模拟遮荫对互花米草和海三棱蔗草种子萌发及幼苗生长的影响

通过绿色薄膜遮光模拟植被遮荫,研究了遮荫对外来种互花米草和土著种海三棱草种子萌发及幼苗生长的影响。结果发现:遮荫对互花米草种子萌发率没有影响,但显著降低了海三棱草种子的萌发率;在遮荫条件下,两种植物幼苗的高度显著增加,单株幼苗的茎叶干重和总干重显著降低,幼苗的1周相对生长率显著降低,其中海三棱草幼苗1周相对生长率降低的幅度明显大于互花米草。这表明,遮荫对海三棱草的幼苗更新和生长具有明显的抑制作用。互花米草群落对海三棱草的遮荫可能是其在长江口竞争取代海三棱草的一个重要机理。

Effects of Simulated Canopy Shade on Seed Germination and Seedlings Growth of Spartina alterniflora and Scirpus mariqueter

By simulated canopy shade with green filter,the seed germination rate and seedling growth of introduced Spartina alterniflora and native Scirpus mariqueter were studied.The results obtained here show that simulated canopy shade didn't influence the seed germination rate of S. alterniflora,but significantly decreased that of S. mariqueter. The shoot dry weight,total dry weight and relative growth rate of S.alterniflora and S. mariqueter was significantly lower in simulated canopy shade than that in control treatment respectively,and their shoot height was inversed.In particular,the reduced extent of relative growth rate of S. mariqueter was obviously greater than that of S. alterniflora in simulated canopy shade. This indicated that vegetation canopy shade could strongly restrain the seedlings recruitment and growth of S. mariqueter. Further,the competition displacement mechanism of S. mariqueter population by S. alterniflora might partly be explained from these experiment results in the Yangtze River estuary.