| 英文摘要： |
Although the response of plant productivity and soil biogeochemical processes to nutrient addition has been widely investigated, little is known about the effects of N and P addition on soil aggregate fractions, an important indicator of soil organic C stability. We investigated the effects of exogenous N and P inputs on soil aggregates and their associated organic C in a 6-year fertilisation experiment in a subtropical Chinese fir (Cunninghamia lanceolata) plantation. A wet sieving method was used to determine the aggregate size distribution. Our results showed that the most abundant aggregate was the macroaggregate, ranging between 59% and 74%. The least abundant fraction was the smallest (silt and clay), ranging between 10% and 15%. Neither the soil aggregate fractions nor their associated organic C differed significantly after 6 years of N and P addition at the 0.05 level. In contrast, the oxalate-extractable iron Fe and pyrophosphate-extractable Fe of 0-10 cm soil were significantly decreased by P addition; this may alter aggregate formation over longer periods. Thus, future studies should examine the effects of nutrient addition on aggregates over a longer period. In particular, more attention should be paid to the effects of P addition in subtropical forests. |
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