围垦对海滨地区景观演变及其质心移动的影响——以盐城保护区部分区域为例

将盐城国家级自然保护区(新洋港-四卯酉河段)划分为未围区和围垦区,根据1984-2013 年6 个时相的景观资料,运用RS、GIS 技术和景观生态学方法,分析围垦活动影响下海滨湿地景观格局演变差异。结果如下:①未围区始终保持以自然景观为主,2013 年面积比例占84.6%;1984-2013 年,芦苇和互花米草湿地面积分别增长了4 770.6 和4 202.8 hm²,而碱蓬湿地面积减少了2 656.7 hm²。围垦区大致以2000 年为界,景观结构由自然景观占主导转为人工景观为主;除互花米草外自然植被面积呈下降趋势,而人工景观中水产养殖塘面积不断上升,2013 年比例达60.5%。②未围区景观破碎度自1995 年以后变幅较小,且保持在较低水平,维持在0.27~0.28,斑块形状趋于复杂、自然,景观多样性呈上升趋势,1984-2013 年上升了0.19。围垦区破碎化程度上升明显,1984-2013 年上升了0.27,整体景观趋于简单规则,景观多样性呈下降趋势,1984-2013 年下降了0.26。③未围区景观演变驱动力以自然因素为主,景观类型质心移动具有距离较为连续、方向相对单一的特征。而围垦区由于人类活动介入,围垦区景观类型质心移动更多地表现出无序多变、错综复杂的特征。

Effects of Coast Beach Reclamation on the Change of Landscape Pattern and Its Spatial Centroids: A Case Study in Coastal Wetland of Part of Yancheng National Natural Reserve

Landscape pattern change has received much attention in recent years, since they provide key information of the effects of human activities on landscape. Most of past works mainly focused on the whole landscape pattern rather than the internal variation of the landscape. Meanwhile, lots of studies are about urban area, watershed, forest and wetland, while few have been done on the coast. In China, works about landscape change in the Liaohe River Delta, the Yellow River delta and the Zhujiang River Delta have been conducted at the county scale, and some works have been done concerning the features of coastal landscape at the national scale. To investigate the impact of reclamation on the landscape pattern of coastal wetlands, in this paper, Yancheng National Natural Reserve (from Xinyang Port to Simaoyou River) was chosen as the study area. This area was divided into two parts: unreclaimed (from Xinyang Port to Doulong Port) and reclaimed (from Doulong Port to Simaoyou River) zones. Supported by RS, GIS and FRAGSTATS technologies, using remote sensing data from 1984 to 2013 as basic information resource, the impacts of reclamation on the change of coastal wetland landscape pattern and the displacement of patches' centroids were analyzed. The results indicated that: 1) In unreclaimed zones, the natural landscape remained dominant in the landscape structure, taking 84.6% of the area in 2013. From 1984 to 2013, the wetland of Pragmites communis and Spartina spp. increased by 4770.6 hm² and 4202.8 hm² respectively, while the wetland of Saueda spp. decreased by 2656.7 hm². In reclaimed zones, massive original natural landscape converted to artificial landscape types during 1984-2013, and the artificial landscape held dominant position in the landscape structure since 2000. The natural vegetation area continuously decreased except Spartina spp., while the aquaculture pond area increased rapidly, reaching 60.5% of the area in 2013. 2) In unreclaimed zones, the landscape fragmentation remained at low level (from 0.27 to 0.28) after 1995, while the shape of patches trended to be complex and irregular. And the landscape diversity increased by 0.19 from 1984 to 2013. On the contrary, in reclaimed zones, the landscape fragmentation had a significant increase of 0.27 during 1984-2013, while the patches' shape trended to be simple and regular, and the landscape diversity decreased by 0.26. 3) In unreclaimed zones, the main driving factor of landscape pattern change was natural forces, and the centroids of landscape types moved continuously and keep the same direction. Conversely, because of the intervention of human activities, the movement of landscape type centroids in reclamation zones was disordered, variable and intricate.