Invasion of Abandoned Agricultural Fields by Acacia Mearnsii Affect Soil Properties in Eastern Cape, South Africa

Abstract

Abstract. Abandoned agricultural fields are susceptible to alien plant invasion because they experienced intensive anthropogenic activities. However, there is limited studies on soil physicochemical changes in alien plant invaded abandoned agricultural fields in comparison to uninvaded abandoned agricultural fields and natural sites. This comparative study explores soil physico-chemical changes in ten-year-old abandoned agricultural fields invaded by Acacia mearnsii in comparison to ten-year-old uninvaded abandoned agricultural fields and natural sites in Eastern Cape, South Africa. Soil physico-chemical properties were measured on topsoil collected from invaded and uninvaded abandoned agricultural fields as well as natural sites over three months. Results on soil nutrient changes between invaded and uninvaded abandoned agricultural fields compared to natural sites were varied, with significantly higher total C and cations of Na and Mg reported in A. mearnsii invaded abandoned agricultural fields, whereas soil pH and P were significantly higher in uninvaded abandoned agricultural fields. Soils underneath invaded abandoned agricultural fields were compact, had high litter mass, reduced infiltration and were repellent compared to soil in uninvaded abandoned agricultural fields and natural sites. It appears that the invasion of A. mearnsii in abandoned agricultural fields has triggered changes in soil physico-chemical properties.

Short Term Soil and Vegetation Recovery After Acacia Mearnsii Removal in Vhembe Biosphere Reserve, South Africa

“…Besides, the canopy of both natural and Acacia species has the potential to provide shelter for soil moisture thus making it high upon being captured by litter (Mugunga and Mugumo, 2013). The removal of A. mearnsii is expected to cause soils to become less repellent given that some studies have shown that invasion by A. mearnsii causes soils to be repellent (Ruwanza, 2017). Contrary, results of this study showed that soils in cleared areas were strongly repellent with the bulk being slightly repellent.…”

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

“…Furthermore, they endanger indigenous flora by contributing to genetic contamination and the extinction of distinctive genetic features [ 13 ]. Invasive plants also impact ecosystem services such as water quality, pollination, and soil nutrient cycles [ 10 , 14 ]. While attempts to battle these invaders are underway, continued, and sustained action is required to maintain South Africa's ecosystems and alleviate the varied repercussions of invasive alien plant species.…”

“…Acacia mearnsii and Acacia dealbata are among the top 10 and 25 invading species, respectively, occupying approximately 2.5 million hectares of South African land [ 19 ]. Much research has focused more on these species due to their wider spread, rapid invasion rates, and potential environmental damage [ 14 ]. 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] ].…”

“…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.…”

“…Nevertheless, the outcomes differ, which makes formulating specific suggestions for crucial ecosystem restoration tactics challenging. Ruwanza [ 14 ] reported that soil pH was significantly higher in uninvaded (4.64) as compared to Acacia mearnsii invaded soils (4.05). Similarly, Balintulo [ 18 ] found significantly higher pH levels in uninvaded compared to both Acacia dealbata cleared and invaded soils in the Tsitsa catchment of the Eastern Cape.…”