Community Composition of Plant-parasitic Nematodes in Native and Cultivated Cerrados of Central Brazil

Communities of plant-parasitic nematodes collected from five different vegetation types (canopy woodland, savannah, gallery forest, cultivated perennial, and annual plants) and soils (yellowish red latosols, dark red latosols, arenosols, acrisols, and gleysols) were studied. Ninety percent of the soil samples collected from savannah contained at least four genera of plant-parasitic nematodes. The highest population densities were recovered from perennial plants and from acrisols. Nematodes from perennial and annual plants formed one cluster, which had a similar flexible-beta distance to that from the gallery forest. The distance in the native savannah and in canopy woodland was very different. Distance values for the soil aspect were similar for arenosols, yellowish, and dark red latosols. The value for acrisols was much larger than for the other soils.     

Pollination and Breeding System of Vellozia squamata (Liliales: Velloziaceae): A Species of the Brazilian Cerrados

The pollination biology and breeding system of Vellozia squamata (Velloziaceae), a species of cerrado vegetation in Central Brazil, were studied. V. squamata is unusual in being pollinated by a few, generalist bee species despite having very large flowers, and having a distinctive pulsed flowering phenology. The species is self-incompatible but with a late-acting, post-fertilization rejection mechanism.     

Breeding biology of White‐rumped Tanagers in central Brazil

ABSTRACT White‐rumped Tanagers (Cypsnagra hirundinacea) are widely distributed in northern Brazil, Bolivia, and Paraguay, and are classified as vulnerable in the state of Paraná and as endangered in the state of São Paulo, Brazil. Little is currently known about their breeding biology. We studied the breeding behavior of White‐rumped Tanagers in the Cerrado (Neotropical savanna) in central Brazil from 2002 to 2007. The breeding period extended from mid‐August to mid‐December. Nests were cup‐shaped and located mainly in trees of the genus Kielmeyera at a mean height of 3.7 ± 0.3 m (SE). Clutch sizes varied from one to three eggs and the incubation period lasted an average of 16.0 ± 0.3 d. Incubation was by females only and started with the laying of the first egg. Mean nest attentiveness (percent time on nests by females) was 64 ± 0.08%. Nestlings were fed by males, females, and, when present, helpers. The mean rate of food delivery rate to nests was 5.2 ± 0.4 items/h, with rates similar for males (mean = 2.7 ± 0.3 items/h) and females (mean = 2.4 ± 0.3 items/h). The mean duration of the nestling period was 12.1 ± 0.5 d. Compared to many temperate species of tanagers, White‐rumped Tanagers in our study had relatively small clutches, low nest attentiveness, and long incubation periods. As with other tropical species, such characteristics might be due to food limitation or high rates of nest predation.     

Three new species of Fufius Simon, 1888 (Araneae,Cyrtaucheniidae) from Brazil with the redescription of Fufius funebris Vellard, 1924 and description of the female of Fufius lucasae Guadanucci & Indicatti, 2004

The mygalomorph neotropical genus Fufius Simon, 1888 comprises ten species, distributed from Guatemala in Central America to southeastern Brazil, in South America. Most of the species were described from northern South America, in the Amazonian region. Only F. funebris Vellard, 1924 and F. lucasae Guadanucci & Indicatti, 2004 are known from regions more to the south of the continent. Herein we describe three new Brazilian species, Fufius minusculus sp. n. and F. jalapensis sp. n. from the state of Tocantins, and F. candango sp. n. from Distrito Federal. The female of F. lucasae is described for first time and the male and female of F. funebris are redescribed based on specimens collected at the type locality.     

A comparative study of aluminium and nutrient concentrations in mistletoes on aluminium‐accumulating and non‐accumulating hosts

Mistletoes offer a unique model to study interactions among Al and nutrients in vascular plants, because they grow and reproduce on hosts with distinct Al uptake strategies. We investigated Al distribution and nutrient relations of mistletoes on Al‐accumulating and non‐accumulating hosts. We hypothesised that mistletoes would exhibit similar leaf nutrient and Al concentrations as their host plants, but a strong compartmentalisation of Al when growing on Al‐accumulators. We measured concentrations of N, P, K, Ca, Mg, Cu, Fe, Mn, Zn in leaves and Al in leaves, seeds and branches of Phthirusa ovata and Psittacanthus robustus infecting Miconia albicans, an Al‐accumulator, and Ph. ovata infecting Byrsonima verbascifolia, a non‐Al‐accumulator. High leaf concentrations of Al in Ph. ovata only occurred while parasitizing the Al‐accumulating host; there was no accumulation in branches or seeds. In P. robustus, large concentrations of Al were found in leaves, branches and seeds. Mistletoe seed viability and leaf nutrient concentrations were not affected by Al accumulation. Passive uptake of Al, Ca, Mg, Mn and Cu in mistletoes was evidenced by significant correlations between mistletoes and host leaf concentrations, but not of N, P and K. Al was retranslocated to different plant organs in P. robustus, whereas it was mostly restricted to leaves in Ph. ovata. We suggest that Al might have some specific function in P. robustus, which only parasitizes Al‐accumulator hosts, while the host generalist Ph. ovata can be considered a facultative Al‐accumulator.     

The Potential Role of Scattered Trees for Ant Conservation in an Agriculturally Dominated Neotropical Landscape

Although biological conservation has traditionally focused on the protection of pristine areas, it is becoming increasingly evident that efforts should also be made toward the maintenance of biological diversity in human‐managed ecosystems. We evaluated the potential role of scattered, remnant trees in enhancing ant diversity in agricultural lands within a biodiversity hotspot, namely the Cerrado savannas of central Brazil. Ant collections were performed in, beneath, and away from the crowns of a native tree species growing in planted pastures, soy fields, and in small (<400 ha) savanna reserves. Significantly more ant species were found beneath than 30 m away from scattered trees. The magnitude of this effect was similar in soy fields and in pastures at all scales of our analyses, except at the landscape scale where the effect was comparatively greater in soy fields. Most of the species that occurred more frequently beneath than away from trees nest on ground, indicating that the conservation value of scattered trees goes beyond the mere protection of arboreal ant species. Soy plantations presented a particular species‐poor ground‐dwelling fauna when compared with savannas, whereas differences in the number and composition of arboreal species were less marked. In contrast, the diversity of arboreal‐ and ground‐dwelling ants recorded in and beneath pasture trees was nearly as high as the one found in savannas. It is suggested that pasture trees can have an important value for ant conservation off reserves, particularly in regions where most of the native vegetation has already been cleared.     

Nodule ultrastructure and initial growth of Anadenanthera peregrina (L.) Speg. var. falcata (Benth.) altschul plants infected with rhizobia

The anatomy and ultrastructure of root nodules of Anadenanthera peregrina var. falcata (Leguminosae-Mimosoideae) were analysed, as was plant growth. To ensure that nodules developed, seedlings were inoculated with a mixture of six strains of rhizobia. Nodules were produced that differed in appearance-and probably also effectiveness-but their structure was similar and they showed characteristics typical of indeterminate nodules, such as persistent meristematic tissue and a gradient of cells at different stages of development. Many starch grains were present in inner cortex cells and interstitial cells of infected tissue. Infected cells were densely packed with bacteroids, which contained many poly-beta-hydroxybutyrate granules. The high incidence of these granules, together with high levels of starch accumulation in interstitial cells, suggested low N2-fixation efficiency of the rhizobia isolates used for inoculation. In the symbiosomes of early-senescent infected cells, reticulum-like structures, small vesicles and a fibrillar material were observed; these may be related to bacteroid degradation. In the cytoplasm of late-senescent infected cells, many vesicles and membrane-like structures were observed, probably associated with membrane degradation of bacteroids and peribacteroids. The total biomass of plants inoculated with rhizobia was low and their xylopodia and shoots had low levels of N compared with noninoculated plants fertilized with ammonium nitrate. However, inoculated plants did not show N-deficiency symptoms and grew better than non-inoculated plants without N fertilization. These growth results, together with ultrastructural observations of nodules, suggest that nitrogen fixation of rhizobia isolates associated with Anadenanthera peregrina var. falcata roots is poor.     

The value of a tree species (Caryocar brasiliense) for a stingless bee Melipona quadrifasciata quadrifasciata

The expansion of crop lands and increased logging for charcoal production in the Brazilian savannahs (cerrados) has reduced richness and abundance of Meliponini bees. This may be a consequence of limitation in the availability of potential nesting substrate. The role of a cerrado-tree (Caryocar brasiliense) in providing nesting substrate for Melipona quadrifasciata quadrifasciata was evaluated. Tree (p= 0.006) and branch (p= 0.001) diameters, number of suitable branches (n= 513), height of the trees and availability of trees suitable for bee nesting were all important to the conservation of M. quadrifasciata. However, the high availability of nesting substrate did not seem to limit nest density nor cause the clumped pattern of nest distributions found for the study site. Nests (n= 48) were found mainly in individuals of C. brasiliense (n= 46) suggesting an active tree selection. In addition, nests located on the highest branches (mean = 4.6 m, sd = 1 m, n= 46) had lower probability of being extirpated by human honey collectors.     

Effects of Fire on Seedling Diversity and Plant Reproduction (Sexual vs. Vegetative) in Neotropical Savannas Differing in Tree Density

Little is known about the effects of fire on the structure and species composition of Neotropical savanna seedling communities. Such effects are critical for predicting long‐term changes in plant distribution patterns in these ecosystems. We quantified richness and density of seedlings within 144 plots of 1 m² located along a topographic gradient in long‐unburned (fire protected since 1983) and recently burned (September 2005) savannas in Brazil. These savannas differ in tree density and canopy cover. Sites along the gradient, however, did not differ in species composition prior to the fire. In recently burned savannas we also evaluated the contribution of vegetative reproduction relative to sexual reproduction by quantifying richness and density of root suckers. Finally, we tested seed tolerance to pulses of high temperatures—similar to those occurring during fires on the soil surface and below—of five dominant savanna tree species. Seedlings were more abundant and diverse in unburned than in burned savannas. Seedling species composition differed among unburned and burned savannas probably reflecting early differences in root: shoot biomass allocation patterns. In recently burned savannas, root suckers were more abundant and diverse than seedlings. Relatively long exposures (>10 min) of temperatures of 90 °C reduced seed germination in all studied species suggesting a negative effect of fire on germination of seeds located at or aboveground level. Because vegetative reproduction contributes more than sexual reproduction in burned environments, frequent fires are likely to cause major shifts in species composition of Neotropical savanna plant communities, favoring clonally produced recruits along tree density/topographic gradients.