Why woody plant modularity through time and space must be integrated in fire research?

Different ecosystems evolved and are maintained by fire, with their vegetation hosting species with a wide diversity of persistence strategies allowing them to insulate their body and resprout new branches after fire disturbance. Changes in fire regime are predicted due to climate change, either by promoting more frequent and/or severe fires or by reducing the number of fire events due to the limitation of fuel load. Predicting the future of fire-driven ecosystems is a complex task as species' survival depends on many factors that vary in space and time. Since plants are constantly experiencing new environments as they grow through meristem development, woody plant modularity, modules morpho-physiological aspects and their integration should be considered when investigating species strategies in fire-prone ecosystems: according to their position and their tissue composition, plants' modules experience fire differently and will contribute differently to other modules and the whole plant survival, with consequences cascading over the overall vegetation structure. Growth modules may hold the key to understanding how fast plants can get protected from fire, ultimately helping us to predict which species will persist across changing fire regimes. We present an empirical example showing how different fire-return intervals translate into distinct pressures on the timing, protection and location of modules, and discuss how these can translate into modifications in the vegetation structure due to climate change.

Correlating Coffea canephora 3D architecture to plant photosynthesis at a daily scale and vegetative biomass allocation.

Coffea canephora (C. canephora) has two botanical varieties, Robusta and Conilon. Intraspecific variability was hypothesized and projected for the selection of C. canephora plants able to maintain production in the context of global climate changes. For that, architectural, C-assimilation and biomass analyses were performed on 17-month-old Robusta (clones 'A1' and '3 V') and Conilon (clones '14' and '19') varieties grown in non-limiting soil, water and mineral nutrient conditions. Nondestructive coffee plant architecture coding, reconstruction and plant photosynthesis estimations were performed using a functional-structural plant modeling platform OpenAlea. 3D reconstructions and inclusion of parameters calculated and estimated from light response curves, such as dark respiration (Rd), maximum rate of carboxylation of RuBisCO and photosynthetic electron transport allowed the estimation of instantaneous and daily plant photosynthesis. The virtual orchard leaf area index was low, and light was not a limiting factor in early C. canephora development stages. Under such conditions, Robusta assimilated more CO2 at the plant and orchard scale and produced higher total biomass than Conilon. Lower plant daily photosynthesis and total biomass were correlated to higher Rd in Conilon than in Robusta. Among the architectural traits, leaf inclination, size and allometry were most highly correlated with plant assimilation and biomass. Relative allocation in leaf biomass was higher in '19' Conilon than in young Robusta plants, indicating intraspecific biomass partitioning. Similarly, variation in relative distribution of the root biomass and the root volume reflected clonal variation in soil occupation, indicating intraspecific variability in space occupation competitiveness. Coffea canephora denoted high root allocation in both Conilon and Robusta clones. However, relevant differences at subspecific levels were found, indicating the high potential of C. canephora to cope with drought events, which are expected to occur more frequently in the future, because of climate changes. The methodology developed here has the potential to be used for other crops and tree species. Highlights Functional-structural plant model was used to estimate photosynthesis on a plant and daily scales in Coffea canephora (C. canephora). Among the architectural traits, leaf shape and inclination had the most impact on photosynthesis and biomass. Under non-limiting conditions, Robusta had higher plant photosynthesis and biomass than Conilon. A higher leaf biomass allocation in Conilon clone '19' than in Robusta suggested variety-specific partitioning. Variation in the relative distribution of the root biomass indicated C. canephora intraspecific soil occupation variability.

Ecosystem engineering in the arboreal realm: heterogeneity of wood-boring beetle cavities and their use by cavity-nesting ants.

Wood-boring beetle larvae act as ecosystem engineers by creating stem cavities that are used secondarily as nests by many arboreal ant species. Understanding the heterogeneity and distribution of available cavities and their use by ants is therefore key to understanding arboreal ant community assembly and diversity. Our goals were to quantify the abundance and diversity of beetle-produced cavity resources in a tropical canopy, reveal how ants use these resources, and determine which characteristics of the cavity resource contribute to ant use. We dissected branches from six common tree species in the Brazilian Cerrado savanna, measuring cavity characteristics and identifying the occupants. We sampled 2310 individual cavities, 576 of which were used as nests by 25 arboreal ant species. We found significant differences among tree species in the proportion of stem length bored by beetles, the number of cavities per stem length, average entrance-hole size, and the distribution of cavity volumes. The likelihood that a cavity was occupied was greater for cavities with larger entrance-hole sizes and larger volumes. In particular, there was a strong positive correlation between mean head diameters of ant species and the mean entrance-hole diameter of the cavities occupied by those ant species. Wood-boring beetles contribute to the structuring of the Cerrado ant community by differentially attacking the available tree species. In so doing, the beetles provide a wide range of entrance-hole sizes which ant species partition based on their body size, and large volume cavities that ants appear to prefer.

Plant design gets its details: Modulating plant architecture by phase transitions.

Plants evolved different strategies to better adapt to the environmental conditions in which they live: the control of their body architecture and the timing of phase change are two important processes that can improve their fitness. As they age, plants undergo two major phase changes (juvenile to adult and adult to reproductive) that are a response to environmental and endogenous signals. These phase transitions are accompanied by alterations in plant morphology and also by changes in physiology and the behavior of gene regulatory networks. Six main pathways involving environmental and endogenous cues that crosstalk with each other have been described as responsible for the control of plant phase transitions: the photoperiod pathway, the autonomous pathway, the vernalization pathway, the temperature pathway, the GA pathway, and the age pathway. However, studies have revealed that sugar is also involved in phase change and the control of branching behavior. In this review, we discuss recent advances in plant biology concerning the genetic and molecular mechanisms that allow plants to regulate phase transitions in response to the environment. We also propose connections between phase transition and plant architecture control.

From one cell to many: Morphogenetic field of lateral root founder cells in Arabidopsis thaliana is built by gradual recruitment.

The reiterative process of lateral root (LR) formation is widespread and underlies root system formation. However, early LR primordium (LRP) morphogenesis is not fully understood. In this study, we conducted both a clonal analysis and time-lapse experiments to decipher the pattern and sequence of pericycle founder cell (FC) participation in LR formation. Most commonly, LRP initiation starts with the specification of just one FC longitudinally. Clonal and anatomical analyses suggested that a single FC gradually recruits neighboring pericycle cells to become FCs. This conclusion was validated by long-term time-lapse live-imaging experiments. Once the first FC starts to divide, its immediate neighbors, both lengthwise and laterally, are recruited within the hour, after which they recruit their neighboring cells within a few hours. Therefore, LRP initiation is a gradual, multistep process. FC recruitment is auxin-dependent and is abolished by treatment with a polar auxin transport inhibitor. Furthermore, FC recruitment establishes a morphogenetic field where laterally peripheral cells have a lower auxin response, which is associated with a lower proliferation potential, compared to centrally located FCs. The lateral boundaries of the morphogenetic field are determined by phloem-adjacent pericycle cells, which are the last cells to be recruited as FCs. The proliferation potential of these cells is limited, but their recruitment is essential for root system formation, resulting in the formation of a new vascular connection between the nascent and parent root, which is crucial for establishing a continuous and efficient vascular system.

Leaf orientation of maize plants as influenced by seed positioning in the soil / Orientação foliar de plantas milho influenciada pelo posicionamento da semente no solo

Adequate positioning of the seed in the planting furrow allows the maize leaves to be oriented perpendicularly in relation to the sowing row, minimizing overlap and self-shading. The aim of this study was to investigate the positioning of flat and round maize seeds in the furrow and its effects on leaf orientation and plant architecture in the horizontal plane. The experiment was conducted in pots in a greenhouse, using 20C-sieve (flat) and 22R-sieve (round) seeds of the Balu 280 PRO hybrid, at a sowing depth of 0.04 m. The experiment was laid out in a completely randomized design with a 5 × 2 factorial arrangement [five seed positions and two shapes (flat and round)] with eight replicates, totaling 80 plots. Leaf orientation was evaluated at the V3 stage. Seed size and shape did not show a significant interaction with seed positioning, suggesting that maize leaf orientation was only influenced by seed positioning. The treatments involving seeds laid in a vertical position pointing toward the bottom of the pot and horizontally with the face that contains only the endosperm (dorsal face) down are the most favorable, regardless of seed shape.(AU)

O adequado posicionamento da semente de milho no sulco pode possibilitar a orientação perpendicular das folhas em relação à linha de semeadura, minimizando sobreposição e auto sombreamento. O objetivo deste estudo foi avaliar o posicionamento de sementes de milho chata e redonda no sulco de semeadura e os seus efeitos na orientação das folhas e na arquitetura da planta no plano horizontal. O experimento foi conduzido em vasos sob condições de casa de vegetação, sendo utilizadas sementes de peneiras 20C (chatas) e 22R (redondas) do híbrido Balu 280 PRO, com semeadura a 0,04 m de profundidade. O delineamento estatístico utilizado foi inteiramente casualizado, em esquema fatorial 5 x 2 (cinco posições da semente, dois formatos ­ chata e redonda) com oito repetições, totalizando 80 parcelas. A avaliação da orientação da folha foi realizada no estádio V3. O tamanho e o formato das sementes não demonstraram interação significativa com o posicionamento das sementes. Sugerindo que a orientação da folha do milho ocorreu em função do efeito da posição de sementes, sendo mais favoráveis os tratamentos na posição vertical apontada para o fundo do vaso e a posição na horizontal deitado com a face que contém somente o endosperma (dorsal) voltado para baixo, independente da forma.(AU)

Genome-wide association study (GWAS) for morphological and yield-related traits in an oil palm hybrid (Elaeis oleifera x Elaeis guineensis) population.

BACKGROUND: The genus Elaeis has two species of economic importance for the oil palm agroindustry: Elaeis oleifera (O), native to the Americas, and Elaeis guineensis (G), native to Africa. This work provides to our knowledge, the first association mapping study in an interspecific OxG oil palm population, which shows tolerance to pests and diseases, high oil quality, and acceptable fruit bunch production. RESULTS: Using genotyping-by-sequencing (GBS), we identified a total of 3776 single nucleotide polymorphisms (SNPs) that were used to perform a genome-wide association analysis (GWAS) in 378 OxG hybrid population for 10 agronomic traits. Twelve genomic regions (SNPs) were located near candidate genes implicated in multiple functional categories, such as tissue growth, cellular trafficking, and physiological processes. CONCLUSIONS: We provide new insights on genomic regions that mapped on candidate genes involved in plant architecture and yield. These potential candidate genes need to be confirmed for future targeted functional analyses. Associated markers to the traits of interest may be valuable resources for the development of marker-assisted selection in oil palm breeding.

FT/TFL1: Calibrating Plant Architecture.

There is a very large diversity in plant architecture in nature. Over the past few years, novel theoretical concepts and analytical methods have emerged as powerful tools to understand important aspects of plant architecture. Plant architecture depends on the relative arrangement of three types of organs: leaves, shoots, and flowers. During plant development, the architecture is modulated by the balance of two homologous proteins: FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1). The FT/TFL1 balance defines the plant growth habit as indeterminate or determinate by modulating the pattern of formation of vegetative and reproductive structures in the apical and axillary meristems. Here, we present a summarized review of plant architecture and primarily focus on the FT/TFL1 balance and its effect on plant form and development. We also propose passion fruit as a suitable model plant to study the effect of FT/TFL1 genes on plant architecture.

Consumo de água e eficiência produtiva de plantas de trigo tratadas com Etil-trinexapac / Water consumption and yield efficiency of wheat plants treated with Trinexapac-ethyl

O uso eficiente de recursos do ambiente de cultivo, o qual é influenciado por características da planta, é de grande importância para a adaptação de culturas em sistemas de produção. O presente trabalho teve como objetivo estudar o consumo de água e eficiência produtiva de plantas de trigo tratadas com Etil-trinexapac. Foram conduzidos dois experimentos, em cultivo protegido, entre 2014 e 2015. Utilizou-se o delineamento experimental de blocos casualisados em esquema fatorial 2 x 3, com quatro repetições. Dois cultivares de trigo, foram submetidos à aplicação de três doses de Etil-trinexapac (0; 125 e 188 g ha-1 de i.a.) na fase de alongamento do colmo principal. Foram avaliados o consumo de água, altura da planta e distância fonte e dreno e os parâmetros morfológicos da folha bandeira. Ao final do ciclo da cultura foram avaliados os componentes de produção, a produção de grãos e o índice de colheita da cultura. A aplicação de Etil-trinexapac reduziu o crescimento de plantas de trigo, sem afetar produção de grãos. A aplicação do regulador não afeta o consumo de água tampouco índice de colheita da cultura do trigo.

Efficient use of the resources of the growing environment, which is affected by plant traits, is very important for crop adaptation on production system. This work aimed to study the water consumption and yield efficiency of wheat plants treated with Trinexapac-ethyl. Two experiments were carried out, in greenhouse conditions, between 2014 and 2015. Experiments were arranged in randomized blocks design in a factorial 2x3, with four replicates. Two wheat cultivars were sprayed with three Trinexapac-ethyl doses (0, 125 and 188 g a.i. ha-1), at main culm elongation stage. The water consumption, plant height, source-sink distance and the morphological parameters of the flag leaf were evaluated. At the end of the growing cycle, yield and yield components were determined, as well as harvest index. Trinexapac-ethyl reduced plant growth, without affecting grain production. Plant growth regulator application does not reduce either water consumption or wheat crop harvest index.

Consumo de água e eficiência produtiva de plantas de trigo tratadas com Etil-trinexapac / Water consumption and yield efficiency of wheat plants treated with Trinexapac-ethyl

O uso eficiente de recursos do ambiente de cultivo, o qual é influenciado por características da planta, é de grande importância para a adaptação de culturas em sistemas de produção. O presente trabalho teve como objetivo estudar o consumo de água e eficiência produtiva de plantas de trigo tratadas com Etil-trinexapac. Foram conduzidos dois experimentos, em cultivo protegido, entre 2014 e 2015. Utilizou-se o delineamento experimental de blocos casualisados em esquema fatorial 2 x 3, com quatro repetições. Dois cultivares de trigo, foram submetidos à aplicação de três doses de Etil-trinexapac (0; 125 e 188 g ha-1 de i.a.) na fase de alongamento do colmo principal. Foram avaliados o consumo de água, altura da planta e distância fonte e dreno e os parâmetros morfológicos da folha bandeira. Ao final do ciclo da cultura foram avaliados os componentes de produção, a produção de grãos e o índice de colheita da cultura. A aplicação de Etil-trinexapac reduziu o crescimento de plantas de trigo, sem afetar produção de grãos. A aplicação do regulador não afeta o consumo de água tampouco índice de colheita da cultura do trigo.(AU)

Efficient use of the resources of the growing environment, which is affected by plant traits, is very important for crop adaptation on production system. This work aimed to study the water consumption and yield efficiency of wheat plants treated with Trinexapac-ethyl. Two experiments were carried out, in greenhouse conditions, between 2014 and 2015. Experiments were arranged in randomized blocks design in a factorial 2x3, with four replicates. Two wheat cultivars were sprayed with three Trinexapac-ethyl doses (0, 125 and 188 g a.i. ha-1), at main culm elongation stage. The water consumption, plant height, source-sink distance and the morphological parameters of the flag leaf were evaluated. At the end of the growing cycle, yield and yield components were determined, as well as harvest index. Trinexapac-ethyl reduced plant growth, without affecting grain production. Plant growth regulator application does not reduce either water consumption or wheat crop harvest index.(AU)

Variación arquitectónica y morfológica de Hintonia latiflora (Rubiaceae) en relación a la cosecha de corteza y factores ambientales / Architectural and morphological variation of Hintonia latiflora (Rubiaceae) in relation to bark harvest and environmental factors

ResumenHintonia latiflora es una especie ecológicamente rara y económicamente importante del bosque tropical caducifolio de la Cuenca del Balsas, México, cuya corteza se comercializa como medicinal. Las prácticas de descortezado han modificado la forma de las plantas, su arquitectura y morfometría. Se desconoce, si además, existe influencia de factores topogáficos y edáficos sobre estos atributos. Se propone que las condiciones ecológicas en las áreas de distribución y cosecha determinarán las características morfométricas y la variación de la arquitectura de los individuos. Para probar esta hipótesis, evaluamos la relación de factores topográficos y edáficos en diferentes características morfológicas de juveniles (n = 143) y adultos (n = 117) de ocho zonas de cosecha de H. latiflora. Las zonas de cosecha, con una superficie de 0.6 ha, fueron seleccionadas al azar con el apoyo de mapas participativos elaborados por los recolectores del área de estudio. Los datos fueron analizados mediante componentes principales (ACP), y correspondencia canónica (ACC). Los primeros tres CP explicaron el 92.1 % de la variación morfológica; la altura, diámetro basal y cobertura fueron las variables que explicaron las diferencias morfométricas entre juveniles y adultos en las ocho zonas de cosecha. La pendiente del terreno, orientación de la pendiente, profundidad del suelo y pedregosidad, fueron los factores ecológicos estadísticamente relacionados con las diferencias morfométricas. Una menor pendiente, poca pedregosidad, profundidad de suelo, orientación E-O en juveniles (azimut 90˚-270˚) y N-S en adultos (azimuth 0˚-180˚), fueron los factores asociados a mayor altura, número de ramas basales, diámetro basal y cobertura en H. latiflora. Las zonas con mayor intensidad de cosecha estuvieron integradas por árboles monopódicos y algunos individuos basítonos reiterados. Los adultos de estas zonas tuvieron mayor número de frutos. En estos sitios, las plantas de H. latiflora fueron más abundantes y productivas para corteza, pero la alta intensidad de cosecha influyó en la arquitectura vegetal, formando individuos arbustivos multirramificados que originalmente fueron mesótonos. Las áreas con menor intensidad de cosecha estuvieron caracterizadas por pendientes abruptas, suelos superficiales y pedregosos, dominadas por árboles basítonos de menor talla, delgados y escasos en el área. Estos sitios son los menos recomendados para cosecha, debido a que producen menos corteza por árbol, pero sirven para mantener a la especie en el lugar. Con base en estos resultados, podemos desarrollar programas de rehabilitación en áreas afectadas por la explotación comercial, establecer plantaciones forestales en sitios clave para asegurar el desarrollo de individuos con características deseables para cosecha de corteza y contribuir a la conservación in situ de H. latiflora en la Cuenca del Alto Balsas.

AbstractHintonia latiflora is a rare ecologically and economically important species from the Tropical Deciduous Forest of the Balsas Basin, Mexico, whose bark is traded as medicinal. Debarking practices have modified the shape of plants, their architecture and morphometry; but it is unknown if some topographic and edaphic factors may also influence in these attributes. Here we propose that the ecological conditions of this species distribution and harvesting areas, may determine the morphometric characteristics and the individuals variation in their architecture. To test this hypothesis we assessed the relationship of topographic and edaphic factors on the morphological characteristics of saplings (n = 143) and adults (n = 117), in eight harvesting areas of H. latiflora. The harvesting areas, with a surface of 0.6 ha, were selected randomly with the support of participatory mapping elaborated by gatherers of the study site. Data were analyzed using principal components (PCA) and canonical correspondence (CCA) analyses. The first three PC explained 92.1 % of the morphological variation; height, basal diameter, and coverage, explained morphometric differences in both, saplings and adults, in all eight harvesting zones. The terrain slope, slope orientation, soil depth and stoniness, were ecological factors statistically related with morphometric differences. A lower terrain slope, little stoniness, soil depth, slope orientation E-W in saplings (azimuth 90˚-270˚) and N-S in adults (azimuth 0˚-180˚) were the factors associated to height, number of basal branches, basal diameter and coverage of H. latiflora. Areas with higher harvesting intensity were composed by monopodic trees and some reiterated basitone individuals; the adults of these areas also had more fruits. At these sites, plants of H.latiflora were more abundant and produced more bark, but the high-intensity of harvesting, changes plant architecture, forming shrubby, multi-stemmed individuals, that originally were mesotone trees. Areas with lower harvesting intensity were characterized by steep slopes, shallow and rocky soils, and were dominated by basitone trees of smaller size, thin and scarce in the area. These sites are the least recommended for harvesting, because they produce less bark per tree, and serve to preserve the species at the site. Based on these results, we can develop restoration programs in areas affected by commercial harvesting, establish forestry plantations in key sites to ensure the establishment and development of individuals with desirable characteristics for bark harvesting and contribute to in situ conservation of H. latiflora in the Alto Balsas Basin. Rev. Biol. Trop. 65 (3): 900-916. Epub 2017 September 01.

Breeding common bean populations for traits using selection index

A common bean (Phaseolus vulgaris L.) cultivar must combine desirable genotypes for several traits in order to be accepted by producers and consumers. This study aimed to evaluate selection efficiency when segregating bean populations for traits, by means of a selection index, in order to obtain superior progenies for traits considered. A total of 16 populations from the F4 and F5generations were evaluated in 2011 and 2012, respectively. The traits evaluated were plant architecture, plant disease, grain type and yield. Using standard scores (Z), the sum of the four traits (Z) was obtained and, based on this information, the best populations were identified. The evaluation of selection effectiveness was performed on 31 progenies from each population. The 496 progenies plus eight controls were evaluated in the F5:6and F5:7 generations for the same traits in July and November 2012, respectively. The selection, using the index based on the sum of standardized variables (Z), was efficient for identifying populations with superior progenies for all the traits considered.

Breeding common bean populations for traits using selection index

A common bean (Phaseolus vulgaris L.) cultivar must combine desirable genotypes for several traits in order to be accepted by producers and consumers. This study aimed to evaluate selection efficiency when segregating bean populations for traits, by means of a selection index, in order to obtain superior progenies for traits considered. A total of 16 populations from the F4 and F5generations were evaluated in 2011 and 2012, respectively. The traits evaluated were plant architecture, plant disease, grain type and yield. Using standard scores (Z), the sum of the four traits (Z) was obtained and, based on this information, the best populations were identified. The evaluation of selection effectiveness was performed on 31 progenies from each population. The 496 progenies plus eight controls were evaluated in the F5:6and F5:7 generations for the same traits in July and November 2012, respectively. The selection, using the index based on the sum of standardized variables (Z), was efficient for identifying populations with superior progenies for all the traits considered.(AU)

Bouldering: an alternative strategy to long-vertical climbing in root-climbing hortensias.

In the Neotropics, the genus Hydrangea of the popular ornamental hortensia family is represented by climbing species that strongly cling to their support surface by means of adhesive roots closely positioned along specialized anchoring stems. These root-climbing hortensia species belong to the nearly exclusive American Hydrangea section Cornidia and generally are long lianescent climbers that mostly flower and fructify high in the host tree canopy. The Mexican species Hydrangea seemannii, however, encompasses not only long lianescent climbers of large vertical rock walls and coniferous trees, but also short 'shrub-like' climbers on small rounded boulders. To investigate growth form plasticity in root-climbing hortensia species, we tested the hypothesis that support variability (e.g. differences in size and shape) promotes plastic responses observable at the mechanical, structural and anatomical level. Stem bending properties, architectural axis categorization, tissue organization and wood density were compared between boulder and long-vertical tree-climbers of H. seemannii. For comparison, the mechanical patterns of a closely related, strictly long-vertical tree-climbing species were investigated. Hydrangea seemannii has fine-tuned morphological, mechanical and anatomical responses to support variability suggesting the presence of two alternative root-climbing strategies that are optimized for their particular environmental conditions. Our results suggest that variation of some stem anatomical traits provides a buffering effect that regulates the mechanical and hydraulic demands of two distinct plant architectures. The adaptive value of observed plastic responses and the importance of considering growth form plasticity in evolutionary and conservation studies are discussed.

Does plant architectural complexity increase with increasing habitat complexity?: a test with a pioneer shrub in the Brazilian Cerrado / A complexidade arquitetural de plantas aumenta com a complexidade do habitat?: um teste com um arbusto pioneiro de Cerrado

Understanding variation in plant traits in heterogeneous habitats is important to predict responses to changing environments, but trait-environment associations are poorly known along ecological gradients. We tested the hypothesis that plant architectural complexity increases with habitat complexity along a soil fertility gradient in a Cerrado (Neotropical savanna) area in southeastern Brazil. Plant architecture and productivity (estimated as the total number of healthy infructescences) of Miconia albicans (SW.) Triana were examined in three types of vegetation which together form a natural gradient of increasing soil fertility, tree density and canopy cover: grasslands (campo sujo, CS), shrublands (cerrado sensu strico, CE) and woodlands (cerradão, CD). As expected, plants growing at the CS were shorter and had a lower branching pattern, whereas plants at the CD were the tallest. Unexpectedly, however, CD plants did not show higher architectural complexity compared to CE plants. Higher architectural similarity between CE and CD plants compared to similarity between CS and CE plants suggests reduced expression of functional architectural traits under shade. Plants growing at the CE produced more quaternary shoots, leading to a larger number of infructescences. This higher plant productivity in CE indicates that trait variation in ecological gradients is more complex than previously thought. Nematode-induced galls accounted for fruit destruction in 76.5% infructescences across physiognomies, but percentage of attack was poorly related to architectural variables. Our data suggest shade-induced limitation in M. albicans architecture, and point to complex phenotypic variation in heterogeneous habitats in Neotropical savannas.(AU)

O entendimento da variação dos atributos de plantas em ambientes heterogêneos é importante para prever respostas às mudanças climáticas; entretanto, a resposta de atributos das plantas às mudanças ambientais é pouco conhecida ao longo de gradientes ecológicos. Testou-se a hipótese de que a complexidade arquitetural de Miconia albicans (SW.) Triana aumenta com a complexidade ambiental, ao longo de um gradiente de fertilidade de solo em um Cerrado no sudeste brasileiro. A arquitetura e a produtividade (estimada por meio do número total de infrutescências sadias) foram examinadas em três tipos de vegetação, que formam um gradiente de fertilidade de solo, de densidade de árvores e de cobertura vegetal: campo sujo (CS), cerrado sensu stricto (CE) e cerradão (CD). Plantas crescendo no CS foram menores e apresentaram menor complexidade arquitetural, enquanto plantas no CD foram maiores. No entanto, de forma inesperada, plantas no CD não demonstraram maior complexidade arquitetural quando comparadas às plantas de CE, e a maior similaridade arquitetural entre plantas de CE e CD, quando comparadas com plantas de CE e CS, sugere que a expressão de atributos funcionais da arquitetura é limitada sob condições de sombra. Plantas de CE produziram mais ramos quaternários e maior número de infrutescências, sendo que a maior produtividade destas plantas indica que a variação de atributos em gradientes ecológicos é mais complexa do que se pensava anteriormente. Galhas de nematóides destruíram 76,5% das infrutescências nas vegetações, mas a porcentagem de ataque não esteve fortemente correlacionada com as variáveis arquiteturais. Os resultados do presente trabalho sugerem limitação na expressão da arquitetura da planta induzida pela sombra e apontam para uma complexa variação fenotípica na colonização de ambientes heterogêneos de savanas neotropicais.(AU)

Does plant architectural complexity increase with increasing habitat complexity? A test with a pioneer shrub in the Brazilian Cerrado / A complexidade arquitetural de plantas aumenta com a complexidade do habitat? Um teste com um arbusto pioneiro de Cerrado

Understanding variation in plant traits in heterogeneous habitats is important to predict responses to changing environments, but trait-environment associations are poorly known along ecological gradients. We tested the hypothesis that plant architectural complexity increases with habitat complexity along a soil fertility gradient in a Cerrado (Neotropical savanna) area in southeastern Brazil. Plant architecture and productivity (estimated as the total number of healthy infructescences) of Miconia albicans (SW.) Triana were examined in three types of vegetation which together form a natural gradient of increasing soil fertility, tree density and canopy cover: grasslands (campo sujo, CS), shrublands (cerrado sensu strico, CE) and woodlands (cerradão, CD). As expected, plants growing at the CS were shorter and had a lower branching pattern, whereas plants at the CD were the tallest. Unexpectedly, however, CD plants did not show higher architectural complexity compared to CE plants. Higher architectural similarity between CE and CD plants compared to similarity between CS and CE plants suggests reduced expression of functional architectural traits under shade. Plants growing at the CE produced more quaternary shoots, leading to a larger number of infructescences. This higher plant productivity in CE indicates that trait variation in ecological gradients is more complex than previously thought. Nematode-induced galls accounted for fruit destruction in 76.5% infructescences across physiognomies, but percentage of attack was poorly related to architectural variables. Our data suggest shade-induced limitation in M. albicans architecture, and point to complex phenotypic variation in heterogeneous habitats in Neotropical savannas.

O entendimento da variação dos atributos de plantas em ambientes heterogêneos é importante para prever respostas às mudanças climáticas; entretanto, a resposta de atributos das plantas às mudanças ambientais é pouco conhecida ao longo de gradientes ecológicos. Testou-se a hipótese de que a complexidade arquitetural de Miconia albicans (SW.) Triana aumenta com a complexidade ambiental, ao longo de um gradiente de fertilidade de solo em um Cerrado no sudeste brasileiro. A arquitetura e a produtividade (estimada por meio do número total de infrutescências sadias) foram examinadas em três tipos de vegetação, que formam um gradiente de fertilidade de solo, de densidade de árvores e de cobertura vegetal: campo sujo (CS), cerrado sensu stricto (CE) e cerradão (CD). Plantas crescendo no CS foram menores e apresentaram menor complexidade arquitetural, enquanto plantas no CD foram maiores. No entanto, de forma inesperada, plantas no CD não demonstraram maior complexidade arquitetural quando comparadas às plantas de CE, e a maior similaridade arquitetural entre plantas de CE e CD, quando comparadas com plantas de CE e CS, sugere que a expressão de atributos funcionais da arquitetura é limitada sob condições de sombra. Plantas de CE produziram mais ramos quaternários e maior número de infrutescências, sendo que a maior produtividade destas plantas indica que a variação de atributos em gradientes ecológicos é mais complexa do que se pensava anteriormente. Galhas de nematóides destruíram 76,5% das infrutescências nas vegetações, mas a porcentagem de ataque não esteve fortemente correlacionada com as variáveis arquiteturais. Os resultados do presente trabalho sugerem limitação na expressão da arquitetura da planta induzida pela sombra e apontam para uma complexa variação fenotípica na colonização de ambientes heterogêneos de savanas neotropicais.

Allometry of the babassu palm growing on a slash-and-burn agroecosystem of the eastern periphery of Amazonia / Allometria da palmeira babaçu em um agroecossistema de derruba-e-queima na periferia este da Amazônia

Babassu (Attalea speciosa C.Martius, Arecaceae) is a palm with extraordinary socioeconomic and ecologic importance in large areas of tropical Brazil, especially in frequently burned and degraded landscapes. Nevertheless, surprisingly little is known about this keystone species. This paper investigates the allometry of babassu, in order to improve understanding on palm architecture and to provide researchers with an efficient tool for aboveground biomass estimation of juvenile and adult palms. Juvenile leaf biomass can be accurately predicted with the easily measurable minimum diameter of rachis at 30 cm extension. Adult palm biomass can be estimated based on woody stem height, a variable fairly easily measurable on-field. Leaf biomass of adult palms was highly variable, averaged 31.7 percent of aboveground biomass and can be estimated only indirectly through the relationships between wood:leaf-ratio and total aboveground biomass. Carbon contents varied little in the babassu palm, without size- or growth-stage related differences, suggesting the general applicability of values (42.5 percent C for stems, 39.8 percent C for leaves). As a consequence of the limited secondary diameter growth inherent to palms, stem diameter of adult palms is unrelated to palm height and biomass. Stem tapering decreases with increasing palm height. This is partially compensated by increasing wood density in near cylindrical stems. Nevertheless, maximum babassu palm height of about 30 meters appears to be dictated by mechanical stability constraints. All allometric relationships of babassu described in this study are not affected by vegetation stand age, indicating the general applicability of these relationships.

A palmeira babaçu (Attalea speciosa C.Martius, Arecaceae) tem grande importância socioeconômica e ecológica em grande parte da área tropical brasileira, especialmente em áreas degradadas por queimadas freqüentes na Amazônia. No entanto, ainda pouco se sabe sobre as características ecológicas desta espécie-chave. Este estudo investiga a alometria do babaçu com o objetivo de estabelecer uma metodologia eficiente na estimativa da biomassa aérea de palmeiras juvenis e adultas e para um melhor entendimento da sua arquitetura. A biomassa de palmeiras juvenis pode ser estimada facilmente e com precisão com o diâmetro mínimo das ráquis das folhas a 30 cm de extensão. A biomassa de palmeiras adultas pode ser estimada com base na altura do tronco lenhoso, também relativamente de fácil medição em campo. A biomassa foliar das palmeiras adultas foi em media 31,7 por cento da biomassa aérea, porém houve uma alta variação e, portanto, somente pode ser estimada indiretamente através da relação entre a razão madeira:folha e biomassa aérea total. Os teores de carbono no babaçu apresentaram baixa variação, sem diferenças sistemáticas em relação ao tamanho ou estágio de crescimento, o que aponta à aplicabilidade geral dos valores 42.5 por cento C para troncos, 39.8 por cento C para folhas. Em conseqüência do limitado crescimento secundário do diâmetro inerente de palmeiras, não houve relação do diâmetro de tronco com a altura e a biomassa das palmeiras adultas. Observou-se que o afilamento do caule diminui com o aumento da altura das palmeiras, o que é parcialmente compensado pelo incremento da densidade de madeira em troncos quase-cilíndricos. No entanto, a altura máxima do babaçu, de cerca de 30 metros, aparentemente está definida por limitações na estabilidade mecânica. Todas as relações alométricas aqui descritas são independentes da idade da vegetação, indicando a aplicabilidade geral das relações encontradas.

Allometry of the babassu palm growing on a slash-and-burn agroecosystem of the eastern periphery of Amazonia

Babassu (Attalea speciosa C.Martius, Arecaceae) is a palm with extraordinary socioeconomic and ecologic importance in large areas of tropical Brazil, especially in frequently burned and degraded landscapes. Nevertheless, surprisingly little is known about this keystone species. This paper investigates the allometry of babassu, in order to improve understanding on palm architecture and to provide researchers with an efficient tool for aboveground biomass estimation of juvenile and adult palms. Juvenile leaf biomass can be accurately predicted with the easily measurable minimum diameter of rachis at 30 cm extension. Adult palm biomass can be estimated based on woody stem height, a variable fairly easily measurable on-field. Leaf biomass of adult palms was highly variable, averaged 31.7% of aboveground biomass and can be estimated only indirectly through the relationships between wood:leaf-ratio and total aboveground biomass. Carbon contents varied little in the babassu palm, without size- or growth-stage related differences, suggesting the general applicability of values (42.5% C for stems, 39.8% C for leaves). As a consequence of the limited secondary diameter growth inherent to palms, stem diameter of adult palms is unrelated to palm height and biomass. Stem tapering decreases with increasing palm height. This is partially compensated by increasing wood density in near cylindrical stems. Nevertheless, maximum babassu palm height of about 30 meters appears to be dictated by mechanical stability constraints. All allometric relationships of babassu described in this study are not affected by vegetation stand age, indicating the general applicability of these relationships.

A palmeira babaçu (Attalea speciosa C.Martius, Arecaceae) tem grande importância socioeconômica e ecológica em grande parte da área tropical brasileira, especialmente em áreas degradadas por queimadas freqüentes na Amazônia. No entanto, ainda pouco se sabe sobre as características ecológicas desta espécie-chave. Este estudo investiga a alometria do babaçu com o objetivo de estabelecer uma metodologia eficiente na estimativa da biomassa aérea de palmeiras juvenis e adultas e para um melhor entendimento da sua arquitetura. A biomassa de palmeiras juvenis pode ser estimada facilmente e com precisão com o diâmetro mínimo das ráquis das folhas a 30 cm de extensão. A biomassa de palmeiras adultas pode ser estimada com base na altura do tronco lenhoso, também relativamente de fácil medição em campo. A biomassa foliar das palmeiras adultas foi em media 31,7% da biomassa aérea, porém houve uma alta variação e, portanto, somente pode ser estimada indiretamente através da relação entre a razão madeira:folha e biomassa aérea total. Os teores de carbono no babaçu apresentaram baixa variação, sem diferenças sistemáticas em relação ao tamanho ou estágio de crescimento, o que aponta à aplicabilidade geral dos valores 42.5% C para troncos, 39.8% C para folhas. Em conseqüência do limitado crescimento secundário do diâmetro inerente de palmeiras, não houve relação do diâmetro de tronco com a altura e a biomassa das palmeiras adultas. Observou-se que o afilamento do caule diminui com o aumento da altura das palmeiras, o que é parcialmente compensado pelo incremento da densidade de madeira em troncos quase-cilíndricos. No entanto, a altura máxima do babaçu, de cerca de 30 metros, aparentemente está definida por limitações na estabilidade mecânica. Todas as relações alométricas aqui descritas são independentes da idade da vegetação, indicando a aplicabilidade geral das relações encontradas.