Guillermo Martínez Pastur

Neochelanops michaelseni (Pseudoscorpiones: Chernetidae) as a potential bioindicator in managed and unmanaged Nothofagus forests of Tierra del Fuego

Abstract Bioindicators could act as early warning indicators of environmental changes, ecosystem stress or taxonomic diversity. Pseudoscorpions have rarely been used as bioindicators, due to lack of information about their ecology, habitat selection, niche preferences and requirements, especially in southern Nothofagus forests. We studied the distribution and abundance of a pseudoscorpion species, Neochelanops michaelseni (Simon 1902), in different vegetation types (Nothofagus antarctica and N. pumilio forests, grasslands and peatlands) and examined how this species responded to different forest uses (harvesting and silvopastoral management), to explore its utility as a bioindicator. The study was conducted on long-term plots located at two ranches in Tierra del Fuego, using pit-fall traps during one summer. Neochelanops michaelseni abundance was higher in Nothofagus forests than in open ecosystems, which could be attributed to their affinity for litter and coarse woody debris. In N. pumilio forests, the pseudoscorpions were sensitive to harvesting, with similar abundances in harvested forests (aggregated and dispersed retentions) and grasslands. In N. antarctica forests, differences were not detected among unmanaged and silvopastoral managed forests, probably due to higher understory plant growth, and lesser diminishing of litter and debris by thinning than by harvesting. We conclude that the pseudoscorpion, N. michaelseni, can be a good bioindicator for ecosystem conservation and for evaluating recovery rate in the ecological conditions of impacted Nothofagus forests, and that management practice intensities should be regulated to create more suitable habitats for pseudoscorpion diversity conservation.

Habitat-specific vegetation and seasonal drivers of bird community structure and function in southern Patagonian forests

Biodiversity conservation requires knowledge about the factors that influence the structure and function of biotic assemblages. In southern Patagonian Nothofagus forests, birds are the most abundant and diverse vertebrates and are known to have different requirements for nesting, breeding and feeding. Therefore, we chose this group to analyze key drivers of avian community dynamics; for conservation purposes, this information is requisite to manage Nothofagus forest landscapes and their associated biota. We first characterized forest structure and understory floristic composition in open and closed canopy broadleaved forests of mixed deciduous (MD) and mixed deciduous-evergreen (MDE) species on the southern coast of Tierra del Fuego National Park, Argentina. For each habitat, bird assemblages were assessed using point counts, checklists and mistnetting. We used ANOVAs and multivariate methods to analyze changes in bird species richness, density, and biomass as a function of habitat and seasonal characteristics. Forest structure and understory plant communities influenced avian assemblage and density; MDE forests had significantly greater species richness, but lower density than MD. Plus, particular species were associated with specific understory conditions, such as Anairetes parulus and Zonotrichia capensis whose presence was related to shrubs. Additionally, variations observed between seasons apparently were related to differential uses of each habitat type during certain times of year. Finally, it was not possible to define a single forest type with greater conservation value for birds; each had a specific bird species assemblage. Consequently, our results suggest the importance of a full representation of habitats to preserve the region’s bird diversity, which also has been described for forest invertebrates and understory plants.