Increasing competition for water resources has led to calls for scrutiny of water used by plantations during water management planning. At present, the knowledge to quantify plantation water use is limited. There have been small scale studies and generalised models but these are not linked to operational systems that describe plantation distribution and properties to estimate water use on a catchment or regional scale.
The forest estate model operated in Woodstock (Tasmania), permits extrapolation of water usage results from smallscale estimates to the plantation estate. This allows researchers to assess the impacts of plantation development and silviculture on water supply during the planning process and inform catchment managers planning water allocations.
Data collected from the site is utilised to predict the future availability of wood in native forests and plantations across the forest estate under a variety of management scenarios. It utilises spatial layers of various forest attributes (e.g. forest type, silvicultural regime and age), and growth models developed from forest inventory to predict the basal area of the forests, now and in the future.
The purpose of this project is to clarify the relationships between basal area, sapwood area, leaf area, forest type, age, site quality and water use for the main plantation species in Tasmania.
A Campbell Scientific Aust CR10X data logger, two third party sapflow sensors and a Theta probe are used to measure and calculate sap velocity, transpiration volume and soil volumetric water content. The relationship between these plantation attributes and water usage may then be used to predict future water needs.
The Woodstock project links research results with an operational planning system that contains detailed information of forest type and distribution, allowing water usage of plantations to be assessed in parallel with wood production, which facilitates economic comparisons.