杭州湾南岸围垦土地人类活动强度及对滨海湿地覆被类型的影响

Impacts of human activity on coastal wetland land cover changes related to reclamation on the south coast of Hangzhou Bay

滨海湿地是海陆过渡地带重要的生态系统,开展人类活动对滨海围垦湿地的强度评价,对总结围垦土地覆被类型演变规律、维护滨海湿地生态安全、切实提高海岸带土地资源管理和滨海湿地保护水平具有重要意义。基于Markov、土地开发利用及强度评价模型,构建人类活动强度评估体系,揭示杭州湾南岸滨海湿地的围垦开发强度及覆被类型时空演变规律,并展开一定讨论。研究发现:(1)研究区围垦土地的人类活动强度自南向北呈条带状递减,与距海距离密切相关,土地开发程度不断深化,低活动强度的土地面积逐渐减少,城市建设进程推进显著;(2)滨海围垦土地主要向中度、极高度开发方向转变,人类开发活动普遍高出原土地2~3个强度级,开发增强区分布范围不断扩大,由南向北呈“向海式”扩张,结构上逐渐由分散型向“连片式”转变;(3)滩涂和草滩湿地等自然地类的人工化程度不断加强,逐渐向人工鱼塘及建设用地方向转化。滩涂—草滩湿地、滩涂—水体、草滩湿地—水体、草滩湿地—建设用地是4种主要地类转变组合;(4)围垦土地人类活动强度分异特征显著,滨海乡镇区域内低活动强度的土地分布面积广、开发潜力大、开发前后强度变化差距较大;内陆乡镇已有土地的人工开发程度高、低强度土地存量小、整体土地开发度变化细微。

Coastal wetlands are important ecosystems in the transition zone between sea and land.Therefore,it is important to determine the intensity of human activity,land development,and reclamation related to coastal wetlands in order to maintain their ecological security and effectively improve the management of coastal land resources and coastal wetland protection levels.Based on a Markov model for land development and utilization intensity evaluation,this study constructed a human activity intensity assessment system to reveal the temporal and spatial evolution of land development intensity related to coastal wetland reclamation along the south coast of Hangzhou Bay,China.The key results are as follows:(1)The human activity intensity of reclamation land decreases from south to north,which is closely related to distance from the sea.The degree of land development is increasing with time,whereas the area of land with low development is gradually decreasing,and the urban construction process is progressing significantly.(2)Coastal reclamation land is typically evolving toward medium and extremely high development directions,and human activity intensity is generally 2–3 levels higher than that of the original land.Spatially,the distribution area of development reinforcement is expanding continuously from south to north.The type of sea expansion has gradually changed from decentralized to continuous.(3)Natural land,such as tidal flats and grass beach wetlands,has become progressively more artificial through transformation into artificial fish ponds and construction land.Tidal flats/grass beach wetlands,tidal flats/water,grassland wetlands/water,and grassland wetlands/construction are the four main combinations of land transformation.(4)The characteristics of differentiation of reclaimed land vary between towns.In other words,coastal towns have more areas of low intensity human activity land with large development potential,and a large difference in intensity before and after development.Conversely,inland villages exhibit a high level of land development,a small area of low-intensity land,and a minimal change in overall land development.