INVESTIGADORES
SCHOLZ Fabian Gustavo
artículos
Título:
Evapotranspiration of subtropical forests and tree plantations: a comparative analysis at different temporal and spatial scales
Autor/es:
PIEDAD M. CRISTIANO, PAULA I. CAMPANELLO, SANDRA J. BUCCI, SABRINA A. RODRIGUEZ, OSCAR . LEZCANO, FABIAN G. SCHOLZ, NORA MADANES, DÉBORA
Revista:
AGRICULTURAL AND FOREST METEOROLOGY
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2015 vol. 203 p. 96 - 106
ISSN:
0168-1923
Resumen:
The area with tree plantations in the humid subtropical
region of Northern Argentina has recently increased five folds. However, the
impact of this land use change on evapotranspiration (ET), one of the main components
of the hydrologic cycle, has not been evaluated. We studied the ET at tree and
ecosystem levels for native forests and three tree
plantations (Pinus taeda, Araucaria angustifolia and Eucalyptus
grandis). Water consumption of individual trees was estimated using sap flow
measurements. Ecosystem ET was characterized using both
remote sensing derived data products (ETMODIS) for 2000-2011 and
scaling up from tree
sap flow measurements to stand level. Canopy conductance (gc) was
estimated using both sap flow measurements and ETMODIS data. At
individual level, transpiration was positively related to the size of the trees, and the
relationship between tree size and tree transpiration was described well by an exponential function when all
species (both native and cultivated trees) were included in the analysis. The
average annual leaf area index was similar between native forest and tree
plantations. The ET estimates obtained from scaling up sap flow measurements
and ETMODIS were relatively similar in most cases and differed by 4 to
34%, depending on the ecosystem. The tree plantations, regardless of density or
age, did not show higher ETMODIS than
native forests. The ET ranged between 1161 and 1389 mm per year across
native forests and tree plantations according to remote sensing, representing 58 to 69 % of the long term average
annual precipitation. Furthermore the good agreement between ET estimates, with
the exception of E. grandis, obtained
using sap flow and remote sensing provides a
good basis for predicting the effects of land cover conversion from native
forest to most non-native tree plantations on regional ET. Monthly ETMODIS
increased with increasing monthly air saturation deficit (ASD) up to 0.8 kPa, value
at which ETMODIS did not increase further probably due to stomatal
control and low values of gc. Different negative
exponential relationships between gc and ASD were obtained when gc
was calculated by scaling up daily tree sap flow to ecosystem level. Canopy conductance (estimated by remote
sensing) declined in a similar negative exponential fashion with increasing ASD,
and no differences were observed across ecosystem types. The result of increasing
the time step, from daily to monthly, and the spatial scale from individual
tree to stand level, had the consequence to lower, even to eliminate differences
in annual ET and gc among ecosystems in their responses to climate drivers. This suggest
that the nature of ET regulation at individual and ecosystem level is different,
which should be taken into account when predicting the effects of changes in
land use on regional hydrology.