Dynamics and mechanisms of natural restoration of evergreen-deciduous broadleaved mixed forest following clear cutting and slash-and-burn

ObjectiveWith great impacts on forest ecosystem, both clear cutting (CC) and shifting cultivation (slash-and-burn agriculture) were intensive disturbances. Our work aims to study the dynamics and underlying mechanisms of community characteristics of evergreen-deciduous broadleaved mixed forests (EDBMF) following CC and slash-and-burn. This work was also hypothesized to contribute to forest vegetation conservation and the construction of ecological forestry.

MethodUsing data from 98 plots of 20- and 40-year-old stands following CC and slash-and-burn, species abundance distribution (SAD), species composition, rarefied richness and stem abundance were applied to characterize community features. These characteristics were compared among different stands and diameter at breast height (DBH) classes with differences measured by multivariate statistical methods.

ResultThe rarefied richness and stem abundance among those communities were significantly different (P < 0.05): trees with large and intermediate DBH sizes in 20-year-old stand following CC had significant higher stem abundance and rarefied richness values than the 20-year-old stand following slash-and-burn; restoration process following slash-and-burn had changes in stem abundance different from that following CC, also showing significant and more substantial variations. Stands of different recovery stage following the same disturbance also had variation in their species composition at extremely significant level (P < 0.001): along with different restoration progresses, trees with small DBH sizes had relatively strong variations of species compositions, which also reflected shifts in ecological strategy; restoration following slash-and-burn had more obvious and large shifts in species compositions than that following CC. The SAD patterns showed that forest stands following slash-and-burn had higher species dominance, whereas the variations in species abundance declined as restoration from CC progressed.

ConclusionThe EDBMF undergoing CC displayed higher resilience after disturbance, whereas restoration from agricultural abandon merely exhibited higher recovery rate after a period of slow progress. This might be related to the effects of disturbances on abiotic and biotic resources, also reflecting the profound influences of slash-and-burn on community restoration. Moreover, even if the EDBMF showed slow processes of recovering species composition following disturbances, such processes were methodic to some degrees.