Date of Award

1997

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Science, Technology and Engineering

First Advisor

Adrianne Kinnear

Abstract

The northern jarrah forest relies on efficient nutrient cycling for its growth and long term sustainability. The decomposition of organic matter and the recycling of nutrients in such ecosystems are facilitated through the interaction of microflora with a myriad of invertebrates. The recolonisation of invertebrate fauna to rehabilitated bauxite mines is thus of critical importance to the long-term success of rehabilitation. This study investigated the soil and litter mite fauna, important components of the invertebrate community well known for their numerical dominance and high biodiversity. A spring sampling of the mite fauna was undertaken, employing standard soil and litter sampling techniques and temperature controlled heat extraction. The effect of time since rehabilitation was investigated in 2, 5, 10 and 20 year old sites, chosen to represent successional-like stages in rehabilitation. A neighbouring forest control site was selected for comparison. Selected environmental variables known to influence mite abundance and diversity were also measured. The abundance and species richness of the mite community in soil and litter increased with age of the rehabilitated site. The litter habitat of the 10 and 20 year old site displayed similar abundances to those of the forest control site. At the Ordinal level, the Astigmata and Prostigmata were most abundant in the younger sites where vegetation was sparse and canopy cover was minimal. The Cryptostigmata were the numerically dominant Order once the litter and canopy cover developed, in total accounting for 70% of all mites sampled. Distinct species-suites were identified for both the soil and litter, which could be related to the age sequence in litter development of rehabilitated sites. This included a 'generalist' suite that displayed insensitivity to environmental conditions across all sites. An intermediate suite of species that required successional-Iike development of site characteristics, may indicate level of habitat development. A site specific group of species that were restricted to the undisturbed forest site, represent species sensitive to habitat conditions. The study has implications regarding level of taxonomic detail applied, when assessing the success of invertebrate recolonisation in rehabilitated sites. Although mite distribution at the Ordinal level was similar, analysis at the Family and species level revealed clear differences between the rehabilitated sites and the forest control.

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