Intensive Observation Period 1 - IOP1
July 22nd to August 3rd, 2003
grove in Southern Italy
The IOP1 took place in the olive grove
at the test
site of Andria (Southern
Italy, Apulia, 41°12'N, 16°10'E, 175 m a.s.l.)
from July 22nd to August 3rd, 2003, on approximately
level terrain (2° inclined towards NNE). The average stand age was
The distance between the rows was 8.3 m and the tree density was 132
ha, with an average tree height of 5 m. Between the trees was bare soil
canopy was relatively open. Fetch in the main wind directions (W and N)
to 300 m. It has been the first official experiment where most of
project partners were involved in a common field study, bringing in the
instruments and techniques specifically developed in the first year of
project, in order to quantify, characterize, and especially partition
budget components of a typical agricultural land use system (an
grove in Southern Italy).
The main objective of the campaign was the concurrent deployment and use of various, integrated techniques to study water fluxes in the different segments of the Soil-Plant-Atmosphere System in a sparse yet regular tree canopy system, and understand regulative properties of the plants in partitioning water fluxes. Thus, extensive measurements of soil geo-pedological, physical and especially hydrological properties were planned at plot scale, and intensive monitoring of water content at significant points, too. Plant canopy structure was also to be investigated by several destructive and non-destructive techniques. Water flow in the trees was planned to be investigated by several sap-flow methods and by remote-sense techniques, integrated by direct stomatal conductance measurements. General validation of evapotraspiration loss to the atmosphere and eventually partitioning between transpiration and soil evaporation were planned to be gathered through analytical micrometeorological measurements, based on the eddy covariance technique and the measurements of the energy balance components.
A very extensive survey of soil electromagnetical properties was performed by Partner 8 in an area approximately 1 ha large positioned in the normal daytime footprint of the ET fluxes, using the Ground Penetrating Radar technique. It showed interesting features of the soil structure, especially related to the vertical profile, and spatial (horizontal) variability, which demonstrated to be very useful in addressing the sampling strategy of other soil measurements, especially geoelectrical and time-domain reflectometry. The vertical structure of the soil profile often showed thick hard plates of carbonates at 0.2-0.5 m, which could be crucial in determining the movement of water in the soil and the root distribution. Two trenches 1 m deep and several meters long have been dug out in areas where GPR had showed anomalous behaviour or strong gradients of soil electromagnetical properties, in order to better understand the resolution capacity of this technique.
Geolectrical methods based of measurement of electrical resistivity of soil between complex electrodes array configuration have been applied by Partner 6 in specific areas of the plot and around trees which were monitored also by other techniques (sap flow) . The inversion of these readings showed to be able to detect with good resolution the vertical stratification of the soil and even the presence of the bigger tree roots. Also, the parallel measurements of volumetric water content by time-domain reflectometry (TDR) probes, showed a good correlation between electrical resistivity values and local water content. Further validation of these relationships will be possible after the analysis of the extensive soil sampling made by Partner 9 at the same locations where geoelectrical methods have been applied. Partner 6 also studied infiltration properties of the soil, yielding interesting information on proper irrigation management.
Similar (geo)electrical techniques were applied to the study of the resistivity of trunk sections, demonstrating quite well the diameter of the heart wood. These measurements have been carried out in strict cooperation with Partner 5, on trees where sap flow measurements were also run at the same time.
techniques of sap-flow measurements were
applied by Partners 1, 5, and 7, ranging from the simpler Granier-type
to the heat-balance gauges, and the more complex heat field deformation
technique developed by Partner 5. On some trees, all the techniques
applied concurrently, in order to better understand the relative
the methods in the very complex application under study. Indeed, the
trunks showed to be very heterogeneous and variable, as demonstrated
independent techniques (reflection of elastic waves), developed by
However, a remarkable similarity between probes installed on different
has been noticed, and this result could be encouraging for the
these methods in the real world of agricultural water management.
Analytical information on the leaf and canopy energy balance were collected by Partner 4, who deployed instruments for monitoring leaf boundary layer conductance, soil heat flux, global radiation under the canopy and in open areas, air temperature and humidity and windspeed. Thermal images taken by ground camera of foliage kept at different transpiration rates (suppressed with vaseline, not altered, thoroughly wet), in connection with measurements of stomatal resistance provided by Partner 1, should allow the development of remote-sensing techniques for estimating the (evapo)transpiration fluxes. Unfortunately, it was not possible to acquire good Landsat images for the IOP because of poor weather at the time of the satellite pass (see below). These would have been needed for a full testing of upscaling.
Strong effort has been put on the geometrical and biometrical characterization of the olive grove. This activity, lead in the field by Partner 5, has been carried out with the help of Partners 1, 4, and 7. It provided detailed informations on canopy structure and average foliage density, both crucial parameters in interpreting and upscaling some of the sap-flow measurements.
by Partner 7, together with his subcontractor MetInform and the team of
MCR-Lab of the