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Soil micro-organisms in Antarctic dry valleys: resource supply and utilization
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- By D. W. Hopkins, School of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK, B. Elberling, Institute of Geography, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen K., Denmark, L. G. Greenfield, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand, E. G. Gregorich, Agriculture Canada, Central Experimental Farm, Ottawa, Canada K1A 0C6, P. Novis, Manaaki Whenua - Landcare Research, PO Box 69, Lincoln 8152, New Zealand, A. G. O'Donnell, Institute for Research on Environment and Sustainability, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK, A. D. Sparrow, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand, Department of Natural Resources and Environmental Sciences, University of Nevada, 1000 Valley Rd, Reno, NV 89512, USA
- Edited by Geoff Gadd, University of Dundee, Kirk Semple, Lancaster University
- Hilary Lappin-Scott, University of Exeter
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- Book:
- Micro-organisms and Earth Systems
- Published online:
- 06 July 2010
- Print publication:
- 13 October 2005, pp 71-84
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Summary
INTRODUCTION
In 1903, the explorer Robert Scott was one of the first humans ever to see the dry valleys of Antarctica. He called them ‘valley(s) of the dead’ in which ‘we have seen no sign of life, … not even a moss or lichen’. A century later, we know that the soils and rocks are home to many microscopic organisms that Scott could not have seen.
The dry valleys are part of the small percentage of the land surface of the Antarctic continent that is ice-free, amounting to about 4000 km2, and thus have rock and soil surfaces that can be colonized by terrestrial organisms. They are an ancient polar desert, perhaps as much as 2 million years old, located in Victoria Land between about 77 and 79° south (Fig. 1). The valleys are in a precipitation shadow caused by the Transantarctic Mountains, which rise over 4000 m. The Antarctic dry valleys are now recognized as one of the harshest terrestrial environments on Earth, characterized by summer maximum temperatures that rarely exceed 0 °C and only a few tens of millimetres of precipitation, most of which falls as snow and is ablated by strong winds carrying dry air from the polar plateau - potential evaporation far exceeds precipitation (Fig. 1).
4 - Carbon as a substrate for soil organisms
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- By D. W. Hopkins, University of Stirling, E. G. Gregorich, Agriculture and Agri-Food Canada
- Edited by Richard Bardgett, Lancaster University, Michael Usher, University of Stirling, David Hopkins, University of Stirling
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- Book:
- Biological Diversity and Function in Soils
- Published online:
- 17 September 2009
- Print publication:
- 22 September 2005, pp 57-80
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Summary
SUMMARY
In many ecological studies, soil carbon is regarded as a barely differentiated whole with little attention paid to its underlying characteristics.
Although it is widely appreciated that decomposer organisms are nearly infallible as degraders of organic molecules, there are marked differences in the utilisation of different components of organic matter by organisms depending on chemical and physical characteristics, location and availability in time in soil.
We discuss the characteristics of soil carbon as a substrate and emphasise a ‘soil metabolomic’ approach for characterising the range of molecules in complex, composite substrates, and the potential that stable isotope probing offers for linking organisms to their substrates via enrichment of their biomolecules as they exploit isotopically enriched substrates.
Using selected examples, we examine the influence of the chemical characteristics/quality, quantity, location and timing of supply of organic matter on the amount, activity and, where possible, the diversity of soil organisms.
We are some way from unifying relationships between the quality, quantity, location and timing of delivery or availability of soil carbon on the size, activity and diversity of soil organisms. However, we point ways forward in which the information on the physics, chemistry and management are linked to the biology of soils.
Introduction
Currency of soil carbon
Humans view soil carbon in various physical (e.g. aggregates, density fractions), chemical (e.g. carbohydrates, aromatic compounds), biological (e.g. microbial biomass) and even economic (e.g. dollars per tonne or carbon credits) ways which are not usually ecological.