Vegetation recovery dynamics of tropical lowland rain forest in Bawangling of Hainan Island, South China

Abstract

Aims Our objective was to elucidate the trajectory and pattern of tree succession on lands abandoned after mul-tiple 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,espe-cially 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 composi-tion may take centuries or never occur.This should be considered when structuring successional models and pre-dicting carbon accumulation in tropical forest.