Forest expansion into Brazilian savanna due to fire suppression causes precipitous species loss.

RESUMO -(Gochnatia polymorpha (Less.) Cabrera modifi ca sua estrutura foliar devido a diferenças na luminosidade e condições edáfi cas). Gochnatia polymorpha (Less.) Cabrera é uma espécie de Asteraceae com ampla distribuição no bioma cerrado, sendo encontrada em diversas fi sionomias fl orestais da região sudeste do Brasil. O presente estudo descreve alguns caracteres anatômicos foliares dessa espécie e os analisa quantitativamente em função de sua ocorrência nas formações fl orestais e também das diferenças de luminosidade. Foram encontradas diferenças quantitativas em todos os parâmetros anatômicos analisados. Os resultados demonstram que a alta plasticidade anatômica foliar nesta espécie pode ser considerada como uma vantagem adaptativa que a permite ocorrer em diversos ambientes do cerrado. Palavras-chave: cerrado, freqüência estomática, mata de galeria, morfologia foliar, plasticidade anatômica ABSTRACT -(Gochnatia polymorpha (Less.) Cabrera (Asteraceae) changes in leaf structure due to differences in light and edaphic conditions). Gochnatia polymorpha (Less.) Cabrera is a widespread Asteraceae species found in different physiognomies of cerrado (Neotropical savanna) and in forest formations of southeast Brazil. This study describes some leaf anatomy characteristics of this species and quantitatively evaluates them in relation to different environments, as well as under different light conditions. We found quantitative differences in all anatomical parameters analyzed. The results demonstrate that high leaf anatomy plasticity is an adaptive advantage that allows this species to occur in diverse cerrado conditions.

Silicon (Si) application has improved yield and stress tolerance in sugarcane crops. In this respect, C:N:P stoichiometry makes it possible to identify flows and interaction between elements in plants and their relationship with growth. However, few studies have investigated the influence of Si on physiological variables and C:N:P stoichiometry in sugarcane. As such, this study aimed to assess the effect of increasing Si concentrations on the growth and stoichiometric composition of sugarcane plants in the early growth stage. The experiment was conducted in pots, using four Si concentrations (0, 0.8, 1.6 and 3.2 mM). Biomass production, the concentration and accumulation of C, N, P and Si as well as the relationship between them were assessed. Silicon application increased biomass production, the rate of photosynthesis, instantaneous carboxylation efficiency and C, N, P and Si accumulation, in addition to altering stoichiometric ratios (C:N, C:P, N:P and C:Si) in different parts of the plants. The decline in C concentration associated with greater N and P absorption indicates that Si favoured physiological processes, which is reflected in biomass production. Our results demonstrate that Si supply improved carbon use efficiency, directly influencing sugarcane yield as well as C and nutrient cycling.

RESUMO -(Características estomáticas de pares congenéricos de cerrado e mata de galeria crescendo numa região transicional no Brasil Central). Em áreas protegidas do fogo, espécies arbóreas predominantemente florestais conseguem se estabelecer no cerrado e crescer lado a lado com espécies do mesmo gênero que são características destas formações savânicas. Devido às condições ambientais diferenciadas encontradas nas formações de cerrado e de mata, estas espécies congenéricas podem se comportar como grupos funcionais distintos. Neste trabalho foi realizado um estudo comparativo da anatomia dos estômatos e da condutância estomática e taxas de transpiração foliar em 10 pares de espécies congenéricas do cerrado e de mata de galeria e das relações entre as características estomáticas selecionadas e a condutância estomática, já que a morfologia dos estômatos e sua densidade afetam a área para difusão dos gases e sua trajetória através dos poros estomáticos. Cada par foi de uma família diferente. Para a maioria das espécies, a área do poro estomático foi o fator de maior influencia no processo de trocas gasosas, pela sua correlação com a condutância estomática, enquanto a densidade estomática mostrou uma correlação negativa significativa tanto com o comprimento da célula-guarda quanto com a área do poro estomático. As espécies do cerrado apresentaram valores significativamente maiores do comprimento da célula-guarda e do poro estomático. No entanto, para a maioria dos outros parâmetros estomáticos examinados, a maior parte da variação pode ser atribuída a diferenças entre os gêneros, sendo que a variação entre as espécies dos dois ambientes parece ser um produto da historia evolutiva de cada grupo e não reflete uma especialização ao ambiente de cerrado ou de mata de galeria. Palavras-chave: condutância estomática, estômato, poro estomático, transpiraçãoABSTRACT -(Stomatal traits of cerrado and gallery forest congeneric pairs growing in a transitional region in Central Brazil). In fireprotected sites of Central Brazil, forest trees can establish in the neighbouring savanna and grow side by side with cerrado trees of the same genera. Because of the large differences in their native environment, the cerrado and forest species may represent two distinct functional types. In this study we performed a comparative study of stomata anatomical characteristics, stomatal conductance and transpiration of 10 congeneric species pairs of cerrado and gallery forest species. Each pair was from a different family. Because stomatal anatomy and density affect the area and the path for gas diffusion through the stomatal pores, we also assessed possible relationships among the selected stomata traits and stomatal conductance. The area of the stomatal pore was the anatomical trait with the largest influence on gas exchange. Increases in pore area were correlated with an increase in stomatal conductance for most species. On the other hand, stomatal density was negatively correlated with both the length of the guard-cell and the area of the sto...

Plants are sessile organisms that must perceive and respond to various environmental constraints throughout their life cycle. Among these constraints, drought stress has become the main limiting factor to crop production around the world. Water deprivation is perceived primarily by the roots, which efficiently signal the shoot to trigger drought responses in order to maximize a plant's ability to survive. In this study, the tomato (Solanum lycopersicum L.) mutant procera (pro), with a constitutive response to gibberellin (GA), and its near isogenic line cv. Micro-Tom (MT), were used in reciprocal grafting under well-watered and water stress conditions to evaluate the role of GA signaling in root-to-shoot communication during drought stress. Growth, oxidative stress, gene expression, water relations and hormonal content were measured in order to provide insights into GA-mediated adjustments to water stress. All graft combinations with pro (i.e. pro/pro, MT/pro and pro/MT) prevented the reduction of growth under stress conditions without a reduction in oxidative stress. The increase of oxidative stress was followed by upregulation of SlDREB2, a drought-tolerance related gene, in all drought-stressed plants. Scions harboring the pro mutation tended to increase the abscisic acid (ABA) content, independent of the rootstock. Moreover, the GA sensitivity of the rootstock modulated stomatal conductance and water use efficiency under drought stress, indicating GA and ABA crosstalk in the adjustment of growth and water economy.

Epiphytes are hyper‐diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non‐vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer‐reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non‐vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non‐vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events.

We investigated flowering phenology in a semiarid macroclimate along an environmental gradient encompassing neotropical savanna, transition, and seasonally dry tropical forest (SDTF) areas in the Chapada Diamantina Mountains, northeastern Brazil. We expected to find divergence in flowering patterns between the plant communities studied that would be explained by distinct functional traits selected by differences in rainfall volumes and soil properties. Bud and flower productions were monitored in 809 individuals between January 2010 and March 2012. The savanna exhibited a continuous flowering pattern, while the transition and SDTF areas showed seasonal flowering associated with rainfall. Environmental variables and plant traits (wood densities, water potentials, and water storage capacities) were related to the observed flowering strategies of woody species. The high diversity of functional groups in the savanna was determined by higher plant water potentials that were related to low wood densities and the availability of soil water. The role of rainfall, especially the rainfall volumes during the dry season, is critical in defining different flowering patterns at the community level. The physical properties of the soil selected the presence of species with distinct water-use strategies (low wood density species in savanna areas, and high wood density species in the transition zone and forest), which in turn affected their flowering.

RESUMO -(Características funcionais de folhas de sol e sombra de espécies arbóreas em uma mata de galeria no Distrito Federal, Brasil). As matas de galeria são formações fl orestais que ocupam cerca de 10% da área dos cerrados e representam 1/3 da diversidade de espécies arbóreas ali encontradas. Estudos recentes têm demonstrado a importância dessas fl orestas em regiões do Brasil central, mas pouco se sabe sobre a fi siologia e plasticidade de espécies de mata de galeria em relação a variantes ambientais, como a irradiação solar. No presente estudo, foram comparados in situ aspectos fi siológicos e nutricionais de folhas de sol e sombra, em dez espécies arbóreas comumente encontradas em matas de galeria. Folhas de sol apresentaram maiores valores de assimilação de CO 2 em base de área (A area ), condutância estomática (gs), rendimento quântico do fotossistema II (Φ FSII ) e uma maior fração de centros de reação abertos (qL), enquanto folhas de sombra apresentaram uma maior área foliar específi ca. Diferenças não foram encontradas para potencial hídrico foliar, assimilação de CO 2 em base de massa e para a concentração foliar de macronutrientes. Dos atributos foliares analisados, a abertura estomática e o rendimento quântico do fotossistema II foram os principais fatores atuantes na A area em folhas de sol, enquanto em folhas de sombra apenas Φ FSII foi infl uente. As diferenças encontradas demonstram que, assim como em outras formações fl orestais, em mata de galeria as espécies arbóreas possuem a capacidade de se aclimatarem às condições contrastantes de sombreamento que ocorrem neste tipo de ambiente. Palavras-chave: matas de galeria, fotossíntese, nitrogênio, fósforo, luz, fl uorescência, trocas gasosas ABSTRACT -(Leaf functional traits in sun and shade leaves of gallery forest trees in Distrito Federal, Brazil). Gallery forest is a forest formation that covers about 10% of the cerrado biome and represents about 1/3 of cerrado tree diversity in Brazil. Recent studies demonstrate the importance of gallery forest in central regions of Brazil, but little is known about the physiology and plasticity of gallery forest species in relation to environmental variability, particularly in terms of light availability. In this study we compared in situ physiological and nutritional aspects of shade and sun leaves, in ten tree species commonly found in gallery forests. Relative to shade leaves, sun leaves had higher values of CO 2 assimilation rates on an area basis (A area ), of stomatal conductance (gs), of quantum yield of Photosystem II (Φ PSII ); and a larger fraction of PSII centers in the open state (q L ), while shade leaves showed higher specifi c leaf area. However, shade and sun leaves did not differ in terms of leaf water potential, CO 2 assimilation on a mass basis and in leaf concentrations of macronutrients. Φ PSII and gs were the main factors that infl uenced A area in sun leaves, while only Φ PSII signifi cantly affected A area of shade leaves. The differences found here demonstrate that, like in other fo...