Decadal Changes in Habitat-Type Coverage on Horn Island, Mississippi, U.S.A.

Barrier island geomorphic features change over relatively brief timescales in response to the combined effects of wind, waves, currents, sediment supply, coastal subsidence, sea-level rise, and tropical cyclones. Consequently, alterations in the vegetation composition occur with these physiographic changes. A greater understanding of the extent to which such changes have occurred in recent decades may indicate the likely response of barrier islands to the currently anticipated acceleration in sea-level rise and increase in tropical storm frequency and severity under a climate-warming scenario. Using ground data in conjunction with hyperspectral, Light Detection and Ranging (LIDAR), and historical data, this study classified and mapped vegetation on Horn Island, Mississippi, and compared the island land area and habitat-type distribution in 2004 vs. 1978. Total vegetation cover as a percentage of total land area remained virtually unchanged during the 1978–2004 period. However, the relative coverage of wetland habitat types increased, whereas coverage of drier habitat types declined from 1978 to 2004, suggesting an overall modification of island communities in response to relative sea-level rise, storm events, and reduced sediment availability. A noticeable portion of the loss of drier woodland and stable dune habitats was a consequence of changes in land area and elevation on the eastern end of the island