Plant-Parasitic and Free-Living Nematode Community Associated with Oak Tree of Magoebaskloof Mountains, Limpopo Province, South Africa

A study was conducted in the mountains of Magoebaskloof, Limpopo Province, where oak trees grow along the banks of the Broederstroom River. This study revealed that 22 nematode genera were associated with oak trees (<i>Quercus robur</i>). The most frequently occurring nematodes were <i>Aphelenchus</i> sp. (100%) and <i>Plectus</i> sp. (100%), followed by <i>Helicotylenchus</i> sp. (90%). This study examined the relationship between nematodes and the physicochemical properties of the soil using Pearson correlation. It uncovered that the organic matter content (OMC) had a negative correlation with the number of <i>Panagrolaimus</i> sp. (<i>r</i> = −0.770) and <i>Hemicycliophora</i> sp. (<i>r</i> = −0.674). Conversely, the sand percentage positively correlated (<i>r</i> = 0.695) with the number of <i>Hemicycliophora</i> sp. The clay content of the soil showed a positive correlation (<i>r</i> = 0.617) with the number of <i>Ditylenchus</i>. Soil pH demonstrated a significant negative correlation with <i>Acrobeloides</i> sp. (<i>r</i> = −0.877). The canonical correspondence analysis (CCA) explained 63.3% of the relationship between nematodes and soil physicochemical properties. The CCA results indicated that <i>Ditylenchus</i> exhibited a positive correlation with OMC, while the <i>Panagrolaimus</i> and <i>Hemicycliophora</i> species showed a negative correlation with OMC. The results indicated that none of the soil sample sites were under stress. The soil food web analysis revealed that most soil samples were nutrient-enriched with a low C/N ratio. In conclusion, this study revealed that oak trees harbor a high diversity of plant-parasitic and free-living nematodes. The results suggest that soil nematodes, particularly free-living bacterivores, such as <i>Panagrolaimus</i>, can indicate organic matter content in the soil.