Phytosociology of the caatinga in Floresta Nacional de Açu, Rio Grande do Norte, Brazil and surroundings: diversity and biogeography of the woody layer / Fitossociologia da caatinga na Floresta Nacional de Açu, Estado do Rio Grande do Norte, Brasil e entorno: diversidade e biogeografia do componente lenhoso

The semiarid region of Rio Grande do Norte State in the Northeast region of Brazil can be divided into two main geoenvironmental units: Sertaneja Depression and Potiguar Sedimentary Basin. Although the flora of sandy sedimentary basins is usually different from that of crystalline terrains, part of the Potiguar Basin has stony paleo-alluvial deposits, with rolled pebbles, imposing different edaphic conditions to the species. The Floresta Nacional de Açu is located on a stretch of the edge of the Potiguar Basin with pebble deposits, which make the soil stony. The objective of this work was to characterize the phytosociological structure of the caatinga in Floresta Nacional de Açu and its surroundings and to understand the biogeographic links of the local flora with other areas of the Caatinga. We selected areas in the interior and surroundings of FLONA and sampled 1,500 woody individuals, belonging to 33 species. The biogeographical links show that the stony edge of the Potiguar Basin is closer to the flora of the crystalline terrains than to the sandy terrains of other sandy sedimentary basins.

O semiárido do Estado do Rio Grande do Norte pode ser dividido em duas unidades geoambientais principais: Depressão Sertaneja e a Bacia Sedimentar Potiguar. Embora a flora das bacias sedimentares arenosas normalmente seja diferente daquela dos terrenos cristalinos, parte da Bacia Potiguar possui depósitos paleo-aluvionares pedregosos, com seixos rolados, impondo à flora condições edáficas diferentes. A Floresta Nacional de Açu está localizada em um trecho da borda da Bacia Potiguar com depósitos de seixos, que tornam o solo pedregoso. O objetivo deste trabalho foi caracterizar a estrutura fitossociológica da caatinga na FLONA e arredores e compreender os vínculos biogeográficos da flora local em relação a outras áreas da Caatinga. Selecionamos áreas no interior e arredores da FLONA e amostramos 1500 indivíduos lenhosos, pertencentes a 33 espécies. Os vínculos biogeográficos mostram que a borda pedregosa da Bacia Potiguar tem mais proximidade com a flora dos terrenos cristalinos do que com terrenos arenosos de outras bacias sedimentares arenosas.

Socioeconomic differences among resident, users and neighbour populations of a protected area in the Brazilian dry forest.

Protected areas are an important strategy to safeguard biodiversity. However, if social development is not considered, biological conservation targets may not be achieved. In this empirical study, we assess the relationship between poverty and conservation goals in dry forests within a 62,000-ha Brazilian National Park (Caatinga biome). We conducted 81 structured household interviews between January and July of 2016 to assess socioeconomic, resource management and land-use variables. We used non-parametric analysis of variance to test for differences in socioecological variables among families living inside and outside the Park and both (double dwelling). The majority of families (76%) residing inside the Park were living below the poverty line while less than 14% in outside and double dwelling residences faced the same issue. Families living inside the park had lower socioeconomic conditions such as limited water availability, poor house infrastructure, low income, and high dependence on firewood than outside and double dwelling families. They were also more dependent on external financial support and natural resources. We found that failures in protected areas inception and implementation have driven people towards a mutually reinforcing and declining situation in which negative socioeconomic outcomes are associated with nature degradation. Therefore, our results suggest that the future of dry forests, characterized worldwide by the presence of low-income populations, will be largely dependent on conservation strategies that address poverty alleviation and human well-being.

Lévy foraging patterns of rural humans.

Movement patterns resembling Lévy walks, often attributed to the execution of an advantageous probabilistic searching strategy, are found in a wide variety of organisms, from cells to human hunter-gatherers. It has been suggested that such movement patterns may be fundamental to how humans interact and experience the world and that they may have arisen early in our genus with the evolution of a hunting and gathering lifestyle. Here we show that Lévy walks are evident in the Me'Phaa of Mexico, in Brazilian Cariri farmers and in Amazonian farmers when gathering firewood, wild fruit and nuts. Around 50% of the search patterns resemble Lévy walks and these are characterized by Lévy exponents close to 1.7. The other search patterns more closely resemble bi-phasic walks. We suggest potential generative mechanisms for the occurrence of these ubiquitous Lévy walks which can be used to guide future studies on human mobility. We show that frequent excursions and meanderings from pre-existing trails can account for our observations.

Human perceptions of landscape change: The case of a monodominant forest of Attalea speciosa Mart ex. Spreng (Northeast Brazil).

From the perception of human populations, we can assess the changes occurring in certain landscapes and the factors that cause those changes. Such studies have proven helpful in increasing the knowledge of the history of a landscape, recognizing past formations and projecting its future. Our research objective was to determine how a landscape dominated by the palm tree Attalea speciosa, a species of ecological, economic, and cultural importance, has been changing over time by synthesizing and comparing historical documents and local perceptions. This study was conducted in Araripe Environmental Protection Area, Northeast Region, Brazil. To understand local landscape change, we interviewed active harvesters in four communities in which A. speciosa use has been documented. Historical documents were evaluated as a complement to the interview data. According to local informants, areas previously used for cultivation and animal husbandry that were abandoned or decimated by droughts in the region may have fostered the expansion of a monodominant A. speciosa forest. Furthermore, other forms of landscape management resulting from human population growth may also have affected the current and past distribution of this forest.

Recent introduction and recombination in Colletotrichum acutatum populations associated with citrus postbloom fruit drop epidemics in São Paulo, Brazil.

Citrus crops in São Paulo State, Brazil, have been severely affected by postbloom fruit drop disease (PFD), which is caused by Colletotrichum acutatum. This disease leads to the drop of up to 100% of young fruits. Previous studies have assumed that this pathogen exhibits a clonal reproductive mode, although no population genetic studies have been conducted so far. Thus, the genetic structure of six C. acutatum populations from sweet orange orchards showing PFD symptoms was determined using nine microsatellite markers, enabling inference on predominant mode of reproduction. C. acutatum populations exhibit a nearly panmictic genetic structure and a high degree of admixture, indicating either ongoing contemporary gene flow at a regional scale or a recent introduction from a common source, since this pathogen was introduced in Brazil only very recently. Sharing haplotypes among orchards separated by 400 km suggests the natural dispersal of fungal propagules, with the possible involvement of pollinators. A significant population expansion was detected, which was consistent with an increase in host density associated with crop expansion toward new areas across the state. Findings of moderate to high levels of haplotypic diversity and gametic equilibrium suggest that recombination might play an important role in these pathogen populations, possibly via parasexual reproduction or a cryptic sexual cycle. This study provides additional tools for epidemiological studies of C. acutatum to improve prevention and management strategies for this disease.

The effect of management systems and ecosystem types on bark regeneration in Himatanthus drasticus (Apocynaceae): recommendations for sustainable harvesting.

Bark and exudates are widely commercialized non-timber forest products. However, the ecological impacts of the harvesting of these products have seldom been studied. The aim of this study is to investigate the relationship of tree resilience to harvesting intensity in Himatanthus drasticus, a tree that is highly exploited in the Brazilian savanna (Cerrado) for its medicinal latex. Although the traded product is the latex, the traditional harvesting systems involve the removal of the bark of the trees to allow exploitation. A 3-year experiment was conducted in two different Cerrado ecosystems (open savanna and savanna woodland). Trees were debarked at four debarking intensities to simulate the effects of traditional management systems. Measurements of bark growth were taken every 6 months, and quantitative and qualitative indexes of bark regeneration were obtained. The mortality of the debarked trees was low and could not be related to the intensity of harvesting. No signs of attack by fungi or insects were recorded. Compared with other species exploited for bark, H. drasticus is very resilient to harvesting; however, bark regeneration is relatively slow. In both analyzed ecosystems, the regeneration indexes showed higher values in the controls than in the treatments, indicating that 3 years is not sufficient for total recovery of the rhytidome. Bark regeneration occurred primarily by sheet growth and was more rapid in open savanna than in savanna woodland. No differences in the rate of bark recovery were found among management treatments. Based on the results, sustainable harvesting guidelines are suggested for the species.

Characterization of 10 microsatellite loci for Bathysa australis (Rubiaceae).

PREMISE OF THE STUDY: Bathysa australis is a common subcanopy tree from the Atlantic Forest that is pollinated by bees and wasps and produces autochoric seeds. This species exhibits great phenotypic plasticity along the elevational gradient of Serra do Mar in southeastern Brazil. We expect to assess the genetic diversity and gene flow between populations of this species along the elevational gradient. • METHODS AND RESULTS: We developed a microsatellite-enriched genomic library for B. australis, and 10 microsatellite loci were successfully amplified, ranging from one to 13 alleles per locus. The observed and expected heterozygosities ranged from 0.333 to 0.900 (average: 0.629) and 0.564 to 0.900 (average: 0.742), respectively. • CONCLUSIONS: These are the first microsatellite markers developed for the genus Bathysa and may be useful in other species of the Condamineeae tribe. These primers will be an important tool for studies of population ecology and conservation genetics.

Development of SSR markers for Encholirium horridum (Bromeliaceae) and transferability to other Pitcairnioideae.

PREMISE OF THE STUDY: We developed a set of primers for Encholirium horridum, a species closely associated with inselbergs of the Atlantic Forest, to assess genetic diversity, genetic structure, and gene flow between populations of this species. • METHODS AND RESULTS: From an enriched genomic library, 10 primer pairs for polymorphic microsatellite regions were developed. The average number of alleles ranged from eight to 20, and the observed and expected heterozygosities ranged from 0.000 to 1.000, and from 0.000 to 0.929, respectively, across the populations. • CONCLUSIONS: These markers will be useful in evaluating genetic diversity, spatial genetic structure, analysis of gene flow by paternity, and characterization of mating system of E. horridum.

Characterization of microsatellite loci in Himatanthus drasticus (Apocynaceae), a medicinal plant from the Brazilian savanna.

PREMISE OF THE STUDY: We developed a new set of microsatellite markers for studying the genome of the janaguba tree, Himatanthus drasticus (Mart.) Plumel, which is used in folk medicine in northeastern Brazil. These novel markers are being used to evaluate the effect of harvesting on the genetic structure and diversity of natural populations of this species. • METHODS AND RESULTS: Microsatellite loci were isolated from an enriched H. drasticus genomic library. Nine primer pairs successfully amplified polymorphic microsatellite regions, with an average of 8.5 alleles per locus. The average values of observed and expected heterozygosity were 0.456 and 0.601, respectively. • CONCLUSIONS: The microsatellite markers described here are valuable tools for population genetics studies of H. drasticus. The majority of the primers also amplified sequences in the genome of another species of the same genus. This new set of markers may be useful in designing a genetic conservation strategy and a sustainable management plan for the species.