Factors determining relations between stand age and catchment water balance in mountain ash forests

Abstract

There is a well-documented empirical relationship between stand age and water yield for mountain ash (Eucalyptus regnans) forested catchments in the Central Highlands of Victoria, Australia. Catchments covered with old-growth stands of mountain ash yield almost twice the amount of water annually as those covered with re-growth stands aged 25 years. In this paper, we provide a mechanistic hydro-ecologic explanation for this phenomenon. We measured leaf area index (LAI), sapwood area index (SAI) and various water balance components in several mountain ash stands, ranging in age between 5 and 240 years. Sap flow measurements show that sap velocity does not vary appreciably amongst stands of dif..