放牧对三江源区高寒草甸主要植物表型特征的影响

摘要

矮嵩草和高原早熟禾是青藏高原的主要优势植物，研究其对放牧的表型反应对揭示高寒草甸生态系统的放牧响应机制具有代表意义。以青藏高原三江源区高寒草甸为例，通过设置自由放牧与围封禁牧试验，研究了高原早熟禾和矮嵩草茎叶功能性状对放牧的响应。结果表明：与围栏禁牧相比，放牧抑制了高原早熟禾和矮嵩草的生长，导致了2种植物株高、叶面积的显著下降(P <0.05)，植物个体表现出明显的矮小化现象。而长期放牧后，短期围封对于植物叶片数、根长、根粗等功能性状的恢复效果并不显著(P >0.05)，说明放牧退化草原植物性状具有保守性。%Kobresia kansuensis and Poa crymophila are the dominant plants on the Qinghai-Tibetan Plateau, their responses to grazing were studied.The results show that both plant height and leaf area under grazing were significantly lower than them under fencing condition (P < 0.05 ).Individual plants showed obviously dwarfed phenomenon.The short-term fencing was not significantly changed the plant leaf number,root length, root thickness and other functional traits after suffering from a long term grazing(P >0.05).It suggested that plant functional traits degraded under grazing.Therefore,plant dwarf phenomenon was an important trigger mechanism of structural and functional changes in grassland ecological system.