“Fertile island” of Tamarix Chinensis accelerated the carbon decomposition in the coastal wetlands of the Yellow River Delta, China

Fertile island of shrub in the grass-dominated ecosystems would change the spatial distribution of soil organic carbon (SOC) and its fractions, adjusting the SOC dynamics and its response to global warming. However, the effects of fertile island on SOC decomposition and its temperature responses were still less known. An incubation experiment was conducted to investigate how the fertile island of Tamarix Chinensis affects SOC decomposition and its temperature sensitivity (Q10) in the coastal wetlands of the Yellow River Delta, China. Soil samples were collected from two areas, Tamarix Chinensis growing on bare land (SB) and the mixed-growing area of Tamarix Chinensis and herbage (SH). In each area, soil samples were collected from three sites, under the canopy of Tamarix Chinensis (CM), at the edge of the canopy (CP), and outside the canopy (OL). Results showed that the cumulative CO2 production increased from OL to CM due to the following reasons. Fertile island enriched SOC, labile fractions (i.e., O-alkyl and di- O-alkyl C), ammonium under the canopy in both sample areas and increased the relative abundance of labile SOC fractions (i.e., O-alkyl C) in SB, supplying more substrates for microbial decomposition. Subsequently, fertile island stimulated β-glucosidase and invertase activities, accelerating SOC decomposition. Moreover, fertile island decreased the Q10 value in the SB area because of the increased relative abundance of O-alkyl C. This study highlights the importance of O-alkyl C on SOC decomposition and its temperature sensitivity in the coastal wetlands of the Yellow River Delta.