不同施肥措施对我国南方稻田表土有机碳含量及固碳持续时间的影响

基于我国南方38个稻田试验点222个样本的表土有机碳数据，设5种施肥措施类型［无机氮肥(N)、无机氮磷肥配施(NP)、无机氮磷钾肥配施(NPK)、单施有机肥(O)和有机无机肥配施(OF)］，研究了不同施肥措施下我国南方稻田表土有机碳含量的相对年变化量和固碳持续时间.结果表明：5种施肥措施下，稻田表土有机碳含量相对年变化量集中在0～0.4 g·kg^-1·a^-1，两熟制和三熟制的表土有机碳含量相对年均增量分别为0.20和0.26 g·kg^-1·a^-1；有机肥处理(O和OF)比无机肥处理(N、NP和NPK)的表土有机碳含量相对年增量更高，其中，OF处理最高，为0.32 g·kg^-1·a^-1；随着时间的延长，土壤有机碳的累积速率逐渐降低，N、NP、NPK、O和OF处理下表土固碳持续时间分别为22、28、38、57和54年.从土壤固碳角度考虑，有机无机肥配施为我国南方稻田最佳施肥措施.

Community structure and functional groups of soil macrofauna in urban green spaces of Yancheng City, Jiangsu Province in spring

In the last ten-day of April 2011,an investigation was conducted on the soil macrofauna in five different urban green spaces(poplar plantation,park green space,nursery,lawn,and rapeseed field) in Yancheng City of Jiangsu Province,aimed to understand the community structure and functional groups of soil macrofauna in the City in spring.There existed significant differences in the macrofauna group number and abundance among different green spaces.The number and abundance of the functional groups followed as phytophage > saprozoic > camivorous.An obvious surface assembly phenomenon of soil macrofauna was observed.Green space type,soil layer,and their interaction had significant effects on the group number and abundance of soil macrofauna.Among the green spaces except lawn vs.rapeseed field and nursery vs.park green space,there were significant differences in the abundance frequency distribution of phytophage and non-phytophage.Hierarchical clustering and non-metric two-dimensional scaling ordination showed that the soil macrofauna communities were similar between lawn and rapeseed field,but differed between other green spaces.