Influencia del cambio de uso del suelo sobre las reservas de carbono orgánico en el Parque Natural Regional Cortadera, Boyacá (Colombia)

Los páramos almacenan grandes reservas de carbono orgánico en el suelo (COS), influenciados por las condiciones climáticas y biogeoquímicas, propias del ecosistema; sin embargo, su progresiva conversión hacia cultivos, ganadería o minería incide directamente en las reservas de COS. Con el fin de determinar el efecto que ejerce el cambio de uso de suelo sobre la variabilidad de las reservas de COS, se realizó un monitoreo de COS entre 2013, 2018 y 2020, en el Parque Natural Regional Cortadera. Se estudiaron parcelas permanentes de muestreo (PPM), ubicadas bajo tres diferentes usos del suelo: conservado, en recuperación e intervenido. Se analizaron muestras de carbono orgánico y densidad aparente, a dos profundidades (0-15 cm y 15-30 cm). Se encontró que la PPM en escenario conservado presentó los contenidos más altos de COS, con valores de 290,37; 199,22 y 257,5 tC ha-1, para cada uno de los años en estudio; seguido por la PPM en recuperación, que evidenció valores de COS 215,3 tC ha-1, en el 2020, en contraste con la PPM intervenida, que presentó contenidos mínimos de 15,50; 34,01 y 88,06 tC ha-1. Se observó que los mayores contenidos de COS se encuentran a la profundidad de 15 a 30 cm. Dichos aspectos, resaltan la importancia de avanzar en acciones enfocadas a la protección de ecosistemas estratégicos, considerando las constantes amenazas relacionadas con la transformación del paisaje y, con ello, la posibilidad de proveer funciones y servicios asociados a la captura de carbono y la regulación climática.

The paramos accumulate high stocks of soil organic carbon (SOC), influenced by the climatic and biogeochemical conditions of the ecosystem. However, their progressive conversion to crops, livestock, or mining has a direct impact on the SOC stocks. To determine the effect of land use change on the variability of SOC stocks, monitoring of SOC content was conducted between the years 2013, 2018, and 2020 in the Parque Natural Regional Cortadera. Permanent sampling plots (PPS) located under three different land uses were studied: conserved, recovering, and intervened. To do so, samples of soil organic carbon and bulk density at two depths were analyzed (0-15 cm and 15-30 cm). The conserved PPS showed the highest SOC contents, with maximum values of 290.37; 199.22, and 257.5 tC ha-1 for each of the years under study; follow by the recovery PPM that presented COS values of 215.3 tC ha-1 in 2020, in contrast to the intervened PSP that showed minimum contents of 15.50; 34.01 and 88.06 tC ha-1. Furthermore, the highest SOC contents were found at 15-30 cm depth. These factors emphasize the importance of carrying out actions focused on protecting strategic ecosystems such as paramos, taking into account the continuous threats related to the transformation of the landscape and, consequently, the possibility of providing ecosystem functions and services related to carbon capture and climate regulation.

Shape Memory Alloy-Based Soft Finger with Changeable Bending Length Using Targeted Variable Stiffness.

This work described a bioinspired soft robotic finger with variable bending length to conform objects with different sizes by means of selectively varying the structural stiffness of its segments. The basic design is a shape memory alloy-based soft actuator with embedded stiffness-varying structures serving as modifiable endoskeletons. The stiffness-varying structure is composed of shape memory polymer (SMP) embedded with Nichrome (Ni-Cr) wires as heating elements. Joule heating of SMP through Ni-Cr wire inducing its phase change from the glassy state to the rubbery state enables the actuator structure change from the stiff state (E = 125.65 MPa) to the compliant state (E = 3.33 MPa). The Ni-Cr wire was designed with multiple solder tabs to enable the SMP that can be heated segmentally leading to the stiffness reduction of desired segments of finger to obtain different bendable lengths. A finger with three segments was fabricated, and its deformation and actuation force were measured based on different bendable lengths. A gripper was then assembled using two identical fingers where the angle between them can be manually adjusted. The angles for the two fingers with specific bending length were determined to enable them to form a closed configuration when maximum bending is reached. The grasping force of the gripper was then measured, and it was used to grip different objects. Results show that the performance of the gripper in gripping the size and weight of the object was markedly improved compared with the gripper that cannot vary its gripping length.

EVALUACIÓN DE UN TERMOFOSFATO EN EL CRECIMIENTO Y PRODUCCIÓN DE FRESA (Fragaria x ananassa Duch.) cv. 'ALBIÓN' / EVALUATION OF THERMOPHOSPHATE IN GROWTH AND PRODUCTION THE STRAWBERRY Fragaria x ananassa Duch.) cv. 'ALBIÓN'

RESUMEN La fresa es una de las frutas más importantes en el mundo, por sus múltiples usos industriales, medicinales y culinarios. En Colombia, la producción se concentra en los departamentos de Cundinamarca, Antioquia, Norte de Santander, Cauca y Boyacá. Su crecimiento y productividad están determinados por una adecuada fertilización en elementos, como nitrógeno (N), potasio (K), calcio (Ca) y fósforo (P), siendo el P un elemento de gran importancia, en diversos procesos fisiológicos, pero con baja disponibilidad para las plantas, en suelos con condiciones de acidez. Por esta razón, el objetivo de la investigación fue evaluar el efecto de una fuente no convencional de fósforo (termofosfato), en el crecimiento y en la producción de plantas de fresa cv. 'Albión', bajo condiciones del municipio de Viracachá, Boyacá. Se utilizó un diseño experimental completamente al azar, con 4 tratamientos, que correspondieron a dosis crecientes de termofosfato (0, 300, 600 y 900kg ha-1), con 4 repeticiones. Se evaluó el contenido de clorofilas totales, peso seco de parte aérea y raíz, número de estructuras reproductivas, producción de frutos, concentración foliar de P, Ca y silicio (Si). Se presentaron diferencias significativas (P≤0,05) en las variables clorofilas totales, peso seco de raíz, producción por calidad, concentración foliar de P y Si; las demás variables no mostraron diferencias estadísticas. Los mejores resultados, se presentaron con los tratamientos de 300 y 600kg ha-1 de termofosfato, convirtiéndolo en una alternativa de suministro en suelos con problemas de acidez y baja disponibilidad de P.

SUMMARY The strawberry is one of the most important fruits in the world for its multiple industrial, medicinal and culinary uses. In Colombia, the production is concentrated in the departments of Cundinamarca, Antioquia, Norte de Santander, Cauca and Boyacá. Its growth and productivity are determined by an adequate fertilization in elements such as nitrogen (N), potassium (K), calcium (Ca) and phosphorus (P), being P an element of great importance in various physiological processes but with low availability for plants in soils with acidic conditions. For this reason, the aim of this study was to evaluate the effect of an unconventional source of phosphorus (thermophosphate), on the growth and production of strawberry plants cv. 'Albión' under conditions of the municipality of Viracachá, Boyacá. A completely randomized experimental design was used, with 4 treatments, which were increasing doses of thermophosphate (0, 300, 600 and 900kg ha-1) with 4 repetitions. The content of total chlorophylls, dry weight of aerial part and root, number of reproductive structures, production and foliar concentration of phosphorus, calcium and silicon were evaluated. There were significant differences (P≤0.05) in the variables total chlorophyll, root dry weight, production by quality, foliar concentration of P, Ca and silicon (Si); the other variables did not show statistical differences. The best results were presented with the treatments of 300 and 600 kg ha-1 of thermophosphate turning it into an alternative supply in soils with acidity problems and low availability of P.