Environment heterogeneity and seasonal effects in ground-dwelling ant (Hymenoptera: Formicidae) assemblages in the Parque Estadual do Rio Doce, MG, Brazil

Abstract

. Para ambas as estações, a mata alta apresentou a menor média de riqueza e abundância de formigas, fato que corrobora a predição de que ecótones podem apresentar maior diversidade alfa. A riqueza e abundância média de formigas não foram diferentes entre mata baixa e orla de lagoa, ou entre esses habitats e borda de floresta. Os resultados obtidos sugerem que a perda de espécies devido ao desflorestamento provavelmente é maior do que se pensava anteriormente, e que para se compreender os padrões de diversidade e distribuição de espécies de insetos em ecossistemas tropicais deve-se levar em conta um desenho amostral mais compreensivo.PALAVRAS-CHAVE: Diversidade alfa, diversidade beta, efeito de borda, grupo funcional, Mata Atlântica ABSTRACT -This work aimed to explore the response of ant species assemblage to contrasting types of forests in a semideciduous stationary rainforest, in the Parque Estadual do Rio Doce, South Eastern Brazil. We compared antropomorphic borders of this park and natural ecotones, such as lake margins continuous with forests, as well as preserved forests far from ecotones. We investigated whether grounddwelling ant species richness, abundance and composition would change according to forest types and ecotones. We expected greater species richness in interior tall forest, compared with low forest or ecotone habitats. In addition, we tested the effect of climate seasonality on ant assemblages found in each studied vegetation type. Each forest type was surveyed based on a minimum transect sampling unit of 150 m long summing up 30 pit-falls per unit. Two sampling events, one in dry season(September of 2001) and another in the rainy season (January of 2002) were performed. For both seasons, tall forest presented greater total number of ant species, however lower mean ant species and abundance per trap than other forest types, thus corroborating the prediction that ecotones might present high alpha diversity. Mean species richness and abundance did not differ between interior low forest and lake edge, or between these habitats and reserve border. In general, species composition were not clearly defined by forest types. Results here found suggest that species loss or community dominance by generalist species, eventually due to deforestation, is probably a much greater problem than previously thought. However, to understand patterns of insect species diversity and distribution in tropical ecosystem should be taken in account much more comprehensive, spatially explicit sampling designs.

When is the best period to sample ants in tropical areas impacted by mining and in rehabilitation process?

“…Thus, during the dry sampling period, the combination of resource limitation leading to intraspecific competition and reduced activity of specialist arboreal species in control areas probably contributed to similarity among areas in this sampling period. This confirms the abiotic factor effect on the ant distribution due to the intolerance of specialist ant species to changes in conditions and resources (Coelho and Ribeiro 2006).…”

Seasonal Analysis of Taxonomic and Functional Diversity of Poneromorph Ant Assemblages in the Amazon Forest

“…However, even with such variation in rainfall, the fauna of poneromorph ants did not vary between the rainy and dry seasons. Other authors observed variation in species richness or diversity between the dry and rainy seasons in the Atlantic Forest (Coelho & Ribeiro, 2006;Vargas et al, 2007), but the results can be explained by higher average temperature in the rainy season. A seasonal increase in resource availability can be connected to an increase in taxonomic and functional diversity, as it allows ant populations to grow and, consequently, the number of foraging worker ants also grows (Silva et al, 2014).…”

Spatio-temporal patterns of ground-dwelling ant assemblages in a lowland rainforest in southeast Cameroon

“…It is important to understand both spatial and temporal factors shaping ant activity patterns in order to understand many population and ecosystem-level processes (Kaspari and Weiser, 2000). Physical complexity and habitat heterogeneity both influence the availability of ant nesting and foraging sites and consequently spatial patterns of ground-dwelling and -foraging ants (Anderson, 2000;Kaspari and Weiser, 2000;Theunis et al, 2005;Coelho and Ribeiro, 2006;Deblauwe and Dekoninck, 2007). On the other hand, seasonality (temperature and rainfall) influences the ant assemblage on a temporal scale (Panama: Levings, 1983;Kaspari and Weiser, 2000;Hahn and Wheeler, 2002;Brazil: Coelho and Ribeiro, 2006;India: Basu, 1997).…”

“…On the other hand, seasonality (temperature and rainfall) influences the ant assemblage on a temporal scale (Panama: Levings, 1983;Kaspari and Weiser, 2000;Hahn and Wheeler, 2002;Brazil: Coelho and Ribeiro, 2006;India: Basu, 1997). The seasonal patterns of tropical rainforest ants have been poorly studied (Levings, 1983;Coelho and Ribeiro, 2006), especially in Africa.…”