Transpiration in 15 Tree Species Grown on a Phytocapped Landfill Site

Abstract

An alternative landfill capping technique ‘Phytocapping’ (establishing plants on a layer of soil placed over the waste) was trialled at Rockhampton, Australia. In this capping trees act as ‘bio-pumps and ‘rain interceptors’ and soil cover as ‘storage’. They together minimise water percolation leading to reduced leachate production. “Transpiration” is a vital process to maintain the hydrological balance of a particular site. To be successful, the trees must transpire enough water from the soil so as to reduce water percolation through the refuse. Water uptake in trees is influenced by plant growth, tree characteristics, root activities, soil depth, soil water availability as well as climatic conditions (rainfall intensity, wind velocity, relative humidity and temperature). The potential of the tree species to remove water from the system plays a vital role in the sustainability of phytocapping system. Currently very little information is available on water uptake patterns of native species established on landfill sites. Results from this study suggest that the tree species grown on a phytocap are able to take up to 2.1 mm day-1 of water with an average of 1.4 mm day-1.