Soil Biodiversity in Urban Forests as a Consequence of Litterfall Management: Implications for São Paulo’s Ecosystem Services

The growth of urban centers, along with the fragmentation of natural habitats, can interfere with the distribution pattern of species and their abundance, thus compromising the conservation of urban biodiversity. Principal players in this biodiversity are arthropods that help to decompose litterfall, favoring the recycling of nutrients and, hence, are an important part in sustaining the forest fragments that remain in urban areas. Therefore, it is important to study arthropod biodiversity in green urban areas, especially those areas where litterfall management is an important part of maintaining biodiversity. Accordingly, this study evaluated arthropod diversity associated with litterfall in three urban forests with different size and litterfall management practices, including Água Branca Park (ABP) and Tietê Ecological Park (TEP)—Núcleo Engenheiro Goulart in São Paulo City and Chico Mendes Park (CMP) in Osasco City, all belonging to the Metropolitan Region of São Paulo (MRSP), Brazil. Four litterfall harvests were carried out in each park between April and August of 2015 with twelve samples collected with a wood mold (30-cmx30-cm) at randomly points on the forest floor. The collected material was then screened in the laboratory and the arthropods were visually separated and preserved in alcohol 70%. Arthropods were classified by the order to which they belonged. Litterfall was dried in a forced air oven at 65 °C for seven days. Dried litterfall was then separated into leaves, branches, reproductive parts and miscellaneous fragments and weighed. Arthropod diversity was measured by Shannon, Margalef and Pielou indexes and non-metric multidimensional scaling analysis (NMDS) using the Manhattan distance index. Litterfall weight was compared by one-way ANOVA. The orders Hymenoptera, Collembola and Isopoda were dominant in CMP, ABP and TEP, respectively but multiple rare orders had a presence in all parks, albeit at different abundance. NMDS showed abundance similarity among the parks; however, TEP showed greater richness, Shannon diversity and evenness. The fractions of leaf litterfall and reproductive parts were different between the CMP and TEP. Overall, our results confirm that neither litterfall management, nor park size, is a final determinant of arthropod distribution, even though the abundance of dominant species was shown to differ in each park.