O baixo rio São Francisco foi impactado por mudanças no fluxo do rio causadas por políticas públicas implementadas nas últimas décadas causadas pela geração de energia elétrica. O objetivo deste trabalho foi avaliar o uso de geotêxteis fabricados a partir de fibras naturais no controle da erosão na margem do rio São Francisco. Geotêxtil , Syagrus coronata Geotêxtil e Bare Soil sem geotêxteis, localizado na margem direita do baixo rio São Francisco, no município de Amparo de São Francisco, estado de Sergipe, nordeste do Brasil. Entre os geotêxteis testados, os geotêxteis Syagrus coronata e Juncus sp foram temporalmente mais eficientes no controle da erosão, produzindo menor quantidade de sedimentos, embora na resistência e durabilidade das fibras, Typha latifolia apresentou melhores resultados.
A dinâmica da cobertura florestal na Bacia Hidrográfica do Rio São Francisco (BHRSF) pode ser avaliada por métricas de ecologia da paisagem. O objetivo deste trabalho foi avaliar a fragmentação florestal na Bacia Hidrográfica do Rio São Francisco, Brasil, por meio de métricas de ecologia da paisagem e quantificar a cobertura florestal nas unidades de conservação federais (UCs) presentes, para os biomas Caatinga, Mata Atlântica e Cerrado nos anos de 1997, 2007 e 2017. O mapeamento dos fragmentos foi realizado considerando área e quantidade dos fragmentos florestais, divididos nas seguintes classes de tamanho: (1) pequeno (até 10 ha); (2) médio (entre 10 e 100 ha); e (3) grande (maiores que 100 ha). As métricas, área, forma e borda, foram calculadas no software Fragstats® 4.2. As métricas números de fragmentos (NP), área de classe (CA), tamanho médio dos fragmentos (MPS) e densidade de borda (ED) dos fragmentos florestais dos biomas Caatinga e Cerrado na BHRSF comprovam que a Bacia está em processo de fragmentação florestal, principalmente nos grandes fragmentos, que tiveram suas áreas reduzidas, e nos de tamanho médio, que tiveram aumento da quantidade de bordas. De forma geral, a proteção de áreas florestais nas UCs da Caatinga e Cerrado não foram eficazes em manter a cobertura florestal, haja vista o desmatamento nestas áreas protegidas em 20 anos. Medidas como pagamentos por serviços ambientais ou restauração florestal devem ser utilizadas pelo poder público e sociedade em conjunto com a criação e manutenção de áreas florestais protegidas. A Mata Atlântica foi o único bioma a apresentar aumento na cobertura florestal e redução da fragmentação florestal na BHRSF. Iniciativas como o pacto da restauração da Mata Atlântica e Lei da Mata Atlântica de 2006 podem ter favorecido esse aumento da cobertura florestal.
Intense soil preparation and disturbance in crops, over time, reduces the quantity and quality of soil organic matter. Given this context, this work aimed to determine soil carbon stocks and labile fractions under agroforestry system (AFS) and toposequences in an altitude marsh, Taquaritinga do Norte, Pernambuco, Brazil. The study was carried out at the Yaguara farm, and the areas studied were native forest with 4.57 ha and coffee plantation in shade with native forest with 25.59 ha. Soil samples were collected in four trenches measuring 1.5 x 1.5 x 0.60 m, with a distance of 50 meters. Soils were collected at depths of 0–20, 20–40 and 40-60 cm, followed by chemical, physical and density analyzes to determine soil carbon stocks and labile fractions. The area with shaded coffee showed higher values of soil carbon stocks at depths of 0-20 cm and 20-40 cm. At a depth of 40-60 cm, the AFS top toposequence showed the highest carbon stock with 11.73 Mg ha-1, followed by the area with native vegetation with 10.6 Mg ha-1, slope with 9.23 Mg ha-1 and pediment with 7.00 Mg ha-1. It was found that the top toposequence with shaded coffee exhibited a greater stock of labile carbon at depth 0-20 cm with a value of 1.06 Mg ha-1, followed by the bedding areas (SAF) with 0.88 Mg ha-1, native forest with 0.79 Mg ha-1 and slope with 0.67 g kg-1. However, the area of native vegetation showed the highest value of labile carbon at a depth of 40-60 cm. It was concluded that the area with shaded coffee in the top toposequence showed great capacity to increase total carbon stocks and labile carbon stocks of soil organic matter.
Background
Vetiver grass (Chrysopogon zizanioides L. Roberty) is one of the most studied and applied species in soil bioengineering techniques all over the world, but there are technical information related to its root system deserving a better comprehension provided by different methodologies’. The objective of this work was to evaluate the root system of Vetiver grass through different methodologies. The trench method evaluated 50 images in 10 × 10 cm squares in its vertical face. The volumetric ring method uses a metallic ring with a volume of 50 cm3 (diameter ≅ 4.6 cm and height ≅ 3.0 cm) to collect samples in the same trench’s vertical face. A hand auger hole method worked with soil samples and roots removed from the surface up to 0.50 m depth. The monolith method comprises a 0.50 m wide, 0.50 m long, and 1 m deep monolith. A spatial correlation between root volume and root area was observed in the kriging maps by the volumetric ring method.
Results
The root area values for both the volumetric ring method and the hand auger hole method were similar, up to 0.10 to 0.20 m. On the analyzed variables, the root area showed the best correlation coefficient among the root methods, especially those that use the limited spatial distribution by its sampling collection, such as the volumetric ring method and the hand auger hole method (r = 0.526, p < 0.05).
Conclusions
The studied methods can be separated in different groups, such as those that provide more detailed information on the behavior and distribution of the root system, like trench and monolith methods and the methods that better describe the morphological characteristics of the features, like the volumetric ring method. Both require greater spatial coverage, and therefore have greater precision.
Buffel grass has characteristics of resistance and rapid recovery to prolonged drought, however, few studies indicate this resistance to salinity. Thus, the objective was to evaluate the relationship between salt stress and the growth dynamics, green mass production and area of Buffel grass. The experiment was conducted in an entirely randomized design, with three levels of salinity and ten repetitions, totaling 30 experimental units. Measurements of height, cutting and weighing of green mass were made in three periods, with intervals of 28 days between them, and photography of the leaves for analysis in ImageJ software in the last period. The data obtained were submitted to the Shapiro-Wilk normality test and Bartlett's homogeneity test. Kruskal-Wallis non-parametric test and Dunn's post-test was applied for data that did not follow normality, and ANOVA test and Tukey's post-test for those that followed normality and homogeneity. The results indicate that there was no significant difference in height for the treatments with or without salt, so even with the addition of salt there was no interference in growth, but when compared in relation to the periods, it can be observed that the last period was different from the others, this can be explained by the vegetative vigor of the plant, because when it is younger it has more efficient cell multiplication, but as it suffers injuries, the vigor is decreased and growth is slower. Therefore, there are some differences in the behavior of grass submitted to salinity, but they do not significantly interfere in its development.
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