RESEARCH PAPER: Integration of CO sub(2) flux and remotely-sensed data for primary production and ecosystem respiration analyses in the Northern Great Plains: potential for quantitative spatial extrapolation

• Published in: Global ecology and biogeography 2005-05, Vol.14 (3), p.271-292
• Main Authors: Gilmanov, Tagir G, Tieszen, Larry L, Wylie, Bruce K, Flanagan, Larry B, Frank, Albert B, Haferkamp, Marshall R, Meyers, Tilden P, Morgan, Jack A
• Format: Article
• Language: English
• ISSN: 1466-822X; 1466-8238
• DOI: 10.1111/j.1466-822X.2005.00151.x

Aim: Extrapolation of tower CO sub(2) fluxes will be greatly facilitated if robust relationships between flux components and remotely sensed factors are established. Long-term measurements at five Northern Great Plains locations were used to obtain relationships between CO sub(2) fluxes and photosynthetically active radiation (Q), other on-site factors, and Normalized Difference Vegetation Index (NDVI) from the SPOT VEGETATION data set. Location: CO sub(2) flux data from the following stations and years were analysed: Lethbridge, Alberta 1998-2001; Fort Peck, MT 2000, 2002; Miles City, MT 2000-01; Mandan, ND 1999-2001; and Cheyenne, WY 1997-98. Results: Analyses based on light-response functions allowed partitioning net CO sub(2) flux (F) into gross primary productivity (P sub(g)) and ecosystem respiration (R sub(e)). Weekly averages of daytime respiration, gamma sub(day), estimated from light responses were closely correlated with weekly averages of measured night-time respiration, gamma sub(night) (R super(2) 0.64 to 0.95). Daytime respiration tended to be higher than night-time respiration, and regressions of gamma sub(day) on gamma sub(night) for all sites were different from 1 : 1 relationships. Over 13 site-years, gross primary production varied from 459 to 2491 g CO sub(2) m super(-2) year super(-1), ecosystem respiration from 996 to 1881 g CO sub(2) m super(-2) year super(-1), and net ecosystem exchange from -537 (source) to +610 g CO sub(2) m super(-2) year super(-1) (sink). Maximum daily ecological light-use efficiencies, epsilon sub(d,max) = P sub(g)/Q, were in the range 0.014 to 0.032 mol CO sub(2) (mol incident quanta) super(-1). Main conclusions: Ten-day average P sub(g) was significantly more highly correlated with NDVI than 10-day average daytime flux, P sub(d) (R super(2) = 0.46 to 0.77 for P sub(g)-NDVI and 0.05 to 0.58 for P sub(d)-NDVI relationships). Ten-day average R sub(e) was also positively correlated with NDVI, with R super(2) values from 0.57 to 0.77. Patterns of the relationships of P sub(g) and R sub(e) with NDVI and other factors indicate possibilities for establishing multivariate functions allowing scaling-up local fluxes to larger areas using GIS data, temporal NDVI, and other factors.