Metadata record for data from ASAC Project 1180
Global change, biodiversity and conservation in terrestrial and coastal ecosystems on Heard and McDonald Islands: statistical models for monitoring and predicting effects of climate change and local human impacts on invertebrates.
We identified the major environmental variables as altitude and vegetation type. We selected sites for sampling by ... designing a stratified survey that sampled along gradients of altitude and vegetation type. We included 60 sites in the survey design, distributed across Heard Island in five areas or blocks: Round Hill, Scarlet Hill, Cape Lockyer, Long Beach and Mt Drygowski. This level of sampling was achievable within the five-month period and was sufficient to produce reliable statistical models of invertebrate distribution in the subantarctic (Davies and Melbourne, 1999).
We included altitude as a continuous variable (i.e. altitude was measured to +/- 5 meters). For the purpose of getting a reasonably balanced design and for selecting sites we defined altitude classes as: 0-100 m, 100-200 m, 200 - 300 m, 300 - 400 m, 400-500 m, 500-600 m, 600 m +. We included five vegetation categories, which were not meant to cover all kinds of vegetation but instead span the range of vegetation types. Our vegetation classes were Poa cookii dominated (greater than 75%), Pringlea dominated (greater than 75%), Azorella dominated (greater than 75%), feldmark (less than 50% vegetation but with the vegetation that is present consisting of at least 50% moss), and 'patchy Azorella' (50-75% Azorella but less than 75% total vegetation). Not all vegetation classes occurred at all altitudes so we have crossed vegetation with altitude to give roughly 13-16 altitude-vegetation combinations. At most we managed to find between 10-13 sites in each of five areas giving us a total of 60 sites.
At all of our sites, we took pitfall samples, and at a selected subset of sites (20 sites) we did hand searches to get density estimates. The trapping took place between January and March 2001. The species that we trapped were: Anatalanta aptera, Myro kerguelenensis, Canonopsis sericeus, Ectemnorhinus viridis, Bothrometopus brevis, Bothrometopus gracilipes, Notodiscus hookeri, Embryonopsis halticella, Calycopteryx mosleyi, Amalopteryx maritima. We produced statistical models that describe the distribution of these species over Heard Island, based on altitude and vegetation type.
We took standardised photographs of a 10 m transect at each of our 60 sample sites. These will allow us to look for changes in vegetation composition at these sites in the future. The photographs are in a digital format.
The fields in this dataset are: