Understory vegetation removal reduces the incidence of non-additive mass loss during leaf litter decomposition in a subtropical Pinus massoniana plantation

Abstract

Improvement cutting or harvesting can change the coverage of understory vegetation, which can significantly influence the litter decomposition process in plantations. However, difference in potential non-additive mass loss in response to understory vegetation changes is poorly studied. A field litterbag experiment involving various litter types and treatments with no understory vegetation removal, shrub removal, herb removal and whole-understory vegetation removal was conducted to examine non-additive mass loss. During approximately 2 years of decomposition, the decomposition rate of shrub and herb components was accelerated in the mixed litter with full understory vegetation. There was significant non-additive mass loss during decomposition in the plots with trees, shrubs and herbs, while the incidence of non-additive mass loss was lower in the plots with understory vegetation removal. Statistical analysis revealed a significant difference between the expected mass loss calculated with the data from the corresponding decomposition plots and that calculated with the data from the plots with whole-understory vegetation removal. Our results show that understory vegetation removal can inhibit litter decomposition in Masson pine plantation ecosystems in subtropical China. We highlight that non-additive litter decomposition should be assessed on the basis of litter species composition and decomposition microenvironments in situ.