<![CDATA[Integrated cattle–oil palm farming systems (SISKA) have been widely promoted in Indonesia, yet quantitative information on the forage potential of plantation understory vegetation remains limited and site-specific. This study assessed the composition, dominance structure and dry-matter (DM) attributes of understory vegetation in smallholder oil palm plantations (<10 years old) managed under a cattle–oil palm integration scheme in Tanah Laut Regency, South Kalimantan, Indonesia. Vegetation was sampled using twenty 1 × 1 m quadrats per site. For each species, relative density (RD), relative frequency (RF) and a simplified Importance Value Index (IVI = RD + RF) were calculated. Palatability was confirmed by direct observation of cattle intake, and DM content was determined by oven-drying herbage samples to constant weight. A total of 12 species from 7 families were recorded, consisting of grasses (Poaceae), sedges (Cyperaceae), legumes (Fabaceae) and broad-leaved forbs. The understory was strongly dominated by grasses, with Axonopus compressus showing the highest RD (60.36%), RF (16.67%) and IVI (77.03), and a relatively high DM content (33.51%), making it the keystone species in the ground layer. Almost all species (11 of 12; 92%) were classified as palatable to cattle, while only Peperomia pellucida was rejected and contributed negligibly to DM due to its low abundance and very low DM percentage (5.78%). The coexistence of productive grasses, nitrogen-fixing legumes and various forbs indicates a moderately diverse understory community that can provide a continuous, though heterogeneous, forage supply. These findings provide a site-specific, vegetation-based baseline for estimating forage DM potential and designing grazing strategies in SISKA systems, contributing to more productive and sustainable cattle–oil palm integration in Indonesia.]]>
