Cássia Beatriz Rodrigues Munhoz

Dinâmica temporal do estrato herbáceo-arbustivo de uma área de campo limpo úmido em Alto Paraíso de Goiás, Brasil

This study evaluated the floristic and structural dynamics of a community of herbaceous-shrub species in an area of moist grassland in Alto Paraiso de Goias. Th e fi rst inventory was undertaken in 2000 (T0) and the second in 2007 (T1). Shannons diversity between the periods was compared by Hutchesons´s t-test, and the floristic similarity by the Chao-Sorensen similarity index. Floristic composition and cover, between periods and lines, were evaluated by detrended correspondence analysis (DCA). We sampled 98 species, 88 at T0 and 67 at T1; 31 were unique to T0 and 10 to T1. Floristic diversity in the community was high in both periods, but diff erent between them (t = 7.12, p <0.001), due to variation in species number and coverage. Similarity between the two surveys was high (Chao-Sorensen CI = ± 0.841 ± 0.074). The DCA ordination indicated relationships between the floristic composition and cover with a gradient of moisture and organic matter in the soil identified in T0. Th ere were changes in the lines in the seasonal zones, which became more similar in those constantly saturated with water. During an interval of seven years the moist grassland showed changes in floristic composition and mainly in structure due to increased cover of the clumped tussock perennial species, which were favored by higher soil moisture due to high rainfall in the region.

Seed tolerance to heating is better predicted by seed dormancy than by habitat type in Neotropical savanna grasses

Open savannas and wet grasslands are present under the same seasonal macro-climate in central Brazil. However, in open savannas, temperatures during fires are higher than in wet grasslands. Grasses dominate both ecosystems and exhibit large variation in seed dormancy. We hypothesise that seeds of grass species from open savannas are more tolerant to heating than those of wet grasslands. Also, assuming that dormant seeds remain longer in the soil than non-dormant seeds – thus being more likely to burn – we expect that dormant seeds are more tolerant to heating than non-dormant seeds. We tested the effects of heating at 80 and 110°C for 2.5 and 5.0 min on the survival of seeds of 14 species, seven from each community, containing dormant and non-dormant species. Seeds of most species survived at 80°C, but seeds from open savannas maintained greater survival for 5 min than seeds from wet grasslands. Seeds of most species died at 110°C, but dormant seeds survived more than non-dormant seeds. We conclude that species with seed dormancy experience selection for covarying characteristics that allow tolerance to heating in hotter fires. Our findings suggest that both seed dormancy and habitat-specific fire temperatures may contribute to the evolution of seed fire tolerance in Neotropical savannas.

Vascular flora in dry-shrub and wet grassland Cerrado seven years after a fire, Federal District, Brazil

Studies of temporal dynamics for grassland sites report that fire suppression plays a crucial role in floristic changes. The objective of this study was to verify whether after seven years without fire, communities showed variations in terms of composition, life forms, pollination and dispersal syndromes. The first survey (T0) was conducted from September 1999 to October 2000, while the second (T1) took place from August 2006 to August 2007. The floristic results in T1 were compared with the survey in T0 through the Sorensen similarity index and Chi-square tests. Over time, there were differences in the composition, life forms and pollination and dispersion syndromes. The evidence of changes suggests that the frequency of the fire regime can be considered the main agent for change in the flora of these communities.

Richness pattern and phytogeography of the Cerrado herb–shrub flora and implications for conservation

Aims The herb–shrub flora has been widely neglected in science and conservation policy throughout the world, so that this biodiversity component remains largely unknown. The objective of this study was to elucidate the spatial patterns of species richness and phytogeographic regions of the Cerrado herb–shrub flora, and to estimate the percentage of areas with high species richness that is still covered by natural vegetation and is located in protected areas or priority areas for conservation. Location Central Brazil and surrounding territories. Methods To estimate the pattern of species richness we produced species distribution models (SDMs) for 5362 species using botanical records combined with 17 least correlated environmental variables. All SDMs were tested against a bias-corrected null model and the 5039 significant SDMs were stacked to generate the pattern of botanical richness. The resulting presence–absence matrix was subjected to a partitioning around medoids (PAM) cluster analysis to delineate phytogeographic regions. Results The pattern of species richness indicated that highest levels of richness are in the central–south and west parts of the Cerrado. The study recognized two floristically distinct clusters at the core of the Cerrado region, and seven additional regions that share floristic elements with the two core clusters. Many areas with high levels of modelled species richness are located outside protected and priority areas for conservation. Conclusions We recognized patterns of regional variation, reflected in the phytogeographic division. Furthermore, we show that the current protected areas in Brazil do not effectively protect high richness areas of the herb–shrub flora.

Relação entre a vegetação e as propriedades do solo em áreas de campo limpo úmido no Parque Nacional de Sete Cidades, Piauí, Brasil

Variations in soil proprieties seem to determine the spatial distribution of plant communities in the moist grassland. The aim of this study was to evaluate the relationship between the floristic composition and structure of the herbaceous-subshrub layer and soil and spatial variables in grassland communities in the National Park of Sete Cidades, Piaui, Brazil. The composition and linear coverage of the species were assessed by the line-intercept method. A total of 17 lines of 10 m, subdivided in sections of 1 m, were distributed into six distinct areas. Soil samples were collected for chemical and textural analysis. We sampled 71 taxa in 46 genera and 25 families. Through canonical correspondence analysis (CCA) the lines sampled were separated into three groups, associated with the textural and chemical soil properties, which coincided with the most similar sites. The multi-response permutation procedures (MRPP) found significant differences between groups of the CCA. The environmental variables most strongly correlated were Cu, Fe, aluminum saturation, silt, Zn, base saturation and sand, accounting for 37.9% of data variation. The spatial distance between the lines accounted for 16.8% of the explained variance. The distribution of the wet grasslands in the park seems to be determined by texture and soil fertility gradients.

The rediscovery of Philcoxia goiasensis (Plantaginaceae): lectotypification and notes on morphology, distribution and conservation of a threatened carnivorous species from the Serra Geral de Goiás, Brazil

SummaryWe report the rediscovery of Philcoxia goiasensis, a rare carnivorous plant that was until recently only known from the type collection. We lectotypify the species and provide an updated description along with notes on morphology, distribution and conservation. We also present refined illustrations and the first known photographs of P. goiasensis in the wild. It was recently collected in two locations in the Northeast of Goiás, Brazil and is assessed as Critically Endangered (CR).

Cloning and characterization of novel cyclotides genes from South American plants.

Cyclotides are multifunctional plant cyclic peptides containing 28‐37 amino acid residues and a pattern of three disulfide bridges, forming a motif known as the cyclic cystine knot. Due to their high biotechnological potential, the sequencing and characterization of cyclotide genes are crucial not only for cloning and establishing heterologous expression strategies, but also to understand local plant evolution in the context of host‐pathogen relationships. Here, two species from the Brazilian Cerrado, Palicourea rigida (Rubiaceae) and Pombalia lanata (A.St.‐Hil.) Paula‐Souza (Violaceae), were used for cloning and characterizing novel cyclotide genes. Using 3′ and 5′ RACE PCR and sequencing, two full cDNAs, named parigidin‐br2 (P. rigida) and hyla‐br1 (P. lanata), were isolated and shown to have similar genetic structures to other cyclotides. Both contained the conserved ER‐signal domain, N‐terminal prodomain, mature cyclotide domain and a C‐terminal region. Genomic sequencing of parigidin‐br2 revealed two different gene copies: one intronless allele and one presenting a rare 131‐bp intron. In contrast, genomic sequencing of hyla‐br1 revealed an intronless gene—a common characteristic of members of the Violaceae family. Parigidin‐br2 5′ and 3′ UTRs showed the presence of 12 putative candidate sites for binding of regulatory proteins, suggesting that the flanking and intronic regions of the parigidin‐br2 gene must play important roles in transcriptional rates and in the regulation of temporal and spatial gene expression. The high degree of genetic similarity and structural organization among the cyclotide genes isolated in the present study from the Brazilian Cerrado and other well‐characterized plant cyclotides may contribute to a better understanding of cyclotide evolution.

Tree diversity and above-ground biomass in the South America Cerrado biome and their conservation implications

Less than half of the original two million square kilometers of the Cerrado vegetation remains standing, and there are still many uncertainties as to how to conserve and prioritize remaining areas effectively. A key limitation is the continuing lack of geographically-extensive evaluation of ecosystem-level properties across the biome. Here we sought to address this gap by comparing the woody vegetation of the typical cerrado of the Cerrado–Amazonia Transition with that of the core area of the Cerrado in terms of both tree diversity and vegetation biomass. We used 21 one-hectare plots in the transition and 18 in the core to compare key structural parameters (tree height, basal area, and above-ground biomass), and diversity metrics between the regions. We also evaluated the effects of temperature and precipitation on biomass, as well as explored the species diversity versus biomass relationship. We found, for the first time, both that the typical cerrado at the transition holds substantially more biomass than at the core, and that higher temperature and greater precipitation can explain this difference. By contrast, plot-level alpha diversity was almost identical in the two regions. Finally, contrary to some theoretical expectations, we found no positive relationship between species diversity and biomass for the Cerrado woody vegetation. This has implications for the development of effective conservation measures, given that areas with high biomass and importance for the compensation of greenhouse gas emissions are often not those with the greatest diversity.

Effects of Nutrient Additions on the Diversity of the Herbaceous-Subshrub Layer of a Brazilian Savanna (Cerrado)

The anthropogenic increase of nutrient availability in natural ecosystems is related to different impacts as soil acidification and loss of biodiversity. The present work investigated the effects of nutrient additions on the diversity of the herbaceous-subshrub layer of a Brazilian savanna. The experimental design consisted of an unfertilized control and four fertilization treatments as follows: + N (100 kg N ha−1 year−1 as (NH4)2SO4), + P (100 kg of P ha−1 year−1 as Ca(H2PO4)2 + CaSO4.2H2O), + NP (100 kg of N + 100 kg of P ha−1 year−1 as (NH4)2SO4 plus Ca(H2PO4)2 + CaSO4.2H2O) and + Ca (4,000 kg of dolomitic limestone and CaSO4.2H2O). Nutrient treatments were applied twice yearly between 1998 and 2006. Soil physic-chemical analyses were performed and related to the results of vegetation surveys performed in April 2009. Calcium (Ca) addition increased the soil pH in all Ca fertilized plots, while the additions of nitrogen (N), nitrogen and phosphorus (NP) and phosphorus (P) decreased soil pH. The floristic diversity was high in all treatments but differed significantly between them (p < 0.01). NP plots presented the lowest richness and the control plots showed the highest richness. Species cover and environmental variables were correlated to axes 1 and 2 in the Canonical Correspondence Analysis (F = 1.14; p = 0.035). In our study the invasive grass Melinis minutiflora (African C4 grass) responded to P and N + P treatments but was absent in the N plots, probably due to P limitation. The low cover of M. minutiflora in control and in Ca plots may be due to competition with native species, since these plots had a high H’ index for the herbaceous-subshrub layer and were probably also P limited. The combination of N + P was especially detrimental to diversity, inducing the invasion by M. minutiflora. The invasion seems to be strongly limited by P and interespecific competition with native species.