Padrões de abundância e diversidade taxonômica de entomobryomorpha (Collembola: Hexapoda) em um gradiente vegetacional da Mata Atlântica

Abstract

Springtails are microarthropods considered to be a basal group of Hexapoda, and are one of the most populous terrestrial taxa on the planet. They are organisms closely related to the edaphic environments and feed on organic matter, forming part of the soil's nutrient cycling chain. Because they are very sensitive to environmental changes, they are also considered efficient bioindicators of environmental quality. The Northeast region of Brazil is home to urban remnants of Atlantic Forest with a high potential for edaphic diversity, but which are subject to increasing anthropogenic pressures, and recognizing the diversity and ecological dynamics they harbor is fundamental for their management and maintenance. This study sampled the Entomobryomorpha collembolan fauna of the Parque Estadual Dunas do Natal along a vegetation gradient (High, Middle and Low Forest) and in two seasonal regimes (rainy and dry), with the aim of analyzing species richness and diversity between the seasons studied, as well as their microhabitat preferences. In addition to collecting the specimens, environmental parameters such as phytophysiognomy, air temperature and relative humidity, soil pH, leaf height and canopy cover were measured. After collection, the specimens were sorted in the laboratory under a stereomicroscope, morphotyped and mounted on slides for taxonomic identification. The analyses included: (1) PERMANOVA to test the effects of phytophysiognomies and seasonality, (2) binomial (abundance) and double Poisson negative distribution models (diversity α), (3) Whittaker's index (diversity β), and (4) IndVal for indicator species. A total of 2.335 specimens of Entomobryomorpha were collected, distributed in two families, six subfamilies, nine genera and 19 species/morphospecies in the two collection periods, with the Entomobryidae family predominating. The Lepidocyrtinae subfamily stood out for its abundance in the rainy periods, especially Lepidocyrtus sp. 1, while Lepidocyrtinus pseudoannulata showed greater tolerance to drier conditions. Diversity α and species richness were significantly higher in the rainy season, confirming the influence of climatic factors such as humidity and temperature on the ecology of these organisms. The Upper Forest showed greater diversity and abundance of species during the dry period, reinforcing the role of the denser canopy and greater moisture retention as factors favoring the maintenance of assemblages. The Lower Forest, on the other hand, with less stratified vegetation and greater exposure to the sun, recorded less diversity, especially during the dry season. The results highlight the influence of environmental factors, such as moisture availability and structural heterogeneity, on the seasonal dynamics and distribution of springtails. The predominance of indicator species, such as Rhynchocyrtus sp. 1 and L. pseudoannulata, in certain phytophysiognomies reinforces the relevance of these areas for conservation and sustainable management. This study not only validates the hypothesis that phytophysiognomies and seasonality shape the ecology of Entomobryomorpha, but also expands knowledge about their distribution in the northeastern Atlantic Forest, highlighting: (1) The role of stable microhabitats (e.g., High Forest) as seasonal refuges; (2) The relevance of generalist species (e.g., Rhynchocyrtus sp. 1) for assessing anthropogenic impacts; (3) The need for regional approaches in conservation strategies, given the variability of responses between biomes.