ABSTRACT We tested a new type of wind-transported particle collector (multidirectional traps, MDt) in southeast Spain to forecast particle movement in three different soil types. The MDt collectors are easy to manufacture from thermoplastic filaments with an industrial 3D printer. The collectors tested were very efficient. Our research was carried out on unplowed Calcisols and on orange and olive-cropped Fluvisols and Luvisols, respectively. The results from the logs of nine vaned masts, each with four MDt collectors at different heights, on Calcisols, Fluvisols and Luvisols were compared with the wind erodible fraction of these soils (EF) empirically estimated and with their erosion rates calculated in a wind tunnel of our own design with a built-in laser scanner. These new collectors can differentiate the collected sediments by their direction of origin and arranged in a network of masts, enabling to distinguish overall particle loss or deposition, which is not detectable with the wind tunnel due to the work scale and no windward deposits, as it is a closed device. Comparison of the calculated EF and the total mass of transported particles recorded by the MDt collectors showed very good correlation (R2 = 0.9144) with an even better relationship between the results of the wind tunnel and collectors (R2 = 0.9741). Required precision, financing, and execution time are important in determining the use of the device. We conclude that this device shows good potential.

Abstract The distribution of the biomass of fine, medium, and thick roots, the concentration of soil organic carbon (COS), the apparent density (Da), the COS stores in the first 90 cm of depth were studied in three forests with a predominance of oak (Quercus sp.) located in central Mexico (Morelos) The estimated age of the trees in the forests was (a) ≈ 40 years or late, (b) ≈ 20 years, and (c) ≈ 10 years or earlier. We found that the SOC concentration and SOC stores decreased as the soil depth increased while the Da increased. More than half of the stored COS accumulates in the first 30 cm of the profile. The biomass of fine roots presented an exponential decrease pattern as depth increased, while the biomass of medium and thick roots had an irregular pattern, but always with a tendency to decrease as depth did. In the forests of the three indicated ages, the biomass of fine, medium, and thick roots had a higher correlation with Da than with COS stores. The regression coefficients (R2) of the linear models relating Da to the COS content were in the range of 0.61 and 0.72.

Resumen Se estudió la distribución de la biomasa de raíces finas, medias y gruesas, la concentración carbono orgánico del suelo (COS), la densidad aparente (Da), los almacenes de COS, en los primeros 90 cm de profundidad en tres bosques con predominio de encino (Quercus sp.) ubicados en la zona centro de México (Morelos). La edad estimada de los árboles de los tres bosques fue (a) ≈ 40 años o maduro, ≈ 20 años o medio y ≈ 10 años o joven. En general, la concentración de COS y los almacenes de COS decrecieron a medida que lo hacía la profundidad del suelo, en tanto que la Da aumentaba. Más de la mitad del COS almacenado se encontró en los primeros 30 cm del perfil. La biomasa de raíces finas presentó un patrón de disminución exponencial con la profundidad, mientras que la biomasa de las raíces medias y gruesas tuvo un patrón irregular, pero siempre con tendencia a disminuir a medida que lo hacía la profundidad. En los bosques de las tres edades indicadas, la biomasa de raíces finas, medias y gruesas presentó mayor correlación con la Da que con los almacenes de carbono orgánico del suelo. Los coeficientes de ajustes (R2) de los modelos de regresión lineal que relacionan Da con el contenido de COS se ubicaron entre 0.61 y 0.72.

Abstract The estimation of biomass in seasonally tropical dry forests requires basic information that for some species is scarce. To help solve this deficit, we generated allometric equations for five species of tropical dry forest (TDF). Equations for each tree species studied, for two groups of species, and all species together are reported. The equations were of the power type, based on diameter at breast height (dbh). The allometric model of each species included was fitted resulting in high values of the coefficient of determination using only the variable dbh. The allometric equations for each of the five forest species differed from each other (p < 0.05). Species grouped according to similar specific wood density showed a better fit of the model (p < 0.05), particularly those with high values for this parameter, than when considering only one species. The biomass of all species was predicted correctly by using only the measures of the basal area. However, the coefficient of determination increased, and the estimated error decreased, when the specific wood density was added to the model. Finally, the best fit of the model is attained by adding the tree height to the equation. The last two characteristics, however, were not significant when determining the individual models for each species.

Resumen La estimación de biomasa en los bosques tropicales estacionalmente secos requiere de información básica que para algunas especies es escasa. Para contribuir a solventar este déficit, se generaron ecuaciones alométricas para cinco especies de bosque seco tropical (TDF). Se presentan las ecuaciones para cada especie arbórea estudiada, para dos grupos de especies y todas las especies juntas. Las ecuaciones generadas fueron del tipo exponencial basadas en el diámetro a la altura del pecho (dap). El modelo alométrico de cada especie incluida se ajustó con valores altos del coeficiente de determinación utilizando únicamente la variable dap. Las ecuaciones alométricas para cada una de las cinco especies forestales difieren entre sí (p <0.05). Las especies agrupadas de acuerdo con una densidad de madera específica similar mostraron un mejor ajuste del modelo (p <0.05), particularmente aquellas con valores altos para este parámetro, más que cuando se considera una sola especie. La biomasa de todas las especies se predijo correctamente utilizando solo las medidas del área basal. Sin embargo, el coeficiente de determinación aumentó y el error estimado disminuyó al agregar la densidad de madera específica al modelo. Finalmente, agregando la altura del árbol a la ecuación se logra el mejor ajuste del modelo. Las dos últimas características, sin embargo, no fueron significativas al momento de determinar los modelos individuales para cada especie.

RESUMO Um estudo de erosão eólica foi realizado em um túnel de vento, onde amostras de sedimentos foram estudadas por uma câmera de visão artificial. Essas imagens podem ser ampliadas para análise posterior. As análises de imagens foram principalmente colorimetria, número de partículas presentes e seu tamanho. A erodibilidade do vento no solo foi analisada com as análises de imagens em função de outros resultados laboratoriais. Antrossolos foram os solos mais erodíveis, enquanto Calcissolos mostrou a maior resistência à ação erosiva do vento. As características do sedimento mostram a influência da altura da armadilha com a diminuição do tamanho, número e escuridão da partícula à medida que a altura do transporte aumenta. Uma ANOVA de dois fatores para altura do efeito principal mostrou que houve diferenças significativas no número e tamanho de partículas para sedimentos entre 0-15 cm e 40-70 cm de altura. Os solos podem ser agrupados por diferenças no número de partículas e tamanho em diferentes alturas em Antrossolos e Leptossolos altamente erodíveis, Calcissolos e Arenossolos não erodíveis, nos quais as partículas finas já estavam esgotadas pela erosão natural do vento. A agregação apresentou um padrão similar com valores decrescentes de Calcissolos e Leptossolos para Antrossolos e, finalmente, Arenossolos, onde apenas grãos de areia foram observados em armadilhas adesivas.

ABSTRACT A wind erosion research was carried out in a wind tunnel where sediment samples acquired were studied by an artificial vision camera. These images could be enlarged for further analysis. Image analyses were mainly colorimetry, number of particles present and their size. Soil wind erodibility was analyzed with the image analyses supported by other laboratory results. Anthrosols were the most erodible soils, whereas Calcisols showed the highest resistance to the erosive action of wind. Sediment characteristics show the influence of trap height with decreasing particle size, number and darkness as transport height increases. A two-factor ANOVA for main effect height showed that there were significant differences in particle number and size for sediments trapped 0-15 cm and 40-70 cm high. Soils could be grouped by differences in particle number and size at different heights into highly erodible Anthrosols and Leptosols, non-erodible Calcisols and Arenosols, in which fine particles were already depleted by natural wind erosion. Aggregation showed a similar pattern with decreasing values from Calcisols and Leptosols to Anthrosols and finally Arenosols, where only single sand grains were observed in adhesive traps.

ABSTRACT The present work analyzes the effectiveness of windbreaks against wind erosion through the study of streamline patterns and turbulent flow by means of sonic anemometry and sediment traps. To this end, windbreaks composed of plastic meshes (7.5 m long and 0.7 m tall) were used. Windbreaks are a good means to reduce wind erosion, as they produce a positive effect on the characteristics of air currents that are related to wind erosion processes. Due to their ease of installation and dismantling, plastic meshes are widely used in areas where they are not required permanently. In our study, the use of a mesh of 13 × 30 threads cm−2 and 39 % porosity resulted in an average reduction of 85 % in face velocity at a height of 0.4 m and a distance of 1 m from the windbreak. The turbulence intensity i increased behind the windbreak because the reduction of mean of air speed on the leeside caused by the flow of air through the windbreak. Fluctuation levels, however, remained stable. The mean values of turbulence kinetic energy k decreased by 65 % to 86 % at a distance of 1 m from the windbreak and at a height of 0.4 m. The windbreak reduces erosion and sediment transportation 2 m downwind (2.9 times the windbreak height). Nevertheless, sediment transportation was not reduced at a height of 1.0 m and the effect of the windbreak was not observed at a distance of 6 m downwind (8.6 m times the windbreak height).