funcional das plantas promoveu, parcialmente, a limpeza da ?gua e, tamb?m, a fertilidade do solo em pastagens restaurados, mas n?o impediu a invas?o. Esp?cies invasoras, por sua vez, comprometem a influ?ncia da diversidade de plantas nativas na din?mica de nutrientes no solo, uma vez que afetam negativamente a produ??o de biomassa das plantas nativas. Esse efeito tem o potencial para criar um feedback positivo para novas invas?es. Tais resultados podem servir de suporte para o desenvolvimento de futuros projetos de restaura??o com ?nfase no controle de esp?cies invasoras e na restaura??o do funcionamento dos ecossistemas, uma vez que pode indicar quais esp?cies s?o mais adequadas para maximizar a fertilidade do solo e, tamb?m, a qualidade da ?gua do solo. Por fim, esta tese oferece uma contribui??o para o aprofundarmos o entendimento a respeito dos feedbacks entre plantas e solos. / Biodiversity positively affects several ecosystem functions. Nevertheless, the mechanisms by which biodiversity affects ecosystems are still poorly understood and call for new experimental studies designed to identify its underlying components. Previous studies have suggested that more diverse plant communities can provide more ecosystem stability due to complementarity and redundancy effects. Plant species diversity can act on different levels of the ecosystem properties. A clear example is the effect of plant diversity on nutrient dynamics of terrestrial ecosystems. Plant diversity can alter rates of soil nutrient accumulation and nutrient loading in aquatic systems. However, human impacts on natural ecosystems are leading to habitat and biodiversity loss. Such losses will ultimately jeopardize ecosystem functions and its associated services that are vital for human well-being. Therefore, the development of adequate restoration projects is paramount to mitigate anthropogenic impacts, while contributing to the conservation of biodiversity. Restoration projects offer the possibility to develop a solid knowledge on the functioning of ecosystems facing disturbance. For achieving this knowledge, we need to conduct theory-based restoration experiments in order to assess the variability, predictability and reliability of functioning from restored ecosystems. In this context, this PhD thesis is based on three experiments testing how plant diversity and functional traits would influence the functioning of restored ecosystems. The objectives are to investigate (i) the plant species and traits that are most efficient for retaining nutrients in the soil, thus reducing nutrient leaching losses and its consequent impact on aquatic systems; (ii) the effects of plant species richness and phylogenetic diversity on restoration success (measured as biomass production and plant survival) in a recently restored riparian forest; and (iii) the influence of an invasive alien plant species on soil and soil water nutrients in communities with different levels of functional diversity. The experiments conducted during this thesis are in accordance with recent studies that investigate how different measures of biodiversity and sources of stress could affect ecosystem functioning. The main results of this thesis reveal that (i) only one species (Mimosa tenuiflora) could influence water cleaning and soil nutrient content. Additionally, plant traits related to shoot dry matter content (SDMC) and root water content (RWC) are more important for controlling individual functions related to water and nutrient retention in the soil, while only traits related to biomass production affected ecosystem multifunctionality; (ii) the use of phylogenetically distant species can increase restoration success by positively affecting plant biomass production; and (iii) plant functional diversity partially promotes water cleaning and soil fertility in restored systems, nevertheless did not prevent invasion. In turn, invasive species disrupts the influence of plant diversity on soil nutrient dynamics by jeopardizing native plant biomass production thus, potentially, creating a positive feedback for further invasions. These results support future restoration projects focusing on invasive species control and ecosystem functions, indicating which species are most suitable for restoration to maximizing soil fertility and soil water quality. Finally, this thesis offers a contribution to the knowledge of plant-soil feedbacks.

Diversos estudos teóricos, experimentais e observacionais têm demonstrado que as relações entre a biodiversidade e as funções ecossistêmicas (BEF) são determinadas pela estrutura funcional da comunidade (ou seja, pela distribuição dos atributos das suas espécies constituintes). Isso pode ocorrer por meio de dois mecanismos mutuamente não exclusivos: (1) a hipótese de dominância (também denominada de efeito de relação de massa), na qual os processos ecossistêmicos são influenciados pela média ponderada na comunidade de um dado atributo funcional (CWM) considerado relevante; (2) a hipótese de complementaridade, na qual a maior variabilidade de um atributo funcional na comunidade (FD) é uma expressão da complementariedade de nicho, o que beneficia o desempenho dos processos ecossistêmicos. Embora ambos os mecanismos já tenham sido amplamente estudados em comunidades de plantas em pequenas escalas espaciais, análises globais considerando distintos biomas ainda são necessárias. Neste estudo, a relação entre biodiversidade e funcionamento dos ecossistemas foi avaliada com base na integração entre uma base de dados global de parcelas de vegetação (sPlot), uma base de dados de atributos de espécies de plantas (TRY) e dados do Índice de Vegetação por Diferença Normalizada (NDVI) obtidos por sensoriamento remoto. O objetivo foi verificar, simultaneamente, os efeitos de dominância e de complementaridade sobre a produção de biomassa vegetal em ecossistemas campestres em todo o mundo. Os dados sobre a estrutura funcional das comunidades (CWM e FD) foram obtidos a partir da base de dados sPLOT e TRY, utilizando para isso atributos funcionais de plantas ecologicamente relevantes. O NDVI, considerado como aproximação da produtividade da vegetação, representa uma medida do funcionamento do ecossistema e foi obtido a partir do produto MOD13Q do sensor MODIS, com resolução espacial de 250m. Para garantir que as medidas de NDVI fossem derivadas apenas de ecossistemas campestres, sem a interferência de outras fisionomias vegetais, foram descartadas as parcelas do sPlot com presença de paisagens heterogêneas no seu entorno mediante consulta a um mapa global de cobertura e uso da terra (Globcover2009). Para quantificar os efeitos independentes da dominância e da complementariedade sobre as variações no NDVI , com controle das variáveis climáticas, foi utilizada uma análise de regressão múltipla do tipo commonality. Os resultados demonstraram que o principal preditor da variação no NDVI correspondeu a um conjunto de atributos funcionais das espécies dominantes relacionados com o espectro de economia da comunidade vegetal (atributos fast-slow), indicando a prevalência da hipótese de dominância (R2 ajustado = 0,65). Os efeitos evidentes da dominância e os efeitos potenciais da complementariedade são discutidos no contexto da sua relação com os fatores abióticos, sendo que a precipitação pluviométrica, em particular, parece ter maior influência tanto sobre a composição de atributos quanto sobre a produtividade. Apesar de algumas limitações metodológicas, a abordagem inovadora utilizada neste trabalho pode ajudar a esclarecer as relações entre biodiversidade e funções ecossistêmicas em escala global, dentro de uma perspectiva integradora e baseada em dados. / Theoretical, experimental and observational studies show that biodiversity ecosystem functioning (BEF) relationships are determined by functional community structure (i.e. trait distributions in a community) through two mutually non-exclusive mechanisms: (1) The dominance hypothesis (a.k.a. mass ratio effect) links ecosystem processes to the community weighted mean (CWM) of a relevant effect trait. (2) The complementarity hypothesis states that higher variability of a trait value within a community (FD) reflects niche complementarity enhancing ecosystem processes. While both mechanisms have been extensively studied in plant communities at small spatial scales, there is a need for global analyses across biomes. Here, a data driven approach to the BEF question is presented integrating a global vegetation plot database with a trait database and remotely sensed NDVI. The objective of this study was to simultaneously evaluate dominance and complementarity effects in grassland systems worldwide. Data on functional community structure (CWM and FD) were obtained from the global vegetation plot database sPlot in combination with the plant trait database TRY using 18 ecologically relevant plant traits. Ecosystem functioning at the selected sPlot sites (n = 2941) was measured as NDVI at a spatial resolution of 250m using the MODIS product MOD13Q (annual peak NDVI being a proxy of productivity). The landcover map Globcover2009 was used for characterization of landscape heterogeneity and landcover at each site, and plots in heterogeneous non-grassland pixels were discarded. Multiple regression commonality analysis was used to disentangle the contributions of complementarity and dominance effects to the variation in NDVI, while controlling for climate variables (adjusted R2 = 0.65). The results show that a plant community economics spectrum referring to the “fast-slow traits” of the dominant species in the community was the strongest predictor of the NDVI values in the grassland systems (dominance effect). Both, evident dominance and potential complementarity effects are discussed against the background of their interplay with abiotic factors and it is noted that especially precipitation seems to drive trait composition and productivity. Despite methodological shortcomings, the novel approach presented in this paper is considered a step towards a more integrative data-driven BEF debate at the global scale

Deux facteurs principaux, une fois combinés, permettent de comprendre l’assemblage des communautés, soient i) l’environnement (abiotique et biotique), qui agit comme un filtre sélectionnant les espèces les mieux adaptées aux conditions données, et ii) les traits fonctionnels, sur lesquels s’effectue ce filtrage environnemental puisqu’ils peuvent conférer des avantages sélectifs sous diverses conditions. Il est donc essentiel d’établir des relations fiables entre les conditions environnementales et la structure fonctionnelle des communautés afin de pouvoir identifier et comprendre les mécanismes régissant l’assemblage des communautés. Cependant, plusieurs facteurs tels que les interactions entre variables à différentes échelles spatiales peuvent complexifier la situation et c’est pourquoi, malgré une quantité grandissante d’études sur le sujet, les processus d’assemblage des communautés restent difficiles à définir et à généraliser. Cette thèse vise donc à i) mieux définir et quantifier les relations trait-environnement des systèmes d’herbacées au travers de différentes échelles spatiales et ii) déterminer l’influence de ces relations sur l’assemblage des communautés et le fonctionnement des écosystèmes. Pour réaliser ces objectifs, j’ai travaillé avec les données de programmes ayant collecté des données taxonomiques et fonctionnelles sur les communautés d’herbacées à travers la France (DivHerbe et DivGrass) et, à moindre mesure, l’Europe (VISTA). Ces bases de données couvrent donc de larges gradients climatiques régionaux ainsi que des gradients environnementaux plus locaux relatifs à la qualité des sols et aux perturbations.J’ai d’abord testé l’importance de considérer à la fois des variables environnementales locales et régionales ainsi que leurs interactions pour déterminer la structure fonctionnelle et taxonomique des communautés. J’ai ensuite étudié comment l’importance relative des processus menant soit à la convergence ou à la divergence fonctionnelle peut changer le long d’une succession, puis comment ces deux types de processus influencent notre capacité à prédire l’assemblage des communautés à partir des traits fonctionnels. Finalement, j’ai présenté comment les résultats au niveau des communautés peuvent être utiles pour étudier le niveau des écosystèmes. Les résultats de cette thèse démontrent que les variables climatiques régionales interagissent fortement avec les variables environnementales locales pour influencer les processus locaux déterminant l’assemblage des communautés. Évaluer le contexte régional semble donc nécessaire afin d’éviter des interprétations erronées des patrons d’assemblage observés. Travaillant avec ces deux niveaux de variation environnementale, une dissociation important entre la variation taxonomique et fonctionnelle des communautés a été mise à jour, reflétant l’importance de considérer plusieurs facettes de biodiversité pour comprendre la dynamique des communautés. Les résultats ont aussi démontré que les processus d’assemblage menant à la convergence et à la divergence ont un impact très différent et prédictible sur les relations liant les traits et les abondances des espèces, c’est-à-dire notre capacité à prédire l’assemblage des communautés à partir des traits. Finalement, toutes ces notions, relatives aux relations trait-environnement et à l’assemblage des communautés basé sur les traits, ont été utilisées dans un contexte de biogéographie fonctionnelle. Il a été démontré qu’il était possible de construire des cartes de valeurs de traits fonctionnels dans les prairies permanentes à l’échelle de la France, à partir de variables environnementales. Certaines propriétés écosystémiques ont ensuite pu être prédites à partir de ces cartes. Ces travaux ont donc permis d’illustrer les défis à surmonter pour utiliser nos connaissances de l’écologie fonctionnelle en vue d’une conservation et d’une exploitation viables de nos écosystèmes. / There are two main factors which, combined together, allow understanding community assembly : i) the environment (both abiotic and biotic), which acts as a filter selecting species according to how well-adapted they are to given conditions, and ii) functional traits, on which this environmental filtering occurs since they represent species adaptations to particular conditions. It is thus essential to establish reliable relationships between environmental conditions and the functional structure of communities in order to identify and understand the mechanisms driving community assembly. However, several factors such as cross-scale interactions between environmental variables complicate the situation. This is why, despite a growing body of studies on the subject, processes of community assembly are still poorly understood and are difficult to generalize. The purpose of this thesis is to i) better define and quantify the trait-environment relationships in herbaceous systems across different spatial scales and ii) determine the influence of those relationships on community assembly and on ecosystem functioning. To realize these objectives, I worked with data from programs which assembled taxonomic and functional data on herbaceous communities across France (DivHerbe and DivGrass) and, to a lesser extent, Europe (VISTA). These databases thus cover large regional climatic gradients, as well as more local environmental gradients related to soil quality and disturbances. I first tested the importance of simultaneously considering local and regional environmental variables as well as their interactions to determine the taxonomic and functional structure of communities. Then, I studied how the relative importance of processes leading to either functional convergence or divergence can change along a successional gradient, and how these two types of processes influence our ability to predict community assembly from functional traits. Finally, I presented how the results at the community-level can be used to study the ecosystem-level. The results of this thesis demonstrate that regional climatic variables strongly interact with local environmental variables in driving the local processes responsible for community assembly. Assessing the regional context is thus necessary in order to avoid erroneous interpretations of observed assembly patterns. Working with those two levels of environmental variation, important discrepancies were found between taxonomic and functional variations across communities, reflecting the importance of considering several aspects of biodiversity in order to understand community dynamics. The results also demonstrated that the assembly processes leading to functional convergence and divergence have a very different and predictable impact on the relationships between traits and species relative abundances, i.e. on our ability to predict community assembly from traits. Finally, these notions related to trait-environment relationships and to trait-based community assembly were used in a functional biogeography framework: It was possible to build maps of functional traits values in permanent grasslands across France using environmental variables. These maps then allowed predicting particular ecosystem properties. Thus, this work allowed illustrating some challenges that we are facing in using our knowledge in functional ecology to build sustainable conservation and exploitation plans for our ecosystems.

Les plantes, comme tous les êtres vivants, entretiennent un rapport double à leur environnement. L’environnement sélectionne quelles stratégies peuvent s’établir, et les stratégies ainsi sélectionnées façonnent en retour cet environnement. Cette boucle de rétroaction environnementale, lorsqu’elle est alimentée par une variabilité de formes, est le moteur de l’évolution, de l’assemblage des communautés et du développement écosystémique, et détermine en fin de compte les propriétés émergentes des écosystèmes.Les approches issues de l’écologie théorique reconnaissent depuis longtemps cette dualité, comme en témoignent les concepts de "niche de besoin" et "niche d’impact" au cœur de la théorie contemporaine de la niche. Similairement, les approches type « théorie des jeux » comme la dynamique adaptative reconnaissent le rôle central joué par la boucle de rétroaction environnementale en tant que moteur des dynamiques éco-évolutives.Dans cette thèse, j'unifie ces deux perspectives théoriques et les applique à des problèmes écologiques variés, dans le but de comprendre comment les interactions réciproques entre les plantes et leur environnement déterminent les traits adaptatifs des plantes et les propriétés émergentes des écosystèmes.Dans un premier temps, je propose un cadre mathématique général et rigoureux à la théorie contemporaine de la niche et la méthode graphique qui lui est associée. Après avoir étendu ce cadre à la prise en compte d’un continuum de stratégies en interaction à l’aide d’enveloppes géométriques, je montre comment appliquer la théorie contemporaine de la niche à deux perspectives, à savoir les dynamiques éco-évolutives et l’assemblage de communautés par remplacements successifs de stratégies.Dans un second temps, j’applique cette approche à l’étude de l’évolution des défenses des plantes contre les herbivores le long de gradients de nutriments, en considérant l’évolution des traits d’acquisition de la ressource, de tolérance et de résistance aux herbivores. Je montre que la prise en compte des transferts trophiques conduit à la sélection de stratégies compétitives mais sans défense dans les environnements pauvres, alors que ce sont toujours des stratégies défendues (résistantes, tolérantes, ou la coexistence des deux) qui dominent dans les environnements riches en nutriments. Mes résultats mettent en évidence le rôle central joué par la rétroaction plante-herbivores dans la détermination des patrons de défense des plantes.Dans un troisième temps, je montre comment la théorie contemporaine de la niche peut être étendue pour prendre en compte la facilitation. J’utilise ensuite cette approche pour montrer comment la colonisation d’un substrat nu par une communauté de plantes fixatrices d’azote couplée au recyclage des nutriments peut donner naissance à de la succession par facilitation. Contrairement aux modèles habituels de succession, je montre que la succession par facilitation donne lieu à un développement autogène de l’écosystème ainsi qu’un régime de bistabilité entre la végétation et le substrat nu en fin de succession. Enfin, je propose une nouvelle théorie de la succession basée sur les ratios de ressources.Pris dans leur ensemble, ces nouveaux développements démontrent que la théorie de la niche peut être adaptée à l’étude d’un large champ de situations écologiques, de la facilitation aux dynamiques éco-évolutives et à l’assemblage des communautés. Dans ce cadre conceptuel, mon approche basée sur les enveloppes s’avère être un outil efficace pour passer de l’échelle individuelle à l’échelle de l’écosystème, en assimilant le remplacement adaptatif d’espèces à une plasticité des propriétés écosystémiques. Cette approche permet alors de décrire l’émergence des boucles de régulation qui contrôlent le fonctionnement des écosystèmes, comme l’illustrent mes résultats le long de gradients de nutriments sur la transition entre régimes de succession ou encore l’émergence de culs-de-sac trophiques. / As living organisms, plants present a dual relationship with their biotic and abiotic environment. The environment selects plant strategies that can establish, and selected strategies in turn impact and shape the environment as they spread. When fueled by variation ,this environmental feedback loop drives evolution, community assembly and ecosystem development, and eventually determines the emergent properties of ecosystems.Theoretical ecology approaches have long recognized this duality, as it is at the core of contemporary niche theory through the concepts of requirement and impact niche. Similarly, game-theoretical approaches such as adaptive dynamics have emphasized the role played by the environmental feedback loop in driving eco-evolutionary dynamics. However, niche theory could benefit from a more individualistic, selection based perspective, while adaptive dynamics could benefit from niche theory’s duality and graphical approach.In my dissertation, I unify these theoretical perspectives and apply them to various ecological situations in an attempt to understand how the reciprocal interaction between plants and their environment determines plant adaptive traits and emergent ecosystem functions.First, I introduce a general and rigorous mathematical framework to contemporary niche theory and the associated graphical approach. By extending these ideas to a continuum of interacting strategies using geometrical envelopes, I show how contemporary niche theory enables the study of both eco-evolutionary dynamics and community assembly through species sorting. I show how these two perspectives only differ by the range of invaders considered, from infinitesimally similar mutants to any strategy from the species pool. My results also emphasize the fact that selection only acts on the requirement niche, evolution of the impact niche being just an indirect consequence of the former.Second, I use this approach to study the evolution of plant defenses against herbivores along a nutrient gradient, by considering the joint evolution of resource acquisition, tolerance and resistance to herbivores. I show that trophic transfers lead to the selection of very competitive, undefended strategies in nutrient-poor environments, while defended strategies -- either resistant, tolerant or the coexistence of both -- always dominate in nutrient-rich environments. My results highlight the central, and often underestimated, role played by plant-environment feedbacks in shaping plant defense patterns.Third, I extend contemporary niche theory to facilitation originating from positive environmental feedback loops. I use these new tools to show how colonization of a bare substrate by a community of nitrogen-fixing plants coupled with nutrient recycling can lead to facilitative succession. Contrarily to previous competition-based succession models, I point out that facilitative succession leads to autogenic ecosystem development, relatively ordered trajectories and late succession bistability between the vegetated ecosystem and the bare substrate. By showing how facilitative succession can turn into competition-based succession along an increasing nitrogen gradient, I derive a new resource-ratio theory of succession.Overall, these new theoretical developments demonstrate that niche theory can be adapted to study a broad range of ecological situations, from facilitation to eco-evolutionary dynamics and community assembly. Within this framework, my envelope-based approach provides a powerful tool to scale from the individual level to the ecosystem level, lumping selection-driven species turnover into plastic ecosystem properties. This, is turn, helps describing the emergence at the ecosystem scale of regulation feedback loops that drive ecosystem dynamics and functioning, as exemplified by my results along increasing resource gradients showing a transition from facilitation- to competition-based succession or the emergence of trophic dead-ends.

O funcionamento dos ecossistemas é o fluxo de matéria e de energia ao longo dos seus componentes bióticos e abióticos. A manutenção de tal funcionamento é crucial para promover os serviços ecossistêmicos dos quais a humanidade depende. Atividades antrópicas, como a agricultura e a urbanização podem alterá-los significativamente e, por isso, o entendimento dos impactos positivos e negativos de tais alterações bem como o desenvolvimento de ferramentas de avaliação da biodiversidade são importantes para a conservação. A diversidade funcional é um componente da diversidade biológica que leva em conta o papel que cada espécie desempenha no ecossistema e, portanto, deve refletir o funcionamento do ecossistema de forma mais acurada. Esta tese teve por objetivos relacionar o funcionamento do ecossistema e os seus serviços a ações antrópicas, bem como propor a abordagem funcional como indicadora da biodiversidade de áreas naturais. No primeiro capítulo, avalio padrões espaciais e temporais da exposição dos tipos de vegetação que ocorrem no Brasil à luz artificial, um dos principais símbolos da urbanização e da vida moderna. Os resultados mostram que a maioria deles apresenta alguma porcentagem de sua área expostos à luz artificial. Em alguns deles, porém, ainda é possível encontrar o brilho natural do céu noturno, o que nos permite sugerir a elaboração de políticas de desenvolvimento de distribuição de luz com foco no mínimo impacto, ao contrário das políticas de mitigação adotadas por países onde a iluminação é excessivamente difundida. No segundo capítulo mapeio padrões espaciais e temporais da provisão de dois serviços ecossistêmicos (polinização e estoque de carbono) e um serviço ambiental (espaço para viver) e avalio os impactos da agricultura sobre estes serviços, na área coberta pelo cerrado, na região central do Brasil. Os serviços ecossistêmicos avaliados descaíram significativamente ao longo do tempo e a região conhecida como MATOPIBA (entre os estados do Maranhão, Tocantins, Piauí e Bahia) foi identificada como um importante remanescente. Por isso, recomendo a criação de unidades de conservação de proteção integral na área. Identifiquei também sobreposição da disponibilidade destes serviços com áreas indígenas, o que ressalta a importância da manutenção destas áreas para a disponibilidade dos serviços. No terceiro capítulo exploro, por meio de revisão bibliográfica, o status da diversidade funcional na literatura científica no campo da Conservação Biológica. Os resultados permitiram visualizar o paradigma da transferência de conhecimento e identificar o potencial desta abordagem para elaboração de indicadores da biodiversidade. Por fim, no quarto capítulo, estabeleço uma lista de espécies de plantas que podem ser indicadoras da diversidade funcional em áreas cobertas por cerradão no estado de São Paulo. Tais indicadores devem ser usados em conjunto para monitoramento e diagnóstico da biodiversidade quando o objetivo é manter o funcionamento do ecossistema. As conclusões do estudo contribuem para elucidar a interferência das atividades antrópicas nos ecossistemas naturais, para levantar formas de minimizá-los e para aprimorar as formas de avaliação da biodiversidade. / Ecosystem functioning is the flow of energy and matter through the biotic and abiotic ecosystems components. The maintenance of this functioning is essential to the ecosystem services provisioning upon which humans depend. Anthropogenic activities such as agriculture and urbanisation may change it. Thus, conservation strategies rely on the understanding of the positives and negatives impacts from this changes and on the development of measurements of biodiversity. Functional diversity is a biodiversity component which considers the role of each species in the ecosystem, and, as a consequence, may reflect the ecosystem functioning more accurately. This thesis aims the establishment of the relationships between ecosystem functioning, ecosystem services and anthrogenic activities as well as purpose functional approach as biodiversity indicator of natural areas. In the first chapter, I assessed spatial and temporal patterns of exposition of the Brazilian vegetation types to the artificial light which is one of the urbanisation symbols. The results show that most of them are affected by artificial light. However, in some of them it is still possible to find a natural sky background, which allow suggesting the formulation of light distribution policies focused on minimal impact instead of mitigation, as adopted by countries where light is excessively widespread. In the second chapter, I mapped spatial and temporal patterns of two ecosystem services provisioning (pollination and carbon stocks) and one environmental service (living space) and assessed the impacts of agriculture in these services in Cerrado area, in the central region of Brazil. The ecosystem services I assessed declined significatively over time and the MATOPIBA region (around Maranhão, Tocantins, Piaui, and Bahia States) was identified as an important remint. Thus I recommended the creation of strictly protected areas in that region. I also identify overlap of these services with indigenous land, highlighting its importance for the ecosystem services provisioning. In the third chapter I explored through literature survey, the status of functional diversity in the scientific literature related to the Biological Conservation field. The results allow visualise the paradigm of knowledge transfer and identify the potential use of this approach for developing indicators of biodiversity. Finally, in the fourth chapter, we established a list of plant species that are functional diversity indicators in cerradão areas in São Paulo State. These indicators should be use as a set for the monitoring and diagnosis of biodiversity when the goal is to maintaining ecosystem functioning. The conclusions of the study contribute to clarify some lack of knowledge concerned to the impacts of human activities on ecosystem functioning, to raise means to minimise them, and to improve means of ecological integrity assessment.

Future global change scenarios predict a dramatic loss of biodiversity for many regions in the world, potentially reducing the resistance and resilience of ecosystem functions. Once before, during Plio-Pleistocene glaciations, harsher climatic conditions in Europe as compared to North America led to a more depauperate tree flora. Here we hypothesize that this climate driven species loss has also reduced functional diversity in Europe as compared to North America. We used variation in 26 traits for 154 North American and 66 European tree species and grid-based co-occurrences derived from distribution maps to compare functional diversity patterns of the two continents. First, we identified similar regions with respect to contemporary climate in the temperate zone of North America and Europe. Second, we compared the functional diversity of both continents and for the climatically similar subregions using the functional dispersion-index (FDis) and the functional richness index (FRic). Third, we accounted in these comparisons for grid-scale differences in species richness, and, fourth, investigated the associated trait spaces using dimensionality reduction. For gymnosperms we find similar functional diversity on both continents, whereas for angiosperms functional diversity is significantly greater in Europe than in North America. These results are consistent across different scales, for climatically similar regions and considering species richness patterns. We decomposed these differences in trait space occupation into differences in functional diversity vs. differences in functional identity. We show that climate-driven species loss on a continental scale might be decoupled from or at least not linearly related to changes in functional diversity. This might be important when analyzing the effects of climate-driven biodiversity change on ecosystem functioning.

Climate change has created potential major threats to global biodiversity. The multiple components of climate change are projected to affect all pillars of biodiversity, from genes over species to biome level. Of particular concerns are "tipping points" where the exceedance of ecosystem thresholds will possibly lead to irreversible shifts of ecosystems and their functioning. As biodiversity underlies all goods and services provided by ecosystems that are crucial for human survival and wellbeing, this paper presents potential effects of climate change on biodiversity, its plausible impacts on human society as well as the setting in addressing a global crisis. Species affected by climate change may respond in three ways: change, move or die. Local species extinctions or a rapidly affected ecosystem as a whole respectively might move toward its particular "tipping point", thereby probably depriving its services to human society and ending up in a global crisis. Urgent and appropriate actions within various scenarios of climate change impacts on biodiversity, especially in tropical regions, are needed to be considered. Foremost a multisectoral approach on biodiversity issues with broader policies, stringent strategies and programs at international, national and local levels is essential to meet the challenges of climate change impacts on biodiversity.

Soil biodiversity and related ecosystem functions are neglected in most biodiversity assessments and nature conservation actions. We examined how society, and particularly policy makers, have addressed these factors worldwide with a focus on Europe and explored the role of soils in nature conservation in Germany as an example. We reviewed past and current global and European policies, compared soil ecosystem functioning inand outside protected areas, and examined the role of soils in nature conservation management via text analyses. Protection and conservation of soil biodiversity and soil ecosystem functioning have been insufficient. Soil-related policies are unenforceable and lack soil biodiversity conservation goals, focusing instead on other environmental objectives.We found no evidence of positive effects of current nature conservation measures in multiple soil ecosystem functions in Europe. In German conservation management, soils are considered only from a limited perspective (e.g., as physicochemical part of the environment and as habitat for aboveground organisms). By exploring policy, evidence, and management as it relates to soil ecosystems, we suggest an integrative perspective to move nature conservation toward targeting soil ecosystems directly (e.g., by setting baselines, monitoring soil threats, and establishing a soil indicator system).

Les écologistes reconnaissent depuis longtemps que les organismes sont soutenus par le flux, l’emmagasinage et le renouvellement d’énergie et de matériel de l’écosystème, puisqu’ils sont nécessaires au métabolisme biologique et à la construction de biomasse. L’importance des organismes dans la régularisation des processus écosystémiques est maintenant de plus en plus considérée. Situé au centre des chaînes trophiques aquatiques, le zooplancton influence les flux d’énergie et de matériel dans les écosystèmes. Plusieurs de leurs caractéristiques sont connues comme étant de bons indicateurs de leur effet sur l’environnement, notamment leur taille, contenu corporel et taux métabolique. La plupart de ces caractéristiques peuvent être appelées « traits fonctionnels ». Alors que l’emploi des traits devient de plus en plus populaire en écologie des communautés aquatiques, peu ont su utiliser cette approche afin de concrètement lier la structure des communautés zooplanctoniques aux processus écosystémiques. Dans cette étude, nous avons colligé les données provenant d’une grande variété de littérature afin de construire une base de données sur les traits du zooplancton crustacé contribuant directement ou indirectement aux flux de C, N et P dans les écosystèmes. Notre méta-analyse a permis d’assembler plus de 9000 observations sur 287 espèces et d’identifier par le fait même ce qu’il manque à nos connaissances. Nous avons examiné une série de corrélations croisées entre 16 traits, dont 35 étaient significatives, et avons exploré les relations entre les unités taxonomiques de même qu’entre les espèces marines et d’eaux douces. Notre synthèse a entre autres révélé des patrons significativement différents entre le zooplancton marin et dulcicole quant à leur taux de respiration et leur allométrie (masse vs. longueur corporelle). Nous proposons de plus une nouvelle classification de traits liant les fonctions des organismes à celles de l’écosystème. Notre but est d’offrir une base de données sur les traits du zooplancton, des outils afin de mieux lier les organismes aux processus écosystémiques et de stimuler la recherche de patrons généraux et de compromis entre les traits. / Ecologists have long recognized that organisms are sustained by the flux, storage and turnover of ecosystem energy, which fuels biological metabolism, and material, used to construct biomass. Over the past three decades, the importance of individual organisms in regulating ecosystem processes, such as consumer-driven nutrient cycling, has been increasingly recognized. Occupying a central position in aquatic food webs, zooplankton are known to influence other trophic levels and exert a strong influence on energy fluxes or material processing in ecosystems. Several species’ characteristics have been pointed out as being good indicators, or predictors, of the effect of zooplankton on their environment, including individual body size, corporal stoichiometry and specific physiological rates. Most of these characteristics can also be termed “functional traits”. While the use of traits has recently gained popularity amongst aquatic community ecologists, few have applied this approach to concretely link zooplankton community structure to ecosystem processes. In the present study, we compiled data from a wide variety of literature to construct a database of crustacean zooplankton species and their traits contributing directly or indirectly to C, N or P ecosystem fluxes. Our literature search yielded over 9000 empirical observations on 287 different species and thereby allowed identification of knowledge gaps in the literature. We explored trait relationships amongst taxonomic units and between marine and freshwater habitats. Of all cross-correlations tested among 16 zooplankton traits, 35 were significant, with most traits being related to body mass. Our synthesis revealed significantly different patterns between freshwater and marine zooplankton respiration and allometry (body mass vs. length). We propose a novel trait classification scheme according to both organismal and ecosystem functions. Our goal is to provide a database for zooplankton functional traits, tools to link organisms to ecosystem processes, and to promote a search for general patterns and trade-offs amongst traits.