上海外环线绿地群落凋落物对土壤水分物理性质的影响

Effects of greenbelt plant communities' litterfalls in Shanghai Outer Ring on soil water physical properties

选取上海外环线绿化带8个人工植物群落为对象，以裸地为对照，研究了凋落物量、土壤孔隙性状和持水特性，探讨了城市绿地群落凋落物对土壤水分物理性质的影响。结果表明：各群落0～10cm土壤的最大持水量、毛管持水量、最小持水量、质量含水量、体积含水量、毛管孔隙度、非毛管孔隙度、总孔隙度和土壤通气度均显著高于裸地（P〈0．05），而容重均显著低于裸地（P〈0．05）；10～20cm土壤水分物理性质差异不显著；凋落物年凋落量与绿地群落0～10cm土壤毛管孔隙度呈显著负相关，而与绿地群落0～10cm土壤持水特性相关性均不显著；凋落物现存量与绿地群落0～10cm土壤总孔隙度和通气度呈显著正相关，与0～10cm土壤容重呈显著负相关；而凋落物年凋落量、现存量与绿地群落10～20cm土壤水分物理性质相关性均不显著；绿地群落凋落物蓄积能有效改善绿地群落内表层土壤（0～10cm）水分物理性质，主要是改良土壤孔隙状况；在绿地养护中应保留绿地群落凋落物。

Taking eight artificial plant communities in the greenbelts of Shanghai Outer Ring as test objects and with bare land as the control, this paper studied the amount of litter falls and the characteristics of soil porosity and water-holding, aimed to approach the effects of the litter falls of urban greenbelt plant communities on soil water physical properties. The results showed that in upper soil layer （0-10 cm） , soil maximal water-holding capacity, capillary water-holding capacity, minimal water-holding capacity, mass water content, volume water content, capillary porosity, non-capillary porosity, total porosity, and aeration were significantly higher （ P 〈 0. 05 ） in greenbelts than in bare land, while soil bulk density was in adverse ; but in lower soil layer （ 10 -20 cm） , there were no significant differences in these parameters between greenbelts and bare land. The capillary porosity in upper soil layer had significant negative correlation but water-holding characters had less correlation with annual litterfall, and the total porosity and aeration had significant positive correlations but bulk density had significant negative correlation with litter stock. No significant correlations were observed between the water physical properties in lower soil layer and the annual litterfall and litterfall standing stock. It was suggested that the litterfall stock of greenbelt plant communities could effectively improve soil water physical properties, especially the porosity of upper soil layer, and thus, should be reserved during urban greenbelt management.