青藏高原高寒草甸花期物候和群落结构对氮、磷、钾添加的短期响应

在中国科学院海北高寒草甸生态系统定位站的矮嵩草草甸水肥样地进行了氮、磷、钾施肥添加试验,研究了施肥对植物花期物候和群落结构的影响。结果表明,施肥使矮嵩草草甸有效积温增加,地下5cm和地上10cm有效积温的大小均为:氮磷钾对照;施肥使垂穗披碱草、甘青剪股颖、冷地早熟禾、矮嵩草、黑褐薹草、双柱头藨草、美丽风毛菊的始花期、终花期显著推迟(P0.05),而鹅绒委陵菜和麻花艽的始花期、终花期显著提前(P0.05);施肥后禾草的花期持续期小于莎草和杂类草;与对照相比,垂穗披碱草-麻花艽、垂穗披碱草-美丽风毛菊、甘青剪股颖-麻花艽和冷地早熟禾-麻花艽的开花时间(始花期)上的差异变小,种间开花时间重叠增加;非度量多维尺度分析的检验结果为,对照、钾、磷和氮处理下其群落之间的相似程度逐渐降低,添加氮、磷促进了非相似性群落的形成。熵值法综合评价分析得出,对矮嵩草草甸添加氮、磷后,花期物候响应较为敏感的物种为:垂穗披碱草、矮嵩草、麻花艽和美丽风毛菊。

Short-term responses of flowering phenology and community structure to nitrogen,phosphorus and potassium in an alpine meadow on the Qinghai-Tibetan Plateau

Fertilizers (N,P & K)were applied to a Kobresia humilis meadow at the Haibei Alpine Meadow E-cosystem Research Station to determine the effects of fertilizer on plant flowering phenology and community structure.Fertilizer application increased the effective accumulated soil temperature at 5 and 10 cm depth:ni-trogen>phosphorus>potassium>control treatment.The first floweing day and end flowering day was delayed in a number of plant species including Elymus nutans ,Agrostis hugoniana ,Poa crymophila ,Kobresia humi-
lis ,Carex atrofusca ,Scirpus distigmaticus and Saussurea superb (P <0.05),whereas in Potentilla anserine and Gentiana straminea flowering was advanced (P <0.05).Flowering duration in Gramineae was lower than in Cyperaceae and Forbs following fertilizer application.The application of nitrogen and phosphorus promoted the formation of a heterogeneous community.Heterogeneity,assessed using nonmetric multidimensional scal-ing,was lowest in control fertilizer treatments followed by potassium,phosphorus,and finally nitrogen appli-cation.It was concluded that E .nutans ,K .humilis ,G.straminea and S .superb were sensitive to the applica-tion of nitrogen and phosphorus in K .humilis meadow.