Analysis of Invertebrate abundance from soils cores on Macquarie Islands.
In the summer of 1986-87, total invertebrate abundances were measured quantitatively at eight sites, representing four vegetation types: feldmark, Stilbocarpa herbfield, Pleurophyllum meadow and Poa foliosa tall tussock grassland (P. Greenslade, unpubl. data). Between 11 and 16 soil cores were sampled at each site. Each ... core was 5 cm wide by 5 cm deep and invertebrates were extracted using Tulgren funnels. Numbers of invertebrates from each core are expressed as animals per square metre (.m-2). The mean density for the total of 120 cores was 29702.m-2 plus or minus 3564 SE and ranged from a low site mean of 2646.m-2 plus or minus 513 SE at a feldmark site on the plateau at 250m, to high site means of 97740.m-2 plus or minus 15898 SE and 62894.m-2 plus or minus 20804 SE at two Stilbocarpa dominated, coastal eastern slopes, both at 20 m a.s.l. Poa foliosa dominated sites at 40 m and 100m a.s.l. displayed intermediate mean densities of 20599.m-2 plus or minus 4241 SE and 20567.m-2 plus or minus 2670 SE, respectively. A Pleurophyllum dominated site on the plateau at 250m a.s.l. also exhibited a low mean site density of 6,664.m-2 plus or minus 1224 m-2 SE, while one on North Head at a lower elevation of 100m a.s.l., was higher at 24107.m-2 plus or minus 4155. A higher mean density of 19417.m-2 plus or minus 3674 was also found at feldmark site on North Head at only 100 m a.s.l. These figures show that altitude appeared to have a stronger influence on invertebrate abundance than vegetation type. The total mean density is similar to those found in temperate grassland and herbfields in other parts of Australia where a mean of about 25000 invertebrates.m-2 might be expected (King and Hutchinson, 1992). Barendse and Chown (2001) found a similar mean density for feldmark of 1800.m-2 on Marion Island but rather higher mean density of 50 000.m-2 in Azorella selago cushions, a vegetation type not sampled on Macquarie Island. Collembola dominated the Macquarie Island fauna numerically, followed by Acarina. Barendse and Chown (2001) found the same groups dominated in Azorella selago cushions and bare ground on Marion. Of interest was the high density of the introduced Hypogastrura purpurescens under Stilbocarpa polaris on Macquarie Island.
See also the metadata record &Report on invertebrate field work, Macquarie Island, December 1986-January 1987& for further information.
The fields in these datasets are:
KA/EW, Kontia andersoni and earthworms
AV, Arthurdendyus vegrandis
SEW, small earthworms
Density per square metre