Acta Botanica Brasilica
[SJR: 0.364] [H-I: 23] [2 followers] Follow
Open Access journal
ISSN (Print) 0102-3306
Published by SciELO [724 journals]
- Occurrence of arbuscular mycorrhizal fungi in high altitude sites of the
Patagonian Altoandina region in Nahuel Huapi National Park (Argentina)
Abstract: ABSTRACT Knowledge of the occurrence and diversity of arbuscular mycorrhizal fungi (AMF) in National Parks is essential for the establishment of policies for conservation. The aim of this study was to characterize the AMF communities in the Patagonian Altoandina region in Nahuel Huapi National Park, Argentina. We surveyed AMF spores associated with the rhizospheres of 9 plant species in the Patagonian Steppe (PS), Challhuaco Hill (ChH), Catedral Hill (CH), and Tronador Hill (TH) regions and detected a total of 27 Glomeromycota species. Acaulospora laevis was dominant at all sites. The AMF community was dominated by Acaulosporaceae, as regards the number of species and contribution of each one to the total number of spores. Three Glomeromycota families were detected at PS, the site with the lowest elevation; whereas five to six families were detected at ChH, CH, and TH. Cluster analysis indicated that the AMF communities were grouped according to habitat. We concluded that certain patterns of the AMFcommunity structure detected were equivalent to those of high-altitude environments from other studies, while others were unique to the Patagonian region; thus suggesting that historical influences like dispersion and speciation played a critical role in shaping AMF community composition in such high-altitude environments.
- A contingent valuation study of buriti ( Mauritia flexuosa L.f.) in the
main region of production in Brazil: is environmental conservation a
Abstract: ABSTRACT The immature leaves of the buriti palm (Mauritia flexuosa) are widely harvested in the municipality of Barreirinhas, Maranhão, for the production of handicrafts, which are sold to locals and tourists. The increasing demand for these artisanal goods is stimulating the emergence of an informal market for immature buriti leaves, leading to an intensification of their extraction and resulting in negative effects on local buriti palm populations and the ecosystem. Thus, the objective of the present study was to assess the environmental value of the buriti palm tree based on the maximum willingness to pay (WTP) for its conservation, using the contingent valuation method. Among the respondents, 99.74% reported that the palm species should be protected and the majority of them (65.75%) agreed to pay for its conservation (annual WTP R$ 179.49 ± 222.05). Multivariate analysis revealed that the WTP was not influenced by the socio-economic profile of the respondents. The main reasons for non-WTP are related to dissatisfaction with the government and the belief that financial contributions would not solve problems of environmental damage. Overall, the evaluated population believes that environmental conservation is not an obligation of the government or that of the population, but is a collective responsibility.
- Do the structures of macaw palm fruit protect seeds in a fire-prone
Abstract: ABSTRACT Fire is an abiotic disturbance that regulates vegetation structure and biodiversity. Some plant species have adapted to fire prone environments by evolving protective structures. Acrocomia aculeata (macaw palm) is widely distributed throughout tropical America, and is found in environments continuously influenced by anthropogenic fire. We aimed to determine whether the fruit characteristics of A. aculeata enable seeds to resist the effects of fire and also the consequent effects of fire on fruit biometric traits and embryo viability. After a fire event in a region of pasture-forest transition, we marked 30 individuals of A. aculeata. The trees were separated by UPGMA analysis into 5 groups according to fire exposure, ranging from trees with no exposure to trees with fruit completely exposed to fire. Fruit exposure to high temperatures led to lower values in fruit fresh weight, length, density, and processable mass.Fire had no significant effect on seed biometric variables, because of the structures of the fruit, including its lignified endocarp and its insulating and mucilaginous mesocarp. These structures helped to maintain the embryos viability by preventing oxidative damage. In conclusion, the fruit structure of the macaw palm may facilitate seed persistence, even when subject to increasingly frequent fire events.
- Corticolous myxobiota of the Pernambuco Center of Endemism, Brazil
Abstract: ABSTRACT Situated within the Atlantic Forest domain, the Centro de Endemismo Pernambuco (Pernambuco Center of Endemism) - CEPE is regarded as a priority for biodiversity conservation worldwide. Covering an area of approximately 56,000 km2, it encompasses part of the states of Alagoas, Pernambuco, Paraíba and Rio Grande do Norte in northeastern Brazil. Here we present an identification key to 73 species of Myxomycetes that compose the known corticolous myxobiota of the Dense Ombrofilous Lowland Forest, Semideciduous Lowland Forest, Restinga Forest and Mangrove environments of CEPE. Specimens included here were found developed in natural conditions in the field or obtained through moist chamber culture. Among the species found, Arcyria cinerea, Clastoderma debaryanum, Cribraria confusa, C. violacea and Echinostelium minutum were the most common; and Comatricha longipila, Licea pedicellata, Paradiachaeopsis longipes, Perichaena calongei and Stemonaria fuscoides were the most rare. Our data indicates that the species richness of corticolous myxomycetes in rainforests is lower than that of temperate forests. These same data also suggest that taxonomic diversity (mean number of species per genus) is similar to, or higher than, that found in temperate regions of the world.
- Effects of flooding and its temporal variation on seedling recruitment
from the soil seed bank of a Neotropical floodplain
Abstract: ABSTRACT Evaluation of the effects of flooding on seedling recruitment from seed banks helps in understanding vegetation regeneration in floodplains. We studied the effects of simulated flooding on richness and abundance of, and temporal variation in, seedling recruitment from the soil seed bank of a floodable savanna of the Pantanal wetland, under two conditions: 1) Post-flood = inundated for 30 days followed by irrigation; 2) Non-flooded = only irrigated. We recorded emerged seedlings biweekly for 120 days and found a total of 124 species for the two treatments, the most abundant species were annual herbs (e.g., Richardia grandiflora and Euploca procumbens) and annual graminoids (e.g., Digitaria ciliaris and Cyperus haspan). Flooding positively influenced seedling richness and abundance, while seedling emergence from the non-flooded soil was slower, but continued during all periods. The different temporal patterns between treatments showed that flooding increases the abundance of emerged seedlings and acts as a trigger for explosive recruitment shortly after water depletion.
- Patterns of species richness and abundance among cactus communities
receiving different rainfall levels in the semiarid region of Brazil
Abstract: ABSTRACT This study examines the variation in cacti species richness and abundance among sites with different average rainfall and soil types. We assessed a total of 3,660 individuals of six species of Cactaceae: Cereus jamacaru, Melocactus zehntneri, Pilosocereus gounellei, Pilosocereus pachycladus, Tacinga inamoena, and Tacinga palmadora. The greatest species richness and abundance of cacti were at locations with low rainfall and more clayey soils. The species studied differed in multidimensional representation, with some species being more positively related to soils with a higher proportion of fine particles (M. zehntneri and P. gounellei), while others were negatively related to soils with a higher proportion of coarser particles (T. inamoena) or positively related to areas with higher rainfall and vegetation cover (C. jamacaru and P. pachycladus). The differential responses of the species of Cactaceae studied in relation to the gradients analyzed demonstrates the need for more research into the relationship between cacti and environmental variables in semiarid ecosystems with high environmental heterogeneity.
- Spatial patterns of two co-occurring savanna and forest tree species in a
dense fire-protected savanna fragment
Abstract: ABSTRACT Savanna-forest transition under fire-exclusion could be explained by differential competitive performance of savanna and forest species under shading/fire-exclusion. Aiming to understand strategies related to either habitat affinity, we investigated spatial patterns of a savanna and a forest species in a fire-protected savanna. We predicted that: savanna species would have lower abundance than the forest species due to a restriction in the number of open microsites; segregation of size classes and a trend from clumping to regularity with size for forest species due to absence of microsite limitation and intra-specifc competition; and spatial association and increasing clustering with size for savanna species due to microsite limitation. To test these predictions, we described spatial patterns of plants in two size classes in three plots of 0.5 ha. We analyzed spatial patterns and associations of size classes using SADIE methodology. Different from what we expected, both species were more abundant among the studied plots and exhibited an increasing aggregation from small to large size classes. We also found a positive spatial association between size classes of both. These results suggest that both savanna and forest species produce similar spatial patterns independently of habitat affinity. We discuss the possible processes responsible for the observed patterns.
- Morpho-anatomical and morphometric studies of the floral structures of the
distylous Oldenlandia salzmannii (Rubiaceae)
Abstract: ABSTRACT The genus Oldenlandia (Rubiaceae) has a conflicting generic delimitation, with representatives that show different floral syndromes. Oldenlandia salzmannii is a marshy herb that is widespread in South America. It is heterostylous, specifically distylous, and self-compatible. Recent molecular phylogenetic studies found that this species forms a clade that is isolated from the remaining described taxa of Oldenlandia. Information about the floral anatomy and reproductive biology of genera in the Spermacoceae tribe, particularly Oldenlandia, is insufficient, especially among the neotropical species. Accordingly, the present study aimed at contributing information on the reproductive biology of Oldenlandia salzmannii by analyzing its floral morpho-anatomy, morphometrics and phenology of both floral morphs. These analyses were conducted with natural, cultivated and fixed material using optical and scanning electron microscopes. Morphologically, the species is typically heterostylous with two floral morphs, long-styled and short-styled, the main difference being the indument of the corolla. The short-styled flowers have larger anthers and pollen grains. Morphometrics show a high degree of herkogamic reciprocity. The mature ovules have a hemitropous position, which is the first record of this position for the Spermacoceae tribe. This study represents the first comprehensive morphological study of Oldenlandia salzmannii.
- Does inter-plant variation in sprouting time affect the
growth/reproduction trade-off and herbivory in a tropical tree
Abstract: ABSTRACT The timing of phenological events varies within and among populations, affecting the performance of individual plants differently. We evaluated the effects of relative variation in sprouting time on the display of reproductive events, vegetative growth and herbivory in Copaifera langsdorffii (Fabaceae). A total of 93 trees of C. langsdorffii was monitored daily to determine their sprouting time. We collected ten terminal branches of each plant to evaluate vegetative growth, production of defense compounds and insect herbivore damage. The sprouting time for the studied population lasted 67 days. Variation in sprouting time did not affect the probability of plants to enter the reproductive stage. Plants that entered the reproductive stage showed greater vegetative biomass. Variation in sprouting time had a negative relationship with branch growth and a positive relationship with the number of leaflets. Leaf phenol concentration did not vary in relation to sprouting time or plant phenology, but herbivory was higher in plants that sprouted later. The relationships among plant sprouting time, vegetative development and display of reproductive stage in C. langsdorffii are discussed. The results of this study also suggest that early sprouting prior to the rainy season is a strategy used by C. langsdorffii to escape herbivores attacks.
- Vertical distribution of epiphytic bryophytes in Atlantic Forest fragments
in northeastern Brazil
Abstract: ABSTRACT The microclimatic gradient established from the forest understory to the canopy provides a range of different conditions for the establishment of bryophytes along the height of a tree. We investigated epiphytic bryophyte communities of four fragments of Atlantic Forest with the aim of describing their vertical zonation and assessing differentiation among the communities of the different fragments. In each fragment, five host trees were selected from which bryophyte samples were collected in four height zones from the base to the canopy. Furthermore, 10 plots were demarcated in each fragment where bryophytes were collected from the understory. In total, 114 bryophyte species were found on the 20 sampled phorophytes, plus an additional 51 species in the understory, for a total of 165 species. Species composition of height zones differed significantly between communities of the trunk base and the canopy. The samples from the understory included 77% of all species. Among all species found, 10 showed a significant preference for a specific height. Around 70% of the bryophyte species grew as mats; this life form occurred in all trees and height zones. The results showed a weak, yet significant, vertical gradient, which differs from what is usually found in the Atlantic Forest.
- Phenology of the multi-use tree species Carapa guianensis in a floodplain
forest of the Amazon Estuary
Abstract: ABSTRACT Carapa guianensis is a multi-use tree species that is used for the production of timber and non-timber forest products (NTFPs) that are used and sold by rural Amazonian populations. Here we aimed to evaluate the phenophases of C. guianensis in várzea forest and relate them to climatic seasonality. Phenophases of flowering (flower buds and open flowers), fruiting (unripe and ripe fruits), and leaf flush and leaf fall were recorded for 30 individual trees during a 25 month period. Relationships between rainfall and the proportion of trees in each phenophase were tested using Generalised Linear Models with quasi-binomial errors. Flowering was found to peak in the driest months of the year (September to December), while fruiting peaked during the wettest months of the year when river levels are at their highest (January to May). Leaf flush and leaf fall occurred simultaneously throughout the year, regardless of seasonality. Strong seasonality in flowering and fruiting of C. guianensis likely represents a reproductive strategy that maximizes pollination and hydrochorous seed dispersal. This study has the potential to aid in planning the timing of seed collection and oil extraction activities, thus contributing to the sustainable exploitation of this tree.
- Rapateaceae in the state of Pará, Brazil
Abstract: ABSTRACT Rapateaceae comprises approximately 19 genera and 131 species distributed in the Neotropics, with the exception of Maschalocephalus, which is endemic to West Africa. In Brazil, there are nine genera and 38 species. The present paper is based on a taxonomic study of the species of Rapateaceae that occur in the state of Pará. Botanical specimens from seven herbaria were analyzed and the occurrence of five genera and eight species was confirmed for the state. An identification key to the genera and species, descriptions, illustrations and selected specimens are provided.
- Epiphytic ferns in swamp forest remnants of the coastal plain of southern
Brazil: latitudinal effects on the plant community
Abstract: ABSTRACT Community structure and spatial distribution of epiphytic ferns in swamp forest remnants along the coastal plain of the state of Rio Grande do Sul were analyzed. A total of 440 trees were sampled in fifty-seven 10 x 10 m plots. Each phorophyte was divided into five ecological zones (strata), where all species of epiphytic ferns were recorded. A total of 34 species representing 18 genera in six families were recorded. Polypodiaceae was the most represented family with 17 species, and Microgramma vacciniifolia had the highest epiphytic importance value. Characteristic holoepiphyte was the predominant ecological category, representing 70 % of the species. Ordination analysis showed a gradual change in floristic composition between ecological zones with richness differing significantly between strata. We observed that with increasing latitude there was a decrease in mean temperature and total rainfall, but an increase in frosts. These climatic and phytogeography changes result in a reduction in species richness and a change in the structure of epiphytic fern communities in a north-to-south direction. The importance of swamp forest remnants of the coastal plain to the diversity of epiphytic ferns is discussed.
- Do fruit morphology and scarification affect germination and predation
rates of Babassu seeds'
Abstract: ABSTRACT Seed predation is a natural phenomenon that can occur either before or after dispersal and can significantly reduce the economic value and reproductive potential of plants. The babassu palm (Attalea vitrivir, Arecaceae) is important to rural communities that extract oil from its fruits for a wide variety of uses. We evaluated the predation and germination of A. vitrivirseeds in Pandeiros River Environmental Protection Area (EPA-Pandeiros) in Minas Gerais State, Brazil. Sixty individual plants were evaluated to determine their fruiting patterns. Seed predation and germination were evaluated in the natural environment for eight months for fruits divided into two treatments: scarified and intact. Germination of fruits submitted to these same treatments was also evaluated under greenhouse conditions. Our results indicated that fruiting is continuous in this species and that fruit morphology does not influence either germination or predation. Likewise, fruit scarification did not influence seed germination. Pachymerus cardo (Coleoptera: Chrysomelidae) preferentially oviposited on scarified fruits, but only after their dispersal. The predation rate in the natural environment was 14.6%. Germination was not observed under natural conditions, but reached 33.05% under greenhouse conditions.
- Do gender and age influence agroforestry farmers' knowledge of tree
species uses in an area of the Atlantic Forest, Brazil'
Abstract: ABSTRACT This study aimed to explore the extent of knowledge of tree species and their uses by agroforestry farmers in the Vale do Ribeira, Brazil, to verify whether gender and age are related to species knowledge in different use categories. The study was conducted using semi-structured interviews, guided tours, direct observation and collection and identification of botanical material. Analyses were based on the frequency with which plants were mentioned. Forty farmers (17 women and 23 men aged 18 to 78 years) were interviewed. There were significant differences in the species richness cited exclusively by each gender; the number of species mentioned by men (36 sp.) was higher than by women (11 sp.). Men exhibited a greater knowledge of such categories as construction, organic matter, fuel, animal feed, technology and beekeeping, whereas there were no significant differences for food, medical and other categories. Age was also a distinguishing factor; younger people mentioned the lowest number of species (74 sp.) compared to adults (163 sp.) and the elderly (150 sp.). The greater number of species mentioned exclusively by men may indicate the existence of specialized knowledge, whereas environmental constraints and the availability of plant resources may limit the knowledge of young people.
- Selection of aggressive pathogenic and solopathogenic strains of Ustilago
maydis to improve Huitlacoche production
Abstract: ABSTRACT Ustilago maydis is a basidiomycete known as the causative agent of 'common smut', worldwide disease of maize that is recognized by the galls it forms, which have considerable potential as a gourmet food. Results of infection are quite variable, even under optimal greenhouse conditions. In order to find pathogenic strains able to be used as a highly infective and stable inoculum for the successful production of galls either in greenhouses or in the field, ears with gall symptoms containing teliospores were recovered from maize plants. The teliospores were suspended in water and plated on nutrient-rich medium. Twenty-six colonies developed, containing three types of yeast-like colonies: saprotrophic, pathogenic, and solopathogenic. DAPI staining confirmed the presence of solopathogenic strains with diploid sporidia. Groups of different mating types were found when pairs of the 26 strains were arranged resembling partial-diallel combinations. Amplification of the partial b locus revealed that the strains found harbor the alleles b3 and b4, allowing the formation in dikaryotic strains of heterodimeric regulatory proteins associated with fungal development and pathogenicity. In this study, we isolated compatible haploid and solopathogenic diploid strains for their high capacity for inducing smut.
- How does resprouting response differ among three species of savanna trees
and in relation to plant size'
Abstract: ABSTRACT 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, Brasília, 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.
- First record of Isachne ligulata (Poaceae: Micrairoideae) in Brazil and a
key for the Brazilian species of the genus
Abstract: ABSTRACT While performing a taxonomic revision of the Neotropical species of Isachne, analysis of herbarium collections revealed the occurrence of Isachne ligulata in Brazil. We provide a description and the first illustration of I. ligulata, along with comments on its ecology, distribution and morphological affinities with related South American species. We also provide an identification key for the Brazilian species of the genus.