Journal of the Royal Society of New Zealand abstracts
Biodiversity of indigenous tussock grassland sites in Otago, Canterbury and the central North Island of New Zealand III. Soil microorganisms
S. U. Sarathchandra1, G. Burch1, S. T. Sayer1, N. W. Waipara2, N. R. Cox1, A. Ghani1, N. L. Bell1, M. O’Callaghan4, S. D. Young4, B. I. P. Barratt3, C. M. Ferguson3, and R. J. Townsend4
1AgResearch Ltd, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand. upali.sarathchandra@agresearch.co.nz
2Landcare Research, Private Bag 92 170, Auckland, New Zealand.
3AgResearch Ltd, Invermay Research Centre, Private Bag 50 034, Mosgiel, New Zealand.
4AgResearch Ltd, Lincoln, P.O. Box 60, Lincoln, New Zealand.
Abstract Bacterial and fungal communities in indigenous tussock grassland soils were studied at four locations, Mt Benger and Deep Stream (Otago), Cass (Canterbury) and Tukino (central North Island). Soil samples collected from inter-tussock and tussock areas were used to enumerate total culturable bacteria (colony forming units (CFU)) as well as a number of specific groups of bacteria, fungal types and diversity, and soil microbial functional diversity. Soil microbial biomass carbon (C) and nitrogen (N) as well as extractable C and N were also determined. Fungal populations were lowest at Mt Benger while fluorescent Pseudomonas was lowest at Cass. In these indigenous soils, bacterial CFU were c. 30 times lower and fungal populations c. 10 times greater than in developed New Zealand pastoral soils. CFU of bacteria in complex media (r-strategists) were similar in magnitude to bacteria growing on weak CA medium (K-strategists). The microbial biomass C in indigenous grassland soils were also significantly greater than that found in developed pastoral soils, possibly due to dominance of fungi in indigenous soils. Microbial C and N were lower in Cass and Tukino sites compared to Mt Benger and Deep Stream sites. Microbial nitrogen was also significantly greater (P < 0.001) in inter-tussock than under tussock samples. The functional diversity of soil microbes, was significantly greater (P < 0.01) in inter-tussock samples compared to tussock samples at all sites except Mt Benger. The total microbial activity, as measured by the colour development in Biolog plates (Average Well Colour Development (AWCD)), was low in Cass soil compared to others. Eighty-three types of fungi belonging to 30 genera were recovered from the four sites. The diversity of fungi found in Otago sites was greater than in the other two sites (P < 0.001). Fusarium spp. that are often common in pastoral soils were conspicuous by their rarity in indigenous soils.
Keywords functional diversity; microbial biomass; microorganisms; indigenous grassland; New Zealand; soil
R04019; Received 5 October 2004; accepted 30 June 2005; Online publication date 21 September 2005
Journal of the Royal Society of New Zealand Volume 35, Number 3, September, 2005, pp 321–337
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