Dalbergia Miscolobium Research Articles

Anemochorous and zoochorous seeds of trees from the Brazilian savannas differ in fatty acid content and composition.

Fatty acids (FAs) stored as triacylglycerols (TAGs) are an important source of carbon and energy for germination and seedling development, particularly for plants with small wind-dispersed seeds, allowing greater efficiency in storing both energy and carbon. These plants should be under strong selection to produce seeds rich in FAs and with large amounts of saturated FAs. Their closely packed single-chain configuration allows greater packing, more carbon and energy per unit mass, and are less costly to produce. Efficient carbon storage would be less crucial for zoochorous species, which can reach much larger seed sizes (mass). We analysed the transesterified FA profile from seeds of 22 anemochorous and zoochorous tree species from the Cerrado savannas of Central Brazil. We tested if seed FA content covaried with seed mass and if anemochorous and zoochorous seeds differed in FA contents and distribution. Fatty acids were an important seed source of carbon and energy for most species. Fifteen different FAs were identified. Oleic, linoleic and linolenic tended to be the predominant unsaturated FAs. Oleic acid corresponded to more than 60 % of the total transesterified FAs in seeds of Kielmeyera coriacea, Qualea dichotoma and Triplaris americana. Linoleic acid corresponded to more than 50 % of total FA in Dalbergia miscolobium, Parkia platycephala and Ferdinandusa elliptica while linolenic acid was the dominant component in Inga cylindrica. Across species, palmitic and stearic were the dominant saturated FAs. The only exception was lauric acid (68 % of total FA) in seeds of Qualea grandiflora. On a log10 scale, as the seed increased in mass, accumulation of FAs tends to proceed at a faster rate in anemochorous species than in zoochorous species. They also became increasingly richer in saturated FAs. Zoochorous species had seed TAGs with higher proportion of polyunsaturated FAs.

How Deep Can the Endophytic Mycobiome Go? A Case Study on Six Woody Species from the Brazilian Cerrado

Elucidating the complex relationship between plants and endophytic fungi is very important in order to understand the maintenance of biodiversity, equity, stability, and ecosystem functioning. However, knowledge about the diversity of endophytic fungi from species of the native Brazilian Cerrado biome is poorly documented and remains largely unknown. These gaps led us to characterize the diversity of Cerrado endophytic foliar fungi associated with six woody species (Caryocar brasiliense, Dalbergia miscolobium, Leptolobium dasycarpum, Qualea parviflora, Ouratea hexasperma, and Styrax ferrugineus). Additionally, we investigated the influence of host plant identities on the structure of fungal communities. Culture-dependent methods coupled with DNA metabarcoding were employed. Irrespective of the approach, the phylum Ascomycota and the classes Dothideomycetes and Sordariomycetes were dominant. Using the cultivation-dependent method, 114 isolates were recovered from all the host species and classified into more than 20 genera and 50 species. Over 50 of the isolates belonged to the genus Diaporthe, and were distributed into more than 20 species. Metabarcoding revealed the phyla Chytridiomycota, Glomeromycota, Monoblepharomycota, Mortierellomycota, Olpidiomycota, Rozellomycota, and Zoopagomycota. These groups are reported for the first time as components of the endophytic mycobiome of Cerrado plant species. In total, 400 genera were found in all host species. A unique leaf endophytic mycobiome was identified in each host species, which differed not only by the distribution of fungal species, but also by the abundance of shared species. These findings highlight the importance of the Brazilian Cerrado as a reservoir of microbial species, and emphasize how endophytic fungal communities are diversified and adapted.

Atividade Inibitória e Estudos de Docking da Catepsina V para Isoflavanoides de Dalbergia Miscolobium Benth

Plant extracts from Dalbergia genus have demonstrated a wide range of biological activities including analgesic, antidiabetic, anti-inflammatory and antimicrobial. In this work, the chemical study of the extracts from the leaves and branches of Dalbergia miscolobium led to the identification of five isoflavonoids: prunetin, di- O -methyldaidzein, 8- O -methylretusin, duartin and sativan by means of nuclear magnetic resonance data. The inhibition activity of these isoflavonoids were screened against cathepsin V at concentration of 100 µM. Duartin and sativan showed remarkable activity against cathepsin V displaying inhibition values of 89% and 88%, respectively. In addition, docking simulations to predict the binding mode in this protein were performed and the results showed that the duartin is nicely bound to the cathepsin V and stabilized by two hydrogen bonds. The isoflavans duartin and sativan showed an important inhibition percentage of cathepsin V, which can be considered as targets into cathepsin V inhibitors investigation and further chemical study of Dalbergia species may afford novels isoflavonoids cathepsin inhibitors.

Environmental variables drive phenological events of anemocoric plants and enhance diaspore dispersal potential: A new wind-based approach

Phenological studies of Brazilian savanna vegetation have described a generalized phenological pattern for all species, mainly based on rainfall and temperature. Few studies have considered wind as an explanatory factor; abiotic factors may impact differently on phenophases, and one phenophase may influence the performance of another. Thus, we aim to describe the phenological patterns of five anemocoric plant species (Aspidosperma tomentosum, Dalbergia miscolobium, Kielmeyera coriacea, Peixotoa tomentosa and Qualea multiflora) in the face of different climatic conditions, mainly evaluating the effects of wind on the ripe diaspore. We addressed three main questions: (1) What is the phenological behavior of each of these five anemocoric species in a seasonal environment? (2) Which climatic variables best explain each phenophase? (3) Does the dispersal of ripe diaspores peak shortly after deciduousness? We found that (i) our focal species showed similar phenological patterns, except for the floral bud and flower phenophases of two species (A. tomentosum and P. tomentosa), and the young fruit phase; (ii) each abiotic variable has a specific level of influence for each phenophase, but the most important variables were rainfall and wind speed; and (iii) the dispersal peak of ripe diaspores occurred shortly after deciduousness, and when plants had fewer leaves. We conclude that the phenological patterns of these five anemocoric plants are similar, but that the patterns observed are not necessarily those described for Cerrado species. Additionally, we found that wind is an important factor in the expression of specific phenophases, and that the performance of some phenological events can be influenced by others, especially diaspore dispersal.

Anatomical, physiological and allometric contrasts of the Cerrado tree Dalbergia miscolobium in full sun and shade environments

The Brazilian Cerrado is a mosaic comprised of different vegetation formations and consequently, different environmental conditions. Tree density modifies the availability of light and affects species distribution. Thus, seedlings of species with a broad distribution should show contrasting anatomical, morphological, and physiological traits depending on environmental conditions, and this should account for a higher phenotypic plasticity as part of their survival strategies. Our aim was to investigate the ability of Dalbergia miscolobium, a widespread species in the Cerrado, to modify physiological, allometric, and anatomical traits under full sunlight and shade conditions. In a shade environment, D. miscolobium had increased tree height, number of leaves, chlorophyll content, and specific leaf area; in full sun, nett photosynthesis, stomatal conductance, transpiration, and leaf thickness increased. Also, root-to-shoot ratio (R:S ratio) was ∼70% greater in the full sun than the shade. A high relative distance phenotypic index, which quantifies phenotypic plasticity by the relative distance among the individual traits, was observed for R:S ratio (0.37), indicating the ability of D. miscolobium to change its biomass allocation in different environments. The contrasts in the studied traits under the two light conditions may be related to changes in carbon investment with light availability. This phenotypic plasticity may explain the broad distribution of D. miscolobium.

Woody biomass accumulation in a Cerrado of Central Brazil monitored for 27 years after the implementation of silvicultural systems

The Brazilian Cerrado is the second largest biome in Brazil, and its natural landscapes have undergone transformations, due in large part to anthropic activities. However, little is known about the effects of these activities on the natural regeneration of Cerrado vegetation. Thus, the objective of this study was to evaluate the accumulation of woody biomass in an area of a Cerrado sensu stricto that was monitored for 27 years after the implementation of six silvicultural systems.A period of 17 years was sufficient for the woody community of the Cerrado sensu stricto to naturally recover its original stock of aerial biomass after the application of silvicultural systems. A Few woody species contribute to the total aerial biomass accumulated over time, and such contribution is variable with time and with the type of silvicultural system.At 27 years after cutting, the largest fraction of biomass accumulated in the area were represented by the species Miconia leucocarpa, Blepharocalyx salicifolius, Schefflera macrocarpa, Qualea grandiflora, Dalbergia miscolobium, Eriotheca pubescens, Qualea parviflora and Caryocar Brasiliense, which also demonstrated higher fire resistance.A period of 17 years after the implementation of silvicultural systems is considered sufficient for an area to recover naturally to the original stock of woody biomass at the community level. This result causes a greater reduction in the biomass of fire-sensitive species and transforms a Cerrado from a carbon sink into a source of CO2 emissions to the atmosphere.

Estrutura e diversidade de trechos de Cerrado <i>sensu stricto</i> às margens de rodovias no estado de Minas Gerais

Estradas são um dos principais fatores de degradação conhecidos do Cerrado, pois, apesar de sua relevância econômica, causam recortes em extensas massas contínuas de biota natural. De acordo com o Código Florestal Brasileiro, a vegetação às margens de rodovias deve ser considerada como de preservação permanente. Entretanto, escassos são os estudos que visam avaliar o real potencial conservacionista destas áreas. O objetivo do estudo foi avaliar o estágio de conservação do estrato arbóreo do Cerrado localizado nas faixas de proteção das rodovias MG-190, MG-223, BR-365 e BR-352. Foram amostradas 40 parcelas de 50 x 10 m nas margens dessas rodovias e demarcados todos os indivíduos arbóreos vivos com circunferência a 30 cm do solo maior ou igual 15 cm. Foram calculados os parâmetros fitossociológicos de densidade, dominância e frequência relativa, valor de importância, equabilidade de Pielou e os índices de diversidade de Shannon-Weaver e Simpson. A riqueza foi estimada utilizando os estimadores Jackknife 2 eBootstrap. Foram amostrados 790 indivíduos pertencentes a 88 espécies e 35 famílias. O índice de diversidade de Shannon-Weaver foi 3,64 nats.ind-1, o índice de Simpson foi 0,94 e a equabilidade foi 0,81. As espécies mais comuns no levantamento foram Dalbergia miscolobium, Piptocarpha rotundifolia, Machaerium acutifolium, Ouratea hexasperma e Stenocalyx dysentericus. As famílias com maior número de espécies foram Fabaceae (20 espécies), Myrtaceae (8 espécies) e Bignoniaceae (7 espécies). A riqueza estimada foi de 108 espécies pelo estimador Bootstrap e de 159 pelo estimador Jackknife 2, demonstrando que o número de espécies nas margens das estradas pode ser maior do que a encontrada em alguns Cerrados protegidos. Pode-se inferir que as margens de rodovias conservam um importante montante da flora arbórea do Cerrado, o que preconiza a sua manutenção, dado a atual situação de degradação intensiva do Cerrado.

Relationships between moisture content and flammability of campestral Cerrado species in Jalapão

The objective of this study was to analyze the relationships between moisture content and the flammability of campestral Cerrado species in the Jalapao region. For that, six species were collected (Trachypogon spicatus, Aristida sp., Davilla elliptica, Byrsonima verbascifolia, Hirtella ciliata and Dalbergia miscolobium) and analyzed in four moisture levels (H1, H2, H3 and H4). The tests were performed in the epirradiator, with 50 replicates of 1 g sample for each species, to obtain the ignition frequency (IF), the mean time to ignition (MTI), the time of combustion (MTC) and flame height (MFH). Correlations between moisture and other variables were r = 0.94 (MTI), r = -0.43 (MTC), r = -0.87 (MFH) and r = -0.73 (IF). The linear regression equations had R²aj values of 0.87 (MTI); 0.15 (MTC); 0.74 (MFH) and 0.50 (IF). There was influence of humidity in the change of flammability variables, however, there was little variation in the flammability values (FV), except for the species Aristida sp., and Dalbergia miscolobium, showing the high flammability of most species, even at the highest levels of moisture content.

How does resprouting response differ among three species of savanna trees and in relation to plant size?

Cerrado tree species can survive fire by resprouting. Generally, large and less damaged plants produce new branches and leaves from stem buds (aerial), whereas small and highly injured individuals would resprout from the stem base or from underground organs (basal). We compared the three most common Cerrado woody plant species in a savanna area of the IBGE Ecological Reserve, Brasilia, Brazil, aiming to verify if the resprouting strategy (aerial or basal) differed between species and if that was related to plant size. Guapira noxia had small-sized plants, a higher percentage of trunk charred and more individuals with basal resprouting, while Eriotheca pubescens had large-sized plants with a greater intensity of aerial resprouting, Basal resprouting was associated with disturbance severity for Dalbergia miscolobium, while plant size was associated with aerial resprouting for E. pubescens. None of variables explained the variation in resprouting of G. noxia. The results showed that the post-fire regeneration strategy varied according to the species, confirming other studies of post-fire resprouting.

Transferability of microsatellite markers across six Dalbergia (Fabaceae) species and their characterization for Dalbergia miscolobium

In this study, 18 microsatellite markers previously developed and characterized for two Dalbergia species (Dalbergia nigra and Dalbergia monticola) were tested for six other species of the genus: Dalbergia decipularis, Dalbergia ecastaphyllum, Dalbergia elegans, Dalbergia frutescens, Dalbergia miscolobium, and Dalbergia sissoo. All species except D. sissoo are native to Brazil, and some have high-quality timber. Among the tested loci, 14 showed successful amplification in at least two species, and polymerase chain reaction (PCR) conditions were optimized for each of 8–12 transferred markers. Nine polymorphic loci were characterized for 50 individuals of two population of D. miscolobium. The total number of alleles for each locus ranged from 4 to 13. The observed and expected heterozygosity (He and Ho) ranged from 0.111 to 1.000 and from 0.108 to 0.842, respectively. All markers transferred from D. nigra and D. monticola in this study can be used to perform future population genetics studies of this important genus.

CLASSIFICAÇÃO FISIOLÓGICA DE SEMENTES FLORESTAIS QUANTO À TOLERÂNCIA À DESSECAÇÃO E AO COMPORTAMENTO NO ARMAZENAMENTO

RESUMO Este trabalho teve por objetivo classificar sementes de espécies florestais nativas da bacia do Alto Rio Grande quanto à tolerância à dessecação e ao comportamento no armazenamento. Testes de germinação e de umidade foram feitos para cada espécie: com as sementes recém-beneficiadas, imediatamente ao atingir 12% e 5% de umidade, e após três meses de armazenamento a -18°C, apenas para sementes com 5% de umidade. Com base nos testes de germinação e umidade, as sementes foram classificadas em recalcitrantes, intermediarias e ortodoxas. As sementes de Brosimum gaudichaudii, Erythroxylum deciduum, Eugenia pleurantha, Myrcia venulosa, Nectandra megapotamica foram classificadas como recalcitrantes (22.7% das espécies). Foram classificadas como intermediárias as sementes de Aegiphila sellowiana, Aspidosperma parvifolium, Blepharocalyx salicifolius, Casearia lasiophylla, Cassia occidentalis, Dalbergia miscolobium, Diospyros brasiliensis, Diospyros hispida, Ilex brevicuspis, Ilex cerasifolia, Myrocarpus fastigiatus, Senna aversiflora e Senna splendida (59.1% das espécies). Miconia albicans, Platycyamus regnellii, Styrax camporum e Piptadenia gonoacantha foram classificadas como ortodoxas (18.2% das espécies).

EFEITO DE ALTAS TEMPERATURAS NA GERMINAÇÃO DE SEMENTES DE Plathymenia reticulata Benth. E Dalbergia miscolobium Benth.

RESUMOO fogo é comum no Cerrado e, geralmente, ocorre durante a seca, quando várias espécies frutificam ou dispersam as sementes. Entretanto, pouco se sabe sobre os efeitos do fogo na germinação das espécies do Cerrado. Este trabalho investigou o efeito da exposição a altas temperaturas na germinação de sementes de Dalbergia miscolobium Benth. e Plathymenia reticulata Benth., comuns no Cerrado e com uso potencial para recuperação de áreas degradadas e na recomposição de áreas de preservação permanente. As sementes foram coletadas em agosto de 2011, pesadas, separadas em três classes de tamanho e expostas a três temperaturas: 80 ºC, 100 ºC e 150 ºC por 2 e 5 minutos. Após os tratamentos, as sementes foram colocadas para germinar. A exposição a altas temperaturas afetou, de forma diferenciada, a germinação das espécies. Independentemente da classe de tamanho, a exposição das sementes até 100 °C, por 2 e 5 minutos, não alterou a germinação de D. miscolobium (91%). Entretanto, apenas as sementes maiores germinaram após a exposição a 150 °C, porém com redução significativa na germinação (53%; p<0,01). Para P. reticulata, a exposição a 80 °C por 2 e 5 minutos e a 100 °C por 2 minutos não alterou a germinação (71%), e nenhuma semente germinou após a exposição a 150 °C. A baixa resistência das sementes às altas temperaturas pode afetar significativamente o recrutamento de novos indivíduos após a ocorrência de queimadas no Cerrado.

Avaliação da capacidade de rebrotamento pós-distúrbio das plantas lenhosas típicas dos campos rupestres

RESUMO. As plantas possuem eficientes mecanismos a fim de se estabelecerem e permanecerem no ambiente. Um desses mecanismo e capacidade de rebrotamento que algumas especies apresentam, muitas delas associadas a ambientes propensos a queimadas como e o caso dos ambientes dos campos rupestres. Nesse trabalho foi avaliado a capacidade e morfologia de rebrotamento pos disturbio em duas populacoes tipicas nos campos rupestres da Serra do Cipo, testando a hipotese de que o fogo (agente do disturbio) e um agente seletivo dessas especies e que elas apresentam entao esse mecanismo de rebrotamento pos-disturbio. Para o trabalho foram escolhidas as populacoes de Dalbergia miscolobium e de Vochysia thyrsoideae que perderam biomassa sobre o solo devido a intensa queimada na Serra do Cipo. Essas especies apresentaram portanto, diferentes estrategias de rebrotamento onde D. miscolobium rebrotou a partir do chao, de estruturas capazes de armazenar amido (lignotuber) que favorecem esse tipo de recomposicao de biomassa. Por outro lado, V. thyrsoidea garante a protecao de suas gemas pela espessura do CAP. Essas gemas protegidas passam a rebrotar a partir da casca da arvores, chamadas de gemas epicormicas. Nossos dados alem de mostrar o sucesso de recuperacao dos orgaos fotossinteticos a partir do rebrotamento e das caracteristicas da arquitetura de construcao dos modulos para cada especie, nos permitiu sugerir que o sucesso do rebrotamento e recuperacao da biomassa sobre o solo, esteja relacionado com a quantidade de recursos alocados para essa funcao. O fogo portanto, pode atuar como agente seletivo de especies eficientes quanto ao rebrotamento nos campos rupestres, uma vez que as caracteristicas de rebrotamento exibidas para esse ambiente e similar as caracteristicas apresentadas por outras especies em outros ambientes tambem propensos a queimadas. [Palavras chave: arquitetura de arvores, biomassa, brotamento vegetativo, Cerrado, Dalbergia miscolobium, fogo, Serra do Cipo, Vochysia thyrsoidea]

Concordance between Phylogeographical and Biogeographical Patterns in the Brazilian Cerrado: Diversification of the Endemic Tree Dalbergia miscolobium (Fabaceae)

Few studies have addressed the phylogeography of species of the Cerrado, the largest savanna biome of South America. Here we aimed to investigate the phylogeographical structure of Dalbergia miscolobium, a widespread tree from the Cerrado, and to verify its concordance with plant phylogeographical and biogeographical patterns so far described. A total of 287 individuals from 32 populations were analyzed by sequencing the trnL intron of the chloroplast DNA and the internal transcribed spacer of the nuclear ribosomal DNA. Analysis of population structure and tests of population expansion were performed and the time of divergence of haplotypes was estimated. Twelve and 27 haplotypes were identified in the cpDNA and nrDNA data, respectively. The star-like network configuration and the mismatch distributions indicated a recent spatial and demographic expansion of the species. Consistent with previous tree phylogeographical studies of Cerrado trees, the cpDNA also suggested a recent expansion towards the southern Cerrado. The diversity of D. miscolobium was widespread but high levels of genetic diversity were found in the Central Eastern and in the southern portion of Central Western Cerrado. The combined analysis of cpDNA and nrDNA supported a phylogeographic structure into seven groups. The phylogeographical pattern showed many concordances with biogeographical and phylogeographical studies in the Cerrado, mainly with the Cerrado phytogeographic provinces superimposed to our sampling area. The data reinforced the uniqueness of Northeastern and Southeastern Cerrados and the differentiation between Eastern and Western Central Cerrados. The recent diversification of the species (estimated between the Pliocene and the Pleistocene) and the ‘genealogical concordances’ suggest that a shared and persistent pattern of species diversification might have been present in the Cerrado over time. This is the first time that an extensive ‘genealogical concordance’ between phylogeographic and phytogeographic patterns is shown for the Cerrado biome.

Crescimento de Dalbergia miscolobium em substrato de rejeito da mineração de quartzito fertilizado

Growth of Dalbergia miscolobium Benth was evaluate under quartzite mining reject with chemical and organic fertilization, aiming at to support actions for restoration of degraded areas after quartzite mining. A greenhouse experimentation was carried out in a completely randomized design with four replications The treatments consisted of five combinations of chemical (CF) and organic (OF) fertilizer and an additional treatment without CF or OF (Control). The combinations were: 100%CF; 25%OF+75%CF; 50%OF+50%CF; 75%OF+25%CF; 100%OF. Doses of 100% CF and OF were of 25 mg N, 25 mg P2O5, 20 mg K2O and 5 g of bovine manure per dm³ of reject. The plants of D. miscolobium responded to chemical fertilization with recommended doses, without addition of bovine manure. The accumulation of nutrients at recommended doses in shoots of D. miscolobium were: N > K > Ca > S > P > Mg > Mn > Fe > Cu > B > Zn. The quartzite mining reject of may be a favorable habitat for D. miscolobium growth when with chemical fertilization.

Pollen grain morphology of Fabaceae in the Special Protection Area (SPA) Pau-de-Fruta, Diamantina, Minas Gerais, Brazil

The presented paper considered the pollen morphology of thirteen species belonging to seven genera of the Fabaceae family occurring in the Pau-de-Fruta Special Protection Area (SPA), Diamantina, state of Minas Gerais, Brazil. The pollen grains of six species of Chamaecrista [C. cathartica (Mart.) H.S. Irwin & Barneby, C. debilis Vogel, C. flexuosa (L.) Greene, C. hedysaroides (Vogel) H.S. Irwin & Barneby, C. glandulosa (L.) Greene, and C. papillata H.S. Irwin & Barneby] have a similar morphology, characterized by three long colporated apertures with a central constriction. The species share specific morphological features regarding pollen size, endoaperture type (circular, lalongate or lolongate) and SEM ornamentation patterns of the exine (rugulate with perforations or perforate). Andira fraxinifolia Benth., Dalbergia miscolobium Benth, Galactia martii DC, Periandra mediterranea (Vell.) Taub., Senna rugosa (G.Don) H.S. Irwin & Barneby and Zornia diphylla (L.) Pers showed different pollen types in small to large size; oblate spheroidal to prolate form; colpus or colporus apertures; circular, lalongate or lolongate endoapertures and distinctive SEM ornamentation patterns of the exine (perforate, microreticulate, reticulate or rugulate with perforations). Only Stryphnodendron adstringens (Mart.) Coville presents polyads. The pollen morphology variation of these species allowed the Fabaceae family to be characterized as eurypalynous in the SPA Pau-de-Fruta.

Heat shock effects on seed germination of five Brazilian savanna species

Fire is considered an important factor in influencing the physiognomy, dynamics and composition of Neotropical savannas. Species of diverse physiognomies exhibit different responses to fire, such as population persistence and seed mortality, according to the fire frequency to which they are submitted. The aim of this study is to investigate the effects of heat shocks on seed germination of Anadenanthera macrocarpa (Benth.) Brenan, Dalbergia miscolobium Benth., Aristolochia galeata Mart. & Zucc., Kielmeyera coriacea (Spreng.) Mart. and Guazuma ulmifolia Lam., which are native species of the Brazilian savanna. The temperatures and exposure times to which the seeds were submitted were established according to data obtained in the field during a prescribed fire: 60 °C (10, 20 and 40 min), 80 °C (5, 10 and 20 min) and 100 °C (2, 5 and 10 min). Untreated seeds were used as controls. Seeds of A. galeata and K. coriacea showed high tolerance to most heat treatments, and seeds of A. macrocarpa showed a significant reduction in germination percentage after treatments of 80 °C and 100 °C. Treatments of 100 °C for 10 min reduced germination percentage for all species except G. ulmifolia, which has dormant seeds. For this species, germination was accelerated by heat treatments. The high temperatures applied did not interfere with the time to 50% germination (T(50) ) of the tolerant seeds. Seeds of the savanna species K. coriacea and A. galeata were more tolerant to heat shocks than seeds of the forest species A. macrocarpa. Guazuma ulmifolia, the forest species with seeds that germinate after heat shock, also occurs in savanna physiognomies. Overall, the high temperatures applied did not affect the germination rate of the tolerant seeds.

Allometry of some woody plant species in a Brazilian savanna after two years of a dry season fire

Studies of allometry are important in explaining effects of fire and herbivory, for estimating biomass in forests, and so on. There has been extensive research on plant allometry in temperate and tropical forests, showing that plant architecture often adjusts to the elastic similarity model, but not in Brazilian savannas (cerrado). We studied allometry of Dalbergia miscolobium, Diospyros hispida, Erythroxylum suberosum, Miconia albicans, M. ligustroides, Schefflera vinosa, and Xylopia aromatica in a cerrado sensu stricto area that was affected by a fire in August 2006. We expected that the study species would not adjust to any of the allometric models considered common for forest species ("constant stress", "elastic similarity", and "geometric growth"), and that there would be differences in allometry in burnt and unburnt patches. We sampled two species in 60 5 × 5 m contiguous plots placed in three transects, and five species in 100 5 × 5 m contiguous plots placed in five transects, where we measured the diameters at soil level (DSL) and the heights of all shoots. We used standardized major axis regressions on log-transformed data. The regression slope between the height and DSL was higher than 1.0 (p < 0.05) for four species, showing a greater height than would be expected under geometric growth, not predicted by theoretical models. We found significant differences (p < 0.05) in regression slopes and/or correlation coefficients between burnt and unburnt plots for five species, indicating that fire may influence plant allometry in the Brazilian cerrado, and that such a response is highly variable between species.

Relações entre propriedades químicas, físicas e energéticas da madeira de cinco espécies de cerrado.

Os objetivos da pesquisa foram caracterizar e avaliar a influência das propriedades químicas (teores de lignina, holocelulose e extrativos) da madeira de cinco espécies lenhosas de Cerrado (Pterodon pubescens, Dalbergia miscolobium, Sclerolobium paniculatum, Stryphnodendron adstringens e Vochysia thyrsoidea) na densidade básica e na contração volumétrica da madeira; nos rendimentos e densidade aparente do carvão vegetal. As amostras foram coletadas em área de manejo florestal em Brasília, provenientes de três árvores de cada espécie, perfazendo um total de 15 amostras. Não houve diferença significativa entre as espécies para o teor de extrativo da madeira e rendimento gravimétrico em carvão vegetal. Pterodon pubescens, Dalbergia miscolobium e Sclerolobium paniculatum se destacaram por apresentarem, respectivamente, as maiores densidades básicas (0,82, 0,80 e 0,78 g/cm3); os maiores teores de lignina (31,74, 32,31 e 31,42%); as maiores densidades aparentes do carvão vegetal (37, 43 e 37%). Por outro lado Stryphnodendron adstringens e Vochysia thyrsoidea apresentaram, respectivamente, os maiores teores de holocelulose (72,22 e 74,84%). O teor de lignina apresentou correlação positiva e significativa com a densidade básica da madeira e com a densidade aparente do carvão vegetal e não apresentou correlação significativa com a retração volumétrica e com o rendimento gravimétrico. O teor de holocelulose apresentou correlação negativa e significativa com a densidade básica da madeira e com a densidade aparente do carvão vegetal. Os extrativos totais não apresentaram correlação significativa com nenhuma das variáveis analisadas.

Fitossociologia e diversidade florística em área de cerrado sob vários níveis de antropização, Rio Pardo de Minas, MG

Este estudo teve como objetivo avaliar a diversidade e a similaridade florística de ambientes de Cerrado, sob diferentes níveis de antropização por uso agrícola e extrativismo, e gerar base de dados para subsidiar propostas de desenvolvimento sustentável para a região Norte de Minas e sistemas de agricultura tradicional. Foram amostradas 4 áreas nos seguintes ambientes: Areião, Areiãozinho, Chapada de Latossolo e Tabuleiro, cujas identificações foram feitas a partir de informantes-chave na Comunidade Água Boa, em Rio Pardo de Minas (MG). As unidades amostrais foram distribuídas em 8 parcelas de 20 x 50 m, com 5 subparcelas. Foram medidos indivíduos arbóreos com circunferência ao nível do solo maior ou igual a 15 cm. Para análise dos índices fitossociológicos foram calculados os parâmetros densidade, dominância, freqüência, área basal e valor de importância, para cada ambiente. Para a diversidade florística foi calculado o índice de Shannon (H') e para análise da similaridade o índice de Jaccard (Sij). Em todos os ambientes, foi encontrado um total de 477 indivíduos, distribuídos em 21 famílias, com 48 espécies botânicas identificadas e 27 indivíduos não identificados. As cinco famílias mais importantes (maior VI) foram Fabaceae/Papilionoideae, Apocynaceae, Vochysiaceae, Sapotaceae e Fabaceae/Caesalpinoideae. Já as dez espécies de maior importância foram Pouteria ramiflora, Dalbergia miscolobium, Hancornia speciosa, Macherium opacum, Sclerolobium paniculatum var. subvelutinum, Qualea grandiflora, Aspidosperma tomentosum, Byrsonima pachyphylla, Vochysia thyrsoidea e Hymenaea stigonocarpa. O índice H' foi de 3,01; 2,72; 2,48 e 2,09 para Areião, Areiãozinho, Chapada do Latossolo e Tabuleiro, respectivamente. O índice Sij indicou, para todas as combinações entre os ambientes, que existia pouca similaridade florística entre eles.