Sandblasting as a possible factor controlling the distribution of plants on a coastal dune system.
The intensity of the abrasive effect of wind-borne sand - sandblasting - in addition to other environmental factors was measured at two vegetation zones on a sandy beach and one site at an inland area in Chiba Prefecture, Japan. One zone on the beach included foredunes sparsely vegetated by dune species such as Carex kobomugi and Calystegia soldanella. The other zone, which was located ∼50 m inland from the first zone, was a flat grassland dominated by inland species such as Miscanthus sinensis and Imperata cylindrica var. koenigii. The inland site consisted of short grasslands located 3 km inland from the beach. The intensity of sandblasting was estimated by the whiteness of a transparent plastic sheet exposed to the air for 2 weeks. This sheet turned whitely opaque when it was abraded by wind-borne sand. The other environmental factors measured at the beach were intensity of salt spray, soil water content, soil salinity, and sand accumulation, while the intensity of salt spray was the only additional factor measured at the inland site. The intensity of sandblasting was considerably higher at the foredune zone, while that at the grassland zone was as low as that at the inland site. Considerable salt spray was detected at the foredune and grassland zones. Differences in other environmental factors were small between the two zones on the beach. In order to compare the difference in tolerance to sandblasting, a jet of sand was applied to one ordinary species, Carex kobomugi, from the foredune and two species, M. sinensis and I. cylindrica var. koenigii, from the grassland zone. The difference in tolerance was determined by the decrease in the area of green leaf after applying sandblasting with a commercial sandblaster and/or spraying with sea water. M. sinensis and I. cylindrica var. koenigii lost much of the leaf area after sandblasting and salt spraying, while Carex kobomugi lost only a little. These results indicated that one of the characteristic environmental factors of a foredune is the high intensity of sandblasting accompanied by salt spray, and that species found in the foredune are more tolerant to sandblasting than species distributed in more inland areas.