Efecto de los cortafuegos sobre el ensamble de hormigas (Hymenoptera, Formicidae) en una región semiárida, Argentina

Abstract

ABSTRACT. Effects of firebreaks on ant density (Hymenoptera, Formicidae) in a semiarid region, Argentina. In arid and semiarid regions, the presence of roads or firebreaks can affect microclimatic variables that influence the abundance of soil nesting ants. We studied ant nest density in environments with different soil types (loose and compacted soil), and vegetation cover (shrubland, grassland and bare soil) south of Caldenal, La Pampa, Argentina. We selected three areas with woody cover (shrubland), herbaceous cover (grass), and 80% of bare soil (firebreaks) within a 12 ha study area where large herbivores were excluded. We recorded soil surface temperature, humidity, pH and degree of soil compaction in each area. The density of nests was assessed by randomly placing three transects (80 m x 5 m) in each experimental unit. Soil temperature was higher in firebreaks and soil compaction was higher in the shrubland and the grassland. No differences in ant assemblage were found regarding nest density among environments. However, Acromyrmex striatus (Roger, 1863) was found mostly in firebreaks where loose soil with greater porosity allows more gas exchange and water infiltration. Our findings revealed that the construction of firebreaks favors the establishment of leaf-cutting ants, which due to their competitive advantage, could negatively affect ant and plant composition in the community. KEYWORDS.Nesting, disturb, soil. RESUMEN.En las regiones áridas y semiáridas los bordes de los caminos o cortafuegos pueden afectar variables micro-climáticas las cuales, a su vez, alteran la abundancia de las hormigas que nidifican en el suelo. Se estudió la densidad de nidos en ambientes con diferentes características edáficas (suelos sueltos y compactados), y de cobertura de vegetación (monte cerrado, pastizal y suelo desnudo). El área de estudio se encuentra en el sur del Caldenal (sudeste de La Pampa), tiene 12 ha clausuradas al pastoreo con seis unidades experimentales en cada una de las cuales se seleccionaron tres sitios con cobertura leñosa (monte), con cobertura herbácea (pastizal) y con el 80% de suelo desnudo (cortafuegos). En cada sitio se registraron la temperatura superficial, y la humedad, el pH, y el grado de compactación del suelo. La densidad de nidos se evaluó colocando tres transectas (80 m x 5 m) al azar por cada unidad experimental. La temperatura del suelo fue mayor en los cortafuegos y la compactación del suelo fue mayor en los ambientes de monte y pastizal. El ensamble de hormigas estudiado no mostró diferencias (p>0,05) de nidificación entre los ambientes. En cambio, Acromyrmex striatus (Roger, 1863) se encontró principalmente en los cortafuegos donde los suelos sueltos con mayor porosidad permiten mayor intercambio gaseoso e infiltración de agua. La construcción de cortafuegos favorece el establecimiento de especies cortadoras de hojas que por ventajas competitivas podrían afectar negativamente la composición de la comunidad de hormigas y las comunidades vegetales.

Forgotten role of fires in Central European forests: critical importance of early post-fire successional stages for bees and wasps (Hymenoptera: Aculeata)

“…Most of the available data on the impact of wildfire have been collected in the subtropics. Forest fires in the subtropics have been studied in relationship to communities of Hymenoptera (Potts et al 2003;Ratchford et al 2005;Tizón et al 2010;Cruz-Sánchez et al 2011;Mateos et al 2011;Arnan et al 2013;Lázaro-González et al 2013), Coleoptera and Lepidoptera (Elia et al 2012).…”

Myrmecological diversity (Hymenoptera: Formicidae) in Tamaulipas, México

“…This result is directly related to modifications to the microclimate, which have mainly occurred due to the change in land use and loss of vegetation cover due to human settlements and agricultural and livestock activities (Halfter, 2011). When the physical environment is completely modified, the soil temperature increases, and humidity is lost; these changes lead to an increase in certain species, with numerical abundance in the colonies because they have high physiological tolerance to extreme and wideranging climates that are widespread (Rojas-Fernández, 2001;Tizón et al, 2010).…”

Fire effects on the ant community in areas of native and exotic vegetation

“…The disturbance indicator group could be considered a good management tool if the biology of the species that composes it was widely known. In this work, the group was made by grouping species or genera whose response to disturbances is documented (Folgarait, 1998;Tizón et al, 2010;Fuster, 2014;Villalba et al, 2014;Arcusa, 2016). In this way, it was possible to monitor the increase of these species and estimate the time of resilience.…”