Abstract:

Aims Our objective was to elucidate the trajectory and pattern of tree succession on lands abandoned after multiple cycles of shifting cultivation in comparison to old-growth communities.

Methods We established seven 100 m × 100 m plots in lowland sites. There were two old-growth forest plots, one 12-year-old fallow plot, two 25-year-old fallow plots, and two 55-year-old fallow plots. We recorded species, diameter at breast height (DBH), and height of all woody stems (excluding lianas) ≥1 cm DBH in 100 subplots (10 m × 10 m) in each plot. Analysis methods included non-metric multidimensional scaling (NMS).

Important findings NMS showed large differences in community composition between fallow and old-growth forest, even after 55 years of natural recovery. Saplings (DBH < 5 cm) showed more convergence with old-growth forest composition than did adult trees (DBH ≥10 cm). Species accumulation rates for all three ages of fallow plots were slower than for old-growth forests. The recovery of community structure was relatively faster, especially for tree height, but structural complexity did not reach that of old-growth forests. Sprouting stems accounted for 39.9% of density and 55.9% of basal area in the 12-year-old fallow plot, but less in older plots. The proportion of three functional groups (pioneer, non-pioneer light-demanding and shade-tolerant species) showed directional patterns of change during succession, indicating that pattern of recovery was determined by life-history traits. However, cessation of recovery during mid succession indicated that return to pre-disturbance species composition may take centuries or never occur. This should be considered when structuring successional models and predicting carbon accumulation in tropical forest.

Key words: community recovery, disturbance, functional groups, Hainan Island, secondary forest, shifting cultivation, tropical lowland rain forest