INVESTIGADORES
PARUELO Jose Maria
artículos
Título:
Patterns and controls of above-ground net primary production in meadows of Patagonia. A remote sensing approach
Autor/es:
IRISARRI, G.; OESTERHELD, M.; PARUELO, J.M; TEXEIRA, M.
Revista:
JOURNAL OF VEGETATION SCIENCE
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2012 vol. 23 p. 114 - 126
ISSN:
1100-9233
Resumen:
Questions: (1) Can above-ground net primary production (ANPP) of Patagonian
meadows be estimated from remote sensing? (2) How does ANPP of Patagonian
meadows change in space and time?
Location: Northwestern Patagonia, meadows embedded in a steppematrix (39?
43°S, 70?72ºW; area: 85 000 km2).
Methods: For the first question, we contrasted field ANPP measurements with
MODIS high-spatial resolution (pixel size: 0.0625 km2) data and developed a
model that estimates radiation use efficiency. For the second question, we
applied the model to a 6-year MODIS record for 14 meadows whose physiognomic
heterogeneity was known frompreviouswork.
Results: Up to 77%of the field-based ANPP variation was accounted for by the
absorbed photosynthetic radiation, based on a linear transformation of the normalized
difference vegetation index derived from MODIS data. Mean radiation
use efficiency was 0.54 g dry matter MJ1. ANPP ranged between 610 and
1060 g m2 year1, which represents three to 5.3 times the ANPP of the surrounding
arid and semi-arid steppes. The inter-annual coefficient of variation of
ANPP was 10%, which is higher than other systems of similar productivity, but
much lower than the surrounding steppes (33%). At the level of management
units (paddock), ANPP spatial variations were mainly related to the proportion
of Prairies, a proxy for low topographic position in the landscape, and longitude,
a proxy for precipitation. ANPP inter-annual variation was most related to latitude,
a proxy for temperature.
Conclusion: The model developed and tested can be used to infer ANPP from
remote sensing data at a spatial resolution that allows one to detect variability
within meadows and management units. Variations at both the physiognomic
unit and paddock level were associated with geographic patterns and topography.
Meadows were three to five times more productive and less fluctuating
than nearby steppes. When compared with other ecosystems, their productivity
was high, butmore variable inter-annually, likely due to exceptionally high variability
of precipitation in Patagonia.