Observations on Earthworm Communities and Soils in Various Natural and Man-Affected Ecosystems

Earthworms are important members of the soil fauna since they regulate fundamental soil functions such as organic matter breakdown, fertility, structure and water balance. However, so far, their community assemblages have been poorly investigated in Greece. In this context, the earthworm communities of forty five sites in Greece, belonging to three types of ecosystems—terrestrial water bodies, undisturbed (natural) sites and cultivated (agricultural and urban) fields—were investigated using the combined method of digging and hand sorting followed by the application of a 0.4% formaldehyde solution. Specific soil parameters and various environmental characteristics were examined as potential factors affecting the abundance and species richness. The results showed no statistically significant difference between ecosystem densities. The species number was significantly different between ecosystems, with the cultivated fields exhibiting richer communities, with a mean of 5.3 ± 0.6 species per site compared to the natural areas with 2.4 ± 0.5 species per site, while the water bodies showed intermediate numbers (3.6 ± 0.5 species per site). Finally, earthworm densities were positively correlated with species number and percentage vegetation cover and negatively with clay. These results may contribute to understanding how different land uses affect earthworm communities.

Semideciduous seasonal forest opiliofauna (Arachnida, Opiliones), State of Paraná, Brazil

Harvestmen are arachnids that play an important role in organic matter breakdown. However, there are many ecosystems in Brazil, including Conservation Units, which lack information about these organisms or are sub-sampled. Even in areas of Atlantic forest, a biome that hosts the greatest diversity and endemic rates of these arthropods in the world. In this perspective, the purpose of this study was to survey the harvestmen fauna in areas of Semideciduous Seasonal Forest in the Ilha Grande National Park, Paraná, southern Brazil, from February to November 2019, totaling 15 days and 60 hours, on six islands in the Paraná River. A total of 170 specimens was collected, distributed in five genera, comprising two species and three morphotypes. The low species richness may reflect the isolation of populations imposed by the island effect, however the study expanded the geographic distribution of Parapachyloides uncinatus and Discocyrtus invalidus, for which until then there was no record of occurrence in the Paraná State.

From Litterfall to Breakdown in Streams: A Review

This paper is a review of recent (≤10 years) information on litterfall, standing stock of benthic organic matter, breakdown rates, and fungal colonization of organic matter in streams. In some cases, recent research reinforces the findings of classic reference papers. In other cases, the additional knowledge provided by recent research introduces a higher variation in the processes analyzed. In many aspects, especially those concerning stream organic matter, the review is biased towards the temperate North American streams, reflecting the fact that most research was carried out there. However, during the 1990s European studies increased enormously, especially those related with instream processes, such as leaf litter decomposition. The first part of this review analyzes the origin of allochthonous organic matter to streams (litterfall, retention, and storage), and it provides data on the amounts estimated in different streams and on the methodology used in the studies. The second part analyzes the fate of detritus in streams: mechanisms of leaf breakdown, relative importance of fungi and bacteria, factors affecting the activity of microbial decomposers, and chemical changes of leaf litter during decomposition. A list of breakdown rates of several different leaf species is given, together with the methodology used, and the main characteristics of the incubation streams.