Water consumption of subtropical forests and tree plantations: a comparative analysis at different temporal and spatial scales.

CRISTIANO; CAMPANELLO, P; BUCCI, S; RODRIGUEZ; LEZCANO; SCHOLZ; MADANES,N; DI FRANCESCANTONIO, D.; OLIVA CARRAS, L.; ZHANG; GOLDSTEIN G

AGRICULTURAL AND FOREST METEOROLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 p. 96 - 109

0168-1923

tThe area of tree plantations in the humid subtropical region of Northern Argentina has recently increasedfive folds. However, the impact of this land use change on evapotranspiration (ET), one of the maincomponents of the hydrologic cycle, has not been evaluated. We studied the ET at tree and ecosystemlevels for native forests and three tree plantations (Pinus taeda, Araucaria angustifolia and Eucalyptusgrandis). Water consumption of individual trees was estimated using sap flow measurements. EcosystemET was characterized using both remote sensing derived data products (ETMODIS) for 2000?2011 andscaling up from tree sap flow measurements to stand level. Canopy conductance (gc) was estimated usingboth sap flow measurements and ETMODISdata. At individual level, transpiration was positively related tothe size of the tree, and the relationship was well described by an exponential function when all species(both native and cultivated trees) were included in the analysis. The average annual leaf area index wassimilar between native forest and tree plantations. The ET estimates obtained from scaling up sap flowmeasurements and from ETMODISwere relatively similar in most cases and differed by 4?34%, dependingon the ecosystem. The tree plantations, regardless of density or age, did not show higher ETMODISthannative forests. The ET ranged from 1161 to 1389 mm per year across native forests and tree plantationsaccording to remote sensing, representing 58?69% of the annual precipitation. Furthermore, the goodagreement between ET estimates, with the exception of E. grandis, obtained using sap flow and remotesensing provide a good basis for predicting the effects of land conversion from native forest to most non-native tree plantations on regional ET. Monthly ETMODISincreased with increasing monthly air saturationdeficit (ASD) up to 0.8 kPa, value at which ETMODISdid not increase further probably due to stomatalcontrol and low values of gc. Different negative exponential relationships between gcand ASD wereobtained when gcwas 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, fromdaily 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 gcamong ecosystems in their responses to climate drivers.This suggests that the nature of ET regulation at individual and ecosystem levels could be different, whichshould be taken into account when predicting the effects of changes in land use on regional hydrology.© 2015 Elsevier B.V. All rights reserved.