Inadequate soil management practices adopted in the Brazilian semi-arid region contribute to erosive processes. Agroforestry systems (AFs) have been considered an alternative to reduce water erosion. This study aimed to evaluate the impact of two alternatives AFs, a traditional and an intensive cropping system on the losses of sediments, water, organic carbon and nutrients caused by water erosion in comparison to the natural vegetation (caatinga) in a semi-arid region of northeastern Brazil. The agroecosystems studied were: agrosilvopasture (AGP) which consisted of an alley cropping system, cultivated with Leucaena leucocephala and maize, within an area composed by 22% of native trees (200 native trees per hectare) which was grazed during the dry season; silvopasture (SILV) that was composed by 38% of native trees (260 trees per hectare) with a stocking rate of 20 ewes during whole year; traditional agrosilvopasture (TRAG) being managed as following: total deforestation, burning of the residues, cropped with maize for 2 years (1998 and 1999) and fallow during 8-10 years; and intensive cropping (IC) system which was deforested and burned in 1997 followed by cultivation of maize from 1998 to 2002, and thereafter by a fallow period of 8-10 years similar to TRAG. Two areas of native forest (NF1, NF2) known as 'caatinga', used as grassland during the dry season and as a source of wood, were selected and used as reference of steady state in the comparative study in relation to the cultivated sites. Sediment and water losses as a result of erosion were collected during two rainy seasons, i.e. 2003 and 2004, and nutrients and organic carbon contents were determined. Soil samples were collected and organic carbon, pH in water, pH in KCl, water dispersible clay (WDC) and hydraulic conductivity (K 0 ) were measured. In 2003, sediment and water losses did not differ significantly among all treatments. However, in 2004, TRAG (0.70 Mg ha -1 ) and NF1 (1.37 Mg ha -1 ) showed the highest sediment losses, whereas TRAG and IC presented the highest water losses. On average, nutrients losses in cropped areas were lower than in natural vegetation (NF1, NF2).

-This study evaluated the contribution of agroforestry (AFS) and traditional systems to carbon sequestration and nutrient reserves in plants, litter and soil. The study was carried out in the semiarid region of Brazil in a long-term experiment on an experimental farm of the goat and sheep section of the Brazilian Agricultural Research Corporation (Embrapa). Two agroforestry systems were investigated: agrosilvopastoral (ASP) and forest-pasture areas (SP) as well as traditional agriculture management (TM), two areas left fallow after TM (six fallow years -F6 and nine fallow years -F9) and one area of preserved Caatinga vegetation (CAT). Soil, litter and plants were sampled from all areas and the contents of C, N, P, K, Ca and Mg per compartment determined. The AFS (ASP and SP) had higher nutrient stocks than the traditional and intermediate stocks compared to the preserved Caatinga. In the ASP, a relevant part of the nutrients extracted by crops is returned to the system by constant inputs of litter, weeding of herbaceous vegetation and cutting of the legume crops. After fallow periods of six and nine years, carbon and nutrient stocks in the compartments soil, litter and herbaceous plants were similar to those of the preserved Caatinga (CAT), but still lower than under natural conditions in the woody vegetation.Keywords: Agroecology; Family farming; Agroforestry. SEQUESTRO DE CARBONO E RESERVA DE NUTRIENTES EM DIFERENTES SISTEMAS DE USO DA TERRA

In order to ensure the sustainability of agroecosystems, biodiversity must be a priority. Agroforestry, which includes trees, is an example of such diverse systems. We evaluated plant diversity and aboveground biomass production to assess whether areas under fallow following traditional cultivation return to their initial condition. Also, plant diversity and aboveground biomass production were assessed in agroforestry systems (AFS) to determine if these were similar to unmanaged ecosystems. Another objective of the study was to observe the influence of plant diversity on aboveground biomass production in plant communities and also in the population of the dominant species, Cordia oncocalyx. Plant diversity was evaluated by assessing species richness, as well as using Shannon's (H 0 ) and Pielou's (J 0 ) indices. Aboveground plant biomass was evaluated in two AFS: agrosilvopastoral (ASP) and silvopastoral (SP), and also in a traditionally managed agricultural system (AG), areas that had been under fallow for six years (F6) and nine years (F9) and an area of unmanaged caatinga (CAT) vegetation. We observed that the ASP system had a lower diversity and number of species, especially tree species. However, it sustained the same total biomass production as CAT and fallow areas. The SP system, despite having lower H 0 and J 0 indices as well as lower total biomass production, had a similar number of species to CAT and cropped and fallow systems AG, F6 and F9. Plant biomass in F6 and F9 had recovered to productivity levels of unmanaged CAT vegetation; however the diversity indices were not restored to the same level. Plant diversity did not have an effect on the productivity of the agroecosystems. Likewise, annual biomass production by C. oncocalyx is not dependent upon diversity, but it is influenced by the growth stage of individuals.

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As plantas medicinais são importantes por se constituírem como parte da própria história. E dessa relação homem-natureza, nasceram os conhecimentos e os saberes tradicionais, a partir dos quais se fundam cultura e experiências na utilização de plantas medicinais. Nesse contexto, este trabalho teve como objetivo analisar como os saberes etnobotânicos, especificamente das plantas medicinais têm contribuído para o cuidado com a saúde das famílias de alguns estudantes em realidades divergentes, nesse período de pandemia da Covid-19. Assim, realizou-se uma análise comparativa entre duas escolas, uma escola localizada no “campo”, zona rural de Madalena, Ceará, Brasil, a escola EEM João dos Santos de Oliveira e a outra, escola localizada na região metropolitana de Fortaleza, em Pacajus, Ceará, Brasil, denominada EEM Dione Maria Bezerra Pessoa. Quanto aos procedimentos metodológicos, a pesquisa partiu de um questionário semiestruturado com a finalidade da coleta e produção de dados, utilizando-se das abordagens quantitativa e qualitativa. Os sujeitos da pesquisa foram 60 estudantes, 30 de cada escola. O estudo revelou que a localização e etnosaberes adquiridos pelos estudantes do campo e na região metropolitana, não apresentam divergências significativas, considerando a variação de convívio social e cultural.