Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan 410125, China.
Huanjiang Observation and Research Station for Karst Ecosystems, Huanjiang, Guangxi 547100, China.
Sci Rep. 2017 Feb 17;7:41402. doi: 10.1038/srep41402.
Understanding the effect of land use on soil carbon, nitrogen, and microbial activity associated with aggregates is critical for thorough comprehension of the C and N dynamics of karst landscapes/ecosystems. We monitored soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC), and C: C ratio in large macro- (>2 mm), small macro- (0.25-2 mm), and micro- (0.053-0.25 mm) aggregates to determine the changes in soil properties under different land uses in the karst area of Southwest China. Five common land-use types-enclosure land (natural system, control), prescribed-burning land, fuel-wood shrubland, pasture and maize fields-were selected. Results showed that pasture and maize fields remarkably decreased the SOC and TN concentrations in aggregates. Conversion of natural system to other land uses decreased MBC (except for prescribed-burning) and increased C: C ratios in aggregates. The extent of the response to land uses of SOC and TN concentrations was similar whereas that of MBC and C: C ratios differed across the three aggregate sizes. Further, the SOC concentrations were significantly higher in macro-aggregates than micro-aggregates; the MBC and C: C ratios were highest in small macro-aggregates. Therefore, small macro-aggregates might have more active C dynamics.
了解土地利用对与团聚体相关的土壤碳、氮和微生物活性的影响，对于深入理解喀斯特景观/生态系统的碳和氮动态至关重要。我们监测了土壤有机碳 (SOC)、总氮 (TN)、微生物生物量碳 (MBC) 和 C:C 比在大团聚体（>2 毫米）、小团聚体（0.25-2 毫米）和微团聚体（0.053-0.25 毫米）中，以确定在不同土地利用方式下土壤性质的变化在中国西南喀斯特地区。选择了五种常见的土地利用类型——围封土地（自然系统，对照）、计划火烧地、薪柴灌丛地、草地和玉米地。结果表明，草地和玉米地显著降低了团聚体中的 SOC 和 TN 浓度。将自然系统转化为其他土地利用方式会降低 MBC（计划火烧地除外）并增加团聚体中的 C:C 比。SOC 和 TN 浓度对土地利用的响应程度相似，而 MBC 和 C:C 比在三种团聚体大小上有所不同。此外，SOC 浓度在大团聚体中明显高于微团聚体；MBC 和 C:C 比在小团聚体中最高。因此，小团聚体可能具有更活跃的碳动态。
