Impacts of elevated CO2 and ecosystem restoration on belowground biodiversity in Cumberland Plain Woodlands

Abstract

Land-use intensification and climate change are among the most pressing challenges to which terrestrial ecosystems must adapt. Both of these factors reduce above and belowground biodiversity, and influence critical ecosystem functioning essential for resilience and stability. Assessing how biodiversity is affected can help re-focus strategies for managing ecosystems such as the critically endangered Cumberland Plain Woodlands (CPW). In this project, my main aims were to i) quantify how belowground communities of oribatid mites respond to elevated atmospheric carbon dioxide concentration using the Eucalyptus Free Air CO2 Enrichment (EucFACE) facility in Richmond, NSW and ii) assess whether active and/or passive restoration of CPW can be indicated by changes in belowground biodiversity and ecosystem functioning. I focussed on oribatid mites because of their potential as bioindicators (high species diversity, sensitivity to disturbance) and their importance in ecosystem functioning. I further tested the robustness of Next Generation Sequencing (NGS) minibarcodes as a method for characterising oribatid mite community composition alongside morphological approaches. Soil faunal communities showed no clear response to e[CO2], instead oribatid mite densities were found to be higher in areas with more soil moisture, greater P bioavailability and litter fall mass. Greater total mite densities were correlated with higher dicotyledon and woody litter cover, although the effect size was minimal. Oribatid mites were also more diverse in areas with greater leaf and twig fall mass. The NGS data identified almost three times the number of species than the morphological approach, and corroborated the lack of e[CO2] effect on oribatid community structure. There was a shift in oribatid mite communities between the restoration categories (degraded, short and long-term restoration), which was significant using the sequencing approach. Moreover, short-term actively restored and long-term passively restored sites had higher mite abundances than degraded sites, but the effect was not significant due to high site variability. Total mite abundances were positively correlated with soil moisture, native species aboveground coverage, total plant species richness and calcium bioavailability. The difficulties in determining abundance and diversity from the NGS data is compensated by the similarities that were evident between the community composition correlations in both studies based on the morphological and sequencing approaches. This further validates the use of metabarcoding as a rapid assessment of community structure in field trials and eco-monitoring assessments.

Date of Award	2017
Original language	English