Date of Award

2004

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Computing, Health and Science

First Advisor

Dr Melinda Hillery

Abstract

A study conducted in the Ridges State Forest, Yanchep was designed to investigate the relationship between plant species richness, vegetation association and ground dwelling invertebrate species richness. Four plant communities were sampled at two scales of measurement. Two treatments were located in woodland and two in heath. Within each vegetation association, plant communities that were representative of both high and low species richness were selected. Three invertebrate orders, Araneae, Coleoptera and Araneae were sorted to morphospecies level. Ordinal richness was also investigated. Two-way ANOVAs indicated that there was no relationship between plant species richness, vegetation association· or the interaction between these factors for ordinal richness, Araneae or Coleoptera species richness. However, a significant relationship between Hemiptera and plant species richness was found to exist when analysed at a fine scale of 1m2. Spearman's rank order correlations also demonstrated that there was an association between Hemiptera richness and plant species richness. Treatments were also surveyed for life form species richness. The study revealed that shrub richness was a better indicator of overall plant species richness then herbs and grasses. The study also investigated the role that a number of environmental attributes play in determining ground dwelling ·invertebrate species richness. Spearman's rank order correlations indicated highly significant results for soil and litter moisture. Temperature was also a major determining factor. Ground dwelling invertebrate species richness does not appear to be related to litter cover and depth. The project has, however, demonstrated that although there is no direct association between ground dwelling invertebrate species richness and certain other environmental parameters measured during the study there are a number of parameters that are cross correlated with each. There is obviously a complex interaction and on close inspection some of these results suggest that ground dwelling invertebrate species richness· may be associated with vegetation structure. It is recommended that future studies investigate this association in more detail with particular attention being paid to the relation that exists between Hemiptera and plant species richness.

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