Changes in biotic and abiotic drivers of seedling species composition during forest recovery following shifting cultivation on Hainan Island, China

Seedlings play an important role in the processes of plant community succession. We compared seedling (dbh < 1 cm) species composition and diversity over a chronosequence (18-, 30-, 60-year-old second growth and old growth forest) after shifting cultivation in a tropical lowland rain forest area on Hainan Island, China. Seedling diversity reached a maximum in the 60-year-old second growth forest, which is consistent with the intermediate disturbance hypothesis. With the progression of secondary succession, canopy openness (CO), soil organic matter, soil phosphorus content, and tree abundance showed a general decreasing trend; soil water content and tree basal area showed a general trend of increase, while soil pH and other nutrients reached maximum values and tree richness reached a minimum value at intermediate stages of succession. Seedling composition and diversity were significantly affected by soil water, pH, soil nutrient content, and biotic factors in the 18-year-old second gr...