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Meta-analysis synthesizes individual research results on the same subject and provides information that indicates bottlenecks in research. Due to the massive production of data, integrative analyzes are necessary, presenting more consistent views of biological phenomena. Broad themes such as plants’ response to climate change have been the subject of meta-analyses since 1996, as there is a global concern about the effect of elevated CO\(_{2}\) on plants and forests. We propose using meta-analysis to compile existing data, including studies related to the effects of high CO\(_{2}\) on Brazilian biomes’ vegetation. For that, we found 36 articles on the theme after a systematic review. Physiological parameters such as photosynthesis, leaf area, and non-structural carbohydrates are essential to understand the plant’s responses to elevated CO\(_{2}\) using meta-analysis. However, these parameters are not present in a considerable portion of the literature, decreasing the statistical power of meta-analytical strategies. The meta-analysis of plants’ biological responses is usually performed with several species, although there are also studies with single species. The use of many species increases the variance of the effects, highlighting the need for multilevel modeling to consider the dependence among data on the same species. We discuss how to carry out studies considering the variables needed in future meta-analyses to contribute to better data integration relevant to national reports. In this way, we expect that meta-analytical strategies could be essential for national decision-making and complement global analyses such as those made by the IPCC.

Reproductive and pollination biology studies are crucial to understand processes of diversification in plants. The facultative apomictic orchid Zygopetalum mackayi comprises a potential model in the Neotropics to understand the role of asexuality in the reproductive success of plants. Adventive embryogenesis is the main mechanism behind the production of clonal embryos in Z. mackayi and it has been associated with polyembryony. Previous studies suggested all seeds (mono-/polyembryonic) to be of apomictic origin. If so, we expect to find no difference in seed viability from self- and cross-pollinations, considering monoembryonic and polyembryonic seeds. To test this prediction, we estimated how pollen origin affects fruit set and seed viability. We also investigated if reproduction is dependent on pollinators and described how pollination is achieved. We collected phenological and pollination data in one natural population and sampled five additional populations for studies of the reproductive system. To access seed viability, we stained seeds with a tetrazolium solution. Z. mackayi is a generalized food-deceptive species pollinated by Bombus pauloensis. This species is also dependent on pollinators for reproduction as individuals are unable to perform spontaneous self-pollination. Self- and cross-pollination treatments yielded mainly monoembryonic seeds, but crossed flowers produced more viable monoembryonic seeds than self-pollinated ones. Sexual reproduction is dominant in Z. mackayi because monoembryonic seeds are more frequent in both cross- and self-pollinated flowers and more viable when pollen comes from a different individual. Self-pollinated flowers set more polyembryonic seeds than crossed ones, although there were no differences in seed viability between treatments considering all types of seeds produced. We hypothesize that embryo abortion by inbreeding depression in self-pollinated flowers is compensated by apomictic reproduction in Z. mackayi, as polyembryonic seeds are a common outcome of apomixis. We propose polyploidy, not pollen limitation, is responsible for the evolution of apomixis in this orchid species.

Questions: Does the spatial association between isolated adult trees and understorey plants change along a gradient of sand dunes? Does this association depend on the life form of the understorey plant? Location: Coastal sand dunes, southeast Brazil. Methods: We recorded the occurrence of understorey plant species in 100 paired 0.25 m 2 plots under adult trees and in adjacent treeless sites along an environmental gradient from beach to inland. Occurrence probabilities were modelled as a function of the fixed variables of the presence of a neighbour, distance from the seashore and life form, and a random variable, the block (i.e. the pair of plots). Generalized linear mixed models (GLMM) were fitted in a backward step-wise procedure using Akaike’s information criterion (AIC) for model selection. Results: The occurrence of understorey plants was affected by the presence of an adult tree neighbour, but the effect varied with the life form of the understorey species. Positive spatial association was found between isolated adult neighbour and young trees, whereas a negative association was found for shrubs. Moreover, a neutral association was found for lianas, whereas for herbs the effect of the presence of an adult neighbour ranged from neutral to negative, depended on the subgroup considered. The strength of the negative association with forbs increased with distance from the seashore. However, for the other life forms, the associational pattern with adult trees did not change along the gradient. Conclusions: For most of the understorey life forms there is no evidence that the spatial association between isolated adult trees and understorey plants changes with the distance from the seashore, as predicted by the stress gradient hypothesis, a common hypothesis in the literature about facilitation in plant communities. Furthermore, the positive spatial association between isolated adult trees and young trees identified along the entire gradient studied indicates a positive feedback that explains the transition from open vegetation to forest in subtropical coastal dune environments.

Decomposition was studied in a reciprocal litter transplant experiment to examine the effects of forest type, litter quality and their interaction on leaf decomposition in four tropical forests in south-east Brazil. Litterbags were used to measure decomposition of leaves of one tree species from each forest type:Calophyllum brasiliensefrom restinga forest;Guapira oppositafrom Atlantic forest;Esenbeckia leiocarpafrom semi-deciduous forest; andCopaifera langsdorffiifrom cerradão. Decomposition rates in rain forests (Atlantic and restinga) were twice as fast as those in seasonal forests (semi-deciduous and cerradão), suggesting that intensity and distribution of precipitation are important predictors of decomposition rates at regional scales. Decomposition rates varied by species, in the following order:E. leiocarpa>C. langsdorffii>G. opposita>C. brasiliense. However, there was no correlation between decomposition rates and chemical litter quality parameters: C:N, C:P, lignin concentration and lignin:N. The interaction between forest type and litter quality was positive mainly becauseC. langsdorffiidecomposed faster than expected in its native forest. This is a potential indication of a decomposer's adaptation to specific substrates in a tropical forest. These findings suggest that besides climate, interactions between decomposers and plants might play an essential role in decomposition processes and it must be better understood.

The stress gradient hypothesis (SGH) postulates how the balance between plant competition and facilitation shifts along environmental gradients. Early formulations of the SGH predicted that facilitation should increase monotonically with stress. However, a recent theoretical refinement of the SGH postulates stronger facilitation under moderate stress, followed by a decreasing role of facilitation in the most severe environments. We conducted field experiments along the most severe part of a coastal dune gradient in southeast Brazil to test the effect of stress on the intensity and importance of the net interactions between two tree species. First, we compared the performance of distinct life stages of Ternstroemia brasiliensis in the presence and absence of Guapira opposita adults along a beach-to-inland gradient, a gradient of environmental severity. To test the effect of one stress factor in particular, we also manipulated water availability, a limiting resource due to the sandy soils. At the most severe part of the coastal gradient (i.e. closest to the seashore), both intensity and importance of the interaction between G. opposita and T. brasiliensis were negatively related to stress, with a pattern consistent across distinct life stages of the target species. However, the sign of the net interaction depended on the life stage of the target species. Our results provide empirical evidence that the role of facilitation tends to wane, leading to neutral or even negative net interactions between species as stress reaches its maximum, as predicted by the recent refinements of the SGH.

The proximity of adult neighbors often increases the performance of woody seedlings under harsh environmental conditions but this nurse plant effect becomes less intense when abiotic stress is alleviated, as predicted by the stress gradient hypothesis (SGH). Although some studies have tested how the net nurse effect is changed by stress, few studies have tested how the mechanism that drives the facilitative effect of nurse responds to changes in stress. We conducted field experiments in a subtropical coastal dune to test if shading drives the known nurse effect of adults of the tree Guapira opposita on seedling performance of another tree species, Ternstroemia brasiliensis. We transplanted T. brasiliensis seedlings to three neighbor environments: under a G. opposita crown, under artificial shade and without neighbor as a control. Furthermore, assuming that proximity to the seashore correlates with stress intensity, we tested if the potential shade-driven facilitation became less intense as stress decreased. Regardless of the proximity to the seashore, after a year, the survival of T. brasiliensis seedlings was twice as high when the seedlings were under G. opposita or under artificial shade compared to the control, indicating that the nurse effect is driven by shade and that this facilitation mechanism is constant along the stress gradient. However, G. opposita and artificial shade had a negative effect on seedlings growth. Overall, our results showed that the facilitation mechanism behind the nurse effect did not wane as the stress was reduced. Furthermore, in spite of the potential costs in terms of biomass production, our study highlights the potential of nurse plants and artificial shade as techniques to improve the survival of transplanted seedlings used in the restoration of degraded shrubland coastal dunes.

We examined the effects of soil mesofauna and the litter decomposition environment (above and belowground) on leaf decomposition rates in three forest types in southeastern Brazil. To estimate decomposition experimentally, we used litterbags with a standard substrate in a full-factorial experimental design. We used model selection to compare three decomposition models and also to infer the importance of forest type, decomposition environment, mesofauna, and their interactions on the decomposition process. Rather than the frequently used simple and double-exponential models, the best model to describe our dataset was the exponential deceleration model, which assumed a single organic compartment with an exponential decrease of the decomposition rate. Decomposition was higher in the wet than in the seasonal forest, and the differences between forest types were stronger aboveground. Regarding litter decomposition environment, decomposition was predominantly higher below than aboveground, but the magnitude of this effect was higher in the seasonal than in wet forests. Mesofauna exclusion treatments had slower decomposition, except aboveground into the Semi-deciduous Forest, where the mesofauna presence did not affect decomposition. Furthermore, the effect of mesofauna was stronger in the wet forests and belowground. Overall, our results suggest that, in a regional scale, both decomposers activity and the positive effect of soil mesofauna in decomposition are constrained by abiotic factors, such as moisture conditions.

Canadian Bureau for International Education (CBIE) of Canada Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) NSERC Discovery Empirical studies in salt marshes, arid, and alpine systems support the hypothesis that facilitation between plants is an important ecological process in severe or 'stressful' environments. Coastal dunes are both abiotically stressful and frequently disturbed systems. Facilitation has been documented, but the evidence to date has not been synthesized. We did a systematic review with meta-analysis to highlight general research gaps in the study of plant interactions in coastal dunes and examine if regional and local factors influence the magnitude of facilitation in these systems. the 32 studies included in the systematic review were done in coastal dunes located in 13 countries around the world but the majority was in the temperate zone (63%). Most of the studies adopt only an observational approach to make inferences about facilitative interactions, whereas only 28% of the studies used both observational and experimental approaches. Among the factors we tested, only geographic region mediates the occurrence of facilitation more broadly in coastal dune systems. the presence of a neighbor positively influenced growth and survival in the tropics, whereas in temperate and subartic regions the effect was neutral for both response variables. We found no evidence that climatic and local factors, such as life-form and life stage of interacting plants, affect the magnitude of facilitation in coastal dunes. Overall, conclusions about plant facilitation in coastal dunes depend on the response variable measured and, more broadly, on the geographic region examined. However, the high variability and the limited number of studies, especially in tropical region, indicate we need to be cautious in the generalization of the conclusions. Anyway, coastal dunes provide an important means to explore topical issues in facilitation research including context dependency, local versus regional drivers of community structure, and the importance of gradients in shaping the outcome of net interactions. Univ São Paulo, Inst Biociencias, Dept Ecol, São Paulo, Brazil York Univ, Dept Biol, Toronto, ON M3J 2R7, Canada Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD 21218 USA FAPESP: 2012/09794-7 Web of Science

A concentração de dióxido de carbono (CO2) na atmosfera aumentou desde a revolução industrial até a atualidade. O aumento de CO2 na atmosfera pode resultar em alterações fisiológicas e bioquímicas, que podem influenciar no crescimento das plantas e mudar o metabolismo dos carboidratos. O Brasil é a nação tropical mais rica em termos de armazenamento de carbono florestal e detentora da maior biodiversidade do planeta. Contudo, trabalhos sobre o efeito do elevado CO2 (eCO2) nas plantas em clima neotropical, em especial do Brasil, não têm sido incluídos em meta-análises globais. Portanto, este trabalho tem como objetivo sintetizar quantitativamente o conhecimento atual sobre o efeito de eCO2 na vegetação brasileira em experimentos com CO2 realizados no Brasil. Este trabalho está dividido em dois capítulos. O Capítulo I discute a importância da meta-análise em si e seu valor para compreender as respostas das plantas ao eCO2. O Capítulo II apresenta uma meta-análise de estudos efetuados com plantas no Brasil em eCO2. O primeiro capítulo revisa os eventos históricos a respeito da evolução do conhecimento sobre as mudanças climáticas globais no planeta e aponta a meta-análise como ferramenta de grande importância para compreender a fisiologia das plantas em resposta ao aumento de CO2. Propomos neste trabalho o uso de meta-análise para compilar os dados existentes sobre mudanças climáticas. Portanto, entendemos que a meta-análise é uma metodologia estatisticamente rigorosa para integrar resultados de pesquisas primárias sobre o efeito das mudanças climáticas na vegetação. Identificamos que o número de algumas variáveis (C, N e área foliar) comumente medidas em experimentos que analisam as respostas das plantas às mudanças climáticas não estão presentes em número suficiente de estudos para realizar uma meta-análise e discutimos como realizar estudos considerando as variáveis necessárias em futuras meta-análises. A meta-análise do segundo capítulo inclui 36 trabalhos, selecionados a partir de uma revisão sistemática, com experimentos de Câmaras de Topo Aberto (OTC) ou Free-air CO2 Enrichment (FACE) que pesquisaram o efeito do eCO2 em plantas. Nossa meta-análise verificou que a exposição das plantas ao eCO2 resultou no aumento médio significativo da biomassa (+30%), na taxa de assimilação líquida de CO2 (+49%), na eficiência fotossintética do uso da água (+116%), aumento dos níveis de açúcares solúveis totais nas folhas (+7%), na concentração de amido foliar (+58%) e diminuição da condutância estomática (-23%). Não houve mudança nas respostas na taxa de transpiração (E), taxa de CO2 intercelular por CO2 atmosférico (Ci/Ca), taxa máxima de transporte de elétrons (Jmax) e velocidade máxima de carboxilação da enzima Rubisco (Vcmax) em plantas expostas ao eCO2. O hábito de vida das espécies alterou significativamente a resposta da biomassa em árvores e herbáceas, sendo que árvores jovens acumulam mais biomassa do que as herbáceas quando expostas ao eCO2. Em ambos os capítulos, destacamos a importância de que mais estudos sejam realizados com espécies nativas e cultivadas em clima neotropical para melhorar nossa compreensão preditiva das respostas das plantas tropicais ao eCO2. The concentration of carbon dioxide (CO2) in the atmosphere has increased since the industrial revolution to the present. The increase in CO2 in the atmosphere can result in physiological, biochemical changes. In addition to influencing plant growth and changing carbohydrate metabolism. Brazil is the richest tropical nation in terms of forest carbon storage and the greatest biodiversity on the planet. However, studies on the effect of high CO2 (eCO2) on plants in the Neotropical climate, especially in Brazil, have not been included in global meta-analyzes. Therefore, this work aims to quantitatively synthesize current knowledge about the effect of eCO2 on Brazilian vegetation in experiments with CO2 carried out in Brazil. This work is divided into two chapters. Chapter I discusses the importance of meta-analysis itself and its value for understanding plant responses to eCO2; Chapter II presents a meta-analysis of studies carried out with plants in Brazil in eCO2. The first chapter reviews historical events regarding the evolution of knowledge about global climate changes on the planet and points to meta-analysis as a tool of great importance to understand the physiology of plants in response to the increase in CO2. In this work, we propose the use of meta-analysis to compile the existing data on climate change. Therefore, we found that the meta-analysis was a statistically rigorous methodology for integrating results of primary research on the effect of climate change on vegetation. We found that the number of some variables (C, N and leaf area) commonly measured in experiments that analyze plant responses to climate change are not present in a sufficient number of studies to perform a meta-analysis. We discussed how to conduct studies considering the variables needed in futue meta-analyzes. The second chapter meta-analysis includes 36 studies, based on a systematic review, with Open Top Chambers (OTC) or Free-air CO2 Enrichment (FACE) experiments that investigated the effect of eCO2 on plants. Our meta-analysis found that plant exposure to eCO2 resulted in a significant average increase in biomass (+ 30%), in the net CO2 assimilation rate (+ 49%), instantaneous leaf water use efficiency (+ 116%), increased levels of total soluble sugars (+ 7%), starch concentration (+ 58%) and decreased stomatal conductance(-23%). Significant changes have not been observed in the responses in the transpiration rate (E), ratio of intercellular to atmospheric CO2 concentration (Ci/Ca), maximum rate of electron transport (Jmax), and maximum carboxylation rate (Vcmax) in plants exposed to the eCO2. The species\' habit of life significantly altered the response of biomass in trees and herbaceous, with young trees accumulating more biomass than herbaceous when exposed to eCO2. In both chapters, we highlight the importance of further studies being carried out with native species and cultivated in a neotropical climate to improve our predictive understanding of the responses of tropical plants to eCO2.

No início, a teoria de seleção sexual baseava-se somente em episódios pré-acasalamento de competição por parceiros sexuais. Em alguns sistemas de acasalamento, machos tentam monopolizar parceiras através da defesa de recursos usados pelas fêmeas ou guardando diretamente as fêmeas. Em outros sistemas de acasalamento, esse comportamento de monopolização não existe e as táticas dos machos baseiam-se principalmente em achar ou cortejar fêmeas. Em todos cenários, esperava-se usualmente que fêmeas fossem o sexo criterioso na escolha e acasalassem poucas vezes. Contudo, análises genéticas modernas revelaram que frequentemente fêmeas acasalam com diferentes parceiros sexuais, o que permite a ocorrência de episódios de seleção sexual pós-acasalamento, como escolha críptica da fêmea e competição espermática. Agora, para melhor entender processos de seleção sexual, é necessário estimar seleção sexual em diferentes sistemas de acasalamento, integrando episódios de seleção pré e pós-acasalamento. Dessa forma, apresentamos aqui três meta-análises que integram episódios de seleção pré e pós-acasalamento em animais e combinam estimativas de seleção baseadas em indivíduos e em atributos desses indivíduos. No Capítulo 1, mostramos que medidas de sucesso de acasalamento inferidas a partir de testes genéticos produzem estimativas maiores da oportunidade para seleção sexual pré-acasalamento (Is) do que medidas diretas de sucesso de acasalamento. Isso mostra que estimativas genéticas de sucesso de acasalamento não devem ser usadas para calcular-se Is e que elas são mais propícias para o cálculo da oportunidade para seleção sexual pós-acasalamento. Dessa forma, propomos um novo índice de seleção pós-acasalamento: a oportunidade para seleção por fertilização. Sobretudo, nossos resultados mostram também que a oportunidade para seleção sexual pós-acasalamento é comum em animais. No Capítulo 2, mostramos que, quando o comportamento de monopolização ocorre, fêmeas lidam com menor oportunidade para seleção sexual pré-acasalamento e machos lidam com maior oportunidade para seleção sexual pré-acasalamento. Contudo, para ambos sexos, a oportunidade de seleção por fertilização e a oportunidade de seleção total não diferem de acordo com a ocorrência do comportamento de monopolização. Isso mostra que: (i) machos são bem sucedidos em monopolizar fêmeas durante eventos pré-acasalamento, mas fêmeas não são monopolizadas quando se analisa a integralidade dos eventos reprodutivos; (ii) poliandria é comum em animais; e (iii) escolha críptica da fêmea e competição espermática são forças seletivas efetivas. No Capítulo 3, demonstramos pela primeira vez que fêmeas e machos de maior tamanho corporal produzem mais filhotes, corroborando uma antiga hipótese de Charles Darwin sobre a evolução de tamanho corporal em fêmeas. Apesar das vantagens em ser grande quando comportamento de monopolização ocorre, nós também mostramos que indivíduos grandes são igualmente bem sucedidos em diferentes sistemas de acasalamento. Por fim, mostramos que investir em atributos envolvidos em fertilização aumenta o sucesso reprodutivo de machos, demonstrando novamente a relevância de episódios de seleção sexual pós-acasalamento. The theory of sexual selection was initially based only on pre-mating episodes of intrasexual competition for sexual partners. In some mating systems, males try to monopolize females by guarding them or by defending resource(s) used by females. In other mating systems, such monopolization behavior is absent and male mating tactics are mainly based on finding or courting females. In all scenarios, females were usually expected to be the choosy sex and mate just a few times. However, modern genetic paternity analyses revealed that females frequently mate with different partners, leading to post-mating episodes of sexual selection, such as cryptic female choice and sperm competition. To better understand sexual selection processes, it is necessary to estimate sexual selection in different mating systems, integrating pre- and post-mating episodes of selection. Therefore, here we present three hierarchical meta-analyses that integrate pre- and post-mating selection episodes across animals, and combine individual-based and trait-based estimates of sexual selection. In Chapter 1, we show that mating success measures inferred from genetic analyses produce higher estimates of the opportunity for pre-mating sexual selection (Is) than measures of actual mating success. This shows that genetic estimates of mating success should not be used to calculate Is and that they would be better employed to estimate the opportunity for post-mating sexual selection. Therefore, we propose a new post-mating selection index: the opportunity for fertilization selection. More importantly, our results show that the opportunity for post-mating sexual selection is ubiquitous among animals. In Chapter 2, we show that, when monopolization behavior occurs, females face a lower opportunity for pre-mating sexual selection and males face a higher opportunity for pre-mating sexual selection. However, for both sexes, the opportunity for fertilization selection and the opportunity for selection do not differ according to the occurrence of monopolization behavior. This shows that: (i) males succeed in economically monopolizing females during pre-mating events, but females are not monopolized by males when we look at the whole reproductive process; (ii) polyandry is ubiquitous among animals; and (iii) cryptic female choice and sperm competition are effective selective forces. In Chapter 3, we demonstrate for the first time that larger females and males sire more offspring, corroborating a long-standing Darwinian hypothesis on the evolution of female body size. Despite the advantages of being larger when monopolization behavior occurs, we also show that large individuals are equally successful in different mating systems. Finally, we show that investing in fertilization-related traits results in higher fitness for males, demonstrating again the relevance of post-mating sexual selection.

Plants established next to other plants may have their performance positively or negatively affected by their neighbors, which characterizes interactions of facilitation and competiton, respectively. Facilitation and competition, however, may occur simultaneously and understanding which one predominates in pairwise interactions under different ecological contexts is important to comprehend the structure of plant communities. According to the stress-gradient hypothesis (SGH), facilitation is expected to prevail in more severe environments, but the outcome of interactions may change depending on features of interacting individuals, such as life form and ontogenetic stages. As harsh conditions and high diversity of plant life-forms are characteristic of coastal dunes, the amount of studies about plant interactions has been rapidly increasing in these ecosystems, with apparent divergent conclusions. However, until now, there is not a systematic and quantitative synthesis about the factors affecting the net outcome of facilitation and competition in these ecosystems. We conducted a meta-analysis to investigate the effects of environmental stress and the simultaneous influence of plant life form and ontogenetic stage on the outcome of facilitation and competition in coastal dunes around the world. We used four performance measures to estimate the outcome of interactions: abundance, survival, growth, and reproduction. Contrary to what was expected by SGH, we found that negative impacts of neighbors on plant reproduction increase towards more arid conditions, but this effect was not observed for other performance measures. Our results also indicate that woody neighbors facilitate the survival of woody seedlings and the reproduction of herbs, while herbaceous neighbors facilitate the growth of other herbaceous plants. Overall, the outcome of plant interactions in coastal dunes depends on the performance variable measured and on both environmental conditions and plant features, indicating an interaction between these factors. Such interaction and different mechanisms underlying facilitation and competition should be more investigated in the future. The global scale of our meta-analysis supports generalization of important processes of succession and conservation in coastal dunes. Benefits of woody neighbors to the survival of woody seedlings corroborate the concept of successional feedbacks in the beach-inland physiognomic gradient, and our results reinforce the use of nurse plants in coastal dunes as a valuable tool to restoration of these endangered ecoystems Plantas estabelecidas nas proximidades de outras plantas podem ter sua performance afetada positiva ou negativamente por seus vizinhos, caracterizando, respectivamente, interações de facilitação e competição. Considerando que ambas as interações podem ocorrer de forma simultânea, compreender o predomínio de cada uma delas em diferentes contextos ecológicos é fundamental para o entendimento da estrutura de comunidades vegetais. De acordo com a hipótese do gradiente de estresse (HGE), a facilitação tende a predominar em ambientes mais severos, mas o balanço das interações depende ainda das características dos indivíduos envolvidos, como forma de vida e estágio ontogenético. Como condições ambientais severas e alta diversidade de formas de vida vegetais são características de planícies costeiras, o número de estudos investigando interações entre plantas tem aumentado rapidamente nesses ambientes, com conclusões aparentemente divergentes. No entanto, ainda não há uma síntese sistemática e quantitativa dos fatores que afetam o balanço entre facilitação e competição nesses ecossistemas. Nós realizamos uma meta-análise em escala global para investigar os efeitos do estresse ambiental e a influência simultânea da forma de vida e do estágio ontogenético das plantas sobre o balanço entre facilitação e competição em planícies costeiras. Utilizamos quatro variáveis de performance para estimar o balanço de interações: abundância, sobrevivência, crescimento e reprodução. Ao contrário do predito pela HGE, encontramos que impactos negativos de plantas vizinhas sobre a reprodução de outras plantas aumentam com a aridez do ambiente, mas que esse efeito não é observado para outras variáveis de performance. Nossos resultados também mostram que vizinhos lenhosos facilitam a sobrevivência de plântulas lenhosas e a reprodução de plantas herbáceas, enquanto vizinhos herbáceos facilitam o crescimento de outras herbáceas. De modo geral, o balanço das interações depende da variável de performance medida e tanto de condições ambientais quanto de características das plantas, indicando que esses fatores interagem. Tal interação e os diferentes mecanismos subjacentes à facilitação e à competição devem ser melhor investigados no futuro. A maior sobrevivência de plântulas lenhosas na presença de vizinhos lenhosos corrobora a ideia de retroalimentação positiva no processo sucessional que caracteriza o gradiente fisionômico da praia ao interior. Nossos resultados também reforçam o potencial do uso de plantas-berçários como ferramenta para restauração de planícies costeiras degradadas

A decomposição de serapilheira é um processo fundamental para a ciclagem de nutrientes e a manutenção da fertilidade dos solos em florestas tropicais. Além disso, contribui com os fluxos de carbono para a atmosfera, sendo constantemente discutida no âmbito das mudanças climáticas globais. Dentre os fatores que influenciam na sua dinâmica, o local de origem das espécies vegetais, a qualidade nutricional da serapilheira e a comunidade decompositora do solo tem recebido destaque. Interações entre plantas e decompositores que resultam em uma maior decomposição no local de origem das espécies vegetais em relação a um local externo são denominadas \"home field advantage\" (HFA). O presente estudo teve como objetivos investigar a ocorrência do HFA, bem como a influência das interações entre o local de origem das espécies vegetais, os decompositores do solo e a qualidade nutricional do material vegetal na decomposição de serapilheira em áreas de Floresta Ombrófila Densa Atlântica de terras baixas e montana localizadas no litoral norte do estado de São Paulo. Para isso foi realizado um experimento de decomposição com permuta de material foliar entre as florestas de terras baixas e montana com duração de 250 dias, utilizando folhas senescentes da espécie Rustia formosa, proveniente da floresta de terras baixas, e Licania hoehnei, proveniente da floresta montana, e litter bags com diferentes aberturas de malha para controlar a inclusão exclusão da meso e macro fauna do solo. Também foram quantificadas as concentrações de nutrientes, compostos orgânicos e composição isotópica para determinação da qualidade inicial das serapilheiras e sua dinâmica durante a decomposição. As diferenças na qualidade inicial das espécies não causou diferenciação entre as suas taxas de decomposição. As taxas de decomposição foram semelhantes entre espécies e ambientes, não sendo verificada maior velocidade de decomposição associada com a interação entre as espécies e seus ambientes de origem, o que indica ausência de HFA. Além disso, não foi verificado efeito positivo da fauna do solo na decomposição. A dinâmica química dos detritos foliares evidenciou a imobilização de nitrogênio e acúmulo de lignina ao longo da decomposição, o que indica limitação na atividade microbiana por nitrogênio e baixa qualidade da serapilheira de Rustia formosa e Licania hoehnei. As variações nas concentrações de carbono, nitrogênio e fósforo influenciaram a dinâmica da decomposição ao longo do tempo. Esse estudo contribui para compreensão de como fatores importantes na decomposição interagem em ecossistemas tropicais, e aponta a importância da qualidade da serapilheira e disponibilidade de nutrientes no ambiente como direcionadores da decomposição. Litter decomposition is a key process for nutrient cycling and maintenance of soil fertility in tropical forests, contributing to carbon fluxes to the atmosphere and being constantly discussed in the global climate change scenario. Among the main factors that control decomposition, the place of origin of species, litter quality and soil community are currently with great attention. Interactions between plants and decomposers that lead to a fast decomposition in the place of origin of species related to other sites and species are called home field advantage (HFA). The goal of this study was to investigate the occurrence of HFA, as well the influence of interactions between place of origin, soil decomposers and litter quality on the litter decomposition in areas of lowland and montane Atlantic forest located in the north coast of Sao Paulo state. For this it was performed an decomposition experiment with transplant of litter of Rustia Formosa, from lowland forest, and Licania hoehnei, from montane forest, between the two forests, with duration of 250 days, using litter bags with different mesh sizes to allow and exclude the access of meso and macro soil fauna. It was also quantified nutrient and organic compounds concentration to determine the initial litter quality and its dynamics during decomposition. The differences in initial litter quality between species did not cause differentiation in the decomposition rate. The decomposition rates were similar between species and ambient, with no faster decomposition associated with the interaction between species and its local places of origin, which indicates lack of HFA. Besides that, there was no positive effect of soil fauna on the decomposition. The chemical dynamics of litter pointed out nitrogen immobilization and lignin accumulation during decomposition, which indicates microbial limitation by nitrogen and low litter quality of Rustia Formosa and Licania hoehnei. The variations in carbon, nitrogen and lignin concentration influenced the dynamics of decomposition during the time. This study contributed to the comprehension of how important factors of decomposition can interact in tropical ecosystems, and pointed the importance of litter quality and nutrient availability of the ambient as drivers of decomposition.