Everardo Valadares de Sá Barreto Sampaio

Caatinga revisited: ecology and conservation of an important seasonal dry forest.

Besides its extreme climate conditions, the Caatinga (a type of tropical seasonal forest) hosts an impressive faunal and floristic biodiversity. In the last 50 years there has been a considerable increase in the number of studies in the area. Here we aimed to present a review of these studies, focusing on four main fields: vertebrate ecology, plant ecology, human ecology, and ethnobiology. Furthermore, we identify directions for future research. We hope that the present paper will help defining actions and strategies for the conservation of the biological diversity of the Caatinga.

Residual N and P fertilizer effect and fertilizer recovery on intercropped and sole-cropped corn and bean in semiarid northeast Brazil

The effects of a single 15N and P fertilizer application (16 and 12 kg ha–1) on intercropped and sole-cropped corn and beans was followed over three consecutive years. Grain (0.1–0.9 ton ha–1 yr–1) and straw productions (0.2–2.5 ton ha–1 yr–1) were limited by rainfall and showed small responses to fertilizer. In the first year, plant N uptake was more than twice the fertilizer amounts, while P uptake was less than half the fertilizer amounts. Plant N derived from fertilizer was low (9–19%). Sole corn took up more (34%) than beans (16%) and the combined intercrop (26%) and also had higher recovery of fertilizer in the soil than single beans (50% against 28%). The distribution of fertilizer N and P in the soil showed a similar pattern in all treatments, with a high concentration around the application spot and decreasing concentrations at greater distances and above and below this point. Total P increases in a soil volume 10 cm around the application spot corresponded to 60% of the amount applied. Fertilizer contributions to the second crop were < 3% of total plant N and represented <6% of the applied amount. Therefore, the residual fertilizer effect on production was attributable to P. The patterns of fertilizer N and P distribution in the soil remained similar but N recoveries decreased 14–18%. Despite low rainfall, low productivities and reasonable proportions of fertilizer N remaining in the soil, the residual effects of the applied fertilizer N were too low to justify a fertilizer recommendation based on economic returns on the investment.

Efeito de fungos micorrízicos arbusculares no crescimento de mudas de Leucaena leucocephala (Lam.) de Wit. em solos de caatinga sob impacto de mineração de cobre

The arbuscular mycorrhizal fungi (AMF) can promote plant tolerance to heavy metals and have been indicated for use in revegetation processes. The effect of native and introduced AMF on the growth of seedlings of Leucaena leucocephala on soils of caatinga biome impacted by copper mining (Mineracao Caraiba, Jaguarari Municipality, Bahia State) was evaluated. The experiment was set up in a complete randomized design, in a 3 × 4 factorial arrangement, considering soil from preserved caatinga and substrates of a site from which the topsoil was removed and a site which received copper waste; and four inoculation treatments (uninoculated control, inoculated with Glomus etunicatum, Acaulospora longula, and a mixture of the two fungi), with five replicates. Independently of the inoculation treatment, the area where the topsoil was removed was more indicated for preparing the seedlings of leucaena, while the soil from the waste site was not suitable for growth of this plant and the establishment of mycorrhizal association. Although infective, G. etunicatum was not efficient in promoting growth of leucaena in the impacted areas, while the native AMF, A. longula and the mixture of fungi contributed to the development of the seedlings.

Fungos micorrízicos arbusculares em estádios sucessionais de caatinga na região semi-arida do Brasil

A caatinga e um bioma exclusivamente brasileiro com areas em acentuado processo de desertificacao. Os fungos micorrizicos arbusculares (FMA) atuam na sucessao vegetal favorecendo o estabelecimento das especies vegetais proprias das etapas sucessionais e acelerando a recuperacao para um estadio climax da sucessao. O presente estudo teve como objetivo avaliar a ocorrencia e diversidade de FMA em diferentes estadios sucessionais de caatinga no semiarido paraibano. Parcelas experimentais (30 x 60 m) foram demarcadas em areas representando diferentes estadios sucessionais de caatinga: inicial (revegetacao natural nos ultimos 15 anos); intermediario (revegetacao natural nos ultimos 35 anos); tardio (caatinga madura com mais de 50 anos sem severos disturbios antropicos); e tambem em areas de pasto cercadas e protegidas para representar o momento inicial de sucessao. Parcelas representativas dos quatro estadios foram implantadas com tres repeticoes. Amostras de solo e raizes foram coletadas na camada de 0-15 cm de profundidade, nas estacoes seca e chuvosa. Todas as areas apresentaram baixo potencial de infectividade, sugerindo que a introducao de mudas micorrizadas pode acelerar o processo de revegetacao de parcelas degradadas nessa area. Com excecao das areas em estadio tardio, os reservatorios de glomalina aumentaram com o avanco do processo de sucessao. Areas em estadio tardio de sucessao apresentaram maior riqueza de especies de FMA, indicando que o reestabelecimento da vegetacao tambem exerce efeito significativo sobre a comunidade fungica. Os generos Glomus e Acaulospora foram predominantes em ambas as estacoes, possivelmente por serem bem adaptadas as condicoes de semiarido.

An Index of Susceptibility to Drought (ISD) for the Semiarid Brazilian Northeast

This work presents the development of a composite Index of Susceptibility to Drought (ISD) for semiarid Brazilian Northeast that considers climatology, physical properties, soil usage, social and economic aspects, the risk of harvest losses and the shortage of human and animal drinking water. The index started with the Index FUNCEME of drought Severity (IFS), developed by FUNCEME. Then, it evolved to use some tools proposed by the Joint Research Centre/Organization for Economic Co-operation and Development (JRC/OECD), as well as techniques of multiple imputation for missing data and data winsorization. The work was tested and validated with real data from Rio Grande do Norte State in three climatologic scenarios (dry, regular and rainy). A multivariate analysis test and a Monte Carlo simulation were also produced for a sensibility and strength analysis of the developed model. These analyses validated the composition model and the obtained results with real data. The ISD can be used as a tool to support decision makers in various government levels to help guide the actions for the drought-affected areas.