Monitoring groundwater levels in a native old-growth Cumberland plain forest (Addendum to P0018)
Project leader, researchers and collaborators:
Prof Teresa Gimeno, Prof David Ellsworth, Dist Prof David Tissue, Dr Craig Barton, Dr Tim McVicar CSIRO, Dr Anthony O’Grady CSIRO, Dr Lu Zhang CSIRO
Project summary: Rising levels of atmospheric concentration of CO2 (e[CO2]) are expected to have a major impact on the soil-plant-atmosphere exchange continuum. An expected effect of e[CO2] is to promote forest water savings via stomatal closure at the leaf level. The hydrological implications of this response might be significant and potentially relevant for increases in continental runoff or changes in the rate of ground water discharge/recharge.
The majority of the components of the water balance potentially affected by e[CO2] are being monitored in all study rings (P0018): stand transpiration, total incoming precipitation, canopy interception, stem flow and soil water. Currently on site, soil moisture is sampled by neutron probe from 475 cm deep holes (two per study ring, plus three outside the study ring within the EucFACE study site)every two weeks. This data set provides the facility with high quality information to quantify changes in soil water storage in the stand, but it is insufficient to account for vertical drainage and ground water discharge from stand evapotranspiration. It’s also not possible to exclude the contingency that trees continuously have roots in the water table at the site, which if it were true would change our ability to detect seasonal changes in plant water status. Several active projects at EucFACE depend on knowing this (projects P0014, P0018, P0034).
We propose the installation of three deep wells that can be used for monitoring groundwater at the site. Monitoring changes in the groundwater level will be a crucial element required to close the water balance of the whole forest stand, and subsequently assess the impact of e[CO2] on the hydrological cycle.D