In this study a temporal analysis (2008-2017) was conducted to examine the occurrence of droughts and the spatial distribution of livestock herds in the Brazilian semi-arid region. Maps of vegetation cover, classes of normalized difference vegetation index (NDVI) and normalized difference drought index (NDDI) were used. Image processing took place on the Google Earth Engine platform along with QGIS Software (2.18). Two historical series were created to compare the variation between two herds and the dry monitoring, one called the 1st series (2008-2012) and 2nd series (2013-2017) which were compared using a paired t-test. The comparative analysis showed that the classes of extreme drought and exceptional drought covered the greatest land areas in the 2^nd series, while abnormal drought covered the greatest land area in the 1^st series. The analysis of herds, a reduction in the cattle herd and an increase in goat and sheep herds were noted. This study considers the efficacy of NDDI and NDVI indices to monitor the distribution of droughts in the Brazilian semi-arid region. The geoprocess of Sidra data enabled an analysis of the spatial distribution and temporal variation of the herds in the semi-arid region and how drought may have impacted livestock dynamics.

Management of tropical dry forests in Brazil expanded 450% in the two latest decades; but little is known about the dynamics of these areas. Thus, the objective of this work was to evaluate if the recovery of mean original biomass stocks (MOBS) is a consistent criterion to define cut cycles in a managed forest for charcoal production, and determine the remaining biomass and its contribution to soil carbon stocks. The study was conducted at the Ramalhete Settlement, in General Sampaio, CE, Brazil, in 2018. The explorable shrubby-arboreous biomass (ESAB) and the ESAB mean annual increases (ESAB -MAI) were determined in five areas subjected to clearcutting after 3, 5, 8, 11, and 15 years, and in a preservation area with 40 years of regeneration. Each area was divided into seven plots (20 × 20 m), totaling 42 plots. The ESAB of the plots were compared and the remaining biomass (branches, stumps, and litterfall) in a recently explored area was calculated and converted into organic carbon. The remaining biomass of branches had higher contribution to soil carbon stocks, followed by the litterfall, and stumps. The carbon stocks of the branch component were 3.4-fold higher than those of the litterfall. The recovery of the MOBS of an area after clearcutting should not be used as a criterion to define the cut cycle, since these original carbon stocks do not represent the maximum ESAB production possible in the area; the biodiversity and amount of ESAB in the classes of larger diameter are more adequate criteria.

Análises físicas e hidroquímicas foram realizadas, em poços rasos, com o objetivo de identificar os impactos da irrigação e da sazonalidade climática no processo de salinização e na dinâmica do nível das águas subterrâneas do Distrito Irrigado do Baixo Acaraú - DIBAU, Ceará. As amostragens foram realizadas em dois períodos: dez/2003 a maio/2007; agosto/2010 a julho/2011, em cinco poços rasos (P1, P2, P3, P4, P5), sendo três deles em campos irrigados. Na identificação da similaridade ou dissimilaridade dos teores de íons sódio (Na⁺⁾, cloreto (Cl^-) e nitrato (NO₃ ^-) entre as duas épocas estudadas, bem como entre os poços amostrados, aplicou-se a técnica de análise estatística multivariada de agrupamento hierárquico. Os dados médios foram submetidos à análise de teste de média e confrontados pelo Teste T. As águas dos poços inseridos na área de sequeiro apresentaram as maiores concentrações médias de Na⁺ e Cl^-, 123 mg L^-1 e 253,2 mg L^-1, respectivamente, enquanto os valores médios de NO₃ ^- foram maiores na área irrigada, 16 mg L^-1. Identificou-se elevação do nível do lençol freático nos poços inseridos na área irrigada (P3, P4 e P5) de 6,13; 5,25 e 3,40 m, respectivamente. As menores flutuações sazonais do lençol freático ocorreram nos poços inseridos na área irrigada, mostrando excedentes de lâminas de irrigação e recarga desses poços, durante a estação seca. As concentrações de Na⁺ e de Cl^-, nas águas do lençol freático, são determinadas pelos fatores naturais, diferentemente do que ocorre com as do NO₃ ^-.

The aim of this study was to investigate changes that occurred due to land use and ground cover in the deposition, accumulation and rates of litter decomposition, as well as of soil respirometry, in a dry tropical forest. The study was carried out in two adjacent watersheds in the town of Iguatu, in the State of Ceará, Brazil. One of the watersheds had been under preserved vegetation for 35 years (RC₃₅), while the other had been subjected to thinning for 5 years (TC₅). The main variables among those being analysed were the litter fractions deposited in collectors and accumulated on the ground, the decomposition constant, and soil respirometry. The data were submitted to statistical analysis and compared by t-test (pd”0.05). The total litter deposited in the collectors during the 12 months of monitoring (April 2013 to March 2014) was around 1,300 kg ha^-1 yr^-1 for TC₅, differing statistically (pd”0.05) from RC₃₅ (4,019 kg ha^-1 yr^-1). There was no difference in the litter accumulated on the ground for type of land use (p>0.05). The conservation of litter on the ground in TC₅ is associated with larger inputs of woody, lignified biomass from the thinning, and the consequent lower rates of decomposition and CO₂ emission.

Forest management activities influence fine root development, total soil carbon (TSC) and size of aggregates. A field experiment was carried out in Vertisols of two adjacent catchments in a seasonally dry tropical forest (SDTF) to investigate the thinning on fine-root biomass, stock of the total soil carbon and aggregate size. The catchments are located in the State of Ceará, Brazil. The control catchment of 2.1 ha has been under regenerating vegetation for 35 years (RC35), while the second catchment (1.1 ha) was subjected to thinning (TC5) in December of 2008. The analysed variables were: fine-root biomass in the 0-10, 10-20 and 20-30 cm soil layers, TSC and mean weight diameter of the soil aggregates in the 0-20, 20-40 e 40-60 cm layers. The data were submitted to Pearson correlation analysis and compared by paired t-test (P < 0.05). The 0-10 cm layer of the TC5 management stored double the average amount of fine-roots found in the RC35. Under the TC5 management, stocks of soil TSC increased by 237 and 151% in the 20-40 and 40-60 cm layers, respectively, when compared with RC35. Aggregates 2.15 times greater than those found under RC35 management were obtained in the topsoil (0-20 cm) under the TC5 management. The implementation of thinning in a Vertisol of a SDTF emerges as an alternative management to be considered in projects for sustainability in the semi-arid region, contributing to an improvement in soil structure as well as an increase in the stocks of total carbon.

A new millennium has begun, and a new paradigm in exploitation of natural resources to generate products has emerged. In this sense, a model in line with local environmental reality and based on the sustainable development goals (SDG) proposed by the UN is required. The document addresses the suitability of natural capitals in the Caatinga phytogeographic domain (CPD) for generating products, encompassing primary (solar energy and rainfall) and secondary (soil and vegetation) natural resources. These resources have well-defined scarcity (water, soil, and vegetation) and abundance (solar radiation) characteristics. Water is scarce due to uncertain rainfall and frequent droughts. Due to their fragility, soils, when shallow and/or with a low organic matter content, are susceptible to erosion and salinization. In turn, vegetation is scarce due to low potential for biomass production (50% of the area has a biomass production below 2 Mg ha-1. As for solar energy, there is no uncertainty regarding its occurrence in the CPD. Moreover, the region has the highest solar radiation intensities in Brazil, with daily averages ranging from 4.8 to 6.0 Kwh m-2 within a year. Therefore, a new model must be adopted, in which socioeconomic development is based on the potential of local natural resources. In short, abundant resources should be prioritized over scarce ones. Furthermore, exploitation must be democratized and not only in the hands of few privileged individuals