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Long-term productivity in the cryptoendolithic microbial community of the Ross Desert, AntarcticaAnnual gross productivity of the lichen-dominated cryptoendolithic community was calculated from a computer analysis of photosynthetic response based on laboratory measurements of CO2 exchange and three years (1985-1988) of field nanoclimate data. Photosynthetic optimum increased from -3 to 2 degrees C between irradiance levels of 100 and 1500 micromoles photons m-2 s-1, while the upper compensation point rose from 1 to 17 degrees C. The mean yearly total time available for metabolic activity (temperature above -10 degrees C and moisture present) was 771.3 h for horizontal rock, 421.5 h for northeast-oriented sloped rock, and 1042.2 h for a small depression in horizontal rock (the characteristic site of occasional lichen apothecia). The calculated mean gross productivity value for a horizontal rock was 1215 mg C m-2 y-1, and net photosynthetic gain was 606 mg C m-2 y-1. Net ecosystem productivity (annual accretion of cellular biomass) estimated from long-term events amounted to only about 3 mg C m-2 y-1. The difference between these two values may represent the long-term metabolic costs of the frequent dehydration-rehydration and freezing-thawing cycles or of overwintering, and may account for the leaching of organic substances to the rock. The yearly gross productivity of the cryptoendolithic microbial community of the entire Ross Desert area was estimated at approximately 120,000-180,000 kg C. Of this, 600-900 kg C is in microbial biomass, and much of the rest is soluble compounds that leach into the rocks and possibly percolate to the valleys, providing a source of organic matter for lakes, rivers, and soils.
Document ID
20040112142
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Friedmann, E. I.
(Florida State University Tallahassee 32306)
Kappen, L.
Meyer, M. A.
Nienow, J. A.
Date Acquired
August 21, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Microbial ecology
Volume: 25
Issue: 1
ISSN: 0095-3628
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NAGW-1871
CONTRACT_GRANT: NSG 7337
CONTRACT_GRANT: DPP-83-14180
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Exobiology
Non-NASA Center
NASA Discipline Exobiology
NASA Discipline Number 52-30

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