Ecological linkages between understory vegetation, insect communities, and soil chemical properties in different oil palm plantations

The ecological sustainability in oil palm plantations depends on the complex relationship between biodiversity and soil health. This study investigated the influence of plantation management practices which are different planting spacing of oil palm trees and different method of collecting oil palm fruit bunch on the diversity and abundance of understory vegetation, insect communities and soil chemical properties in two oil palm plantations in Selangor. The diversity and abundance of understory vegetation and insects inhabiting the understory in plantations were quantified using a quadrat, sweep net and handpicking. Soil quality was assessed by comparing the pH levels, electrical conductivity, organic matter (OM), and organic carbon (OC) content at both plantations. A total of 45 understory vegetation species and nine genera were identified from both plantations. Plantation 1 recorded 31 species and five genera with a total of 1630 individuals while Plantation 2 recorded 17 species and four genera with 1248 individuals. Nephrolepis spp. were among the most abundant vegetation species identified from both plantations. The differences in the number of understory vegetation between the plantations were significant as higher planting spacing and traditional methods of oil palm crop collection support more plant richness and abundance. Furthermore, Plantation 1 recorded 1238 insect individuals while Plantation 2 recorded 1160 individuals. Insects from this study were classified into 15 orders and 80 families, with 13 orders and 57 families recorded from Plantation 1 and 11 orders and 59 families in Plantation 2. Ants or the family Formicidae was the predominant insect family collected. The number of insects between plantations did not differ significantly as P > 0.05. Variations in the number of understory vegetation and insects between the areas and plantations were attributed to the differences in human and agricultural activities, resource availability, and plantation management. Regression analyses revealed insignificant relationships between the number of understory vegetation and the number of insects in both plantations. Soil chemical properties (pH, EC, OM and OC) also showed no significant difference with the number of understory vegetation and insects from both plantations except for the number of insects and EC in Plantation 2. These results were suspected primarily due to the human activities, and plantation management. These findings highlighted the vital role of plantation management practices in promoting biodiversity and their potential positive influence on soil quality. The results underscored the importance of sustainable management approaches in enhancing the ecosystem within oil palm plantations in conjunction with the national agenda in SDG goals.