为探讨外来引种的互花米草（Spartina alterni f lora Loisel）在我国海湾的扩展过程，根据1989-2010年遥感影像和野外观测数据，对罗源湾互花米草的分布特征进行分析，结果显示，对该区互花米草近20a的扩展过程划分为3个阶段：前5a其沿着高潮带平行于海岸线呈带状扩展；之后5a在中潮带向湾内快速拓殖；后10 a则扩展缓慢，种群内部的空隙地逐渐被米草覆盖。截至2010年，罗源湾互花米草的总面积约为741．13 hm2。受潮滩环境分带性影响，罗源湾互花米草在高潮带平行于海岸线的扩展速度明显大于垂直于海岸线的扩展速度；在中潮带的快速扩展过程中互花米草倾向于先在潮沟两侧分布，这可能与归槽水和滩面摩阻作用有关，相比较，互花米草在浅洼地的扩展较滞后，该区域随着滩面的淤高过程逐渐被米草覆盖。在其整个扩展过程中，由于互花米草对潮流及悬浮颗粒的阻滞作用，使得其扩展前缘米草斑块和连续种群之间的光滩区成为悬浮颗粒及米草种子容易沉降的区域，互花米草易朝向该区域扩展。%As an“ecological engineer”,Spartina alterni f lora was introduced to China from North Carolina ,Geor-gia and Florida ,in 1979 ,and transplanted firstly in the Luoyuan Bay ,Fujian Province ,China .To explore the ex-panding process of S. alterni f lora ,their characteristics of distribution were analyzed using the remote sensing data of 1989-2010 and field investigations as well .The results show that the expanding process of S .alterni f lora on the tidal flat can be divided into three phases :the first phase of 1989-1994 ,where it expands along the high tidal zone;the second phase of 1995-2000 ,the coverage of S .alterni f lora increases rapidly in the middle tidal zone ;the last 10 a of 2000-2010 ,it expands slowly obviously ,and the gaps area within populations is covered gradually by the vegetation .In the Louyuan Bay ,the total area of S .alterni f lora reached approximately 741.13 hm2 up to 2010 .The expanding rate of S .alterni f lora along the high tidal zone that is parallel to coastal line is higher great-ly than that in the area perpendicular to the coastal line ;meanwhile the S .alterni f lora exhibits different diffusion characteristics in different areas resulted from the impact of the tidal flow and particle deposition .During their quick diffusion ,S .alterni f lora appears to be distributed along the sides of tidal channels ,which may be related to the tidal flow into the tidal channels and the friction effect from sediment boundary .In comparison ,the expanding rate of the S .alterni f lora is slow in shallow depressions ,where is covered gradually by the plant with the deposi-tion of sediments .It is the inhibition effect of tidal flow and trapping effect of the fine particle form S .alterni f lora that makes an appearance of a special zone with a weak tidal flow between patches of the S .alterni f lora popula-tion .This area is a prevail zone for the potential spread of S .alterni f lora in the future .
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