|
Eucalyptus (Ec) and pasture (Pt) are expanding while natural vegetation (Nv) are losing space in the
Paraíba Valley, eastern side of the São Paulo state, Southeast Brazil. For quantification of water and
vegetation conditions, the MODIS product MOD13Q1 was used together with a net of weather stations
and vegetation land masks during the year 2015. The SAFER algorithm was applied to retrieve the actual
evapotranspiration (ET), which was combined with the Monteithꞌs radiation use efficiency (RUE) model
to estimate the biomass production (BIO). Three moisture indices were applied, the climatic water
balance ratio (WBr), the ratio of precipitation (P) to ET, the water balance deficit (WBd), the difference
between P and ET, and the evapotranspiration ratio (ETr), the ratio of ET to the reference
evapotranspiration (ET0). On the one hand, the highest ET rates for the Ec ecosystem should be a negative
aspect under water scarcity conditions; however, it presented the best water productivity. Although the Ec
ecosystem presenting the lowest WBr and WBd values, it had the highest ETr, averaging 0.92, when
comparing to those for Nv (0.88) and Pt (0.79). These results indicated that eucalyptus plants have greater
ability of conserving soil moisture in their root zones, increasing WP, when comparing with Pt and Nv
ecosystems. These water relationships are relevant issues under the land-use change conditions in the
Paraiba Valley, confirming the suitability of using the MODIS products together with weather stations to
study the ecosystem dynamics.
|
