Responses of Leymus arenarius to nutrients: improvement of seed production and seedling establishment for land reclamation

Published source details Greipsson S. & Davy A.J. (1997) Responses of Leymus arenarius to nutrients: improvement of seed production and seedling establishment for land reclamation. Journal of Applied Ecology, 34, 1165-1176.
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Summary

Iceland has vast areas of mobile sand resulting from volcanic activity, glaciers, over-grazing and erosion. Seed of the coastal, dune-building lyme-grass Leymus (Elymus) arenarius is harvested from natural stands for use in land reclamation and stabilisation programmes. The large scale of use dictates that establishment must be through seed rather than clonal propagation. This study investigated the use of fertilizer treatments in managing the production of seeds in a series of four experiments. In some dune areas Leymus plants exhibit loss of vigour. This study investigated whether fertilizer treatments might re-invigorate such moribund plants and rejuvenate seed production.

Study sites: Fertilizer addition experiments were undertaken at two west Icelandic sites: Boholt (100 m.a.s.l.) and Haukadalsheidi (350 m.a.s.l.). Both areas were characterized by Leymus arenarius plants exhibiting lack of vigour.

Fertilizer application: At each site, the experiment comprised 1 x 1 m plots, in four randomized blocks (four treatments x four replicates) of each. The treatments were various additions of nitrogen (N), phosphorus (P) and pottasium (K):

1) Control;

2) N and P added together as Módi™ (52 kg N, 28 kg P/ha/year);

3) N and P added together as Módi™ (104 kg N, 56 kg P/ha/year);

4) N,P,K added together as Grædir™ (96 kg N, 36 kg P, 32 kg K/ha/year).

Fertilizer was added by hand to the surface of plots in early July 1989 and late June 1990.

Harvesting: Leymus spikes were counted and seeds were removed and weighed.

Vegetation competition: As a measure of how other plants faired, at Haukadalsheidi percentage cover of other plant species was estimated using point quadrats (100 pins/plot). At Boholt vegetation was too tall to use this technique so Hieraceum spp. inflorescences were used as a proxy for performance of other species.

At the two dune sites, the seed production of moribund, late-successional lyme-grass Leymus arenarius stands could not be rejuvenated by fertilizer application. It was found that where there was a vegetation response, competing plant species were in fact stimulated to grow at the expense of L.arenarius.

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