青藏高原高寒草甸植物群落结构和功能对氮、磷、钾添加的短期响应

对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、钾及其组合的施肥处理,研究了施肥对植物群落结构和功能的影响。结果表明:(1)施肥使矮嵩草草甸植物群落物种丰富度减少,不同施肥处理下物种丰富度大小分别为:对照钾磷氮氮磷磷钾氮钾氮磷钾。(2)在氮磷配合施肥处理下,矮嵩草草甸植物群落Shannon-Wiener指数显著高于对照,而其它施肥处理对Shannon-Wiener指数影响不显著。(3)在同一施肥处理下,禾草类和莎草类的重要值明显高于豆科和杂类草功能群,不同施肥处理使禾草、莎草、豆科植物的重要值增加,而杂类草重要值减少。(4)与对照相比,不同施肥(除钾外)处理可不同程度的增加植物群落的高度。(5)除钾、磷钾养分添加对矮嵩草草甸地上生物量的影响与对照差异不显著外,其它养分及其组合添加都极显著增加了群落地上生物量,且大小顺序依次为氮磷氮磷钾磷氮钾氮磷钾钾对照。(6)施用不同种类的肥料后,矮嵩草草甸各功能群地上生物量的比例变化明显,禾草和莎草的比例均增加,杂类草的比例减少,而豆科植物无规律性。(7)熵值法综合评价短期施肥处理对矮嵩草草甸群落的影响表明,氮磷、氮磷钾配合施肥是青藏高原高寒草甸最佳施肥选择。

Short-term Responses of Plant Community Structure and Function to Nitrogen,Phosphorus and Potassium Additions in an Alpine Meadow of Qinghai-Xizang Plateau

Different fertilization approaches were used in the Kobresia humilis Meadow in Haibei Alpine Meadow Ecosystem Research Station in order to study the impacts on plant community structure and function.The results showed that:(1)Fertilization reduced the species richness,ranked in the following order:controlled trial>potassium>phosphorus>nitrogen>nitrogen-phosphorus>phosphorus-potassium>nitrogen-potassium>nitrogen-phosphorus-potassium.(2)The treatment,Shannon-Wiener index of nitrogen-phosphorus fertilization treatment was significantly higher than that of the controlled trial (P<0.05),while the other treatments had no significant effects on the Shannon-Wiener index.(3)Under the same fertilizer treatment,the important value of Gramineae,Cyperaceae and Leguminosae increased,but Forbs reduced;the important values of Gramineae and Cyperaceae were obviously higher than those of Leguminosae and Forbs.(4)Different fertilization (except potassium) treatments increased K.humilis meadow plant community height.(5)Potassium and phosphorus-potassium adding had no significant difference (P>0.05),while other nutrients and the combination of nutrients significantly increased K.humilis community aboveground biomass (P<0.01),and the order was that:nitrogen-phosphorus>nitrogen-phosphorus-potassium>phosphorus>nitrogen-potassium>nitrogen>phosphorus-potassium>potassium>controlled trial.(6)Under the different kinds of fertilizer,functional groups biomass ratio of K.humilis meadow changed significantly,Gramineae and Cyperaceae increased,Forbs reduced,and Leguminosae had no general rules.(7)Nitrogen-phosphorus and nitrogen-phosphorus-potassium were the best fertilization choices in this alpine K.humilis meadow on the Qinghai-Xizang Plateau,when comprehensive evaluated using the Entropy method.