Diversidade da mesofauna edáfica em solos com diferentes densidades e distancia da palmeira babaçu (Attalea speciosa Mart.) em Pirapemas, periferia leste da Amazônia

Abstract

Soil organisms are sensitive indicators of soil quality, mainly because they undergo changes with land management and because they reveal the occurrence of environmental disturbances. The mesofauna (organisms between 0.2 and 2 mm) is important in the decomposition of organic matter and nutrient cycling. This research strives to evaluate the impacts of different degrees of babassu palm densityon the soil mesofauna. The field experiment is located in Pirapemas county, Maranhão state, esatern periphery of Amazonia, and consists of three blocks with four diferente babassu palm densities of babassu palms densities (625 palms / ha-1 - 25%, 1250 palms ha-1 - 50%, 1875 palms ha-1 - 75%, 2500 palm-ha-1 - 100% of original palm density). We collected 48 samples (composites of three sub samples) in February 2015 (rainy season) and November 2015 (dry season), extracted soil mesofauna Berlese funnels, and subsequently separated mesofauna orders using a stereoscopic microscope. Mean rainy season total arthropode density varied between 350 to 400 individuals cm³ in 25%, 50% and 75% babassu densities, as oposed to 250 indiduals/cm³ in 100% babassu density and close to the palm trunks. Contrary to this, the density of mesofauna in the dry season was 67 times higher, and without significant differences between the densities/distances of the babassu. The suborder Auchenorrhycha (Hemiptera) dominated the total mesofauna in the rainy and dry season, both with greater abundance (average of 54.1%) and frequency near 100%. The Acari class was also present in the two analyzed periods, the percentage of mites remained around 4% followed by Collembas, which were absent during the dry season. The time of year of collection of the mesofauna of the soil influences its abundance, being favored in the rainy period