Dynamics of the Leaf-Litter Arthropod Fauna Following Fire in a Neotropical Woodland Savanna

Abstract

Fire is an important agent of disturbance in tropical savannas, but relatively few studies have analyzed how soil-and-litter dwelling arthropods respond to fire disturbance despite the critical role these organisms play in nutrient cycling and other biogeochemical processes. Following the incursion of a fire into a woodland savanna ecological reserve in Central Brazil, we monitored the dynamics of litter-arthropod populations for nearly two years in one burned and one unburned area of the reserve. We also performed a reciprocal transplant experiment to determine the effects of fire and litter type on the dynamics of litter colonization by arthropods. Overall arthropod abundance, the abundance of individual taxa, the richness of taxonomic groups, and the species richness of individual taxa (Formiciade) were lower in the burned site. However, both the ordinal-level composition of the litter arthropod fauna and the species-level composition of the litter ant fauna were not dramatically different in the burned and unburned sites. There is evidence that seasonality of rainfall interacts with fire, as differences in arthropod abundance and diversity were more pronounced in the dry than in the wet season. For many taxa the differences in abundance between burned and unburned sites were maintained even when controlling for litter availability and quality. In contrast, differences in abundance for Collembola, Formicidae, and Thysanoptera were only detected in the unmanipulated samples, which had a lower amount of litter in the burned than in the unburned site throughout most of our study period. Together these results suggest that arthropod density declines in fire-disturbed areas as a result of direct mortality, diminished resources (i.e., reduced litter cover) and less favorable microclimate (i.e., increased litter desiccation due to reduction in tree cover). Although these effects were transitory, there is evidence that the increasingly prevalent fire return interval of only 1–2 years may jeopardize the long-term conservation of litter arthropod communities.

Short-term effects of fire on Papilionoidea (Lepidoptera) communities: a pilot study in Mediterranean maquis shrubland

“…In the same way, litter arthropods in fire-disturbed areas in Brazilian woodland savanna showed a decrease in their population density following fire (Vasconcelos et al 2009); similar results were obtained in a study of herbivorous, xylophagous and sap-feeding insects in Turkish Pinus brutia forests (Kaynaş & Gürkan 2008). Nevertheless, some insect species benefit from fire (Lundberg 1984;Holliday 1991;Ahnlund & Lindhe 1992), with some reproducing only in burned forest (Evans 1971;Wikars 1992;Dajoz 2000), immigrating there after a fire (Wikars & Schimmel 2001;Wikars 2002).…”

“…These latter species are known as pyrophilous insects. Some insects, including ants, are very resilient to fire, and show no change in species richness following fire in tropical savanna, but they often undergo significant increases in abundance (Parr & Andersen 2008;Vasconcelos et al 2009). In contrast, other species of Hymenoptera (wasps and bees) and Orthoptera (crickets), as well as other arthropods, such as chilopods (centipedes) and terrestrial crustaceans, show no changes in richness and abundance after fire in the same environment (Andersen & Müller 2000;Pryke & Samways 2012).…”

Soil Fauna Communities and Soil Attributes in the Agroforests of Paraty

“…Silva et al (2009) also observed an increase in the abundance of soil fauna from winter to summer in a secondary forest in Ubatuba, state of São Paulo, southeastern Brazil. These authors attributed that pattern to high moisture content in the soil, commonly observed during the summer (rainy season).…”

“…Soil invertebrates are sensitive to changes in plant cover (Barros et al, 2003), management regime (Aquino et al, 2008;Silva et al, 2012a), and microclimate (Vasconcelos et al, 2009). In the conversion of natural ecosystems into productive systems, the structure of the soil fauna is less altered when the structure of the plant cover is kept similar, i.e., when fields are grown in pastures, and silvopastoral and agrosilvicultural systems are grown in areas originally covered with forests (Lima et al, 2010).…”

Are fire, soil fertility and toxicity, water availability, plant functional diversity, and litter decomposition related in a Neotropical savanna?

“…8 2), which supported the theory that water availability is one of the most important slightly decrease in number of individuals following a fire, but they are able to quickly 10 recover and resume litter breakdown (Vasconcelos et al 2009). Thus, the litter-dwelling 11 activities of these arthropods might not have been significantly affected by burnings, which 12 supressed any possible direct effects of fire on decomposition.…”