Ectatomma ruidum (Roger) como indicadora de diversidad de hormigas cazadoras (Hymenoptera: Formicidae) y relación con estructura vegetal en parches de bosque seco del Caribe colombiano

The community of hunting ants in three patches of tropical dry forest in a coastal strip of Atlántico department was studied in habitats of interior forest and its anthropogenic matrix. The forests chosen were located at the Piojó, Tubará and Barranquilla municipalities. In each habitat a 150 m long transect was established with 15 sampling stations, using pitfall traps, tuna baits, Winkler bags, and manual capture. The most abundant and widely distributed species were Ectatomma ruidum and Odontomachus bauri. A negative high correlation was found between the capture percentage of E. ruidum and overall ants’ richness and diversity; this relationship can be explained given the species capacity and adaptability to find and exploit different kinds of resources in disturbed areas. A different situation occurs with O. bauri, which had a positive correlation with richness and diversity. E. ruidum is proposed in order to monitoring the conservation of these Tropical Dry Forest. In addition, a positive and significant relationship was detected between the richness and abundance of hunting ants and the percentage of vegetation cover and vegetation structure, which validates the importance of a heterogeneous habitat to promote biodiversitySe estudió la comunidad de hormigas cazadoras presente en tres remanentes de bosque seco en la faja costera del departamento del Atlántico, en hábitats de interior de bosque y matriz antrópica. Se escogieron formaciones de bosque localizadas en los municipios de Piojó, Tubará y Barranquilla; se delimitó un transecto de 150 m con 15 estaciones por hábitat, empleando trampas Pitfall, cebos de atún, Winkler y captura manual. Las especies más abundantes y con más amplia distribución espacio-temporal fueron Ectatomma ruidum y Odontomachus bauri. Se encontró una negativa y alta correlación entre el porcentaje de captura de Ectatomma ruidum por hábitats con la riqueza y diversidad de hormigas cazadoras, esta relación puede ser explicada en parte a su adaptabilidad y capacidad de explotar diferentes tipos de recursos en áreas perturbadas, una situación diferente se presenta con la especie O. bauri la cual se correlacionó positivamente con la riqueza y diversidad de ponerinas. E. ruidum puede ser una herramienta para el monitoreo del estado de conservación de bosques con formaciones vegetales similares. Adicionalmente, se estableció una relación positiva y altamente significativa entre la riqueza y la abundancia de ponerinas con el porcentaje de cobertura vegetaly la estructura horizontal y vertical de la vegetación, validando la importancia de un hábitat heterogéneo para promover biodiversidad.

Density and Spatial Distribution of Nests of Ectatomma ruidum and Pheidole fallax (Hymenoptera: Formicidae), as Response to the Recovery of Coal Mine Areas

In this study, the spatial pattern of two ant species of different feeding habits, Ectatomma ruidum and Pheidole fallax (Hymenoptera: Formicidae) was assessed in rehabilitated areas of “Cerrejón” coal mine (Colombia). We tested whether there is a relationship between spatial distribution pattern, age rehabilitation and temporal changes. Three sites with different ages of rehabilitation (1, 9 and 20 years) and a secondary forest were sampled during dry and rainy seasons. Within four plots (6 x 40m) per site, we located, counted and estimated the minimum distance among nests. Our results indicated that the number of active nests varied according to sites and sampling season, E. ruidum had the highest density at both seasons, 166 nests ha-1 (forest) and 1333 nests ha-1 (9-y site). The nest density for P. fallax ranged between 125 and 625 nests ha-1 in the forest and the 20-y site, respectively, and at 1-year site ants were absent. Our results indicated that the nest distribution strongly depended on the scale of observation. A uniform distribution pattern was also found, mainly at the local scale (plot level), while an aggregated and random distribution was found at the site level. We conclude that ant density responded mostly to seasonal changes (dry versus wet season)

Assessment of soil fauna footprints at a rehabilitated coal mine using micromorphology and near infrared spectroscopy (NIRS)

Soil micromorphology in thin section and near infrared reflectance spectroscopy (NIRS) are useful techniques for assessing the participation of soil macrofauna in the formation of aggregates and soil structure. The purpose of this study was to use micromorphological analysis and NIRS techniques to assess the role of soil fauna in the recovery of soil aggregates and in the modification of soil microstructure in a chronosequence of rehabilitated areas at Cerrejon coal mine (La Guajira, Colombia). 64 soil samples were taken from rehabilitated areas (from 1 to 20 years ago) and from natural dry tropical forests Soil macroaggregates were subdivided into three categories: biogenic (BA), physical (PA), and non-aggregated soil (NAS). 32 samples were used for NIRS analysis, while ten thin sections of resin-impregnated soil blocks were micromorphologically analyzed. Principal component analysis of NIRS spectra showed a clear separation between BA, PA, and NAS. Likewise, an increase in BA was observed in the intermediate and advanced stages of rehabilitation. Respect to the micromorphological features, there was a clear change from a matrix of silt-sized quartz, unaccomodated peds, and unstructured materials with non-existent biogenic activity at the 2-year site to the formation of consolidated aggregates, more homogenized soil and increased biological activity at the 20-year site. Soil biological activity, principally the footprint of macrofauna, was recognized using the two techniques as well as at both the micro- and macro-morphology scales. These results reveal how the rehabilitation program being undertaken at Cerrejón mine is promoting the soil macrofauna population and associated bioturbation.This study was supported by a COLCIENCIAS grant, Colombia (Code: 1116-569-34827) and “Vicerrectoría de Investigaciones Extensión y Proyección Social” from Universidad del Atlántico

Cambios en la distribución de nidos y abundancia de la hormiga ectatomma ruidum (Roger 1861) en dos zonas de Colombia

Ectatomma ruidum (Formicidae: Ectatomminae) es una hormiga cazadora ampliamente distribuida en Colombia. Esta especie es de enorme importancia funcional en ecosistemas naturales y perturbados. Se han encontrado removiendo semillas y depredando tanto insectos como garrapatas en potreros. Algunos autores sugieren que esta especie es propia de potreros y otros, que lo es de bosques. En este estudio se examinó la distribución de nidos y abundancia de E. ruidum en bosques y áreas de rehabilitación en el complejo minero de carbón del Cerrejón, en La Guajira, norte de Colombia y se contrastó con lo hallado en otro estudio en el Valle y el Cauca, región del suroccidente, separado cerca de 1000 Km. Al norte, se encontró una alta abundancia de E. ruidum en áreas con mayor tiempo de rehabilitación ecológica y mayor cobertura arbórea; además éstos presentaron una distribución espacial uniforme. Este resultado fue contrario respecto a otro estudio realizado, casi simultáneamente, en los departamentos de Valle y Cauca, en donde E. ruidum presentó baja abundancia en hábitats arbóreos y una distribución con tendencia a ser agregada. En esta área, cuyo clima es más templado, la abundancia de la hormiga en potreros sin árboles fue alta y su distribución aleatoria. Este estudio corroboró que E. ruidum es una especie común en bosques del Caribe colombiano, que la zona geográfica, las condiciones ambientales y, posiblemente, otros factores bióticos, pueden influir en la preferencia de sitios de nidificación y que la plasticidad de esta hormiga posibilita su extensa distribución

Comunidades de hormigas y movimiento de semillas en cinco estados de rehabilitación ecológica en el complejo carbonífero del Cerrejón, Guajira, Colombia

Resume

Ectatomma ruidum (Roger) como indicadora de diversidad de hormigas cazadoras (Hymenoptera Formicidae): y relación con estructura vegetal en parches de bosque seco del Caribe colombiano

Se estudió la comunidad de hormigas cazadoras presente en tres remanentes de bosque seco en la faja costera del departamento del Atlántico, en hábitats de interior de bosque y matriz antrópica. Se escogieron formaciones de bosque localizadas en los municipios de Piojó, Tubará y Barranquilla; se delimitó un transecto de 150 m con 15 estaciones por hábitat, empleando trampas Pitfall, cebos de atún, Winkler y captura manual. Las especies más abundantes y con más amplia distribución espacio-temporal fueron Ectatomma ruidum y Odontomachus bauri. Se encontró una negativa y alta correlación entre el porcentaje de captura de Ectatomma ruidum por hábitats con la riqueza y diversidad de hormigas cazadoras, esta relación puede ser explicada en parte a su adaptabilidad y capacidad de explotar diferentes tipos de recursos en áreas perturbadas, una situación diferente se presenta con la especie O. bauri la cual se correlacionó positivamente con la riqueza y diversidad de ponerinas. E. ruidum puede ser una herramienta para el monitoreo del estado de conservación de bosques con formaciones vegetales similares. Adicionalmente, se estableció una relación positiva y altamente significativa entre la riqueza y la abundancia de ponerinas con el porcentaje de cobertura vegetaly la estructura horizontal y vertical de la vegetación, validando la importancia de un hábitat heterogéneo para promover biodiversidad.

Cambios en las coberturas de la tierra en el periodo 1984 – 2017 y análisis de la amenaza ante inundaciones en el municipio de Campo de la Cruz, Atlántico- Colombia

The present study had the purpose of evaluating the changes produced in the land cover and land use generated by therainy season floods of the Campo de la Cruz municipality, located south east of the department of Atlántico, Colombia.Therefore, a supervised classification of the territory was carried out, through the use of geographic information systems (GIS),to identify the coverage areas of the municipality between the periods 1984 - 2017; using the CORINE Land Cover method toinvestigate these phenomena. The results highlight that during the period 1987 - 2007 the natural vegetation increasedsignificantly by 993.6 ha; on the other hand, during the period 2007 - 2012 there was greater affectation after the flood thatoccurred in 2010, reducing by 2685.6 ha. Additionally, it is important to highlight the identification of a significant crop increaseof 22.13%, in the study period, in contrast to the loss of pasture land; and in a complementary way, 31 extreme events ofmaximum flows associated with the occurrence of the La Niña phenomenon were found. Consequently, based on the analyzescarried out, it was possible to conclude that the high threat increases progressively in the most susceptible covers such as baresoil, crops and the populated area.El presente estudio tuvo el propósito de evaluar los cambios producidos en las coberturas de la tierra y usos del suelo generados por las inundaciones en época lluviosa del municipio Campo de la Cruz, ubicado al sur oriente del departamento del Atlántico, Colombia. Se realizó una clasificación supervisada del territorio, mediante el uso sistemas de información geográfica (SIG), para identificar las superficies de cobertura del municipio entre los periodos 1984 – 2017; utilizando el método CORINE Land Cover para indagar estos fenómenos. Dentro de los resultados se destaca que durante el periodo 1987 – 2007 la vegetación natural aumentó significativamente en 993,6 ha; por otra parte, durante 2007 – 2012 se produjo mayor afectación después de la inundación ocurrida en 2010, reduciéndose en 2685,6 ha. Además, es importante resaltar la identificación de un incremento importante de los cultivos de 22,13 %, en el periodo de estudio, en contraste con la pérdida de terreno de los pastos. De forma complementaria, se encontraron 31 eventos extremos de máximos caudales asociados con la ocurrencia del fenómeno de La Niña. En consecuencia, con base en los análisis realizados, es posible concluir que la amenaza alta aumenta progresivamente en las coberturas más susceptibles como el suelo desnudo, los cultivos y la zona poblada

Unveiling the age and origin of biogenic aggregates produced by earthworm species with their NIRS fingerprint in a subalpine meadow of Central Pyrenees.

In this study the near-infrared reflectance (NIR) spectra signals (750-2,500 nm) of soil samples was compared with the NIR signals of the biogenic aggregates produced in the lab by three earthworm species, i.e., Aporrectodea rosea (Savigny 1826), Lumbricus friendi Cognetti, 1904 and Prosellodrilus pyrenaicus (Cognetti, 1904) from subalpine meadows in the Central Pyrenees. NIR spectral signatures of biogenic aggregates, root-aggregates, and non-aggregated soil were obtained together with soil carbon (C), nitrogen (N), [Formula: see text] and [Formula: see text] determinations. The concentrations of C, N and C:N ratio in the three types of soil aggregates identified were not statistically significant (ANOVA, p>0.05) although non-macroaggregated soil had slightly higher C concentrations (66.3 g kg-1 dry soil) than biogenic aggregates (earthworm- and root-aggregates, 64.9 and 63.5 g kg-1 dry soil, respectively), while concentrations of [Formula: see text] and [Formula: see text] were highest in the root-attached aggregates (3.3 and 0.31 mg kg dry soil-1). Total earthworm density and biomass in the sampled area was 137.6 ind. m-2, and 55.2 g fresh weight m-2, respectively. The biomass of aggregates attached to roots and non-macroaggregated soil was 122.3 and 134.8 g m-2, respectively, while biomass of free (particulate) organic matter and invertebrate biogenic aggregates was 62.9 and 41.7 g m-2, respectively. Multivariate analysis of NIR spectra signals of field aggregates separated root aggregates with high concentrations of [Formula: see text] and [Formula: see text] (41.5% of explained variance, axis I) from those biogenic aggregates, including root aggregates, with large concentrations of C and high C:N ratio (21.6% of total variability, axis II). Partial Least Square (PLS) regressions were used to compare NIR spectral signals of samples (casts and soil) and develop calibration equations relating these spectral data to those data obtained for chemical variables in the lab. After a derivatization process, the NIR spectra of field aggregates were projected onto the PLS factorial plane of the NIR spectra from the lab incubation. The projection of the NIR spectral signals onto the PLSR models for C, N, [Formula: see text] and [Formula: see text] from casts produced and incubated in the lab allowed us to identify the species and the age of the field biogenic aggregates. Our hypothesis was to test whether field aggregates would match or be in the vicinity of the NIR signals that corresponded to a certain species and the age of the depositions produced in the lab. A NIRS biogenic background noise (BBN) is present in the soil as a result of earthworm activity. This study provides insights on how to analyse the role of these organisms in important ecological processes of soil macro-aggregation and associated organic matter dynamics by means of analyzing the BBN in the soil matrix