Forest biomass recovery after different anthropogenic disturbances: relative importance of changes in stand structure and wood density

Abstract

Restoring the functions of disturbed forest to mitigation climate change is a main topic of policy makers. Better understanding of factors that directly influence post- disturbance forest biomass recovery is urgently needed to guide forest restoration and management. In this study, we examine changes in forest stand structure, wood density and biomass of forests recovering from different anthropogenic disturbances that represent forest land-use types in sub- tropical China: plantation, twice-logged and once-logged secondary forests, and compare them with undisturbed old- growth forest. Stand structure and wood density in all dis- turbed forests were evidently different from that of old- growth forest, even after 50-year regrowth. Forest biomass increased along plantation, twice-logged, once-logged and old-growth forests, with total living biomass (TLB) ranging from 150.8 ± 4.6 to 278.4 ± 1.5 Mg ha -1 , aboveground biomass from 111.8 ± 4.2 to 204.1 ± 1.5 Mg ha -1 and coarse-root biomass from 33.0 ± 0.9 to 71.0 ± 0.8 Mg ha -1 . However, fine-root biomass was highest in plan- tation (5.99 ± 0.52 Mg ha -1 ) and lowest in once-logged forest (3.35 ± 0.19 Mg ha -1 ). Both changes in stand structure and functional trait (wood density) directly deter- mine forest biomass recovery according to the result that 10.6,35.5and8.2 %ofvariationinTLBoverthedisturbance gradient were independently explained by basal area (\20 cmdiameter),basal area(C20 cmdiameter)andwood density,respectively.Ourresultssuggestthatrecoveryforest structure to the state associated with undisturbed forests will lead to large carbon sink in disturbed forests. In addition, trait-based managing approach should not be overlooked when maximizing carbon storage is a major management objective.