华南热带海岸生物地貌过程*

海岸生物地貌过程研究海岸带生物过程和动力-沉积-地貌过程之间的双向相互作用,是海岸生态系统响应和反馈全球变化的重要机制,被列为全球变化核心项目海岸带陆海相互作用研究的重点内容。20世纪90年代以来的调查研究揭示了华南红树林和珊瑚礁热带生物海岸生物地貌过程的主要特点。造礁石珊瑚的高生长率和珊瑚礁高堆积速率是珊瑚礁生物地貌过程的物质基础;红树林生态系统的高生产力、高归还率和捕沙促淤功能是红树林生物地貌过程的物质基础。热带生物海岸地貌结构显示分带性和生物地貌类型和动力地貌类型的叠加和共存,潮汐水位严格控制群落分布格局并形成重要的生物地貌界限。热带生物海岸生物地貌过程有利于消除或减缓海平面上升的浸淹效应。热带生物海岸不断加剧的人类活动干扰和生态破坏导致生物地貌功能削弱和海岸资源环境恶化。

BIOGEOMORPHOLOGIC PROCESS OF TROPICAL BIOLOGICAL COASTS OF SOUTH CHINA

Coastal biogeomorphologic process is the result of interaction between biological process and dynamical, sedimentary and geomorphologic processes in coastal zone. It is an important mechanism of the response and feedback of coastal ecosystems to global change and has thus became a focus content of the Land-Ocean Interaction of Coastal Zone, a core project of the Global Changes. The investigation and research since 1990s has revealed some main features of biogeomorphologic process on mangrove and coral reef tropical coasts in South China as follows. The material base for biogeomorphologic process of tropical coral reef coasts is from high growth rate of hermatypic coral and high accumulation rate of coral reefs, and that of mangrove coasts is from high productivity, high return rate and the function of trapping sediments. Landform pattern of tropical biological coasts showed zonation, overlapping, and coexist of biogeomorphologic units and dynamical geomorphologic units. The biogeo￣morphologic units include only mangrove flats in mangrove coasts and reef flats and reef slope in coral reef coasts. Tidal levels control severely community distribution pattern and form important biogeomorphologic boundary lines. The upper limit for the flat coral growth and boundary between inner and outer reef flats is about the Mean Lower Low Water of tropic tide. The limit for hard coral growth from scattered to luxuriant, as well as the break of slope from reef flat to reef slope, is about the Theoretical Lowest Tide. The lower and upper limits of mangrove habitat and mangrove flats are about the Mean Sea Level (or slightly above) and about the Mean Higher High Water of tropic tide respectively. Biogeomorphologic process of tropical biological coasts are beneficial to eliminating or retarding effects of sea level rise. As long as the rate of sea level rise is not higher than the rate of accumulation of coral reef or mangrove flat, coral reefs and mangroves may not be affected by sea level rise. Human activity disturbances and ecologically destructions in tropical biological coasts have reduced their biogeomorphologic function and have worsened coastal resources and environment. The study of biogeomorphologic process of tropical biological coasts in South China is important and practically significant for the study of land-ocean interaction, natural environmental variation and resource sustainable development in the coastal zone.