The objective of this work was to evaluate the soil macrofauna and the bioindicator taxonomic groups associated with different land uses in the Colombian Amazon. Twelve agroforestry arrangements were studied and compared with to the native forest and pasture. For each land use, six monoliths were randomly selected and divided into four layers (litter, and 0-10, 10-20, and 20-30 cm soil depths). The variables considered in the analysis of land use effects were: individuals per square meter, order richness, Shannon’s diversity index, and Pielou’s evenness index. The greatest values for soil macrofauna density and diversity occurred in the forest, in contrast with the pasture. The principal component analysis distinguished land use according to macrofauna diversity, separating the native forest from the other land uses. The cluster analysis indicated the potential of some agroforestry systems to conserve the values of soil macrofauna density and diversity similar to those of the forest. According to the analysis of indicator value, five taxonomic groups (Diplura, Pseudoscorpionida, Araneae, Chilopoda, and Gastropoda), identified as bioindicators, are associated with preserved sites because of the sensitivity of their populations.

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Silvopastoral systems (SPS), an integrated farming system in which tropical grasses are combined with trees and shrubs, have been implemented in the last years in the Amazon region in order to mitigate the impacts generated by the traditional cattle ranching system. However, despite the multiple SPS’s benefits to soil and ecosystem, there is a paucity of comprehensive studies revealing the potential soil health (SH) restoration through SPS. Here, by developing an overall SH index using local native vegetation (Amazon rainforest) as a reference, we aimed to assess SH changes induced by the land transition from the traditional livestock production system to the SPS in the Colombian Amazon region. A chronosequence conformed by three areas: (i) native vegetation, (ii) traditional pasture and (iii) silvopastoral system was established in two study sites located in the Colombian Amazon, specifically in Caquetá State, the second hotspot of deforestation in the Amazon Basin. The results indicated high soil compaction and loss of macrofauna diversity and richness due to pasture management, causing a loss of 9% of soil capacity to function. In contrast, by integrating 31 soil indicators, our SH assessment revealed that SPS was an effective strategy for the recovery of SH, impacting positively multiple soil functions related to nutrient dynamics, water retention and supply, and biological activity.

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ResumenLa densidad, riqueza y diversidad de la macrofauna edáfica son afectadas, entre otros factores, por la configuración de los agroecosistemas y la estacionalidad de la precipitación. Con el fin de evaluar estos efectos en mayo y noviembre de 2011, correspondientes a épocas de máxima y mínima precipitación, respectivamente, se realizaron estudios sobre la composición de la macrofauna edáfica asociada con los arreglos agroforestales ubicados en el Centro de Investigaciones Macagual Cesar Augusto Estrada González, Amazonia, Caquetá, Colombia. El experimento se dispuso en un diseño completo al azar bifactorial con cuatro tratamientos (arreglos agroforestales: AB = abarco -Cariniana pyriformis Miers; CH = caucho Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. ; CP = caucho-parica Schizolobium amazonicum Huber; UV = uvito Genipa Americana L.) y dos épocas (máxima y míni-ma precipitación), y cuatro repeticiones en parcelas divididas. Para explorar las relaciones entre los órdenes de macrofauna, se realizó un análisis de componentes principales y se evalúo el efecto de los arreglos agroforestales con una prueba de Monte Carlo. Los resultados mostraron que la densidad de la macrofauna fue mayor en el periodo de máxima precipitación (1129 individuos) en comparación con el de mínima (598 individuos). Los arreglos agroforestales influyen sobre la presencia o ausencia de algunos grupos taxonómicos (P < 0.05) como Homoptera (Insecta) y Raphidioptera (Insecta); además los UV y AB pueden favorecer a la macrofauna del estrés por sequía.Palabras claves: Edafofauna, fauna del suelo, arreglo agroforestal, época, densidad, riqueza, diversidad, Amazonía. AbstractThe density, richness and diversity of soil macrofauna are influenced by diverse factors such as the configuration of agroecosystems, seasonality, among others. In order to assess this influence, sampling was conducted in May and November 2011, corresponding to the periods of maximum and minimum rainfall respectively on the composition of soil macrofauna associated with agroforestal arragements located in the Research Centre Macagual Cesar Augusto Estrada González property of the University of Amazonia, Colombia. The experiment was conducted under a complete randomized bifactorial design with 4 treatments (agroforestry system) and 2 periods (maximum and minimum precipitation), with 4 replicates in split plots. Principal component analysis was performed to explore the relationships between the orders and the effect of the agroforestal arrangements, which was tested with a test of Monte Carlo. The results showed that the density of the macrofauna was higher in the period of maximum pluvial precipitation compared to the minimum (1129 vs 598 subjects, respectively). The agroforestal arrangements influences the presence or absence of some taxonomic groups of soil macrofauna (P<0.05) as Homoptera and Raphidioptera, besides than UV and AB can favor the macrofauna of the stress due to the drought.

Conversion from Amazon forest to low-management pasture or agriculture causes not only degradation of aboveground vegetation but also negative changes in soil properties and ecosystem services. This study aimed to evaluate the impact of physical soil degradation on termite community changes in three contrasting land uses (natural regeneration, rubber plantations, and silvopastoral systems). Soil physical quality was assessed through a set of physical variables, such as bulk density, porosity, soil macro-aggregation state, Visual Evaluation of Soil Structure (VESS) and penetration resistance, which were summarized in an overall synthetic indicator of physical quality. Besides, transects of 20 × 2 m were established in each land use; each transect was divided into four sections of 5 m to search and collect termites during 1 hour in each section; likewise, termites were collected from blocks of soil 25 × 25 × 10 cm (length, width, and depth, respectively) adapted from the Tropical Soil Biology and Fertility (TSBF) method. In total, 60 transects were evaluated, 20 in each land use. A total of 41 species were collected across the three land uses evaluated: natural regeneration presented 60% of the collected species (25 species), silvopastoral systems 53% (22 species), and rubber plantations 39% (16 species). Additionally, composition species from the silvopastoral, agroforestry systems, and natural regeneration were different, and a close association between these last land uses was observed. Soil physical characteristics showed significant variations between land uses. The rubber plantations presented lowest values of soil physical quality, while the natural regeneration showed high soil physical quality. These changes affected termite community and lead to changes in its composition with disproportionate loss of some species; however, there are some that can acclimate well to the decline in the soil physical quality.

En los municipios de Suaza y Timana se seleccionaron 55 lotes con diferentes rangos altitudinales, condiciones de manejo agronómico y beneficio, para evaluar la relación entre características químicas del suelo y manejo con los atributos sensoriales en taza. El método estadístico utilizado fue Análisis de Correspondencias Múltiples (ACM) y un análisis de PLS para determinar la relación entre los atributos sensoriales y las variables agronómicas de manejo y parámetros de suelo. Se encontro diferencias significativas (P<0,001) para pH, Ca, Mg, Na, SB, Al, P, Zn, así mismo, se encontro diferencias significativas (P<0,01) para K, Mn, M.O y B entre los tipos de suelos. Las tazas encontradas fueron de cuerpo medio, algunas acidas e intermedias con atributos sensoriales representativos. Q3 se relacionó con atributos sensoriales como cuerpo, dulzor, balance, sabor, acidez y estos con variables de manejo del cultivo como densidad de siembra (Ds), edad, altura y elementos químicos con S. Q2 fue una taza afectada por el manejo en el proceso de la fermentación y por características químicas como el pH, SB, Ca, Mg además variables de manejo como sombra la cual depende de la altura en la cual se encuentra el cultivo. Q1 que presento baja calificación en los atributos sensoriales se relacionó con características del suelo como Al y Fe.

El objetivo del presente trabajo fue evaluar la variabilidad del contenido de pigmentos fotosintéticos y la conductancia estomática diaria en relación con las variables ambientales en ecotipos de copoazú (Theobroma grandi orum). Los ecotipos utilizados formaban parte del banco de germoplasma de la Universidad de la Amazonia (Colombia). El estudio se realizó durante el año 2015. Se colectaron cuatro hojas del estrato medio de cuatro plantas por cada ecotipo, para hacer extracción y lecturas a diferentes niveles de absorbancia para determinar el contenido de pigmentos fotosintéticos. Durante las 04:00 a 18:00 h se monitoreó la conductancia estomática (gs) respecto a variables ambientales (humedad relativa, temperatura del aire, radiación y dé cit de presión de vapor (DPV). Se hizo un análisis de varianza utilizando la prueba de Tukey, se realizaron correlaciones y regresiones entre gs y variables ambientales. Los contenidos de cloro la a, b, total y carotenoides entre ecotipos fueron diferentes (P<0,0001), el ecotipo UA-31 presentó los mayores valores, contrastando con el ecotipo UA-37. A nivel de gs, la interacción ecotipo*hora presentaron diferencias signi cativas (P<0,0001). En promedio los ecotipos que presentaron mayores valores de gs fueron UA-67 y UA-039, esta variable presentó correlación negativa con temperatura (-0,84; P<0,0001), radiación (-0,91; P<0,0001) y DPV (-0,94; P<0,0001) contrario a lo presentado para humedad (0,90; P<0,0001). Los resultados sugieren que los ecotipos UA-039 y UA-31 fueron los más adecuados en cuanto al intercambio gaseoso y contenido de pigmentos fotosintéticos.