Data from: 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 growth forests; by soil pH, soil nutrient content, and biotic factors in the 30-year-old second growth forests; by CO, soil nutrient content and tree abundance in the 60-year-old second growth forests; and by CO, soil pH, and soil nutrient content in the old growth forests. At earlier stages of succession, the effect of the proportion of old growth forest in the surrounding landscape on seedling diversity was greater than that of land-use history, but the importance of these drivers was reversed at later stages of succession.

幼苗在植物群落演替过程中发挥着关键作用。本研究针对中国海南岛热带低地雨林区域内刀耕火种后的演替序列（涵盖18年生、30年生、60年生次生林以及原始林），对比了不同样地内胸径（Diameter at Breast Height, DBH）小于1厘米的幼苗物种组成与多样性特征。幼苗多样性在60年生次生林中达到峰值，这一结果符合中度干扰假说（Intermediate Disturbance Hypothesis）。随着次生演替的推进，冠层开度（Canopy Openness, CO）、土壤有机质、土壤磷含量以及树木多度整体呈下降趋势；土壤含水量与树木胸高断面积则整体呈上升趋势，而土壤pH值与其他养分含量在演替中期达到峰值，树木物种丰富度则在该阶段降至最低。在18年生次生林中，幼苗组成与多样性显著受土壤含水量、pH值、土壤养分含量以及生物因子的调控；在30年生次生林中，其主要受土壤pH值、土壤养分含量与生物因子影响；在60年生次生林中，主要受冠层开度（CO）、土壤养分含量以及树木多度调控；而在原始林中，则主要受冠层开度（CO）、土壤pH值与土壤养分含量的影响。在演替早期阶段，周边景观内原始林占比对幼苗多样性的影响强于土地利用历史；但在演替后期，这两类驱动因子的重要性发生了反转。