Soil Moisture and Tree Water Status Dynamics in Mixed-Conifer Forest Southern Sierra Critical Zone Observatory, CA
Event details
| Date | 20.09.2011 |
| Hour | 16:15 |
| Speaker | Dr Jan Hopmans, Dept of Land, Air and Water Resources, University of California Davis, USA |
| Location |
GR C0 01
|
| Category | Conferences - Seminars |
The presentation will show the results of a multi-year deployment of soil moisture sensors to study the hydrologic/ biotic interactions in a mixed-conifer forest at an elevation of ~2000m in the Southern Sierra Critical Zone Observatory (CZO). To better understand root-soil water interactions in a multi-dimensional soil/vegetation system, a mature white fir (Abies concolor) and the surrounding root zone was continuously monitored (sap-flow, canopy stem-water-potential, soil moisture, soil water potential and temperature), to characterize the hydraulics across the soil-root-tree-atmosphere continuum (SPAC) for this single tree. The additional deployment of more than 250 sensors to measure temperature, volumetric water content, soil water matric potential, and snow depth across the watershed complements trunk sap-flow and canopy stem-water-potential measurements. Uncertainty exists in the depth from which tree roots extract soil water, specifically related to the presence of underlying saprolite/ bedrock, and the role of deep moisture storage. To better characterize processes in the subsurface, we excavated the root system of a nearby mature white fir, using compressed air to remove the soil surrounding the tree roots. This method left the roots intact and enabled quantification of root density with depth in addition to in situ root architecture. The roots were imaged using a Terrestrial LiDAR system to build a 3-D model of root size and density relative to presence of soil horizons. LiDAR images allowed us to also determine tree root volume and other related root characteristics. The results from this experiment are part of an ongoing computer modeling study to test assumptions about tree root water uptake, compensated root water uptake, and to analyze soil water stress effects on tree water hydraulics and tree canopy transpiration.
Links
Practical information
- General public
- Free
Contact
- Prof. Marc Parlange, EFLUM