SAND ACCRETION AND SALINITY AS CONSTRAINTS ON THE ESTABLISHMENT OF LEYMUS-ARENARIUS FOR LAND RECLAMATION IN ICELAND

Seed harvested from wild populations of Leymus arenarius is sown exten sively in Iceland to stabilize sandy barrens, on the coast and inland. Sand accretion can reach 50 cm over 3 months in summer near the outwa sh of glacial rivers on the south coast of Iceland and thus may be an important factor influencing survival and growth of L. arenarius. Newl y germinated seedlings had great potential for elongation in darkness (etiolation). The length of the longest etiolated leaf increased signi ficantly with seed mass. The etiolation response proved to be a good p redictor of their ability to emerge from burial with sand. The mean le ngth of etiolated shoots was approx. 16 cm and 40 % of seedlings emerg ed when germinating seeds were buried with 15 cm of sand, whereas none emerged from burial under 20 cm of sand. A moderately high and sustai ned rate of sand deposition (2-4 cm week(-1)), applied to 10-week old seedlings in a glasshouse experiment, significantly increased leaf len gth and the allocation of biomass to shoots, such that overall biomass was slightly but not significantly increased. The growth responses of seedlings of one coastal population and two inland populations of Ley mus arenarius were compared when challenged with salinities ranging fr om 0 to 600 mM NaCl in sand culture. The numbers of tillers produced b y the coastal population was stimulated by salinity in the range 200-4 00 mM NaCl, unlike their inland counterparts. The total dry mass of th e coastal population was less adversely affected by high salinity than that of the two inland populations, mainly because root biomass was r educed less; total leaf area was also slightly less reduced in the coa stal population. The reclamation of sand barrens in Iceland with high accretion rates would benefit from sowing seeds from larger-seeded pop ulations, at a depth of 5-10 cm; at coastal reclamation sites, it woul d be preferable to use seed from the more salt-tolerant coastal popula tions. (C) 1996 Annals of Botany Company