Caatinga Environment Research Articles

Composition and Richness of Arboreal ants in Fragments of Brazilian Caatinga: Effects of Secondary Succession

Ecological succession is a complex processes involving changes in the structure of plant community and it is an important factor determining the structure of arboreal ants assemblages, but little is known about the effects of succession on ant assemblages in regions of Tropical Dry Forests (TDFs), such as the Brazilian Caatinga. The aim of this study was to investigate the effects of ecological succession on the richness and species composition of arboreal ants in fragments of Caatinga, testing the following hypothesis: i) the richness of arboreal ants increases along a gradient of forest succession, in response to tree richness and/or density; ii) species composition of arboreal ants differs among stages of forest succession due to differences in vegetation structure in theses stages. This study was conducted in 15 plots distributed in three areas with different stages of secondary succession (early, intermediate and late). Tree density and richness were used as surrogate of vegetation structure. Ants were sampled using the technique of beating the foliage and baited pitfall traps, where five trees were sampled per plot, totaling 75 individual trees sampled. We sampled 37 species of ants, distributed in 16 genera and five subfamilies. Ant richness differed among stages of succession and seasons, with higher number of species in the late succession and rainy period, also increasing with tree richness and density. Besides, there was a distinct composition of ant species among stages of succession and seasons. Results obtained in this study reinforce the importance of using ants as environmental bioindicators, since the sensitivity to environmental variations of this group enables us to differentiate early and late successional stages of forest succession in Caatinga environment.

First report of modern pollen deposition in moss polsters in a semiarid area of Bahia, Brazil

Recent studies have shown that pollen analyses of natural substrates can produce data valuable for understanding the local pollen productivity and dispersal, deposition, and preservation potential of pollen grains. In this study, we aimed to acquire novel information about the dynamics and preservation of pollen in Caatinga environment through the palynological study of moss polsters. Samples of moss polsters in soil (MPS) and on rock (MPR) were collected from the Canudos Biological Station in the Bahia State (Brazil) and subjected to standard chemical treatments for the extraction of pollen residues. In total, 372 pollen types were recorded from the samples of which the taxonomical affinity of 140 was determined. The most represented families were Fabaceae (23 pollen types/16.42%) and Asteraceae (12 pollen types/8.57%). The MPS samples had a higher pollen concentration (21,042.04 pollen grains/cm²) than the MPR samples (7,829.35 pollen grains/cm²). On the other hand, the MPR samples had a greater diversity (68.26% of the identified pollen types). Qualitative analysis showed that the plants of shrub and subshrub habits had the greatest representation among the pollen types (35.0%). Overall, moss polsters proved to be excellent natural air pollen collectors in Caatinga environment, provided they had moist microhabitats for their development.

Environmental Variables Influence the Composition of Frog Communities in Riparian and Semi-Deciduous Forests of the Brazilian Cerrado

Abstract. A central issue for ecologists is to understand the variables that determine species distribution. Many studies have suggested that environmental variables are the main factors that shape anuran communities. Nevertheless, several natural environments have not been assessed with ecological studies of this nature, including specific ecosystems of the South American Cerrado morphoclimatic domain. In the present study, we investigated the relationship between environmental variables and the spatial distribution of anurans in ecosystems of semi-deciduous and riparian forests in a transitional region between the Cerrado and Caatinga environments in the western Bahia state, Brazil. We collected fauna and environmental variables data in 10 sampling units during two rainy periods. The original information on species composition and abundance in the community was reduced to a single axis using a non-metric multidimensional scaling method (NMDS) and environmental data were reduced to two main factors using...

Does ant richness and composition respond to phytophysiognomical complexity and seasonality in xeric environments?

This study aims to analyze how the vegetation structure (physiognomy) and seasonal changes between seasons (wet and dry) influence richness, diversity and composition of ant species of arboreal and shrubby Caatinga environments. The vegetation structure was significantly different among the three strata for all parameters (mean diameter of vegetation, level of herbaceous cover, degree of coverage and thickness of litter and percentage of canopy cover). We collected 127 ant species. The mean number of species was approximately two times higher in the rainy season than in the dry season. There was no difference in species richness between the arboreal and shrubby Caatinga physiognomies nor interaction between season and physiognomy. Despite the similarity in richness, species composition differed between physiognomies, however we found no difference in composition between seasons. The seasonal differentiation may be mainly related to the variation in the overall numbers of individuals circulating in the environment, since the enhancement of resource availability during rainy season allows the colony to grow or expand foraging activities, which increases local diversity. Water restriction explains the limited diversity in both environments, while the occurrence of species with greater resource specificity may determine differences in ant composition. Differences in composition of each of Caatinga's physiognomy enhance beta diversity, therefore, raising the overall diversity in the Caatinga Domain.

Adaptability in stone tool use by wild capuchin monkeys (Sapajus libidinosus)

Capuchin monkeys are well known for population variation in the use of stone tools and the types of food items consumed. In order to determine adaptability in stone tool use, we investigated a never before studied population of wild capuchin monkey (Sapajus libidinosus) displaying terrestrial habits in a Caatinga environment. To carry out this study we recorded physical evidence of the use of stone tools as well as made direct observations through trap cameras. During a 15-month period, we studied a group of Sapajus libidinosus in Serra Talhada, Pernambuco, Brazil. In total, 257 anvils and 395 hammers were identified, characterized, and monitored. We identified five types of food items exploited at these "tool use sites": Syagrus oleracea (catolé palm), Manihot epruinosa (manioc), Pilosocereus pachycladus (facheiro), Tacinga inamoena (quípa), and Commiphora leptophloeos (imburana de cambão). Five hundred three video clips of capuchin monkeys were recorded, 43 of which involved the use of stone tools. The results indicated evidence of adaptability in tool use by the capuchins. We verified that the rigidity and size of the food item, along with the presence or absence of spines seem to influence the choice of stone tools made by the animals for processing the food. The recurring use of tools for the processing of cacti was especially noteworthy and it appears that the presence of spines predisposes the capuchins to use stones to process them. A significant difference was observed between the characteristics of the anvils and the weight of the hammers according to the food item consumed. The use of tools enabled the animals to access otherwise unavailable or difficult to acquire food items within a Caatinga habitat. Adaptability in the use of stone tools by the capuchin monkey population of Serra Talhada provides an example of the complexity that these primates demonstrate in food processing.

Behavioral adjustments by a small neotropical primate (Callithrix jacchus) in a semiarid Caatinga environment.

We provide the first information on the behavior of a small primate (Callithrix jacchus) inhabiting a semiarid Caatinga environment in northeastern Brazil. We observed behavioral variations in response to temperature fluctuation throughout the day. Due to the high temperatures, low precipitation, and resource scarcity in the Caatinga, as well as the lack of physiological adaptations (e.g., a highly concentrated urine and a carotid rete to cool down the brain) of these primates, we expected that the common marmosets would exhibit behavioral adjustments, such as a prolonged resting period or the use of a large home range. During the six-month period, we collected 246 hours of behavioral data of two groups (10 individuals) of Callithrix jacchus. Most of the observed behavioral patterns were influenced by temperature fluctuation. Animals rested longer and reduced other activities, such as foraging, when temperatures were higher. Both study groups exploited home ranges of 2.21–3.26 ha, which is within the range described for common marmosets inhabiting the Atlantic Forest. Our findings confirm that common marmosets inhabiting the Caatinga adjust their behavioral patterns to cope with the high temperatures that characterize this environment and highlight their ability to survive across a wide range of different environmental conditions.

New land mollusk fauna from Serra da Capivara, Piaui, Brazil, with a new genus and five new species (Gastropoda: Orthalicoidea, Streptaxidae, Subulinidae).

Five new species and one new genus are described from the Serra da Capivara, Piaui, Brazil, a region of semi-dry, Caatinga environment. The described taxa are: Odontostomidae: 1) Clinispira insolita, n. gen. n. sp., possessing strange spire inclination and aperture approaching to the shell apex, it looks closely related to Anostoma, Tomigerus and Biotocus; 2) Cyclodontina capivara n. sp., with well-developed axial ribs and 6 teeth at peristome; 3) Anctusprolatus n. sp., very elongated, with aperture lacking teeth; Simpulopsidae: 4) Rhinus gilbertus n. sp., somewhat elongated and relatively well-sculptured; Streptaxidae: 5) Streptartemon molaris n. sp., possessing a very large basalis tooth at peristome. Two subulinids are also reported from the region: 6) Beckianum beckianum (Pfeiffer, 1846), a population with peculiar pointed shell apex and well-developed axial sculpture; 7) Lamellaxis cf. gracilis (Hutton, 1834), a wide-ranged species that merits further investigation. These descriptions show how scanty is our knowledge on northeast Brazilian malacofauna and may raise efforts for its preservation.

Plant Stem Bark Extractivism in the Northeast Semiarid Region of Brazil: A New Aport to Utilitarian Redundancy Model

We use the model of utilitarian redundancy as a basis for research. This model provides predictions that have not been tested by other research. In this sense, we sought to investigate the stem bark extraction between preferred and less-preferred species by a rural community in Caatinga environment. In addition, we sought to explain local preferences to observe if preferred plants have a higher content of tannins than less-preferred species. For this, we selected seven preferred species and seven less-preferred species from information obtained from semistructured interviews applied to 49 informants. Three areas of vegetation around the community were also selected, in which individuals were tagged, and were measured the diameter at ground level (DGL) diameter at breast height (DBH), and measurements of available and extracted bark areas. Samples of bark of the species were also collected for the evaluation of tannin content, obtained by the method of radial diffusion. From the results, the preferred species showed a greater area of bark removed. However, the tannin content showed no significant differences between preferred and less-preferred plants. These results show there is a relationship between preference and use, but this preference is not related to the total tannins content.

Uso do hábitat, períodos diários de atividade e ecologia térmica de Ameiva ameiva (Squamata: Teiidae) em uma área de caatinga do nordeste do Brasil.

Estudamos o uso dos recursos espaciais, temporais e térmicos pelo lagarto neotropical Ameiva ameiva durante as estaçõesseca e chuvosa em um ambiente de caatinga do nordeste do Brasil. Os lagartos utilizaram os hábitats e micro-hábitats de vegetação baixa, mas nunca foram observados no hábitat rochoso. Os adultos utilizaram usualmente o hábitat arbóreo-arbustivo, enquanto os juvenis foram observados maisfrequentemente no hábitat arbustivo-herbáceo. Diferenças ontogenéticas no uso do espaço parecem estar relacionadas a diferentes necessidades térmicas entre as classes de idade devido a diferenças de tamanho corporal. As temperaturas corporais dos juvenis foram significativamente maiores que asdos adultos. A maioria das espécies de Teiidae possui temperaturas corporais elevadas, usualmente acima de 37oC, e atividade concentrada nas horas mais quentes do dia, como observado em A. ameiva neste estudo. A sazonalidade influenciou o uso do hábitat e os períodos diários de atividade dos adultos, mas não influenciou as temperaturas corporais. Verificamos flutuações anuais na abundância de indivíduos adultos, com um declínio de lagartos ativos na estação seca; esse fenômeno pode estar relacionado à estivação e/ou ao aumento da taxa de mortalidade durante os meses mais secos.

Estudo comparativo da madeira de Mimosa ophthalmocentra Mart. ex Benth e Mimosa tenuiflora (Willd.) Poir. (Fabaceae-Mimosoideae) na caatinga nordestina

Pela importância econômica da madeira de algumas espécies do gênero Mimosa L. ocorrentes na caatinga nordestina e pelo fato de Mimosa ophthalmocentra Mart. ex Benth. (jurema-de-imbira), às vezes, ser confundida com Mimosa tenuiflora (Willd.) Poir. (jurema-preta) ou vice-versa, este trabalho objetivou apresentar novos dados referentes à anatomia e densidade básica da madeira das duas espécies, visando oferecer subsídio para identificação das duas espécies, identificar caracteres anatômicos da madeira relacionando-os com o ambiente caatinga e apresentar o potencial energético que sua madeira possui. O estudo anatômico e a determinação da densidade da madeira foram realizados com amostras ao nível do peito (1,30 m acima do solo) e em dois galhos com diferentes diâmetros, de espécimes ocorrentes nos municípios de Serra Talhada e Sertânia, Pernambuco, Brasil. As espécies apresentam distinção expressa através do tipo de casca, coloração do cerne e do alburno, além das características peculiares da madeira. Mimosa ophthalmocentra apresenta camadas de crescimento distintas, constituídas por linhas de parênquima axial contendo cristais, parênquima axial escasso e menor quantidade de raios por mm². Já Mimosa tenuiflora apresenta camadas de crescimento distintas, porém sem cristais, parênquima axial vasicêntrico, em faixas ou aliforme confluente, e maior percentagem de raios. Ambas apresentam algumas estruturas da madeira com as características anatômicas comuns às diversas espécies do gênero Mimosa, contribuindo assim para uma melhor caracterização do gênero. Pelos parâmetros anatômicos da madeira e pela elevada densidade básica (>0,84 g/cm³), concluiu-se que as duas espécies apresentam perspectivas seguras para a produção de álcool combustível e carvão vegetal desde a fase de lenho juvenil. Mimosa ophthalmocentra apresenta maior potencial energético, pela maior percentagem de fibras e por possuir parênquima escasso e menor percentagem de raios.

Amphibians from the litoranean dunes of northern Piauí State, Brazil

The northern Piauí is characterized by two main physiognomies, the Cerrado and the Caatinga environments, and by transitional habitats comprised mainly by dunes. This research was carried out between December 2005 and April 2007, and aimed at surveying anurans in the sand dunes of the municipality of Ilha Grande, Piauí State. Fourteen anurans species were registered, comprising five families. We increased the geographical distribution of Chaunus granulosus, C. jimi, Scinax x-signatus, Phyllomedusa nordestina, Physalaemus albifrons, Pleurodema diplolister, Leptodactylus pustulatus, and L. vastus on Piauí State. Dendropsophus nanus, Elachistocleis ovalis, Hypsiboas raniceps, Leptodactylus fuscus, L. ocellatus, and Pseudopaludicola mystacalis were registered for the first time in Piauí State.