Eucalyptus reforestation induces soil water repellency

Abstract

Abstract. There is an increasing interest in eucalypt reforestation for a range of purposes in Australia, including pulpwood production, carbon mitigation and catchment water management. The impacts of this reforestation on soil water repellency have not been examined despite eucalypts often being associated with water repellency and water repellency having impacts on water movement across and within soils. To investigate the role of eucalypt reforestation on water repellency, and interactions with soil properties, we examined 31 sites across the south-west of Western Australia with paired plots differing only in present land use (pasture v. plantation). The incidence and severity of water repellency increased in the 5-8 years following reforestation with Eucalyptus globulus. Despite this difference in water repellency, there were no differences in soil characteristics, including soil organic carbon content or composition, between pasture and plantation soils, suggesting induction by small amounts of hydrophobic compounds from the trees. The incidence of soil water repellency was generally greater on sandy-surfaced (<10% clay content) soils; however, for these soils 72% of the pasture sites and 31% of the plantation were not water repellent, and this was independent of measured soil properties. Computer modelling revealed marked differences in the layering and packing of waxes on kaolinite and quartz surfaces, indicating the importance of interfacial interactions in the development of soil water repellency. The implications of increased water repellency for the management of eucalyptus plantations are considered.

Persistence of water repellency in coarse-textured soils under various types of forests in NW Spain

“…Few studies have reported so high persistence in water repellency with soil depth as found in this work. Walden et al (2015) found reforestation with E. globulus to induce water repellency across a range of sites in the southwest of Western Australia; contrary to our results, however, they also found SWR to decrease rapidly with increasing depth. Doerr et al (2006) examined water repellency in soils differing in texture, organic matter content, moisture and management regime at variable depths and concluded that the last two were reliable predictors for SWR.…”

Rethinking soil water repellency and its management

“…Indeed, inputs of organic matter from native vegetation induced SWR to a greater extent than equivalent amounts of organic matter from agricultural species (Harper et al 2000;Walden et al 2015). The contribution of specific residual organic compounds from former native vegetation to SWR in farmland soils is not known but may be significant and help to explain the spatially variable distribution of SWR in these soils (Harper et al 2000).…”

“…Indeed, most likely the legacy of former native vegetation contributes to SWR rather than agricultural land use per se (Harper et al 2000). That said, SWR has been induced under plantation eucalypts established in lands previously used to grow annual pastures, which suggests its expression is sensitive to land-use and specifically to established vegetation (Walden et al 2015).…”

Assessing the ‘two water worlds’ hypothesis and water sources for native and exotic evergreen species in south‐central Chile

“…Hence, water resources are under pressure in Chile. In particular, land cover changes alter catchment discharge, groundwater level and recharge rates (Huber et al ., ; Walden et al ., ) and thereby likely affect either the static or mobile water compartments in soil. In this study, we wanted to test (1) whether the TWW hypothesis holds for our study sites and (2) whether there is a difference in ecohydrological connectivity or (3) water sources (i.e.…”