Are moorland invertebrates resilient to fire? PDF
Preview Are moorland invertebrates resilient to fire?
Are moorland invertebrates resilient to fire? Plate 1 (previous page): Tabanidae on buttongrass flower-head Are moorland invertebrates resilient to fire? by Michael Matthew Maria Driessen Bachelor of Science (Hons) Master of Science Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy University of Tasmania June 2016 Declaration This thesis contains no material which has been accepted for a degree or diploma by the University or any other institution, except by way of background information and duly acknowledged in this thesis, and to the best of my knowledge and belief no material previously published or written by another person, except where due acknowledgement is made in the text of this thesis, nor does the thesis contain any material that infringes copyright. Michael Driessen Statement regarding published work contained in the thesis and of authority of access. The publishers of the paper comprising Chapter 2 hold the copyright for that content, and access to the material should be sought from the respective journals. The remaining non published content of this thesis may be made available for loan and limited copying in accordance with the Copyright Act 1968. Michael Driessen Statement of co-authorship The following people contributed to the publication of work undertaken as part of this thesis: Michael Driessen (MD), School of Land Food, University of Tasmania James Kirkpatrick (JK), School of Land Food, University of Tasmania Peter McQuillan (PM), School of Land Food, University of Tasmania Shifts in composition of monthly invertebrate assemblages in moorland differed between lowland and montane locations but not fire-ages Environmental Entomology 42: 58-73. Located in chapter 2 MD conceived and designed the study. MD conducted the field and laboratory work with contributions from people mentioned in the acknowledgements. MD analysed the data in consultation with JK and PM, and wrote the manuscript. JK edited the manuscript. We the undersigned agree with the above stated “proportion of work undertaken” for the above published peer-reviewed manuscript contributing to this thesis: James Kirkpatrick Alistair Gracie Supervisor A/Head of School School of Land and Food School of Land and Food University of Tasmania University of Tasmania 5 June 2016 6 June 2016 Abstract Fire is an integral part of ecosystem management in many biomes around the world. This is particularly the case for the fire-prone and highly flammable moorlands of the Tasmanian Wilderness World Heritage Area. To maintain ecosystem processes and to conserve biodiversity, fire management in protected areas needs to be based on an understanding of the consequences of fire regimes. Invertebrates are a very diverse group of organisms that are critical for sustaining ecosystem processes. However, world-wide, there are few well-designed, long-term studies involving a broad range of taxa that have investigated the resilience of invertebrates to fire, and none in Tasmanian moorlands. I investigated the resilience of ground- and foliage-active invertebrate assemblages to low-intensity fire in low and moderate productivity moorlands, and identified predictors of assemblage change and its return to the pre-fire state. I used two complementary research designs: (1) a before-after-control impact design that aimed to minimise spatial variation, and (2) a replicated space-for-time design that provided insight into longer-term invertebrate responses to fire, and had a broad spatial scale. Species-level resolution for a broad range of invertebrate groups was used. I found that ground- and foliage-active invertebrate assemblages in moorland were resilient to single fires and to a fire regime with a mean fire interval of at least 24 years in low productivity moorlands and 37 years in moderate productivity moorlands. Low-intensity fire in moorland altered the composition of invertebrate assemblages because many taxa had low abundance in early successional stages. However, contrary to expectations, I found that some ground-active taxa had higher abundance in early successional stages. Very few taxa were absent from early (<3 years) successional stages and none were absent from later successional stages. Return to the pre-fire state was highly deterministic and mediated by the return of vegetation and other habitat elements to the pre-fire state. Vegetation density and several other environmental variables were better predictors of assemblage response to fire than time-since-fire. Invertebrate assemblages in low productivity i moorlands generally took twice as long to return to the pre-fire state than assemblages on moderate productivity soils. Trophic status, position in the environment, association with decaying vegetation and development type were species traits that best predicted invertebrate composition response to fire, but only explained 19% of the variation. These species traits require further investigation before they can be considered useful and other traits need to be considered. Higher level taxa were found to be effective surrogates for species-level identification in representing patterns in invertebrate assemblage structure and detecting the effects of fire. To improve fire management for fauna, further research on functional traits and the influence of spatial and temporal arrangement of fire regimes on biota is required. Plate 2 Cup ringtail damselfly Austrolestes psyche (Hagen in Selys) (Odonata: Lestidae) ii
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