论文部分内容阅读
Soil carbon (C) pools are not only important to governing soil properties and nutrient cycling in forest ecosystems,but also play a critical role in global C cycling.Mulch and weed control treatments may alter the soil C pools by changing organic matter inputs to the forest ecosystem.We studied the 12-month mulch and weed control responses on the chemical composition of soil organic C and the seasonal dynamics of water extractable organic C (WEOC),hot water extractable organic C (HWEOC),chloroform-released organic C (CHC13-released C),and acid hydrolysed organic C (acid hydrolysable C) in a hardwood plantation of subtropical Australia.The results showed that compared to the non-mulch treatment,the mulch treatment significantly increased soil WEOC,HWEOC,and CHCl3-released C over the four sampling months.The weed control treatment significantly reduced the amount of HWEOC and CHCl3-released C compared to the no weed control treatment.Either the mulch or weed control treatment did not significantly affect soil acid hydrolysed organic C.There were no significant seasonal variations in soil WEOC,HWEOC,CHCl3-released C,and acid hydrolysed organic C in the hardwood plantation.Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy was used to study the structural chemistry of soil C pools in HF (hydrofluoric acid) treated soils collected 12 months after the mulch and weed control treatments were applied.Overall,O-alkyl C was the dominant C fractions,accounting for 33-43% of the total NMR signal intensity.The mulch treatment led to higher signal intensity in the alkyl C spectral region and A/O-A ratio (the ratio of alkyl C region intensity to O-alkyl C region intensity),but lower signal intensity in the aryl C and aromaticity.Compared to the no weed control treatment,the weed control treatment reduced signal intensity in the aryl C and aromaticity.Together,shifts in the amount and nature of soil C following the mulch and weed control treatments may be due to the changes in organic matter input and soil physical environments.