科研之友
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摘要
The hypothesis tested in this study is that ice-scars recorded by lakeshore tree stands can be used as an integrative proxy indicator of the overall hydrodynamic disturbance regimes affecting northern lakeshores. A 2-km-long shore segment was divided into 21 sections according to shore orientation and slope. An ice-scar chronology and a wave exposure index value were obtained for each shore section. A significant relationship was found between ice-scar chronology and wave exposure index, which indicates that the mechanical action and physical force of ice activity mainly depend on the same environmental factors determining exposure to wave action (i.e. fetch, wind direction and velocity, and shore slope). The spatial and temporal variability of ice-scar chronology features also corresponded to the distribution of geomorphological features associated with ice activity along the shoreline. Analysis of the hydrological signal associated with these ice-scar chronology features indicated that an increase in ice-push frequency observed in the 1930s can be associated to an increase in wave action related to more frequent spring floods maintaining high lake levels during the ice-free period. This study demonstrates that ice-scars have strong potential as proxy indicators of shore exposure and provide a temporal frame to reconstruct the history of lakeshore disturbance regimes at a local scale. Together, ice-scars and wave exposure index provide essential information to interpret the evolution of lakeshore vegetation mosaics in time and space.
- 出版日期2012-10
