Eucalyptus Camaldulensis Invasion in Riparian Zones Reveals Few Significant Effects on Soil Physico‐Chemical Properties

• Published in: River research and applications 2015-06, Vol.31 (5), p.590-601
• Main Authors: Tererai, F, Gaertner, M, Jacobs, S. M, Richardson, D. M
• Format: Article
• Language: English
• Subjects: ammonium nitrogen; biological invasions; calcium; canopy; copper; ecosystems; Eucalyptus; Eucalyptus camaldulensis; Exchange; exchangeable calcium; introduced plants; invasive plants; invasive species; iron; Litter; magnesium; manganese; Mediterranean climate; nitrate nitrogen; nutrient availability; Nutrients; riparian areas; riparian soils; sampling; Seasons; Soil (material); soil available N; soil cations; Soil moisture; soil N content; soil pH; soil water; spring; temperature; topsoil; tree invasions; winter; zinc
• ISSN: 1535-1459; 1535-1467
• DOI: 10.1002/rra.2762

Many invasive alien plants alter soil‐nutrient regimes of invaded ecosystems, affecting management outcomes. We assessed the effects of Eucalyptus camaldulensis invasions on physical and chemical properties of riparian soils in the Western Cape Province, South Africa. Samples were collected from topsoil beneath the canopy of uninvaded and a gradient of invaded sites, namely, light, moderate and heavy over four seasons. We quantified soil moisture, temperature, litter depth and thickness, primary textural components, concentrations of soil macro (C, N, P and K) and micro (Mn, Zn, Cu and Fe) nutrients, and pH. Available N (NO₃ ⁻‐N and NH₄ ⁺‐N) and P, as well as exchangeable Ca and Mg were also assessed. Soil pH levels were significantly lower in invaded than in uninvaded sites in all seasons. Soil moisture decreased consistently with invasion intensity. Concentrations of macro, micro and available nutrients did not vary significantly along the invasion gradient (p > 0.05), but exchangeable cation content was significantly higher in uninvaded than in invaded sites, especially in winter and spring. Sites invaded by E. camaldulensis had higher litter build‐up than non‐invaded sites, but this appears to have little effect on soil‐nutrient regimes. It appears that restoration following removal of invasive stands of E. camaldulensis will not require major interventions to return soil to pre‐invasion conditions. Copyright © 2014 John Wiley & Sons, Ltd.