LAUSR

Plantation establishment using invasive alien plants is common in South Africa, but the effects of these plants on soil physical properties in the Vhembe biosphere is unknown. In this comparative study, soils underneath Pinus elliottii and Eucalyptus cloeziana were assessed for differences in physical properties compared to soils underneath adjacent natural sites in the Entabeni plantation in the Vhembe biosphere in Limpopo Province, South Africa. Soils were collected from topsoil over 3 months and quantified for gravimetric soil moisture, penetration resistance, soil infiltration, hydraulic conductivity and soil water repellency. For all 3 months, soils from both P. elliottii and E. cloeziana plantations were compact and had low penetration resistance compared to soils from adjacent natural sites. Soil infiltration and hydraulic conductivity were significantly (p < 0.05) lower in soils from plantations compared to soils from adjacent natural sites, and more so from the E. cloeziana plantation than from P. elliottii. Soil water repellency was observed in soils from E. cloeziana only in May and June. Soils from the invasive alien tree plantation have decreased soil moisture, infiltration rate, hydraulic conductivity and are compact as well as repellent (only E. cloeziana), all poor soil physical properties. However, this decline in soil physical properties was not uniform between the two invasive alien plantation species; hence we cannot generalize about the effects of invasive alien plantation species on soil physical properties, and further research is required across different ecological regions.