Soil water under forests (SWUF): a model of water flow and soil water content under a range of forest types

摘要

A new model (soil water under forest, SWUF) is suitable for predicting the daily water content within both surface soil layers and the sub-soil under a range of forest types, and is suitable for use in models of mineralisation of soil organic matter as well as models of forest production. This empirical cascading bucket-type model was largely derived by combining algorithms from well-tested models for prediction of soil water under agriculture. However, it extends these to predict the water content of the litter layer, and the influence of the litter layer, weeds and understorey, and site mounding, on SWUFs. Measurements of soil water content under native forest, and pine and eucalypt plantations, were available for 59 sites across southern Australia. The model was parameterised to about half (27) of these datasets, while the remainder (32) were used for validation, for which the model explained 86% of the variation in observed water content. Sensitivity analysis indicated that important input data required were the observed upper limit of water content, bulk density, and climatic data, particularly solar radiation. The estimated area of ground that was covered by litter and canopy were also important inputs.