The effects of Acacia mearnsii (black wattle) on soil chemistry and grass biomass production in a South African semi-arid rangeland: implications for rangeland rehabilitation

Black (Acacia mearnsii) and silver wattle (Acacia dealbata) invasive tree species impact on soil physicochemical properties in South Africa: A systematic literature review

“…Soil pH, which indicates acidity plays a role in various soil ecosystem functions, such as the availability and solubility of phosphate ions and cations (NH 4 + , K + , Ca 2+ ) [ 30 , 34 ] and microbial abundance and activity [ 35 ]. The low pH in both invaded and cleared soils could possibly be due to increased rates of nutrient leaching induced by acacia species due to increased water infiltration, which is also accelerated in poor nutrient retention soils such as sandy soils [ 26 ]. In addition, litter decomposition and fixed nitrogen nitrification could contribute soil acidification [ 36 ].…”

“…While studies by Balintulo [ 18 ] and Ruwanza [ 14 ] had low available phosphorous in invaded soil as compared to uninvaded soils. Total phosphorous was higher in invaded and cleared soils than uninvaded soils [ 26 ]. Similarly, nitrogen and phosphorous increase can be explained by the large leaf litter generation in acacia trees, which decomposes and releases soil phosphorous [ 37 ].…”

“…Soil K was generally higher on both invaded and cleared soils than uninvaded soil [ 18 , 26 ]. This was similar to cation exchange capacity, whereas Calcium and Magnesium were high on invaded soils and generally low on cleared soils.…”

“…A study by Oelofse et al [ 29 ] carried out in Matatiele under clay loam soils reported no significant difference in bulk density between Acacia mearnsii under cleared and uninvaded sites. Similarly, Gwate et al [ 26 ] reported no significant difference between Acacia mearnsii under invaded, cleared, and uninvaded soils with respect to bulk density. A study by Naudé [ 30 ] reported significantly higher bulk density in Acacia mearnsii under invaded compared to uninvaded soils.…”

“…Determining the effectiveness of restoration efforts, assessing soil recovery, assisting in the establishment of native plants, managing soil nutrients, preventing reinvasion, and promoting long-term ecosystem resilience all depend on an understanding of the characteristics of the soil before, during, and after the removal of invasive species [ [21] , [22] , [23] ]. Numerous researchers have studied the impact of wattle trees on the physicochemical characteristics of the soil [ 14 , 19 , [24] , [25] , [26] ]. Nevertheless, the outcomes differ, which makes formulating specific suggestions for crucial ecosystem restoration tactics challenging.…”