黄河三角洲湿地景观格局动态变化分析

Study on Dynamic Changes of Wetland Landscape Pattern in Yellow River Delta

在RS和GIS技术的支持下,以黄河三角洲1986,1996,2006年的三期TM影像为数据源,利用遥感图像处理软件对近代黄河三角洲湿地信息进行了提取。借助于地理信息系统软件和景观生态学软件,我们对20年来黄河三角洲湿地景观格局的动态变化,以及影响其格局动态变化的驱动力进行了分析。结果表明:(1)近20年来,人工湿地面积有了大幅度的增加,而天然湿地的比重在降低。其中,滩涂和柽柳灌草丛景观明显萎缩。(2)一些重要的景观格局指数的计算结果表明,20世纪90年代以来,黄河三角洲湿地景观斑块个数、香农多样性指数、香农均匀度指数一直在增加。黄河三角洲湿地景观的破碎化程度在加剧,斑块类型更加多样化,湿地景观中没有明显的优势类型且各斑块类型在景观中均匀分布。(3)湿地与湿地、湿地与非湿地之间发生着类型转化。其中,18.1%的芦苇草甸转化为农田;26.6%的翅碱蓬草甸转化为盐田;11.9%的芦苇沼泽转化为芦苇草甸。(4)在黄河三角洲湿地演化的过程中,受到自然和人为方面演化驱动力的共同作用。其中,自然因素主要有:黄河断流、泥沙淤积和自身演替动力等。人为驱动力主要为农田开垦、滩涂的开发与围垦、油田开发和人工建筑等。

In this paper, the information about wetland landscape features of the Yellow River Delta in 1986, 1996, and 2006 were extracted respectively based on TM images and by support of Remote Sensing （RS） and Geographic Information System （GIS） techniques. By analyzing the information, we investigate the spatial and temporal changes of wetland landscape and explore the driving forces for wetland landscape pattern change in the Yellow River Delta within the past 20 years. Our results show that： （ 1 ） the area of man-constructed wetland demonstrated a sharp increase, whereas the proportion of natural wetland decreased accordingly. As an important part of the natural wetland, the tidal flat and Chinese tamarisk shrub wetlands in the Yellow River Delta has significantly shrank in coverage and degraded during the past two decades. （2） Since 1990s, some of the important landscape indices such as the number of patches, Shannon＇s diversity index, and Shannon＇s evenness index have increased. This indicates that the fragmentation degree of wetland landscape in the Yellow River Delta intensified, the type of landscape was much diversified, and each type is distributed uniformly in the wetland landscape and no dominant wetland landscape types can be recognized. （3） Landscape style transfer occurred between wetland and wetland, wetland and non-wetland. During the interval from 1986 to 2006 A. D, about 18.1% Reed meadow had been transferred to farmland, 26. 6% Seablite meadow transferred to salt pan and 11.9% Reed swamp trans-ferred to Reed meadow. （4） The driving forces for wetland landscape pattern change analyses were conducted, and the result implies that both natural factors and anthropogenic factors have played important role in altering the pattern. The former includes decrease of discharge and sediment, self succession, while the latter mainly consists farmland reclamation, exploitation of tidal flat and oilfield development and construction.