Seasonal Variation in Soil Nematode Communities Associated with Different Plants in Sovenga Hills, Limpopo Province, South Africa

Soil nematodes are sensitive indicators of soil ecosystem functioning, yet their seasonal dynamics across tree hosts and edaphic gradients are poorly documented in southern Africa. We sampled rhizosphere soils of pomegranate (Punica granatum), lemon (Citrus sp.), and fig (Ficus carica) across four seasons in Sovenga Hills, Limpopo Province. We explicitly state that the rhizospheres of pomegranate, lemon, and fig were selected because they represent widely cultivated fruit trees in smallholder systems across Limpopo Province, where soil management practices and climate variability may influence nematode community dynamics. The hypothesis is that nematode assemblages exhibit seasonal shifts in diversity, trophic composition, and ecological indices across these hosts. The nematode genera were identified morphologically using standard diagnostic keys. A total of 29 genera were recorded. Bacterivores and herbivores dominated the assemblage, while fungivores, predators and omnivores were less abundant. Notably, Ditylenchus (fungivores) exhibited the highest Prominence Value (PV = 7926.1) and occurred in 83% of samples (Frequency of Occurrence (FO%) = 83), followed by a plant-parasitic nematode, namely Rotylenchulus (PV = 3279.8; FO% = 83%). Shannon diversity ranged from 2.09–2.34, and Maturity Index (MI) varied from 2.41–2.78 across seasons. Food-web indicators showed an enrichment index (EI) of 17–38 and structure index (SI) of 49–71, suggesting a moderately structured but dynamic soil food web. Spring communities exhibited the highest abundance (mean 471.7 individuals), biomass (0.49 µg), and composite/metabolic footprints, while autumn showed higher maturity and structural indices; summer recorded the lowest abundance and biomass. Principal component analysis (PCA) showed a total of 40.78% variation among the samples collected from different seasons and separated winter communities from autumn/spring ones (which partially overlapped). Soil pH, nitrate, phosphate, texture (sand/clay/silt), and electrical conductivity strongly associated with the observed seasonal patterns. The observed seasonal trends suggest that PV and FO% may serve as informative indicators for tracking shifts in nematode assemblages, but these patterns were not statistically significant (p > 0.05) and should therefore be considered preliminary rather than conclusive. These results highlight pronounced seasonal shifts in nematode assemblages and confirm PV and FO% as useful metrics for monitoring soil ecosystem dynamics.